 Chapter 6C. The Bones of the Lower Extremity, Section 1, The Hip Bone. The hip bone is a large, flattened, irregularly shaped bone, constricted in the center and expanded above and below. It meets its fellow on the opposite side in the middle line in front, and together they form the sides and anterior wall of the pelvic cavity. It consists of three parts, the ilium, ischium, and pubis, which are distinct from each other in the young subject, but are fused in the adult. The union of the three parts takes place in and around a large, cuff-shaped, articular cavity, the acetabulum, which is situated near the middle of the outer surface of the bone. The ilium, so-called because it supports the flank, is the superior, broad, and expanded portion which extends upward from the acetabulum. The ischium is the lowest and strongest portion of the bone. It proceeds downward from the acetabulum, expands into a large tuberosity, and then, curving forward, forms with the pubis a large aperture, the obturator foreman. The pubis extends medialward and downward from the acetabulum, and articulates in the middle line with the bone of the opposite side. It forms the front of the pelvis and supports the external organs of generation. The ilium, os ilii. The ilium is divisible into two parts, the body and the ala. The separation is indicated on the internal surface by a curved line, the arcuate line, and on the external surface by the margin of the acetabulum. The body, corpus os ilii. The body enters into the formation of the acetabulum, of which it forms rather less than two-fifths. Its external surface is partly articular, partly nonarticular. The articular segment forms part of the lunate surface of the acetabulum. The nonarticular portion contributes to the acetabular fossa. The internal surface of the body is part of the wall of the lesser pelvis, and gives origin to some fibers of the obturator internus. Below it is continuous with the pelvic surfaces of the ischium and pubis, only a faint line indicating the place of union. The ala, ala os ilii. The ala is the large expanded portion which bounds the greater pelvis laterally. It presents for examination two surfaces, an external and an internal, a crest and two borders, an anterior and a posterior. The external surface, known as the dorsum ilii, is directed backward and lateralward behind, and downward and lateralward in front. It is smooth, convex in front, deeply concave behind, bounded above by the crest, below by the upper border of the acetabulum, in front and behind by the anterior and posterior borders. This surface is crossed in an arched direction by three lines, the posterior, anterior and inferior gluteal lines. The posterior gluteal line, superior curved line, the shortest of the three begins at the crest about five centimeters in front of its posterior extremity. It is at first distinctly marked, but as it passes downward to the upper part of the greater sciatic notch where it ends, it becomes less distinct and is often altogether lost. Behind this line is a narrow, semi-lunar surface, the upper part of which is rough and gives origin to a portion of the gluteus maximus. The lower part is smooth and has no muscular fibers attached to it. The anterior gluteal line, the middle curved line, the longest of the three begins at the crest about four centimeters behind its anterior extremity and, taking a curved direction downward and backward, ends at the upper part of the greater sciatic notch. The space between the anterior and posterior gluteal lines and the crest is concave and gives origin to the gluteus medius. Near the middle of this line a nutrient foreman is often seen. The inferior gluteal line, inferior curved line, the least distinct of the three begins in front at the notch on the anterior border and curving backward and downward ends near the middle of the greater sciatic notch. The surface of bone included between the anterior and inferior gluteal lines is concave from above downward, convex from before backward and gives origin to the gluteus minimus. Between the inferior gluteal line and the upper part of the acetabulum is a rough, shallow groove from which the reflected tendon of the rectus femoris arises. The internal surface of the ala is bounded above by the crest, below by the arcuate line, in front and behind by the anterior and posterior borders. It presents a large, smooth, concave surface called the iliac fossa, which gives origin to the iliacus and is perforated at its inner part by a nutrient canal, and below this a smooth, rounded border, the arcuate line, which runs downward, forward and medialward. Behind the iliac fossa is a rough surface divided into two portions, an anterior and a posterior. The anterior surface, oricular surface, so-called from its resemblance in shape to the ear, is coated with cartilage in the fresh state and articulates with a similar surface on the side of the sacrum. The posterior portion, known as the iliac tuberosity, is elevated and rough for the attachment of the posterior sacroiliac ligaments and for the origins of the sacrospanalis and multifidus. Below and in front of the auricular surface is the pre-auricular sulcus, more commonly present and better marked in the female than in the male. To it is attached the pelvic portion of the anterior sacroiliac ligament. The crest of the ilium is convex in its general outline but is sinuously curved, being concave inward in front, concave outward behind. It is thinner at the center than at the extremities and ends in the anterior and posterior superior iliac spines. The surface of the crest is broad and divided into external and internal lips and an intermediate line. About 5 cm behind the anterior superior iliac spine there is a prominent tubercle on the outer lip. To the external lip are attached the tensor fasciae latte, obliquious externus abdominis and latissimus dorsi and along its whole length the fasciae latte. To the intermediate line the obliquious externus abdominis to the internal lip the fasciae iliacca, the transverse abdominis, quadratus lumborum, sacrospanalis and iliacus. The anterior border of the ala is concave. It presents two projections separated by a notch. Of these the uppermost situated at the junction of the crest and anterior border is called the anterior superior iliac spine. Its outer border gives attachment to the fasciae latae and the tensor fasciae latte, its inner border to the iliacus. While its extremity affords attachment to the inguinal ligament and gives origin to the sartorius. Beneath this eminence is a notch from which the sartorius takes origin and across which the lateral femoral cutaneous nerve passes. Below the notch is the anterior inferior iliac spine which ends in the upper lip of the acetabulum. It gives attachment to the straight tendon of the rectus femoris and to the iliofemoral ligament of the hip joint. Medial to the anterior inferior spine is a broad shallow groove over which the iliacus and pissois major pass. This groove is bounded medially by an eminence, the ilio pectineal eminence which marks the point of union of the ilium and pubis. The posterior border of the a la, shorter than the anterior, also presents two projections separated by a notch. The posterior superior iliac spine and the posterior inferior iliac spine. The former serves for the attachment of the oblique portion of the posterior sacroiliac ligaments and the multifidus. The latter corresponds with the posterior extremity of the auricular surface. Below the posterior inferior spine is a deep notch, the greater sciatic notch. The ischium, oscishii. The ischium forms the lower and back part of the hip bone. It is divisible