 Section 51 of Gray's Anatomy. Part 5. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Reading by Bologna Times. Anatomy of the Human Body. Part 5 by Henry Gray. Surface Anatomy and Surface Markings of Thorax. 5. Surface Anatomy of the Thorax. Bones. The skeleton of the thorax is to a very considerable extent covered by muscles, so that in the strongly developed muscular subject it is for the most part concealed. In the emaciated subject, however, the ribs, especially in the lower and lateral regions, stand out as prominent ridges with the sunken intercostal spaces between them. In the middle line in front, the superficial surface of the sternum can be felt throughout its entire length at the bottom of a furrow, the sternal furrow, situated between the pectoralis majoris. These muscles overlap the anterior surface somewhat, so that the whole width of the sternum is not subcutaneous, and this overlapping is greatest opposite the middle of the bone. The furrow, therefore, is wide at its upper and lower parts, but narrow in the middle. At the upper border of the manubrium sterni is the jugular notch. The lateral parts of this notch are obscured by the tendinous origins of the sternocleidomastoidi, which appear as oblique cords narrowing and deepening the notch. Lower down on the subcutaneous surface is a well-defined transverse ridge, the sternal angle. It denotes the junction of the manubrium and body. From the middle of the sternum, the sternal furrow spreads out and ends at the junction of the body with the xyphoid process. Immediately below this is the infrasternal notch between the sternal ends of the seventh costal cartilages, and below the notch is a triangular depression, the epigastric fossa, in which the xyphoid process can be felt. On either side of the sternum, the costal cartilages and ribs on the front of the thorax are partly obscured by the pectoralis major, through which, however, they can be felt as ridges with yielding intervals between them corresponding to the intercostal spaces. Of these spaces, that between the second and third ribs is the widest, the next two are somewhat narrower, and the remainder, with the exception of the last two, are comparatively narrow. Below the lower border of the pectoralis major, on the front of the chest, the broad flat outlines of the ribs, as they descend, and the more rounded outlines of the costal cartilages are often visible. The lower boundary of the front of the thorax, which is most plainly seen by bending the body backward, is formed by the xyphoid process. The cartilages of the seventh, eighth, ninth, and tenth ribs, and the ends of the cartilages of the eleventh and twelfth ribs. On either side of the thorax, from the axilla downward, the flattened external surfaces of the ribs may be defined. Although covered by muscles, all the ribs, with the exception of the first, can generally be followed without difficulty over the front and sides of the thorax. The first rib, being almost completely covered by the clavicle, can only be distinguished in a small portion of its extent. At the back, the angles of the ribs lie on a slightly marked oblique line on either side of, and some distance from, the spinous processes of the vertebrae. The line diverges somewhat as it descends, and lateral to it is a broad convex surface caused by the projection of the ribs beyond their angles. Over the surface, except where covered by the scapula, the individual ribs can be distinguished. Muscles. The surface muscles covering the thorax belong to the musculature of the upper extremity and will be described in that section. There is, however, an area of practical importance bounded by these muscles. It is limited above by the lower border of trapezius, below by the upper border of latissimus dorsi, and laterally by the vertebral border of the scapula. The floor is partly formed by rhomboidius major. If the scapula be drawn forward by folding the arms across the chest and the trunk bent forward, parts of the sixth and seventh ribs and the interspace between them become subcutaneous and available for osculation. The space is therefore known as the triangle of osculation. Mama. The size of the mama is subject to great variations. In the adult nulliparous female, it extends vertically from the second to the sixth rib and transversely from the side of the sternum to the mid-axillary line. In the male and in the nulliparous female, the mammary papula is situated in the fourth interspace about 9 or 10 cm from the middle line or 2 cm from the costicondral junction. 6. Surface markings of the thorax. Bony landmarks. The second costal cartilage corresponding to the sternal angle is so readily found that it is used as a starting point from which to count the ribs. The lower border of the pectoralis major at its attachment corresponds to the fifth rib. The uppermost visible digitation of serratus anterior indicates the sixth rib. The jugular notch is in the same horizontal plane as the lower border of the body of the second thoracic vertebra. The sternal angle is at the level of the fifth thoracic vertebra while the junction between the body and xyphoid process of the sternum corresponds to the fibrocartilage between the ninth and tenth thoracic vertebrae. The influence of the obliquity of the ribs on horizontal levels in the thorax is well shown by the following line. Quote, if a horizontal line be drawn around the body at the level of the inferior angle of the scapula, while the arms are at the sides, the line would cut the sternum in front between the fourth and fifth ribs, the fifth rib in the nipple line and the ninth rib at the vertebral column. Traves. Diaphragm. The shape and variations of the diaphragm as seen by schiography have already been described, page 407. Surface lines. For clinical purposes and for convenience of description, the surface of the thorax has been mapped out by arbitrary lines. On the front of the thorax, the most important vertical lines are the mid-sternal, the middle line of the sternum, and the mammary, or better mid-clavicular, which runs vertically downward from a point mid-wave between the center of the jugular notch and the tip of the acromion. This latter line, if prolonged, is practically continuous with the lateral line on the front of the abdomen. Other vertical lines on the front of the thorax are the lateral sternal along the sternal margin and the parasternal midway between the lateral sternal and the mammary. On either side of the thorax, the anterior and posterior axillary lines are drawn vertically from the corresponding axillary folds. The mid-axillary line runs downward from the apex of the axilla. On the posterior surface of the thorax, the scapular line is drawn vertically through the inferior angle of the scapula. Plurae. The lines of reflection of the plurae can be indicated on the surface. On the right side, the line begins at the sternoclavicular articulation and runs downward and medialward to the midpoint of the junction between the manubrium and body of the sternum. It then follows the mid-sternal line to the lower end of the body of the sternum or onto the xyphoid process, where it turns lateral and downward across the seventh sternocostal articulation. It crosses the eighth costochondral junction in the mammary line, the tenth rib in the mid-axillary line, and is prolonged thence to the spinous process of the twelfth thoracic vertebra. On the left side, beginning at the sternoclavicular articulation, it reaches the midpoint of the junction between the manubrium and body of the sternum and extends down the mid-sternal line in contact with that of the opposite side to the level of the fourth costochondralage. It then diverges lateralward and is continued downward slightly lateral to the sternal border as far as the sixth costochondralage. Running downward and lateralward from this point, it crosses the seventh costochondralage and from this, onward, it is similar to the line on the right side but at a slightly lower level. Lungs. The apex of the lung is situated in the neck above the medial third of the clavicle. The height to which it rises above the clavicle varies very considerably but is generally about 2.5 cm. It may, however, extend as high as 4 or 5 cm or, on the other hand, may scarcely project above the level of this bone. In order to mark out the anterior borders of the lungs, a line is drawn from each apex point, 2.5 cm above the clavicle and, rather nearer, the anterior than the posterior border of sternocledo mastoidus. Downward and medialward across the sternoclavicular articulation and manubrium sterni, until it meets, or almost meets, its fellow of the other side at the midpoint of junction between the manubrium and body of the sternum. From this point, the two lines run downward practically along the midsternal line as far as the level of the fourth costochondralages. The continuation of the anterior border of the right lung is marked by a prolongation of its line vertically downward to the level of the sixth costochondralage, and then it turns lateralward and downward. The line on the left side curves lateralward and downward across the fourth sternocostal articulation. To reach the peristernal line at the fifth costochondralage, and then turns medialward and downward to the sixth sternocostal articulation. In the position of expiration, the lower border of the lung may be marked by a slightly curved line with its convexity downward, from the sixth sternocostal junction to the tenth thoracic spinous process. This line crosses the midclavicular line at the sixth and the mid-axillary line at the eighth rib. The posterior borders of the lungs are indicated by lines drawn from the level of the spinous process of the seventh cervical vertebra down either side of the vertebral column across the costochondral joints as low as the spinous process of the tenth thoracic vertebra. The position of the oblique fissure in either lung can be shown by a line drawn from the spinous process of the second thoracic vertebra around the side of the thorax to the sixth rib in the midclavicular line. This line corresponds roughly to the line of the vertebral border of the scapula when the hand is placed on the top of the head. The horizontal fissure in the right lung is indicated by a line drawn from the midpoint of the proceeding, or from the position where it cuts the mid-axillary line to the mid-sternal line at the level of the fourth cost of cartilage. Trachea. This may be marked out on the back by a line from the spinous process of the sixth cervical to that of the fourth thoracic vertebra where it bifurcates. From its bifurcation, the two bronchi are directed downward and lateralward, in front the point of bifurcation corresponds to the sternal angle. Esophagus. The extent of the esophagus may be indicated on the back by a line from the sixth cervical to the level of the ninth thoracic spinous process, 2.5 cm to the left of the middle line. Heart. The outline of the heart in relation to the front of the thorax can be represented by a quadrangular figure. The apex of the heart is first determined either by its pulsation or as a point in the fifth interspace, 9 cm to the left of the mid-sternal line. The other three points are A. The seventh right sternocostal articulation. B. A point on the upper border of the third right costal cartilage, 1 cm from the right lateral sternal line. C. A point on the lower border of the second left costal cartilage, 2.5 cm from the left lateral sternal line. A line joining the apex point, A, and traversing the junction of the body of the sternum with the xyphoid process represents the lowest limit of the heart. It's a cute margin. The right and left borders are represented respectively by lines joining A to B and the apex to C. Both lines are convex lateral word, but the convexity is more marked on the right where its summit is 4 cm distant from the mid-sternal line opposite the fourth costal cartilage. A portion