into three portions, a body and two ramai. The body, corpus oscishii. The body enters into and constitutes a little more than two-fifths of the acetabulum. Its external surface forms part of the lunate surface of the acetabulum and a portion of the acetabular fossa. Its internal surface is part of the wall of the lesser pelvis. It gives origin to some fibers of the obturator internus. Its anterior border projects as the posterior obturator tubercle. From its posterior border, there extends backward a thin and pointed triangular eminence, the ischial spine, more or less elongated in different subjects. The external surface of the spine gives attachment to the gemellus superior, its internal surface to the cocogias, leviter ani, and the pelvic fascia. Well to the pointed extremity, the sacrospinus ligament is attached. Above the spine is a large notch, the greater sciatic notch, converted into a foreman by the sacrospinus ligament. It transmits the pyroformus, the superior and inferior gluteal vessels and nerves. The sciatic and posterior femoral cutaneous nerves, the internal pudendal vessels and nerve, and the nerves to the obturator internus and quadratus femoris. Of these, the superior gluteal vessels and nerve pass out above the pyroformus, other structures below it. Below the spine is a smaller notch, the lesser sciatic notch. It is smooth, coated in the recent state with cartilage, the surface of which presents two or three ridges corresponding to the subdivisions of the tendon of the obturator internus, which winds over it. It is converted into a foreman by the sacrotuberous and sacrospinus ligaments, and transmits the tendon of the obturator internus, the nerve which supplies that muscle, and the internal pudendal vessels and nerve. The superior ramus, ramus superior ossiti descending ramus. The superior ramus projects downward and backward from the body and presents for examination three surfaces, external, internal, and posterior. The external surface is quadrilateral in shape, it is bounded above by a groove which lodges the tendon of the obturator internus. Below is continuous with the inferior ramus, in front it is limited by the posterior margin of the obturator foreman. Behind, a prominent margin separates it from the posterior surface. In front of this margin, the surface gives origin to the quadratus femoris, and anterior to this to some of the fibers of origin of the obturator externus. The lower part of the surface gives origin to part of the adductor magnus. The internal surface forms part of the bony wall of the lesser pelvis. In front it is limited by the posterior margin of the obturator foreman. Below it is bounded by a sharp ridge which gives attachment to a falciform prolongation of the sacrotuberous ligament, and more anteriorly, gives origin to the transversus perenei and ischiocavernosis. Posteriorly, the ramus forms a large swelling, the tuberosity of the ischium, which is divided into two portions, a lower, rough, somewhat triangular part, and an upper smooth quadrilateral portion. The lower portion is subdivided by a prominent longitudinal ridge passing from base to apex into two parts. The outer gives attachment to the adductor magnus, the inner to the sacrotuberous ligament. The upper portion is subdivided into two areas by an oblique ridge, which runs downward and outward, from the upper and outer area the semimembranosis arises, from the lower and inner, the long head of the biceps femoris, and the semi-tendinosis. The inferior ramus, ramus inferior osaceae, ascending ramus. The inferior ramus is the thin, flattened part of the ischium, which ascends from the superior ramus and joins the inferior ramus of the pubis, the junction being indicated in the adult by a raised line. The outer surface is uneven for the origin of the obturator externus and some of the fibers of the adductor magnus. Its inner surface forms part of the anterior wall of the pelvis. Its medial border is thick, rough, slightly averted, forms part of the outlet of the pelvis and presents two ridges and an intervening space. The ridges are continuous with similar ones on the inferior ramus of the pubis. To the outer is attached the deep layer of the superficial perineal fascia, fascia of colis, and to the inner, the inferior fascia of the urogenital diaphragm. If these two ridges be traced downward, they will be found to join with each other just behind the point of origin of the transversus perinei. Here the two layers of the fascia are continuous behind the posterior border of the muscle. To the intervening space, just in front of the point of origin of the ridges, the transversus perinei is attached. And in front of this, a portion of the cruse penis felt clitoridus and the ischiocavernosis. Its lateral border is thin and sharp and forms part of the medial margin of the obturator foreman. The pubis, os pubis. The pubis, the anterior part of the hip bone, is divisible into a body, a superior, and an inferior ramus. The body, corpus os pubis. The body forms one-fifth of the acetabulum, contributing by its external surface, both to the lunate surface and the acetabular fascia. Its internal surface enters into the formation of the wall of the lesser pelvis and gives origin to a portion of the obturator internus. The superior ramus, ramus superior os pubis, ascending ramus. The superior ramus extends from the body to the median plane where it articulates with its fellow of the opposite side. It is conveniently described in two portions, vis, a medial flattened part, and a narrow lateral prismoidal portion. The medial portion of the superior ramus, formally described as the body of the pubis, is somewhat quadrilateral in shape and presents for examination two surfaces and three borders. The anterior surface is rough, directed downward and outward, and serves for the origin of various muscles. The adductor longus arises from the upper and medial angle, immediately below the crest. Lower down, the obturator externus, the adductor brevis, and the upper part of the gracilis take origin. The posterior surface, convex from above downward, concave from side to side, is smooth and forms part of the anterior wall of the pelvis. It gives origin to the levator ani and obturator internus and attachment to the pubic prosthetic ligaments and to a few muscular fibres prolonged from the bladder. The upper border presents a prominent tubercle, the pubic tubercle, pubic spine, which projects forward. The inferior cross of the subcutaneous inguinal ring, external abdominal ring, and the inguinal ligament, pupart's ligament, are attached to it. Passing upward and lateralward from the pubic tubercle is a well-defined ridge, forming a part of the pectoneal line, which marks the brim of the lesser pelvis. To it are attached a portion of the inguinal phalx, conjoined tendon of obliquus internus and transversus, the lacunar ligament, gembernus ligament, and the reflected inguinal ligament, triangular fascia. Medial to the pubic tubercle is the crest, which extends from this process to the medial end of the bone. It affords attachment to the inguinal phalx and to the rectus abdominis and pyramidalis. The point of junction of the crest with the medial border of the bone is called the angle. To it, as well as to the symphysis, the superior crust of the subcutaneous inguinal ring is attached. The medial border is articular. It is oval and is marked by eight or nine transverse ridges, or a series of nipple-like processes arranged in rows separated by grooves. They serve for the attachment of a thin layer of cartilage, which intervenes between it and the inter pubic fibrocartilaginous lamina. The lateral border presents a sharp margin, the obturator crest, which forms part of the circumference of the obturator foremen, and affords attachment to the obturator membrane. The lateral portion of the ascending ramus has three surfaces, superior, inferior, and posterior. The superior surface presents a continuation of the pectineal line, already mentioned as commencing at the pubic tubercle. In front of this line, the surface of bone is triangular in form, wider laterally than medially, and is covered by the pectinus. The surface is bounded laterally by a rough eminence, the ileopectoneal eminence, which serves to indicate the point of junction of the ileum and pubis, and below by a prominent ridge which extends from the acetabular notch to the pubic tubercle. The inferior surface forms the upper boundary of the obturator foremen, and presents laterally a broad and deep oblique groove for the passage of the obturator vessels and nerve, and medially a sharp margin, the obturator crest, forming part of the circumference of the obturator foremen and giving attachment to the obturator membrane. The posterior surface constitutes part of the anterior boundary of the lesser pelvis. It is smooth, convex from above downward, and affords origin to some fibers of the obturator internus. The inferior ramus, ramus inferior os pubis, descending ramus. The inferior ramus is thin and flattened. It passes lateralward and downward from the medial end of the superior ramus. It becomes narrower as it descends and joins with the inferior ramus of the ischium below the obturator foremen. Its anterior angle is rough for the origin of muscles. The gracilis along its medial border, a portion of the obturator externus where it enters into the formation of the obturator foremen, and between these two, the adductoris brevis and magnus, the former being the more medial. The posterior surface is smooth and gives origin to the obturator internus and close to the medial margin to the constrictor urethrae. The medial border is thick, rough, and averted, especially in females. It presents two ridges separated by an intervening space. The ridges extend downward and are continuous with similar ridges on the inferior ramus of the ischium. To the external, it is attached to the fascia of coales and to the internal, the inferior fascia of the urogenital diaphragm. The lateral border is thin and sharp, forms part of the circumference of the obturator foremen, and gives attachment to the obturator membrane. The acetabulum, cotyloid cavity. The acetabulum is a deep, cup-shaped, hemispherical depression directed downward, lateralward, and forward. It is formed medially by the pubis, above by the ilium, laterally and below by the ischium. A little less than two-fifths is contributed by the ilium, a little more than two-fifths by the ischium, and the remaining fifth by the pubis. It is bounded by a prominent uneven rim, which is thick and strong above, and serves for the attachment of the glenoidal labrum, cotyloid ligament, which contracts its orifice and deepens the surface for articulation. It presents below a deep notch, the acetabular notch, which is continuous with a circular, non-articular depression, the acetabular fossa, at the bottom of the cavity. This depression is perforated by numerous apertures, and lodges a massive fat. The notch is converted into a foremen by the transverse ligament. Through the foremen, nutrient vessels and nerves enter the joint. The margins of the notch serve for the attachment of the ligamentum teres. The rest of the acetabulum is formed by a curved, articular surface, the lunate surface, for articulation with the head of the femur. The obturator foremen, foremen obturatum, thyroid foremen. The obturator foremen is a large aperture, situated between the ischium and pubis. In the male it is large and of an oval form, its longest diameter slanting obliquely from before backward. In the female it is smaller and more triangular. It is bounded by a thin and even margin to which a strong membrane is attached, and presents, superiorly, a deep groove, the obturator groove, which runs from the pelvis obliquely medialward and downward. This groove is converted into a canal by a ligamentus band, a specialized part of the obturator membrane, attached to two tubercles. One, the posterior obturator tubercle, on the medial border of the ischium, just in front of the acetabular notch. The other, the anterior obturator tubercle, on the obturator crest in the superior ramus of the pubis. Through the canal the obturator vessels and nerve pass out of the pelvis. Structure. The thicker parts of the bone consist of cancelous tissue, enclosed between two layers of compact tissue. The thinner parts, as at the bottom of the acetabulum and the center of the iliac fossa, are usually semi-transparent and composed entirely of compact tissue. Ossification. The hip bone is ossified from eight centers, three primary, one each for the ilium, ischium and pubis, and five secondary, one each for the crest of the ilium, the anterior inferior spine, said to occur more frequently in the male than in the female. The tuberosity of the ischium, the pubic symphysis, more frequent in the female than in the male, and one or more for the Y-shaped piece at the bottom of the acetabulum. The centers appear in the following order. In the lower part of the ilium, immediately above the greater sciatic notch, about the eighth or ninth week of fetal life. In the superior ramus of the ischium, about the third month. In the superior ramus of the pubis between the fourth and fifth months. At birth, the three primary centers are quite separate, the crest, the bottom of the acetabulum, and the ischial tuberosity, and the inferior ramai of the ischium and pubis still being cartilaginous. By the seventh or eighth year, the inferior ramai of the pubis and ischium are almost completely united by bone. About the thirteenth or fourteenth year, the three primary centers have extended their growth into the bottom of the acetabulum, and are there separated from each other by a Y-shaped portion of cartilage, which now presents traces of ossification, often by two or more centers. One of these, the osasatabuli, appears about the age of twelve between the ilium and pubis, and fuses with them about the age of eighteen. It forms the pubic part of the acetabulum. The ilium and ischium then become joined, and lastly the pubis and ischium, through the intervention of this Y-shaped portion. At about the age of puberty, ossification takes place in each of the remaining portions, and they join with the rest of the bone between the twentieth and twenty-fifth years. Separate centers are frequently found for the pubic tubercle and the ischial spine, and for the crest and angle of the pubis. Articulations. The hip bone articulates with its fellow of the opposite side, and with the sacrum and femur. End of section forty-three. The pelvis. The pelvis, so-called from its resemblance to a basin, is a bony ring, interposed between the movable vertebrae of the vertebral column which it supports, and the lower limbs upon which it rests. It is longer and more massively constructed than the wall of the cranial or thoracic cavities, and is composed of four bones, the two hip bones laterally and in front, and the sacrum and coccyx behind. The greater or false pelvis. The greater pelvis is the expanded portion of the cavity situated above and in front of the pelvic brim. It is bounded on either side by the ilium. In front it is incomplete, presenting a wide interval between the anterior borders of the ilia, which is filled up in the fresh state by the parietes of the abdomen. Behind is a deep notch on either side between