of the area of the heart thus mapped out is uncovered by lung and therefore gives a dull note on percussion. The remainder being overlapped by lung gives a more or less resonant note. The former is known as the area of superficial cardiac dullness. The latter as the area of deep cardiac dullness. The area of superficial cardiac dullness is somewhat triangular. From the apex of the heart, two lines are drawn to the mid-sternal line, one to the level of the fourth costal cartilage, the other to the junction between the body and xyphoid process. The portion of the mid-sternal line between these points is the base of the triangle. Latham lays down the following role as a sufficient practical guide for the definition of the area of superficial dullness. Make a circle of 2 inches in diameter around a point midway between the nipple and the end of the sternum. The coronary sulcus can be indicated by a line from the third left to the sixth right sternocostal joint. The anterior longitudinal sulcus is a finger's breadth to the right of the left margin of the heart. The position of the various orifices is as follows. The pulmonary orifice is situated in the upper angle of the third left sternocostal articulation. The aortic orifice is a little below and medial to this, close to the articulation. The left atrial ventricular opening is opposite the fourth costal cartilage and rather to the left of the mid-sternal line. The right atrial ventricular opening is a little lower, opposite the fourth interspace of the right side. The lines indicating the atrial ventricular openings are slightly below and parallel to the line of the coronary sulcus. Arteries. The line of the ascending aorta begins slightly to the left of the mid-sternal line opposite the third costal cartilage and extends upward and to the right to the upper border of the second right costal cartilage. The beginning of the aortic arch is indicated by a line from this latter point to the mid-sternal line about 2.5 cm below the jugular notch. The point on the mid-sternal line is opposite the summit of the arch and a line from it to the right sternoclovicular articulation represents the site of the inominate artery, while another line from a point slightly to the left of it and passing through the left sternoclovicular articulation indicates the position of the left common carotid artery in the thorax. The internal mammary artery descends behind the first six costal cartilages about 1 cm from the lateral sternoline veins. The line of the right inominate vein crosses the right sternoclovicular joint and the upper border of the first right costal cartilage about 1 cm from the lateral sternoline. That of the left inominate vein extends from the left sternoclovicular articulation to meet the right at the upper border of the first right costal cartilage. The junction of the two lines indicates the origin of the superior vena cava, the line of which is continued vertically down to the level of the third right costal cartilage. The end of the inferior vena cava is situated opposite the upper margin of the sixth right costal cartilage about 2 cm from the mid-sternal line. End of Section 51 Recording by David Lawrence While in the site of the inguinal ligament, a sharper fold known as the fold of the groin is easily distinguishable. After distension of the abdomen from pregnancy or other causes, the skin commonly presents transverse white lines which are quite smooth being destitute of papillae. These are known as the strieta gravidarum or strieta albacantes. The linea nigra of pregnancy is often seen as a pigmented brown streak in the middle line between the umbilicus and symphysis pubis. In the middle line of the front of the abdomen is a shallow furrow which extends from the junction between the body of the sternum with the xiphoid process to a short distance between the umbilicus. It corresponds to the linea alba. The umbilicus is situated in the middle line but varies in position as regards to its height. In an adult subject it is always placed above the middle point of the body and in a normal well nourished subject it is from 2 to 2.5 cm above the level of the tubercles of the iliac crests. Bones. The bones in relation with the surface of the abdomen are 1. The lower part of the vertebral column and the lower ribs. And 2. The pelvis, the former having already been described. The latter will be considered with the lower limb. Muscles. The only muscles of the abdomen which have any considerable influence on surface form are the obliquus externus and the rectus. The upper digitations of origin of obliquus externus are well marked in a muscular subject, interdigitating with those in serratus anterior. The lower digitations are covered by the border of latissimus dorsi and are not visible. The attachment of the obliquus externus and internus to the crest of the ilium forms a thick oblique roll which determines the iliac furrow. Sometimes on the front of the lateral region of the abdomen an undulating line marks the passing of the muscular fibers of the obliquus externus. Marks the passing of the muscular fibers of the obliquus externus into its aponeurosis. The lateral markings of the obliquus externus is separated from that of the latissimus dorsi by a small triangular interval, the lumbar triangle, the base of which is formed by the iliac crest and its fore by obliquus externus. The lateral margin of rectus abdominis is indicated by the linea semilunaris which may be exactly defined by putting the muscle into action. The surface of the rectus presents three transverse furrows, the tendinous inscriptions, the upper two of these, vis, one opposite or a little below, the tip of the ziphoid process, and the other midway between this point and the umbilicus are usually well marked. The third opposite the umbilicus is not so distinct. Between the two recti the linea alba can be complicated from the ziphoid process to a point just below the umbilicus. It is represented by a distinct dip between the muscles. Beyond this the muscles are in opposition. Vessels. In thin subjects the pulsation of the abdominal aorta can be readily felt by making deep pressure in the middle line above the umbilicus. Viscara. Under normal conditions the various portions of the digestive tube cannot be identified by simple palpitation. Parastosis of the coils of small intestine can be observed in some persons with extremely thin abdominal walls when some degree of constipation exists. In cases of constipation it is sometimes possible to trace portions of the great intestine by feeling the fecal masses within the gut. In thin persons with relaxed abdominal walls the iliac colon can be felt in the left iliac region rolling under the fingers when empty and forming a distinct tumor when distended. The greater part of the liver lies under cover of the lower ribs and their cartilages, but in the epigastric fossa it comes in contact with the abdominal wall. The position of the liver varies according to the posture of the body. In the erect posture in the adult male the edge of the liver projects about one centimeter below the lower margin of the right costal cartridges and its inferior margin can often be felt in this situation if the abdominal wall is thin. In the supine position the liver recedes above the margin of the ribs and cannot then be detected by the finger. In the prone position it falls forward and is then generally palpable in a patient with loose and lax abdominal walls. Its position varies with the respiratory movements. During a deep inspiration it descends below the ribs. In expiration it is raised. Pressure from without as in tight lacing by compressing the lower part of the chest displaces the liver considerably. Its interior edge frequently extending as low as the crest of the ilium. Again its position varies greatly with the state of the stomach and intestines. When these are empty the liver descends. When they are distended it is pushed upward. The pancreas can sometimes be felt in emaciated subjects when the stomach and colon are empty by making deep pressure in the middle line about 7 or 8 centimeters above the umbilicus. The kidneys being situated at the back of the abdominal cavity and deeply placed cannot be palpitated unless enlarged or misplaced. End of Chapter 52. Recording by David Lawrence in Brampton, Ontario March 2010 Section 53 of Grey's Anatomy Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Recording by John DeCuse, John K. Thomas Verne Anatomy of the Human Body Part 5 by Henry Gray 8. Surface Markings of the Abdomen Bony Landmarks Above the chief bony markings are the xiphoid process, the lower six costocartilages, and the anterior ends of the lower six ribs. The junction between the body of the sternum and the xiphoid process is on the level of the 10th thoracic vertebra. Below the main landmarks are the symphysis pubis and the pubic crest and tubercle. The anterior superior iliac spine and the iliac crest. Muscles. The rectus lies between the linia alaba and the linia semilunaris. The former is indicated by the middle line. The latter, by a curved line, convex lateral ward from the tip of the cartilage of the ninth rib to the pubic tubercle. At the level of the umbilicus, the linia semilunaris is about 7 cm from the middle line. The line indicating the junction of the muscular fibers of obliquus externus with its aponeurosis extends from the tip of the ninth costocartilage to a point just medial to the anterior superior iliac spine. The umbilicus is at the level of the fibrocartilage between the third and fourth lumbar vertebrae. The subcutaneous inguinal ring is situated 1 cm above and lateral to the pubic tubercle. The abdominal inguinal ring lies 1-2 cm above the middle of the inguinal ligament. The position of the inguinal canal is indicated by a line joining these two points. Surface Lines For convenience of description of the viscera and of reference to morbid conditions of the contained parts, the abdomen is divided into nine regions by imaginary planes, two horizontal and two sagittal, the edge of the planes being indicated by lines drawn on the surface of the body. In the older method the upper or subcostal horizontal line encircles the body at the level of the lowest points of the tenth costocartilage. The lower or inter tubercular is a line carried through the highest points of the iliac crest seen from the front, i.e. through the tubercles on the iliac crests about 5 cm behind the anterior superior spines. An alternative method is that of Addison who adopts the following lines. 1. An upper transverse, the transpiloric halfway between the jugular notch and the upper border of the symphysis pubis. This indicates the margin of the transpiloric plane, which in most cases cuts through the pylorus, the tips of the ninth costocartilage and the lower border of the first lumbar vertebra. 