the ilium and the base of the sacrum. It supports the intestines and transmits part of their weight to the anterior wall of the abdomen. The true or lesser pelvis. The lesser pelvis is that part of the pelvic cavity, which is situated below and behind the pelvic brim. Its bony walls are more complete than those of the greater pelvis. For convenience of description it is divided into an inlet bounded by the superior circumference and outlet bounded by the inferior circumference and the cavity. The superior circumference. The superior circumference forms the brim of the pelvis, and included space being called the superior aperture or inlet. It is formed laterally by the pectinial and arcuate lines in front of the crest of the pubes and behind by the anterior margin of the base of the sacrum and sacral vertebral angle. The superior aperture is somewhat heart shaped, obtusely pointed in front, diverging on either side, and encroached upon behind by the projection forward of the promontory of the sacrum. It has three principal diameters. Antero to posterior, transverse, and oblique. The anterior posterior or conjugate diameter extends from the sacral vertebral angle to the symphysis pubis. Its average measurement is about 110 millimeters in the female. The transverse diameter extends from the greatest width of the superior aperture from the middle of the brim on one side to the same point on the opposite. Its average measurement is about 135 millimeters in the female. The oblique diameter extends from the iliopectinial eminence of one side to the sacroiliac articulation of the opposite side. Its average measurement is about 125 millimeters in the female. The cavity of the lesser pelvis is bounded in front and below by the symphysis pubis and the superior ramai of the pubes above and behind by the pelvic surfaces of the sacrum and coccyx, which, curving forward above and below, contract the superior and inferior apertures of the cavity, laterally by a broad smooth quadrilangle area of bone corresponding to the inner surfaces of the body and superior ramus of the ischium and that part of the ilium which is below the arcuate line. From this description it will be seen that the cavity of the lesser pelvis is a short curved canal considerably deeper on its posterior than on its anterior wall. It contains in the fresh subject the pelvic colon, rectum, bladder, and some of the organs of generation. The rectum is placed at the back of the pelvis in the curve of the sacrum and coccyx. The bladder is in front behind the pubic symphysis. In the female the uterus and vagina occupy the interval between these viscera. The lower circumference. The lower circumference of the pelvis is very irregular. The space enclosed by it is named the inferior aperture or outlet, and is bounded behind by the point of the coccyx and laterally by the ischial tuberosities. These immanences are separated by three notches, one in front, the pubic arch formed by the convergence of the inferior rami of the ischium and the pubis on either side. The other notches, one on either side, are formed by the sacrum and coccyx behind, the ischium in front, and the ilium above. They are called the sciatic notches. In the natural state they are converted into foramina by the sacrotuberous and sacrospinous ligaments. When the ligaments are in situ, the inferior aperture of the pelvis is lozenge shaped, bounded in front by the pubic arcuate ligament and the inferior rami of the pubes and ischia, laterally by the ischial tuberosities and behind by the sacrotuberous ligaments and the tip of the coccyx. The diameters of the outlet of the pelvis are two, anterior posterior and transverse. The anterior posterior diameter extends from the tip of the coccyx to the lower part of the pubic symphysis. Its measurement is from 90 to 115 mm in the female. It varies with the length of the coccyx and is capable of increase or diminution on account of the mobility of that bone. The transverse diameter, measured from the posterior parts of the ischial tuberosities, is about 115 mm in the female. Footnote. The measurements of the pelvis given above are fairly accurate, but different figures are given by various authors. No doubt due mainly to differences in the physique and stature of the population from whom the measurements have been taken. Footnote. Axes. A line at right angles to the plane of the superior aperture at its center would, if prolonged, pass through the umbilicus above and the middle of the coccyx below. The axis of the superior aperture is therefore directed downward and backward. The axis of the inferior aperture, produced upward, would touch the base of the sacrum and is also directed downward and slightly backward. The axis of the cavity, i.e., an axis at right angles to a series of planes between those of the superior and inferior apertures, is curved like the cavity itself. This curve corresponds to the concavity of the sacrum and coccyx, the extremities being indicated by the central points of the superior and inferior apertures. A knowledge of the direction of these axes serves to explain the course of the fetus in the passage through the pelvis during parturition. Position of the pelvis. In the erect posture, the pelvis is placed obliquely with regard to the trunk. The plane of the superior aperture forms an angle of from 50 degrees to 60 degrees and that of the inferior aperture, one of about 15 degrees with the horizontal plane. The pelvic surface of the symphysis pubis looks upward and backward. The concavity of the sacrum and coccyx downward and forward. The position of the pelvis in the erect posture may be indicated by holding it so that the anterior superior iliac spines and the front of the top of the symphysis pubis are in the same vertical plane. Differences between the male and female pelvis. The female pelvis is distinguished from that of the male, by its bones being more delicate and its depth less. The whole pelvis is less massive and its muscular impressions are slightly marked. The ilia are less sloped and the anterior iliac spines more widely separated, hence the greater lateral prominence of the hips. The pre-irricular sulcus is more commonly present and better marked. The superior aperture of the lesser pelvis is larger in the female than in the male. It is more nearly circular and its obliquity is greater. The obliquity is shallower and wider. The sacrum is shorter, wider, and its upper part is less curved. The obtrater foramen are triangular in shape and smaller in size than in the male. The superior aperture is larger and the coccyx more movable. The sciatic notches are wider and shallower and the spines of the ischia project less inward. The acetabula are smaller and look more distinctly forward. The ischial tuberosities and the acetabula are wider apart and the former are more averted. The pubic's emphasis is less deep and the pubic arch is wider and more rounded than in the male where it is an angle rather than an arch. The size of the pelvis varies not only in the two sexes but also in different members of the same sex and does not appear to be influenced in any way by the height of the individual. Women of shorter stature, as a rule, have broad pelvis. Occasionally the pelvis is equally contracted in all its dimensions so much so that all its diameters measure 12.5 mm less than the average and this even in well formed women of average height. The principal divergence, however, are found at the superior aperture and affect the relation of the anterior-posterior to the transverse diameter. Thus the superior aperture may be elliptical either in a transverse or an anterior-posterior direction. The transverse diameter