2. A lower transverse line midway between the upper transverse and the upper border of the symphysis pubis. This is termed the trans tubercular, since it practically corresponds to that passing through the iliac tubercles. Behind, its plane cuts the body of the fifth lumbar vertebra. By means of these horizontal planes, the abdomen is divided into three zones named from above, the subcostal, umbilical, and hypogastric zones. Each of these is further subdivided into three regions by the two sagittal planes, which are indicated on the surface by a right and left lateral line drawn vertically through points halfway between the anterior superior iliac spines and the middle line. The middle region of the upper zone is called epigastric, and the two lateral regions, the right and left hypochondriac. The central region of the middle zone is the umbilical, and the two lateral regions, the right and left lumbar. The middle region of the lower zone is the hypogastric or pubic, and the lateral are the right and left iliac or inguinal. The middle regions, this epigastric, umbilical and pubic, can each be divided into right and left portions by the middle line. In the following description of the viscera, the regions marked out by Addison's lines are those referred to. Stomach The shape of the stomach is constantly undergoing alteration. It is affected by the particular phase of the process of gastric digestion, by the state of the surrounding viscera, and by the amount and character of its contents. Its position also varies with that of the body, so that it is impossible to indicate it on the surface with any degree of accuracy. The measurements given refer to a moderately filled stomach with the body in the supine position. The cardiac orifice is opposite the seventh costal cartilage, about 2.5 cm, from the side of the serum. It corresponds to the level of the 10th thoracic vertebra. The pyloric orifice is on the trans pyloric line, about 1 cm, to the right of the middle line, or alternately 5 cm below the seventh right sternocostal articulation. It is at the level of the first lumbar vertebra. A curved line, convex downward, and to the left, joining these points, indicates the lesser curvature. In the left lateral line, the fundus of the stomach reaches as high as the fifth interspace, or the sixth costal cartilage, a little below the apex of the heart. To indicate the greater curvature, a curved line is drawn from the cardiac orifice to the summit of the fundus, then downward and to the left, finally turning medial ward to the pyloric orifice, but passing on its way through the intersection of the left lateral with the trans pyloric line. The portion of the stomach, which is in contact with the abdominal wall, can be represented roughly by a triangular area, the base of which is formed by a line drawn from the tip of the tenth left costal cartilage to the tip of the ninth right cartilage, and the sides by two lines drawn from the end of the eighth left costal cartilage to the ends of the base line. A space of some clinical importance, the space of the trowel overlies the stomach and may be thus indicated. It is semi-lunar in outline and lies within the following boundaries. The lower edge of the left lung, the anterior border of the spleen, the left costal margin and the inferior margin of the left lobe of the liver. Duodenum. The superior part is horizontal and extends from the pylorus to the right lateral line. The descending part is situated medial to the right lateral line. From the trans pyloric line to a point midway between the trans pyloric and trans tubercular lines. The horizontal part runs with a slight upward slope from the end of the descending part to the left of the middle line. The ascending part is vertical and reaches the trans pyloric line where it ends in the duodenum gejunal flexure, about 2.5 centimetres to the left of the middle line. Small intestine. The coils of the small intestine occupy the front of the abdomen. For the most part, the coils of the gejunum are situated on the left side, i.e. in the left lumbar and iliac regions, and in the left half of the umbilical region. The coils of the ilium lie toward the right in the right lumbar and iliac regions. In the right half of the umbilical region and in the hypogastric region, a portion of the ilium is within the pelvis. The end of the ilium, i.e. the iliocolic junction, is slightly below and medial to the intersection of the right lateral and trans tubercular lines. Secum and bromoform process. The secum is in the right iliac and hypogastric regions. Its position varies with its degree of distention. But the midpoint of a line draws from the right anterior superior iliac spine to the upper margin of the symphysis pubis, will mark approximately the middle of its lower border. The position of the base of the bromoform process is indicated by a point on the lateral line, on a level with the anterior superior iliac spine. Ascending colon. The ascending colon passes upward through the right lumbar region, lateral to the right lateral line. The right colic flexure is situated in the upper and right angle of intersection of the subcostal and right lateral lines. Transverse colon. The transverse colon crosses the abdomen on the confines of the umbilical and epigastric regions. Its lower border being on a level slightly above the umbilicus. Its upper border just below the great curvature of the stomach. Descending colon. The left colic flexure is situated in the upper left angle of the intersection between the left lateral and transpiloric lines. The descending colon courses down through the left lumbar region, lateral to the left lateral line as far as the iliac crest. Iliac colon. The line of the iliac colon is from the end of the descending colon to the left lateral line at the left of the anterior superior iliac spine. Liver. The upper limit of the right lobe of the liver in the middle line is at the level of the junction between the body of the sternum and the xiphoid process. On the right side, the line must be carried upward as far as the fifth costal cartilage in the mammary line and then downward to reach the seventh rib at the side of the thorax. The upper limit of the left lobe can be defined by continuing this line downward and to the left to the sixth costal cartilage, five centimeters from the middle line. The lower limit can be indicated by a line drawn one centimeter below the lower margin of the thorax on the right side as far as the ninth costal cartilage. Thence obliquely upward to the eighth left costal cartilage, crossing to the middle line just above the transpilaric plane and finally with a slight left convexity to the end of the line indicating the upper limit. According to Birmingham, the limits of the normal liver may be marked out on the surface of the body in the following manner. Take three points. A. 1.25 centimeters below the right nibble. B. 1.25 centimeters below the tip of the tenth rib. C. 2.5 centimeters below the left nibble. Join A and C by a line slightly convex upward. A and B by a line slightly convex lateralward. And B and C by a line slightly convex downward. The fundus of the gallbladder approaches the surface behind the anterior end of the ninth right costal cartilage close to the lateral margin of the rectus abdominis. Pancreas, figure 12.25. The pancreas lies in front of the second lumbar vertebra. Its head occupies the curve of the duodenum and is therefore indicated by the same lines as that viscous. Its neck corresponds to the pylorus. Its body extends along the transpiloric line. The bulk of its line above this line to the tail, which is in the left hypochondriac region, slightly to the left of the lateral line and above the transpiloric. Spleen. To map out the spleen, the tenth rib is taken as representing its long axis. Vertically, it is situated between the upper border of the ninth and the lower border of the eleventh ribs. The highest point is four centimeters from the middle line of the back at the level of the tip of the ninth thoracic spinous process. The lowest point is in the mid-axillary line at a level of the first lumbar spinous process. Kidneys. The right kidney usually lies about one centimeter lower than the left, but for practical purposes, similar surface markings are taken for each. On the front of the abdomen, the upper pole lies midway between the plane of the lower end of the body of the sternum and the transpiloric plane, five centimeters from the middle line. The lower pole is situated between the transpiloric and intertubular planes, seven centimeters from the middle line. The hylum is on the transpiloric plane, five centimeters from the middle line. Round these three points, a kidney-shaped figure, four centimeters to five centimeters broad is drawn, two-thirds of which lies medial to the lateral line. To indicate the position of the kidney from the back, the parallelogram of Morris is used. Two vertical lines are drawn. The first 2.5 centimeters, the second 9.5 centimeters from the middle line. The parallelogram is completed by two horizontal lines drawn respectively at the levels of the tips of the spinous process of the 11 thoracic and the lower border of the spinous process of the third lumbar vertebra. The hylum is five centimeters from the middle line at the level of the spinous process of the first lumbar vertebra. Ureters. On the front of the abdomen, the line of the ureter runs from the hylum of the kidney to the pubic tubercle. On the back, from the hylum vertically downward, passing practically through the posterior superior iliac spine. Vessels. The inferior epigastric artery can be marked out by a line from a point midway between the interior superior iliac spine and the pubic symphysis to the umbilicus. This line also indicates the lateral boundary of Hesselbach's triangle, an area of importance in connection with inguinal hernia. The other boundaries are the lateral edge of rectus abdominis and the medial half of the inguinal ligament. The line of the abdominal aorta begins in the middle line about four centimeters above the transpiloric line and extends to a point two centimeters below and to the left of the umbilicus. Or, more accurately, to a point two centimeters to the left of the middle line on a line which passes through the highest points of the iliac crests. The point of termination of the abdominal aorta corresponds to the level of the fourth lumbar vertebra, a line drawn from it to a point midway between the interior superior iliac spine and the symphysis pubis indicates the common and external iliac arteries. The common iliac is represented by the upper third of this line, the external iliac by the remaining two thirds. Of the larger branches of the abdominal aorta, the celiac artery is four centimeters, the superior mesenteric two centimeters above the transpiloric line. The renal arteries are two centimeters below the same line. The inferior mesenteric artery is four centimeters above the bifurcation of the abdominal aorta. Nerves. The thoracic nerves on the anterior abdominal wall are represented by lines continuing those of the bony ribs. Determination of the seventh nerve is at the level of the xyphoid process. The tenth reaches the vicinity of the umbilicus. The twelfth ends about midway between the umbilicus and the upper border of the symphysis pubis. The first lumbar is parallel to the thoracic nerves. Its iliohypogastric branch becomes cutaneous above the subcutaneous inguinal ring. Its ilioinguinal branch at the ring. End of section 53. Section 54 of Grey's Anatomy, Part 5. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by John K. Thomas, John Cous, Vern. Anatomy of the Human Body, Part 5. By Henry Gray. Nine. Surface anatomy of the perineum. Skin. In the middle line of the posterior part of the perineum and about four centimeters in front of the tip of the coccyx is the anal orifice. The junction of the mucous membrane of the anal canal with the skin of the perineum is marked by a white line which indicates also the line of contact of the external and internal sphincters. In the interior part of the perineum the external genital organs are situated. The skin covering the scrotum is rough and corrugated but over the penis it is smooth. Extending forward from the anus on to the scrotum and penis is a median ridge which indicates the scrotal raffy. In the female are seen the skin reduplications forming the labia majora and minora laterally. The frenulum of the labia behind and the pupus of the clitoris in front still more anteriorly is the mons pubis. Bones. In the anterolateral boundaries of the perineum the whole outline of the pubic arch can be readily traced ending in the ischial tuberosities. Behind in the middle line is the tip of the coccyx. Muscles and ligaments. The margin of the gluteus maximus forms the posterior lateral boundary and in thin subjects by pressing deeply the sacro tuberous ligament can be felt through the muscle. The only other muscles influencing surface form are the ischiocavernosis covering the cross penis which lies on the side of the pubic arch and the sphincter ani externus which in action closes the anal orifice and causes a puckering of the skin around it. 10. Surface markings of the perineum. A line drawn transversely across in front of the ischial tuberosities divides the perineum into a posterior or rectal and an anterior or urogenital triangle. This line passes through the central point of the perineum which is situated about 2.5 cm in front of the center of the anal aperture or in the male midway between the anus and the reflection of the skin onto the scrotum. Brectum and anal canal. A finger inserted through the anal orifice is grasped by this sphincter ani externus. Passes into the region of the sphincter ani internus and higher up encounters the resistance of the pubo rectalis. Beyond this it may reach the lowest of the transverse rectal folds. In front the urethral bulb and membranous part of the urethra are first identified and then about 4 cm above the anal orifice state is felt. Beyond this the vesiculae seminals if enlarged and the fundus of the bladder when distended can be recognized. On either side is the ischio rectal fossa. Behind are the anal coccygeal body the pelvic surfaces of the coccyx and lower end of the sacrum and the sacrospinus ligaments. In the female the posterior wall and fornix of the vagina and the cervix and body of the uterus can be felt in front while somewhat laterally the ovaries can just be reached. Male urogenital organs the corporea cavernosa penis can be followed backward to the crura which are attached to the sides of the pubic arch. The glans penis covered by the pupus and the external urethral orifice can be examined and the course of the urethra traced along the under surface of the penis to the bulb which is situated immediately in front of the central point of the perineum. Through the wall of the scrotum on either side of the testis can be palpated. It lies toward the back of the scrotum and along its posterior border the epididymis can be felt. Passing upward along the medial side of the epididymis is the spermatic cord which can be traced upward to the subcutaneous inguinal ring. By means of a sound the general topography of the urethra and bladder can be investigated. With the urethroscope the interior of the urethra can be illuminated and viewed directly. With the cistoscope the interior of the bladder is in a similar manner illuminated for visual examination. In the bladder the main points to which attention is directed are the trigone the torus ureturicus the pleike ureturusae and the openings of the ureters and urethra. Female urogenital organs in the pudental cleft between the labia minora and the openings of the vagina and urethra. In the virgin the vaginal opening is partly closed by the hymen after coitus the remains of the hymen are represented by the carunculae hymenals. Between the hymen and the frenulum of the labia is the fossa navicularis while in the groove between the hymen and the labium minus on either side the small opening of the greater vestibular Bartholens gland can be seen. These glands when enlarged can be felt on either side of the posterior part of the vaginal orifice. By inserting a finger into the vagina the following structures can be examined through its wall. Behind from below upward are the anal canal the rectum and the rectutorine excavation. Projecting into the roof of the vagina is the vaginal portion of the cervix uteri with the external uterine orifice. In front of and behind the cervix the anterior and posterior vaginal thornices respectively can be examined. With the finger in the vagina and the other hand on the abdominal wall the whole of the cervix and body of the uterus the uterine tubes and the ovaries can be palpated. If a speculum be introduced into the vagina the walls of the passage the vaginal portion of the cervix and the external uterine orifice can be exposed for visual examination. The external urethral orifice lies in front of the vaginal opening the angular gap in which it is situated between the two converging labia minora is termed the vestibule. The urethral canal in the female is very dilatable and can be explored with the finger. About 2.5 centimeters in front of the external orifice of the urethra are the glands and prepris of the clitoris and still farther forward End of Section 54 Recording by John T. K. HGTP www.validagerlife.com Section 55 of Grey's Anatomy Part 5 This is a LibriVox recording All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Anatomy of the Human Body Part 5 by Henry Gray Surface Anatomy of Upper Extremity Part 1 Skin The skin covering the shoulder and arm is smooth and very movable on the underlying structures. In the axilla there are numerous hairs and many suitoriferous and sebaceous glands. Over the medial side in front of the forearm the skin is thin and smooth and contains few hairs but many suitoriferous glands. Over the lateral side and back of the arm and forearm it is thicker, denser and contains more hairs but fewer suitoriferous glands. In the region of the elechronon it is thick and rough and is very loosely connected to the underlying tissue so that it falls into transverse wrinkles when the forearm is extended. At the front of the wrist there are three transverse furrows in the skin. They correspond respectively from above downward to the positions of the styloid process of the ulna, the wrist joint and the mid-carpal joint. The skin of the palm of the hand differs considerably from that of the forearm. At the wrist it suddenly becomes hard and dense and covered with a thick layer of epidermis. On the thenar eminence these characteristics are less marked than elsewhere. In spite of its hardness and density the skin of the palm is exceedingly sensitive and very vascular but it is destitute of hairs and sebaceous glands. It is tied down by fibrous bands along the lines of flexion of the digits exhibiting certain furrows of a permanent character. One of these, starting in front of the wrist at the tuberosity of the navicular bone curves around the thenar eminence and ends on the radial border of the hand a little above the metacarpal phalangeal joint of the index finger. A second line begins at the end of the first and extends obliquely across the palm to reach the ulnar border about the middle of the fifth metacarpal bone. A third line begins at the ulnar border about 2.5 centimeters distal to the end of the second and extends across the heads of the fifth, fourth and third metacarpal bones. The proximal segments of the fingers are joined to one another on the volar aspect by folds of skin constituting the web of the fingers. These folds extend across about the level of the centers of the proximal phalanges and their free margins are continuous with the transverse furrows at the roots of the fingers. Since the web is confined to the volar aspect, the fingers appear shorter when viewed from in front than from behind. Over the fingers and thumb the skin again becomes thinner especially at the flexures of the joints where it is crossed by transverse furrows and over the terminal phalanges. It is disposed on numerous ridges in consequence of the arrangement of the papillae in it. These ridges form in different individuals distinctive and permanent patterns which can be used for purposes of identification. The superficial fascia in the palm of the hand is made up of dense fibro-fatty tissue which binds the skin so firmly to the palmaraponeurosis that very little movement is permitted between the two. On the back of the hand and fingers the subcutaneous tissue is lax so that the skin is freely movable on the underlying parts. Over the interphalangeal joints the skin is very loose and is thrown into transverse wrinkles when the fingers are extended. Bones The clavicle can be felt throughout its entire length. The enlarged sternal extremity projects above the upper margin of the sternum at the side of the jugular notch and from this the body of the bone can be traced lateralward immediately under the skin. The medial part is convex forward and the surface is partially obscured by the attachments of the sternocleidomestodius and pectoralis major. The lateral third is concave forward and ends at the acromion of the scapula in a slight enlargement. The clavicle is almost horizontal when the arm is lying by the side although in muscular subjects it may incline a little upward at its acromial end which is on a plain posterior to the sternal end. The only parts of the scapula that are truly subcutaneous are the spine and acromion The coracoid process the vertebral border, the inferior angle and to a lesser extent the axillary border can also be readily defined. The acromion and spine are easily recognizable throughout their entire extent forming with the clavicle the arch of the shoulder. The acromion forms the point of the shoulder it joins the clavicle in an acute angle the acromial angle slightly medial to and behind the tip of the acromion. The spine can be felt as a distinct ridge marked on the surface as an oblique depression which becomes less distinct and ends in a slight dimple a little lateral to the spine as processes of the vertebrae. Below this point the vertebral border can be traced downward and lateral word to the inferior angle which can be identified although covered by latissimus dorsi. From the inferior angle the axillary border can usually be traced upward through its thick muscular covering forming with its enveloping muscles the posterior fold of the axilla. The coracoid process is situated 10 centimeters below the junction of the intermediate and lateral thirds of the clavicle it is covered by the anterior border of deltoidius and thus lies a little lateral to the infraclavicular fasso or depression which marks the interval between the pectoralis major and deltoidius. The humerus is almost entirely surrounded by muscles and the only parts which are strictly subcutaneous are small portions of the medial and lateral epicondals. In addition to these however the tubercles and a part of the head of the bone can be felt under the skin and muscles by which they are covered. Of these the greater tubercle forms the most prominent bony point of the shoulder extending beyond the acromion. It is best recognized when the arm is lying passive by the side for if the arm be raised it recedes under the arch of the shoulder. The lesser tubercle directed forward is medial to the greater and separated from it by the intertubercular groove which can be made out by deep pressure. When the arm is abducted the lower part of the head of the humerus can be examined by pressing deeply in the axilla. On either side of the elbow joint and just above it are the medial and lateral epicondals. Of these the former is the more prominent but the medial supercondular ridge passing upward from it is much less marked than the lateral and as a rule is not palpable. Occasionally however the hook shaped supercondular process is found on this border. The position of the lateral epicondal is best seen during semi-flection of the forearm and is indicated by a depression. From it the strongly marked lateral supercondular ridge runs upward. The most prominent part of the ulna the elecronon can always be identified at the back of the elbow joint. When the forearm is flexed the upper quadrilateral surface is palpable but during extension it recedes into the elecronon fossa. During extension the upper border of the elecronon is slightly above the level of the medial epicondal and nearer to this than to the lateral. When the forearm is fully flexed the elecronon and the epicondals form the angles of an equilateral triangle. On the back of the elecronon is a smooth triangular subcutaneous surface and running down the back of the forearm from the apex of this triangle the prominent dorsal border of the ulna can be felt in its whole length. It has a sinuous outline situated in the middle of the back of the limb above but