in the former and the anterior-posterior in the latter greatly exceeding the other diameters. In other instances it is almost circular. In the fetus and for several years after birth the pelvis is smaller in proportion than in the adult and the projection of the sacrovertibular angle less marked. The characteristic differences between the male and female pelvis are distinctly indicated as early as the fourth month of fetal life. Abnormalities There is a rest of development in the bones of the pelvis in cases of extraversion of the bladder. The anterior part of the pelvic girdle is deficient. The superior ramai of the pubes are imperfectly developed and the symphysis is absent. The pubic bones are separated to the extent of from 2 to 4 inches. The superior ramai shortened and directed forward and the obturator foramen diminished in size, narrowed, and turned outward. The iliac bones are straightened out more than normal. The sacrum is very peculiar. The lateral curve instead of being concave is flattened out or even convex with the iliosacral facets turned more outward than normal while the vertical curve is straightened. End of section 44 Section 45 of Grey's Anatomy Part 1 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 Defroster Anatomy of the Human Body Part 1 by Henry Gray The Femur Part 1 The Femur, the longest and strongest bone in the skeleton, is almost perfectly cylindrical in the greater part of its extent. And the erect posture does not vertical, being separated above from its fellow by a considerable interval, which corresponds to the breadth of the pelvis, but inclining gradually downward and medialward, so as to approach its fellow toward its lower part for the purpose of bringing the knee joint near the line of gravity of the body. The degree of this inclination varies in different persons and is greater in the female and in the male, on account of the greater breadth of the pelvis. The femur, like other long bones, is divisible into a body and two extremities. The upper extremity, or proximal extremity. The upper extremity presents for examination a head, a neck, a greater and lesser trochanter. The head, or capid femoris. The head, which is globular and forms rather more than a hemisphere, is directed upward, medialward, and a little forward, the greater part of its convexity being above and in front. Its surface is smooth, coated with cartilage in a fresh state, except over an ovoid depression, the fovea capitis femoris, which is situated a little below and behind the center of the head and gives attachment to the ligamentum teres. The neck, or column femoris. The neck has a flattened pyramidal process of bone, connecting the head with the body and forming with the latter a wide angle opening medialward. The angle is widest in infancy and becomes lessened during growth, so that at puberty it forms a gentle curve from the axis of the body of the bone. In the adult, the neck forms an angle of about 125 degrees with the body, but this varies in inverse proportion to the development of the pelvis and the stature. In the female, in consequence of the increased width of the pelvis, the neck of the femur forms more nearly a right angle with the body than it does in the male. The angle decreases during the period of growth, but after full growth has been attained it does not usually undergo any change. Even in old age, it varies considerably in different persons of the same age. It is smaller and short than in long bones and when the pelvis is wide. In addition to projecting upward and medialward from the body of the femur, the neck also projects somewhat forward. The amount of this forward projection is extremely variable, but on an average is from 12 degrees to 14 degrees. The neck is flattened from before backward, contracted in the middle, and broader laterally than medially. The vertical diameter of the lateral half is increased by the obliquity of the lower edge, which slopes downward to join the body at the level of the lesser trochanter so that it measures one-third more than the antero-posterior diameter. The medial half is smaller and of a more circular shape. Anterior surface of the neck is perforated by a numerous vascular parameter. Along the upper part of the line of junction of the anterior surface with the head is a shallow groove, best marked in elderly subjects. This groove lodges the orbicular fibers of the capsule of the hip joint. The posterior surface is smooth and is broader and more concave than the anterior. The posterior part of the capsule of the hip joint is attached to it about one centimeter above the intertrochanteric crest. The superior border is short and thick and ends laterally at the greater trochanter. Its surface is perforated by a large foramina. The inferior border, long and narrow, curves a little backward to end at the lesser trochanter. The trochanters. The trochanters are prominent processes which avoid leverage to the muscle that rotate the thigh on its axis. They are two in number, the greater and the lesser. The greater trochanter, or trochanter major, great trochanter, is a large irregular quadrilateral eminence situated at the junction of the neck with the upper part of the body. It is directed a little lateralward and backward and in the adult is about one centimeter lower than the head. It has two surfaces and four borders. The lateral surface quadrilateral in form is broad, rough, convex and marked by a diagonal impression which extends from the posterior superior to the anterior inferior angle and serves with the insertion of the tendon of the gluteus medius. Above the impression is a triangular surface, sometimes rough for part of the tendon in the same muscle, sometimes smooth with the interposition of a bursa between the tendon and the bone. Below and behind the diagonal impression is a smooth triangular surface over which the tendon of the gluteus maximus plays, a bursa being interposed. The medial surface of much less extent than the lateral presents at its base deep depression, the trochanteric fossa, or digital fossa, for the insertion of the tendon of the obturator externus. And above and in front of this an impression for the insertion of the obturator internus and gemini. The superior border is free. It is thick and irregular and marked near the center by an impression for the insertion of the piriformis. The inferior border corresponds to the line of junction of the base of the trochanter with a lateral surface of the body. It is marked by a rough, prominent, slightly curved ridge which gives origin to the upper part of the vastus lateralis. The anterior border is prominent and somewhat irregular. It affords insertion at its lateral part to the gluteus minimus. The posterior border is very prominent and appears as a free rounded edge which bounds the back part of the trochanteric fossa. The lesser trochanter, or trochanter minor, small trochanter, is a conical eminence which varies in size in different subjects. It projects from the lower and back part of the base of the neck. From its apex 3 well marked borders extend. Two of these are above. A medial continuous with the lower border of the neck. A lateral with the inter-trochanteric crest. The inferior border is continuous with the middle division of the linea aspera. The summit of the trochanter is rough and gives insertion to the tendon of the psoas major. A prominence of variable size occurs at the junction of the upper part of the neck with a greater trochanter and is called the tubercle of the femur. It is the point of meaning of five muscles. The gluteus minimus laterally, the vastus laterus below and the tendon of the obturator internus 2 gemuli