below where it is rounded off it can be traced to the small subcutaneous surface of the styloid process on the medial side of the wrist. The styloid process forms a prominent tubercle continuous above with the dorsal border and ending below in a blunt apex at the level of the wrist joint. It is most evident when the hand is in a position midway between supination and pronation. When the forearm is pronated another prominence of the head of the ulna appears behind and above the styloid process. Below the lateral epicondal of the humerus a portion of the head of the radius is palpable. Its position is indicated on the surface by a little dimple which is best seen when the arm is extended. If the finger be placed in this dimple and the semi-flexed forearm be alternately pronated and supinated the head of the radius will be felt distinctly rotating in the radial notch. The upper half of the body of the bone is obscured by muscles. The lower half, though not subcutaneous can be readily examined and if traced downward is found to end in a lozen-shaped convex surface on the lateral side of the base of the styloid process. This is the only subcutaneous part of the bone and from its lower end the apex of the styloid process bends medial toward the wrist. About the middle of the dorsal surface of the lower end of the radius is the dorsal radial tubercle best perceived when the wrist is slightly flexed. It forms the lateral boundary of the oblique groove for the tendon of the extensor policies longus. On the front of the wrist are two subcutaneous eminences one on the radial side, the larger and flatter produced by the tuberosity of the navicular and the ridge on the greater multangular the other on the ulnar side by the piezoform. The tuberosity of the navicular is distal and medial is the styloid process of the radius and is most clearly visible when the wrist joint is extended. The ridge on the greater multangular is about one centimeter distal to it. The piezoform is about one centimeter distal to the lower end of the ulnar and just distal to the level of the styloid process of the radius. It is crossed by the uppermost crease which separates the front of the forearm from the palm of the hand. The rest of the volar surface of the bony carpus is covered by tendons and is entirely concealed with the exception of the hamulus of the hamate bone which however is difficult to define. On the dorsal surface of the carpus only the triangular bone can be clearly made out. Distal to the carpus the dorsal surfaces of the metacarpal bones covered by the extensor tendons except the fifth are visible only in very thin hands. The dorsal surface of the fifth is however subcutaneous throughout almost its whole length. Slightly lateral to the middle line of the hand is a prominence frequently well marked but occasionally indistinct formed by the styloid process of the third metacarpal bone. It is situated about four centimeters distal to the dorsal radial tubercle. The heads of the metacarpal bones can be plainly seen and felt rounded in contour and standing out in bold relief under the skin when the fist is clenched. The third is the most prominent. In the palm of the hand the metacarpal bones are covered by muscles tendons and aponeuroses so that only their heads can be distinguished. The base of the metacarpal bone of the thumb however is prominent dorsally distal to the styloid process of the radius. The body of the bone is easily palpable ending at the head in a flattened prominence in front of which are the sesamoid bones. The enlarged ends of the phalanges can be easily felt. When the digits are bent the proximal phalanges form prominences which in the joints between the first and second phalanges are slightly hollow but flattened and square shaped in those between the second and third. Articulations The sternoclavicular joint is subcutaneous and its position is indicated by the enlarged sternal extremity of the clavicle lateral to the long cord-like sternal head of sternocleidomestodius. When the muscles be relaxed a depression between the end of the clavicle and the sternum can be felt defining the exact position of the joint. The position of the acromioclavicular joint can generally be ascertained by determining the slightly enlarged acromial end of the clavicle which projects above the level of the acromion. Sometimes this enlargement is so considerable as to form a rounded eminence. The shoulder joint is deeply seated and cannot be palpated. If the forearm be slightly flexed or fold with its convexity downward is seen in front of the elbow extending from one epicondal to the other. The elbow joint is slightly distal to the center of the fold. The position of the radio-humeral joint can be ascertained by feeling for a slight groove or depression between the head of the radius and the capitulum of the humerus at the back of the elbow joint. The position of the proximal radio ulnar joint is marked on the surface at the back of the elbow by the dimple which indicates the position of the head of the radius. The site of the distal radio ulnar joint can be defined by feeling for the slight groove at the back of the wrist between the prominent head of the ulna and the lower end of the radius when the forearm is in a state of almost complete pronation. Of the three transverse skin furrows on the front of the wrist, the middle corresponds fairly accurately with the wrist joint while the most distal indicates the position of the mid-carpal articulation. The metacarpofilangial and interphalangial joints are readily available for surface examination. The former are situated just distal to the prominences of the knuckles. The latter are sufficiently indicated by the furrows on the volar and the wrinkles on the dorsal surfaces. End of Section 55 Section 56 of Grey's Anatomy Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org Recording by Jean Luft Anatomy of the Human Body Part 5 by Henry Gray Surface Anatomy of Upper Extremity Part 2 Muscles The anterior border of the trapezius presents as a slight ridge running downward and forward from the superior neutral line of the occipital bone to the junction of the intermediate and lateral thirds of the clavicle. The inferior border of the muscle forms an undulating ridge passing downward and medial ward from the root of the spine of the scapula to the spinous process of the 12th thoracic vertebra. The lateral border of the latissimus dorsi may be traced when the muscle is in action as a rounded edge starting from the iliac crest and slanting obliquely forward and upward to the axilla where it takes part with a teres major informing the posterior axillary fold. The pectoralis major conceals a considerable part of the thoracic wall and front. Its external organ presents a border which bounds and determines the width of the external furo. The upper margin is generally well marked medially and forms the medial boundary of a triangular depression. The infra clavicular fossa which separates the pectoralis major from the deltoidius. It gradually becomes less marked as it approaches the tendon of insertion and is closely blended with the deltoidius. The lower border of pectoralis major forms the rounded anterior axillary fold. Occasionally a gap is visible between the clavicular and sternal parts of the muscle. When the arm is raised the lowest slip of origin of pectoralis minor produces a fullness just below the anterior axillary fold and serves to break the sharp outline of the lower border of pectoralis major. The origin of the serratus anterior causes a very characteristic surface marking. When the arm is abducted the lower five or six serrations form a zigzag line and a general convexity forward. When the arm is by the side the highest visible serration is that attached to the fifth rib. The deltoidius with the prominence of the upper end of the humerus produces the rounded contour of the shoulder. It is rounded and fuller in front than behind where it presents a somewhat flattened form. Above its anterior border presents a curved eminence which forms the lateral boundary of the infraclavicular fossa. Below it is closely united with the pectoralis major. Its posterior border is thin, flattened and scarcely marked above but is thicker and more prominent below. The insertion of deltoidius is marked by a depression on the lateral side of the middle of the arm. Of the scapular muscles the only part of its surface form is the teres major. It assists the latissimus dorsi in forming the thick, rounded posterior axillary fold. When the arm is raised the cora cobrachialis reveals itself as a narrow elevation emerging from under cover of the anterior axillary fold and running medial to the body of the humerus. On the front and medial aspects of the arm is the prominence bounded on either side by an interior muscular depression. It determines the contour of the front of the arm and extends from the anterior axillary fold to the bend of the elbow. Its upper tendons are concealed by the pectoralis major and deltoidius. And its lower tendon sinks into the anti-cubital fossa. When the muscle is fully contracted it presents a globular form and the lacertis fibrosis attached to its tendon of insertion becomes prominent as a sharp bridge running downward and medial word. On either side of the biceps brachae at the lower part of the arm the brachialis is discernible. Laterally it forms a narrow eminence extending some distance up the arm. Medially it exhibits only a little fullness above the elbow. On the back of the arm the long head of the triceps brachae may be seen as a longitudinal eminence emerging from under cover of deltoidius and gradually passing into the flattened plane of the tendon of the muscle at the lower part of the back of the arm. When the muscle is in action the medial and lateral heads become prominent. On the front of the elbow are two muscular elevations one on either side separate above but converging below so as to form the medial and lateral boundaries of the anti-cubital fossa. The medial elevation consists of the pronator teres and the flexors and forms a fusiform mass pointed above at the medial epicondyle and gradually tapering off below. The pronator teres is the most lateral of the group while the flexor carpi radialis lying to its medial side is the most prominent and may be forward to its tendon which is situated nearer to the radial than to the ulnar border of the front of the wrist and medial to the radial artery. The palmaris longus presents no surface marking above but below its tendon stands out when the muscle is in action as a sharp tense cord in front of the middle of the wrist. The flexor digitorum sublimus does not directly influence the surface form. The position of its four tendons on the front of the lower part of the forearm is indicated by an elongated depression between the tendons of palmaris longus and flexor carpi ulnaris. The flexor carpi ulnaris determines the contour of the medial border of the forearm and is separated from the extensor group of muscles by the ulnar furrow produced by the subcutaneous dorsal border of the ulnar. Its tendon is evident along the ulnar border of the lower part of the forearm and is most marked when the hand is flexed and adducted. The elevation forming the lateral side of the anti-cubital fossa consists of the brachio radialis the extensors and the supinator. It occupies the lateral and a considerable part of the dorsal surface of the forearm in the region of the elbow and forms a fusiform mass which is altogether on a higher level than that produced by the medial elevation. Its apex is between the triceps brachii and brachialis some distance below the elbow joint. It acquires its greatest breath opposite the lateral epicondyle and below this shades off into a flattened surface. About the middle of the forearm it divides into two diverging longitudinal iminences. The lateral iminence consists of brachioradialis and the extensorus carpiradialis longus and brevis and descends from the lateral supracondylar bridge in the direction of the styloid process of the radius. The medial iminence comprises the extensor digitorum commonis, extensor digiti quinti proprius and the extensor carpi ulnaris. It begins at the lateral epicondyle of the humerus as a tapering mass which is separated above from the oconeus from a well marked furrow and below from the pronator teres and the flexor group by the ulnar furrow. The medial border of the brachioradialis starts as a rounded elevation above the lateral epicondyle. Lower down the muscle forms a prominent mass on the radial side of the upper part of the forearm. Below it tapers to its tendon which may be traced to the styloid process of the radius. The oconeus presents a triangular slightly elevated area immediately lateral to the subcontaneous surface of the olocranin and differentiated from the extensor group by an oblique depression. The upper angle of the triangle is at the dimple over the lateral epicondyle. At the lower part of the back of the forearm in the interval between the two diverging iminences is an oblique elongated swelling. Full above but flattened and partially subdivided below. It is caused by the abductor polychyslongus and the extensor polychysbrevis. It crosses the dorsal and lateral surfaces of the radius to the radial side of the wrist joint whence it is continued on to the dorsal surface of the thumb as a ridge best marked when the thumb is extended. The tendons of most of the extensor muscles can be seen and felt on the back of the wrist. Laterally is the oblique ridge produced by the extensor polychyslongus. The extensor carpi radialis longus is scarcely palpable but the extensor carpi radialis brevis can be identified as a vertical ridge emerging from under the ulnar border of the tendon of the extensor polychyslongus when the wrist is extended. Medial to this, the extensor tendons of the finger can be felt. The extensor digity quintipropius being separated from the tendons of the extensor digitorum communis by a slight furrow. The muscles of the hand are principally concerned as regards surface form in producing the thenar and hypothenar iminences and cannot be individually distinguished. The thenar iminence on the radial side is larger and rounder than the hypothenar which is a long narrow elevation along the ulnar side of the palm. When the palmeris brevis is in action it produces a wrinkling of the skin over the hypothenar iminence and a dimple on the ulnar border. On the back of the hand, the enterosci dorsalis give rise to the elongated swellings between the metacarpal bones, the first forms of a prominent fusiform bulging when the thumb is adducted, the others are not so marked. Archaries Above the middle of the clavicle the pulsation of the subclavian artery can be detected by pressing downward backward and medial word against the first rib. The pulsation of the axillary artery as it crosses the second rib can be felt below the middle of the clavicle just medial to the coracoid process. Along the lateral wall of the axilla, the course of the artery can be easily followed close to the medial border of the coracobrachialis. The brachial artery can be recognized in practicality the whole of this extent along the medial margin of the biceps and the upper two thirds of the arm it lies medial to the humerus that in the lower third it is more directly on the front of the bone. Over the lower end of the radius between the styloid process and flexor carpi radialis, a portion of the radial artery is superficial and is used clinically for observations on the pulse. Veins The superficial veins of the upper extremity are easily rendered visible by compressing the proximal trunks. Their arrangement is described on pages 660 to 662. Nerves The uppermost trunks of the brachial plexus are palpable in short distance above the clavicle as they emerge from under the lateral border of the sternocleidomastoidius. The larger nerves derived from the plexus can be rolled under the finger against the lateral auxiliary wall but cannot be identified. The ulnar nerve can be detected in the groove behind the medial epicondyle of the humerus. End of section 56 Recording by Jean Loft Section 57 of Grey's Anatomy, Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Recording by Jean Hildy-Fulgem Anatomy of the Human Body, Part 5 by Henry Grey 12. Surface Markings The upper extremity Bony Landmarks The bony landmarks as described above are so readily available for surface recognition that no special measurements are required to indicate them. It may be noted, however, that the medial angle of the scapula is applied to the second rib while the inferior angle lies against the seventh. The intertubercular groove of the humerus is vertically below the acromioclavicular joint when the arm hangs by the side with the palm of the hand forward. Articulations The acromioclavicular joint is situated in a plane passing sagittally through the middle line of the front of the arm. The line of the elbow joint is not straight. The radio-humeral portion is practically at right angles to the long axis of the humerus and is situated about 2 cm distal to the lateral epicondal. The ulno-humeral portion is oblique and its medial end is about 2.5 cm distal to the medial epicondal. The position of the wrist joint can be indicated by drawing a curved line with its convexity upward between the styloid processes of the radius and ulna. The summit of the convexity is about 1 cm above the center of a straight line joining the two processes. Muscles The only muscles of the upper extremity which occasionally require definition by surface lines are the trapezius, the latissimus dorsi, and the pectoralis major and minor. The antero-superior border of trapezius is indicated by a line from the superior nucleotline about 3 cm lateral to the external occipital protuberance to the junction of the intermediate and lateral thirds of the clavicle. The line of the lower border extends from the spinous process of the 12th thoracic vertebra to the vertebral border of the scapula at the root of the spine. The upper border of latissimus dorsi is almost horizontal, running from the spinous process of the 7th thoracic vertebra to the inferior angle of the scapula and thence somewhat obliquely to the intertabricular sulcus of the humerus. The lower border corresponds roughly to a line drawn from the iliac crust about 2 cm from the lateral margin of the sacrospinalis to the intertabricular sulcus. The upper margin of pectoralis major extends from the middle of the clavicle to the surgical neck of the humerus. Its lower border is practically in the line of the 5th rib and reaches from the 5th costochondral junction to the middle of the anterior border of deltoidius. The two lines indicating the borders of pectoralis minor begin at the coracoid process of the scapula and extend to the 3rd and 5th ribs respectively, just lateral to the corresponding costal cartilages. On the front of the elbow joint a triangular space, the anti-cubital fossa is mapped out for convenience of reference. The rest of the triangle is a line joining the medial and lateral epicondals, while the sides are formed respectively by the salient margins of the brachioradialis and pronator teres. Mucus sheaths On the volar surfaces of the wrist and hand, the mucus sheaths of the flexor tendons can be indicated as follows. The sheath for flexor polisus longus reaches from about 3 cm above the upper edge of the transverse carpal ligament to the terminal phalanx of the thumb. The common sheath for the flexoris digitorum reaches about 3.5 to 4 cm above the upper edge of the transverse carpal ligament and extends on the palm of the hand to about the level of the centers of the metacarpal bones. The sheath for the tendons to the little finger is continued from the common sheath to the base of the terminal phalanx of this finger. The sheaths for the tendons of the other fingers are separated from the common sheath by an interval. They begin opposite the necks of the metacarpal bones and extend to the terminal phalanges. Arteries The course of the axillary artery can be marked out by abducting the arm to a right angle and drawing a line from the middle of the clavicle to the point where the tendon of the pectoralis major crosses the prominence of the coricobrachialis. Of the branches of the axillary artery the origin of the thoracoachromial corresponds to the point where the artery crosses the upper border of pectoralis minor. The lateral thoracic takes practically the line of the lower border of pectoralis minor. The subscapular is sufficiently indicated by the axillary border of the scapula. The scapular circumflex is given off the subscapular opposite the midpoint of a line joining the tip of the acromion to the lower edge of the deltoid tuberosity while the humeral circumflex arteries arise from the axillary about two centimeters above this. The position of the brachial artery is marked by a line drawn from the junction of the anterior and middle thirds between the anterior and posterior axillary folds to a point midway between the epicondoles of the humerus and continued distally for 2.5 centimeters at which point the artery bifurcates. With regard to the branches of the brachial artery the profunda crosses the back of the humerus at the level of the insertion of deltoidius. The nutrient is given off opposite the middle of the body of the humerus. A line from this point to the back of the medial condyle represents the superior ulnar collateral. The inferior ulnar collateral is given off about 5 centimeters above the fold of the elbow joint and runs directly medial ward. The position of the radial artery in the forearm is represented by a line from the lateral margin of the biceps tendon to the medial side of the front of the styloid process of the radius when the limb is in the position of supination. The situation of the distal portion of the artery is indicated by continuing this line around the radial side of the wrist to the proximal end of the first inter-metacarpal space. On account of the curved direction of the ulnar artery two lines are required to indicate its course. From the front of the medial epicondyle to the radial side of the pisiform bone the lower two-thirds of this line represents two-thirds of the artery. The upper third is represented by a second line from the center of the hollow in the front of the elbow joint to the junction of the upper and middle thirds of the first line. The superficial volar arch can be indicated by a line starting from the radial side and curving distal word and lateral word as far as the base of the thumb with its convexity toward the fingers. The summit of the arch is usually on a level with the ulnar border of the outstretched thumb. The deep volar arch is practically transverse and is situated about one centimeter nearer to the carpus. Nerves In the arm the line of the median nerve is practically the same as that for the brachial artery. At the bend of the elbow the nerve is medial to the artery. The course of the nerve in the forearm is marked by a line starting from a point just medial to the center of one joining the epicondyle and extending to the lateral margin of the tendon of palmaris longus at the wrist. The ulnar nerve follows the line of the brachial artery in the upper half of the arm but at the middle of the arm it diverges and descends to the back of the medial epicondyle. In the forearm it is represented by a line from the front of the medial epicondyle to the radial side of the pisiform bone. The course of the radial nerve can be indicated by a line from just below the posterior axillary fold to the lateral side of the humerus at the junction of its middle and lower thirds. Hence it passes vertically downward on the front of the arm to the level of the lateral epicondyle. The course of the superficial radial nerve is represented by a continuation of this