above. Running obliquely downward and medial from the tubercle is the inter-trochanteric line, or spiral line of the femur. It winds around the medial side of the body of the bone below the lesser trochanter and ends about 5 cm below this eminence in the linea aspera. Its upper half is rough and affords attachment to the iliofemoral ligament of the hip joint. Its lower half is less prominent and gives origin to the upper part of the vastus medialus. Running obliquely downward and medial from the summit of the greater trochanter on the posterior surface of the neck is a prominent ridge, the inter-trochanteric crest. Its upper half forms the posterior border of the great trochanter and its lower half runs downward and medial to the lesser trochanter. A slight ridge is sometimes seen commencing about the middle of the inter-trochanteric crest and reaching vertically downward for about 5 cm along the back part of the body. It is called a linea quadrata and gives attachment to the quadratus femoris and a few fibers of the adductor magnus. Generally, there is merely a slight thickening about the middle of the inter-trochanteric crest, marking the attachment of the upper part of the quadratus femoris. The body or shaft or corpus femoris. The body, almost cylindrical in form, is a little broader above than in the center, broadest and somewhat flattened from before backward below. It is slightly arched so as to be convex in front and concave behind, where it is strengthened by a prominent longitudinal ridge, the linea aspera. It presents for examination three borders, separating three surfaces. Of the borders, one, the linea aspera is posterior, one is medial and the other lateral. The linea aspera is a prominent longitudinal ridge or crest on the middle third of the bone, presenting a medial and a lateral lip and a narrow, rough, intermediate line. Above, the linea aspera is prolonged by three ridges. The lateral ridge is very rough and runs almost radically upward to the base of the greater trochanter. It is termed the gluteal tuberosity and gives attachment to part of the gluteus maximus. Its upper part is often elongated into a roughened crest on which a more or less well-marked rounded tubercle, the third trochanter, is occasionally developed. The intermediate ridge, or pectineal line, is continued to the base of the lesser trochanter and gives attachment to the pectineus. The medial ridge is lost in the inter-trochanteric line. Between these two, a portion of the iliacus is inserted. Below, the linea aspera is prolonged into two ridges, enclosing between them a triangular area, the popliteal surface, upon which the popliteal artery rests. Of these two ridges, the lateral is the more prominent and descends to the summit of the lateral condyle. The medial is less marked, especially at its upper part, where it is crossed by the femoral artery. It ends below at the summit of the medial condyle in a small tubercle, the abductor tubercle, which affords insertion to the tendon of the adductor magnus. From the medial lip of the linea aspera and its prolongations above and below, the vastus medialis arises, and from the lateral lip and its upward prolongation, the vastus lateralis takes origin. The adductor magnus is inserted into the linea aspera, and to its lateral prolongation above and its medial prolongation below, between the vastus lateralis and the adductor magnus two muscles are attached. Via the gluteus maximus inserted above, and the short head of the biceps femoris arising below. Between the adductor magnus and the vastus medialis four muscles are inserted, the iliacus and the pectinus above, the adductor brevis and the adductor longus below. The linea aspera is perforated a little below its center by the nutrient canal, which is directed obliquely upward. The other two borders of the femoris are only slightly marked. The lateral border extends from the anterior or inferior angle of the greater trochanter to the anterior extremity of the lateral condyle. The medial border from the intertrochanteric line adds a point opposite the lesser trochanter to the anterior extremity of the medial condyle. The anterior surface includes that portion of the shaft which is situated between the lateral and medial borders. It is smooth, convex, broader above and below than in the center. From the upper three-fourths of the surface, the vastus intermedius arises. The lower fourth is separated from the muscle by the intervention of the cinevial membrane of the knee joint aniversa. From this upper part of it, the articularis genu takes origin. The lateral surface includes the portion between the lateral border and the linea aspera. It is continuous above with the corresponding surface to the greater trochanter, below with that of the lateral condyle. From its upper three-fourths, the vastus intermedius takes origin. The medial surface includes the portion between the medial border and the linea aspera. It is continuous above with the lower border of the neck, below with the medial side of the medial condyle. It is covered by the vastus medialis. The lower extremity, or distal extremity. The lower extremity, larger than the upper, is somewhat cuboid in form, but its transverse diameter is greater than an antero-posterior. It consists of two oblong eminence known as the condyles. In front, the condyles are but slightly prominent and are separated from one another by a smooth, shallow articular depression called the patellar surface. Behind, they project considerably, and the interveal between them forms a deep notch, the intercondyloid fossa. The lateral condyle is the more prominent and is the broader both in the antero-posterior and transverse diameters. The medial condyle is the longer and when the femur is held with its body perpendicular, projects to a lower level. When, however, the femur is in its natural oblique position, the lower surfaces of the two condyles lie practically in the same horizontal plane. The condyles are not quite parallel with one another. The long axis of the lateral is almost directly antero-posterior, but that of the medial runs backward and medialward. The reposed surfaces are small, rough, and concave and form the walls of the intercondyloid fossa. This fossa is limited above by a ridge, the intercondyloid line, and below by the central part of the posterior margin of the pasterior surface. The posterior cruciate ligament of the knee joint is attached to the lower and front part of the medial wall of the fossa, and the antero-cruciate ligament to an impression on the upper and back part of its lateral wall. Each condyle is surmounted by elevation, the epicondyle. The medial epicondyle is a large convex eminence to which the tibial collateral ligament of the knee joint is attached. At its upper part is the adductor tubicle. Often referred to and behind it is a rough impression which gives origin to the medial head of the gastrocentimus. The lateral epicondyle, smaller and less prominent than the medial, is attached to the fibular collateral ligament of the knee joint. Directly below it is a small depression from which a smooth, well-marked groove curves upward and backward to the posterior extremity of the condyle. This groove is separated from the atricular surface of the condyle by a prominent lip across which a second shallower groove runs vertically downward from the depression. In the fresh state these grooves are covered with cartilage. The popliteus arises from this depression. Its tendons lie on the oblique groove when the knee is flexed and in the vertical groove when the knee is extended. Above and behind the lateral epicondyle is an area for the origin of the lateral head of the gastroemium. Above enters the medial side of which the planteris arises. The articular surface of the lower end of the femur occupies the anterior, inferior and posterior surfaces of the condyle. Its front part is named the patella surface and articulates with the patella. It presents a median groove which extends downward to the intercondyloid fossa and two convexities, the lateral of which is broader, more prominent and extends farther upward than the medial. The lower and posterior parts of the articular surface constitute the tibial surface for articulation with the corresponding condyles of the tibia and minisci. These surfaces are separated from one another by the intercondyloid fossa and from the patella surface by faint grooves which extend obliquely across the condyles. The lateral groove is the better marked, it runs lateralward and forward from the front part of the intercondyloid fossa and expands to form a triangular depression. When the knee joint is fully extended the triangular depression rests upon the anterior portion of the lateral miniscus and the medial part of the groove comes into contact with the medial margin of the lateral articular surface of the tibia in front of the lateral tubercle of the tibial intercondyloid eminence. The medial groove is less distinct than the lateral, it does not reach as far as the intercondyloid fossa and therefore exists only on the medial part of the condyle. It receives the anterior edge of the medial miniscus when the knee joint is extended. Where the groove ceases laterally, the patella surface is seen to be continued backward as a semi-lunar area close to the anterior part of the intercondyloid fossa. This semi-lunar area articulates with the medial verticals fast of patella and forced flexion of the knee joint. The tibial surfaces of the condyles are convex from side to side and from before backward. Each presents a double curve, its posterior segment being an arc of a circle, its anterior part of a cycloid. Footnote. A cycloid is a curve traced by a point in the circumference of a wheel when the wheel is rolled along in a straight line. End of footnote. The architecture of the femur. Note. The following paragraphs are taken almost verbatim from Kosh's article in which we have the first correct mathematical analysis of the femur in support of the theory of the functional form of bone proposed by Wolf and Beirut. End of note. Cock by mathematical analysis has shown that in every part of the femur there is a remarkable adaptation of the inner surface of the bone to the mechanical requirements due to the load of the femur head. The various parts of the femur taken together form a single mechanical structure wonderfully well adapted for the efficient economical transmission of the load of the acetabulum to the tibia. A structure in which every element contributes its midicum of strength in the manner required by theoretical mechanics for maximum efficiency. The internal structure is everywhere so formed as to provide it in an efficient manner for all the internal stresses which occur due to the load on the femur head. Throughout the femur with a load on the femur head, the bony material is arranged in the paths of the maximum internal stresses which are thereby resisted with the greatest efficiency and hence with maximum economy of material. The conclusion is inevitable that the inner structure and outer form of the femur are governed by the conditions of maximum stresses to which the bone is subjected normally by the preponderant load of the femur head, that is by the body weight transmitted to the femur head through the acetabulum. The femur obeys the mechanical laws that govern other elastic bodies under stress. The relation between the computed internal stresses due to the load of the femur head and the internal structure of the different presupportions of the femur is in very close agreement with the theoretical relations that should exist between stress and structure for maximum economy and efficiency and therefore it is believed that the following laws of bone structure have been demonstrated for the femur. 1. The internal structure and external form of human bone are closely adapted to the mechanical conditions existing at every point in the bone. 2. The inner architecture of normal bone is determined by definite and exact requirements of mathematical and mechanical laws to produce maximum of strength with a minimum of material. End of Section 45. Recording by Defroster. Section 46 of Grey's Anatomy Part 1. 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 Morgan Scorpion. Anatomy of the Human Body Part 1 by Henry Grey. The Femur Part 2. The inner architecture of the upper femur. The spongy bone of the upper femur to the lower limit of the lesser trochanter is composed of two distinct systems of trabeculi arranged in curved paths. One which has its origin in the medial inner side of the shaft and curving upward in a fan-like radiation to the opposite side of the bone. The other, having origin in the lateral outer portion of the shaft and arching upward and medially to end in the upper surface of the greater trochanter, neck and head. These two systems intersect each other at right angles. A medial compressive system of trabeculi. As the compact bone of the medial inner part of the shaft nears the head of the femur, it gradually becomes thinner and finally reaches the articular surface of the head as a very thin layer. From a point at about the lower level of the lesser trochanter, two and a half to three inches from the lower limit of the articular surface of the head, the trabeculi branch off from the shaft in smooth curves, spreading radially to cross to the opposite side in two well-defined groups, a lower or secondary group and an upper or principal group. A. The secondary compressive group. This group of trabeculi leaves the inner border of the shaft beginning at about the level of the lesser trochanter and for a distance of almost two inches along the curving shaft with which the separate trabeculi make an angle of about 45 degrees. They curve outwardly and outwardly to cross in radiating smooth curves to the opposite side. The lower filaments end in the region of the greater trochanter. The adjacent filaments above these pursue a more nearly vertical course and end in the upper portion of the neck of the femur. The trabeculi of this group are thin and with wide spaces between them. As they traverse the space between the medial and lateral surfaces of the bone, they cross at right angles the system of curved trabeculi which arrives from the lateral outer portion of the shaft. B. The principal compressive group. This group of trabeculi springs from the medial portion of the shaft just above the group above described and spreads upward and in slightly radial smooth curved lines to reach the upper portion of the articular surface of the head of the femur. These trabeculi are placed very closely together and are the thickest ones seen in the upper femur. They are a prolongation of the shaft from which they spring in straight lines which gradually curve to meet at right angles the articular surface. There is no change as they cross the epiphyseal line. They also intersect at right angles the system of lines which rise from the lateral side of the femur. This system of principal and secondary compressive trabeculi corresponds in position and in curvature with the lines of maximum compressive stress which were traced out in the mathematical analysis of this portion of the femur. B. Lateral tensile system of trabeculi. As the compact bone of the outer portion of the shaft approaches the greater trochanter it gradually decreases