line downward to the junction of the middle and lower thirds of the radial artery. It then crosses the radius and runs distal word to the dorsum of the base of the first metacarpal bone. The axillary nerve crosses the humerus about two centimeters above the center of a line joining the tip of the acromion to the lower edge of the deltoid tuberosity. End of section 57 Recording by Jean Hildy-Fulgium Section 58 of Grey's Anatomy Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org Recorded by Larianne Walden Anatomy of the human body Part 5 by Henry Gray Surface anatomy of the lower extremity Skin The skin of the thigh, especially in the hollow of the groin and on the medial side, is thin, smooth, and elastic and contains few hairs except in the neighborhood of the pubis. Laterally, it is thicker and the hairs are more numerous. The junction of the skin of the thigh with that on the front of the abdomen is marked by a well-defined furrow which indicates the sight of the inguinal ligament. The furrow presents a general convexity downward, but its medial half, which is the better marked, is nearly straight. The skin over the buttock is fairly thick and is characterized by its low sensibility and slight vascularity. As a rule, it is destitute of conspicuous hairs except toward the post anal furrow where in some males they are abundantly developed. An almost transverse fold, the gluteal fold crosses the lower part of the buttock. It practically bisects the lower margin of the gluteus maximus and is most evident during extension of the hip joint. The skin over the front of the knee is covered by thickened epidermis. It is loose and thrown into transverse wrinkles when the leg is extended. The skin of the leg is thin, especially on the medial side and is covered with numerous large hairs. On the dorsum of the foot loosely connected to subjacent parts and contains few hairs on the plantar surface and especially over the heel, the epidermis is of great thickness. And here, as in the palm of the hand, there are neither hairs nor sebaceous glands. Bones The hip bones are largely covered with muscles so that only at a few points do they approach the surface. In front, the anterior superior iliac spine is easily recognized and in thin subjects stands out as a prominence at the lateral end of the fold of the groin. In fat subjects, its position is indicated by an oblique depression at the bottom of which the bunny process can be felt. Proceeding upward and backward from this process, the sinuously curved iliac crest can be traced to the posterior superior iliac spine, the side of which is indicated by a slight depression. On the outer lip of the crest, about five centimeters behind the anterior superior spine is the prominent iliac tubercle. In thin subjects, the pubic tubercle is very apparent, but in the obese it is obscured by the pubic fat. It can, however, be detected by following up the tendon of origin of a doctor longus. Another part of the bony pelvis which is accessible to touch is the ischial tuberosity situated beneath the gluteus maximus. And when the hip is flexed, easily felt, as it is then uncovered by muscle. The femur is enveloped by muscles so that in fairly muscular subjects the only accessible parts are the lateral surface of the greater trochanter and the lower expanded end of the bone. The site of the greater trochanter is generally indicated by a depression owing to the thickness of the glutei, medius, and minimus which project above it. When, however, the thigh is flexed and especially if it be crossed over the opposite one, the trochanter produces a blunt eminence on the surface. The lateral condyle is more easily felt than the medial. Both epicondyles can be readily identified and at the upper part of the medial condyle, the sharp adductor tubercle can be recognized without difficulty. When the knee is flexed, a portion of the patellar surface is uncovered and is palpable. The anterior surface of the patellar is subcutaneous. When the knee is extended, the medial bone is a little more prominent than the lateral. And if the quadriceps femoris be relaxed, the bone can be moved from side to side. When the joint is flexed, the patellar recedes into the hollow between the condyles of the femur and the upper end of the tibia and becomes firmly applied to the femur. A considerable portion of the tibia is subcutaneous. At the upper end, the condyles can be felt just below the knee. The medial condyle is broad and smooth and merges into the subcutaneous surface of the body below. The lateral is narrower and more prominent. And on it, about midway between the apex of the patellar and the head of the fibula, is the tubercle for the attachment of the iliotibial band. In front of the upper end of the bone between the condyles is an oval eminence, the tuberosity, which is continuous below with the anterior crest of the bone. This crest can be identified in the upper two-thirds of its extent as a flexuous ridge, but in the lower third it disappears and the bone is concealed by the tendons of the muscles on the front of the leg. Medial to the anterior crest is the broad surface, slightly encroached on by muscles in front and behind. The medial malleolus forms a broad prominence situated at a higher level and somewhat farther forward than the lateral malleolus. It overhangs the medial border of the arch of the foot. Its anterior border is nearly straight. Its posterior presents a sharp edge which forms the medial margin of the groove for the tendon of tibialis posterior. The only subcutaneous parts of the fibula are the head, the lower part of the body and the lateral malleolus. The head lies behind and lateral to the lateral condyle of the tibia and presents as a small, prominent pyramidal eminence, slightly above the level of the tibial tuberosity. Its position can be readily located by following downward the tendon of biceps femoris. The lateral malleolus is a narrow elongated prominence from which the lower third or half of the lateral surface of the body of the bone can be traced upward. On the dorsum of the tarsus the individual bone cannot be distinguished with the exception of the head of the talus which forms a rounded projection in front of the ankle joint when the foot is forcibly extended. The whole dorsal surface of the foot has a smooth convex outline, the summit of which is the ridge formed by the head of the talus, the navicular, the second cuneiform and the second metatarsal bone. From this it inclined gradually lateral word and rapidly medial word. On the medial side of the foot the medial process of the tuberosity of the calcaneus and the ridge separating the posterior from the medial surface of the bone are distinguishable. In front of this and below the medial malealus is the sustentaculum tali. The tuberosity of the navicular is palpable about 2.5 to 3 centimeters in front of the medial malealus. Farther forward the ridge formed by the base of the first metatarsal bone can be obscurely felt and from this the body of the bone can be traced to the expanded head. Beneath the base of the first phalanx is the medial sesamoid bone. On the lateral side of the foot the most posterior bony point is the lateral process of the tuberosity of the calcaneus with the ridge separating the posterior from the lateral surface of the bone. In front of this the greater part of the lateral surface of the calcaneus is subcutaneous. On it below and in front of the lateral malealus the trochlear process when present can be felt. Farther forward the base of the fifth metatarsal bone is prominent and from it the body and expanded head can be traced. As in the case of the metacarpals the dorsal surfaces of the metatarsal bones are easily defined although their heads do not form prominences. The plantar surfaces are obscured by muscles. The phalanges in their whole extent are readily palpable. Articulations the hip joint is deeply seated and cannot be palpated. The interval between the tibia and femur can always be easily felt. If the knee joint be extended this interval is on a higher level than the apex of the patella. But if the joint be slightly flexed it is directly behind the apex. When the knee is semi-flexed the medial borders of the patella and of the medial condyle of the femur and the upper border of the medial condyle of the tibia bound a triangular depressed area which indicates the position of the joint. The ankle joint can be felt on either side of the extensor tendons and during extension of the joint the superior articular surface of the talus presents below the anterior border of the lower end of the tibia. Muscles Of the muscles of the thigh those of the anterior femoral region contribute largely to surface form. The tensor fascialata produces a broad elevation immediately below the anterior part of the iliac crest and behind the anterior superior iliac spine. From its lower border a groove caused by the iliotibial band extends downward to the lateral side of the knee joint. The upper portion of sartorius constitutes the lateral boundary of the femoral triangle and when the muscle is in action forms a prominent oblique ridge which is continued below into a flattened plane and then gradually merges into a general fullness of the knee joint. When the sartorius is not in action a depression exists between the quadriceps femoris and the adductors and extends obliquely downward and medialward from the apex of the femoral triangle to the side of the knee. In the angle formed by the divergence of sartorius and tensor fascialata just below the anterior superior iliac spine the rectus femoris appears and in a muscular subject its borders can be clearly defined when the muscle is in action. The vastus lateralis forms a long flattened plane traversed by the groove of the iliotibial band. The vastus medialis gives rise to a considerable prominence on the medial side of the lower half of the thigh. This prominence increases toward the knee and ends somewhat abruptly with a full curved outline. The vastus intermedius is completely hidden. The adductories cannot be differentiated from one another with the exception of the upper tendon of adductor longus and the lower tendon of adductor magnus. When the adductor longus is in action its upper tendon stands out as a prominent ridge running obliquely downward and lateralward from the neighborhood of the pubic tubercle informing the medial border of the femoral triangle. The lower tendon of adductor magnus can be distinctly felt as a short ridge extending downward between the sartorius and vastus medialis to the adductor tubercle. The adductories fill in the triangular space at the upper part of the thigh between the femur and the pelvis and to them is due the contour of the medial border of the thigh the gracilis contributing largely to the smoothness of the outline. The gluteus maximus forms the full rounded outline of the buttock. It is more prominent behind, compressed in front and ends at its tendinous insertion in a depression immediately behind the greater trochanter. Its lower border crosses the gluteal fold obliquely downward and lateralward. The upper is part of gluteus medius and is visible but its lower part with gluteus minimus and the external rotators are completely hidden. From beneath the lower margin of gluteus maximus the hamstrings appear. At first they are narrow and not well defined but as they descend they become more prominent and eventually divide into two well marked ridges formed by their tendons. These constitute the upper boundaries of the papillodial fossa. The tendon of biceps femoris is a thick cord running to the head of the fibula. The tendons of the semi-membranosis and semi-tendinosis as they run medialward to the tibia are separated by a slight furrow. The semi-tendinosis is the more medial and can be felt in certain positions of the limb as a sharp cord while the semi-membranosis is thick and rounded. The gracilis is situated a little in front of them. The tibialis anterior presents a fusiform enlargement at the lateral side of the tibia and projects beyond the anterior crest of the bone. Its tendon can be traced on the front of the tibia and ankle joint and thence along the medial side of the foot to the base of the first matatarsal bone. The fleshy fibres of perineus longus are strongly marked at the upper part of the lateral side of the leg. It is separated by furrows from extensor digitorum longus in front and soleus behind. Below the fleshy fibres end abruptly in a tendon which overlaps the more flattened elevation of perineus brevis. Below the lateral medialis the tendon of perineus brevis is the more marked. On the dorsum of the foot the tendons emerging from beneath the transverse cruciate cruel ligaments spread out and can be distinguished as follows. The most medial and largest is tibialis anterior. The next is extensor halusis proprious. Then extensor digitorum longus dividing into four tendons to the second, third, fourth, and fifth toes. And lastly perineus tertius. The extensor digitorum brevis produces a rounded outline on the dorsum of the foot and a fullness in front of the lateral malealis. The interossei dorsalis bulge between the metatarsal bones. At the back of the knee is the papillodial fossa bounded above by the tendons of the hamstrings and below by the gastrocnemius. Below this fossa is the prominent fleshy mass of the calf of the leg produced by gastrocnemius and soleus. When these muscles are in action the borders of gastrocnemius form two well-defined curved lines which converge to the tendocalcaneus. The medial border is the more prominent. At the same time the edges of soleus can be seen forming on either side of gastrocnemius curved immanences of which the lateral is the longer. The fleshy mass of the calf ends somewhat abruptly in the tendocalcaneus which tapers in the upper three-fourths of its extent but widens out slightly below. Behind the medial border of the lower part of the tibia a well-defined ridge is produced by the tendon of tibialis posterior during contraction of the muscle. On the sole of the foot the abductor digitii quintii forms a narrow rounded elevation on the lateral side and the abductor helusis a lesser elevation on the medial side. The flexor digitorm brevis bound down by the plantar aponeurosis is not very apparent. It produces a flattened form and the thickened skin underlying it is thrown into numerous wrinkles. Arteries. The femoral artery as it crosses the brim of the pelvis is readily felt. In its course down the thigh its pulsation becomes gradually more difficult of recognition. When the knee is flexed the pulsation of the papillodial artery can easily be detected in the papillodial fossa. On the lower part of the front of the tibia the anterior tibial artery becomes superficial and can be traced over the ankle into the dorsalis pedis. The latter can be followed to the proximal end of the first intermetatarsal space. The pulsation of the posterior tibial artery becomes evident near the lower end of the back of the tibia and is easily detected behind the medial malleolus. Veins. By compressing the proximal trunks the venous arch on the dorsum of the foot together with the great and small saphenous veins leaving from it are rendered visible. Nerves. The only nerve of the lower extremity located by palpation is the common perineal as it winds around the lateral side of the neck of the fibula. End of section 58 Section 59 of Grey's Anatomy Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Red Valarian Walden Anatomy of the Human Body Part 5 by Henry Gray Bony Landmarks The anterior superior iliac spine is at the level of the sacral promontory the posterior at the level of the spinous process of the second sacral vertebra. A horizontal line through the highest points of the iliac crests passes also through the spinous process of the fourth lumbar vertebra while, as already pointed out the trans tubercular plane through the tubercles on the iliac crests cuts the body of the fifth lumbar vertebra The upper margin of the greater sciatic notch is opposite the spinous process of the third sacral vertebra and slightly below this level is the posterior inferior iliac spine. The surface markings of the posterior inferior iliac spine and the ischial spine are both situated in a line which joins the posterior superior iliac spine to the outer part of the ischial tuberosity. The posterior inferior spine is 5 cm and the ischial spine 10 cm below the posterior superior spine. The ischial spine is opposite the first piece of the coccyx. With the body in the erect posture, the line joining the pubic tubercle to the top of the greater trochanter is practically horizontal. The middle of this line overlies the acetabulum and the head of the femur. A line used for clinical purposes is that of Nelliton drawn from the anterior superior iliac spine to the most prominent part of the ischial tuberosity. It crosses the center of the acetabulum and the upper border of the greater trochanter. Another surface marking of clinical importance is Bryant's triangle which is mapped out thus. A line from the anterior superior iliac spine to the top of the greater trochanter forms the base of the triangle. Its sides are formed respectively by a horizontal line from the superior iliac spine and a vertical line from the top of the greater trochanter. Articulations. The posterior superior iliac spine overlies the center of the sacroiliac articulations. The hip joint may be indicated, as described above, by the center of a horizontal line from the pubic tubercle to the top of the greater trochanter or, more generally, it is below and slightly lateral to the middle of the inguinal ligament. The hip joint is superficial and requires no surface marking. The level of the ankle joint is that of a transverse line about one centimeter above the level of the tip of the medial malleolus. If the foot be forcibly extended, the head of the talus appears as a rounded prominence on the medial side of the dorsum. Just in front of this prominence and behind the tuberosity of the navicular is the talonavicular joint. The calcaneo-cuboid joint is situated midway between the lateral malleolus and the prominent base of the fifth metatarsal bone. The line indicating it is parallel to that of the talonavicular joint. The line of the fifth tarsometatarsal joint is very oblique. It starts from the projection of the base of the fifth metatarsal bone, and if continued would pass through the head of the first metatarsal. The lines of the fourth and third tarsometatarsal joints are less oblique. The first tarsometatarsal joint corresponds to a groove which can be felt by making firm pressure on the medial border of the foot, 2.5 cm in front of the tuberosity of the navicular bone. The position of the second tarsometatarsal joint is 1.25 cm behind this. The metatarsophilangial joints are about 2.5 cm behind the webs of the corresponding toes. Muscles. Some of the muscles require any special surface lines to indicate them, but there are three intramuscular spaces which occasionally require definition. These are the femoral triangle, the adductor canal, and the papyllidial fossa. The femoral triangle is bounded above by the inguinal ligament, laterally by the medial border of the sartorius, and medially by the medial border of adductor longus. In the triangle is the fossa ovalis through which saphenous vein dips to join the femoral. The center of this fossa is about 4 cm below and lateral to the pubic tubercle. Its vertical diameter measures about 4 cm, and its transverse about 1.5 cm. The femoral ring is about 1.25 cm lateral to the pubic tubercle. The adductor canal occupies the medial part of the middle third of the thigh. It begins at the apex of the femoral triangle and lies deep to the vertical part of the sartorius. The papyllidial fossa is bounded above and medially by the tendons of semi-membranosis and semi-tendonosis. Above and laterally by the tendon of biceps femoris. Below and medially by the medial head of gastrocnemius. Below and laterally by the lateral head of gastrocnemius and the planteris. Mucus sheaths The positions of the mucus sheaths around the tendons about the ankle joints are sufficiently indicated in figures 1241 and 1242. Arteries. The points of emergence of the three main arteries on the buttock, that is the superior and inferior gluteals and the internal pudendal, may be indicated in the following manner. With the femur slightly flexed and rotated inward, a line is drawn from the posterior superior iliac spine to the posterior superior angle of the greater trochanter. The point of emergence of the superior gluteal artery from the upper part of the greater sciatic foramen corresponds to the junction of the upper and middle thirds of this line. A second line is drawn from the posterior superior iliac spine to the outer part of the ischial tuberosity. The junction of its lower with its middle third marks the point of emergence of the inferior gluteal and internal pudendal arteries from the lower part of the greater sciatic foramen. The course of the femoral artery is represented by the upper two thirds of a line from a point midway between the anterior superior iliac spine and the synthesis pubis to the adductor tubercle with the thigh abducted and rotated outward. The profund ephemeris arises from it about one to five centimeters below the inguinal ligament. The course of the upper part of the popliteal artery is indicated by a line from the lateral margin of the semi-membranosus at the junction of the middle and lower thirds of the thigh, obliquely downward to the middle of the popliteal fossa. From this point it runs vertically downward for about 2.5 centimeters or to the level of a line through the lower part of the tibial tuberosity. The line indicating the anterior tibial artery is drawn from the medial side of the head of the fibula to a point midway between the malleoli. The artery begins about three centimeters below the head of the fibula. The dorsalis pedis artery is represented on the dorsum of the foot by a line from the center of the interval between the malleoli to the proximal end of the first intermeditarsal space. The course of the posterior tibial artery can be shown by a line from the end of the popliteal artery that is 2.5 centimeters below the center of the popliteal fossa to midway between the tip of the medial malleolus and the center of the convexity of the heel. Its main branch, the peroneal artery, begins about seven or eight centimeters below the level of the knee joint and follows the line of the fibula to the back of the lateral malleolus. The medial and lateral plantar arteries begin from the end of the posterior tibial. The medial extends to the middle of the plantar surface of the ball of the great toe. The lateral to within a finger's breadth of the tuberosity of the fifth meditarsal bone. From this latter point the plantar arch crosses the foot transversely to the proximal end of the first intermeditarsal space. Veins. The line of the great saphenous vein is from the front of the medial malleolus to the center of the fossa ovalis. The small saphenous vein runs from the back of the lateral malleolus to the center of the popliteal fossa. Nerves. The course of the sciatic nerve can be indicated by a line from a point midway between the outer border of the ischial tuberosity and the posterior superior angle of the greater trochanter to the upper angle of the popliteal fossa. The continuation of this line vertically through the center of the popliteal fossa represents the position of the tibial nerve. While the common peroneal nerve follows the line of the tendon of biceps femoris. The lines for the deep peroneal nerve and the continuation of the tibial nerve correspond respectively to those for the anterior and posterior tibial arteries. End of section 59. End of part 5. This concludes anatomy of the human body by Henry Gray.