in thickness. Beginning at a point about one inch below the level of the lower portion of the greater trochanter numerous thin trabeculi are given off from the outer portion of the shaft. These trabeculi lie in three distinct groups. C. The greater trochanter group. These trabeculi rise from the outer part of the shaft just below the greater trochanter and rise in thin curving lines to cross the region of the greater trochanter and end in its upper surface. Some of these filaments are poorly defined. This group intersects the trabeculi of group A which rise from the opposite side. The trabeculi of this group evidently carry small stresses, as is shown by their slenderness. D. The principal tensile group. This group springs from the outer part of the shaft immediately below group C and curves convexly upward and inward in nearly parallel lines across the neck of the femur and ends in the inferior portion of the head. These trabeculi are somewhat thinner and more widely spaced than those of the principal compressive group. B. All the trabeculi of this group cross those of groups A and B at right angles. This group is the most important of the lateral system, tensile, and, as will be shown later, the greatest tensile stresses of the upper femur are carried by the trabeculi of this group. E. The secondary tensile group. This group consists of the trabeculi which spring from the outer side of the shaft and lie below those of the preceding group. They curve upward and medially across the axis of the femur and end more or less irregularly after crossing the midline, but a number of these filaments end in the medial portion of the shaft and neck. They cross at right angles the trabeculi of group A. In general, the trabeculi of the tensile system are lighter in structure than those of the compressive system in corresponding positions. The significance of the difference in thickness of these two systems is that the thickness of the trabeculi varies with the intensity of the stresses at any given point. Comparison of figure 247 with figure 251 will show that the trabeculi of the compressive system carry heavier stresses than those of the tensile system in corresponding positions. For example, the maximum tensile stress at section 8 in the outermost fibre is 771 pounds per square inch, and at the corresponding point on the compressive side the compressive stress is 954 pounds per square inch. Similar comparisons may be made at other points, which confirm the conclusion that the thickness and closeness of spacing of the trabeculi varies in proportion to the intensity of the stresses carried by them. It will be seen that the trabeculi lie exactly in the paths of the maximum tensile and compressive stresses, and hence these trabeculi carry these stresses in the most economical manner. This is in accordance with the well-recognised principle of mechanics that the most direct manner of transmitting stress is in the direction in which the stress acts. Figure 249 shows a longitudinal frontal section through the left femur, which is the mate of the right femur on which the mathematical analysis was made. In this midsection, the system of tensile trabeculi, which rises from the lateral outer part of the shaft, and crosses over the central area to end in the medial portion of the shaft, neck and head, is clearly shown. This figure also shows the compressive system of trabeculi, which rises on the medial portion of the shaft and crosses the central area to end in the head, neck and greater trochanter. By comparing the position of these two systems of trabeculi shown in figure 249 with the lines of maximum and minimum stresses shown in figures 248 and 250, it is seen that the tensile system of trabeculi corresponds exactly with the position of the lines of maximum and minimum tensile stresses, which were determined by mathematical analysis. In a similar manner, the compressive system of trabeculi in figure 249 corresponds exactly with the lines of maximum and minimum compressive stresses computed by the mathematical analysis. The amount of vertical shear varies almost uniformly from a maximum of 90 pounds, 90% of the load on the femur head, midway between sections 4 and 6, to a minimum of 5.7 pounds at section 18. There is a gradual diminution of the spongy bond from section 6 to section 18 parallel with the diminished intensities of the vertical shear. The trabeculi of the upper femur, as shown in frontal sections, are arranged in two general systems, compressive and tensile, which correspond in position with the lines of maximum and minimum stresses in the trabeculi determined by the mathematical analysis of the femur as a mechanical structure. 2. The thickness and spacing of the trabeculi vary with the intensity of the maximum stresses at various points in the upper femur, being thickest and most closely spaced in the regions where the greatest stresses occur. 3. The amount of bony material in the spongy bone of the upper femur varies in proportion to the intensity of the shearing force at the various sections. 4. The arrangement of the trabeculi in the positions of maximum stresses is such that the greatest strength is secured with a minimum of material. Significance of the inner architecture of the shaft. 1. Economy for resisting shear. The shearing stresses are at a minimum in the shaft. It is clear that a minimum amount of material will be required to resist the shearing stresses. As horizontal and vertical shearing stresses are most efficiently resisted by material placed near the neutral plane, in this region a minimum amount of material will be needed near the neutral axis. In the shaft there is very little if any material in the central space, practically the only material near the neutral plane being in the compact bone, but lying at a distance from the neutral axis. This confirms the requirement of mechanics for economy, as a minimum of material is provided for resisting shearing stresses where these stresses are a minimum. 2. Economy for resisting bending moment. The bending moment increases from a minimum at section 4 to a maximum between sections 16 and 18, then gradually decreases almost uniformly to 0 near section 75. To resist bending moment stresses most effectively the material should be as far from the neutral axis as possible. It is evident that the hollow shaft of the femur is an efficient structure for resisting bending moment stresses, all of the material in the shaft being relatively at a considerable distance from the neutral axis. It is evident that the hollow shaft provides efficiently for resisting bending moment, not only due to the load on the femur head, but from any other loads tending to produce bending in other planes. 3. Economy for resisting axial stress. The inner architecture of the shaft is adapted to resist in the most efficient manner the combined action of the minimal shearing forces and the axial and maximum bending stresses. The structure of the shaft is such as to secure great strength with a relatively small amount of material. 4. The distal portion of the femur. In frontal section, in the distal 6 inches of the femur, there are to be seen two main systems of trabeculi, a longitudinal and a transverse system. The trabeculi of the former rise from the inner wall of the shaft and continue in perfectly straight lines parallel to the axis of the shaft and proceed to the epiphyseal line, once they continue in more or less curved lines to meet the articular surface of the knee joint at right angles at every point. Near the centre there are a few thin, delicate, longitudinal trabeculi which spring from the longitudinal trabeculi just described, to which they are joined by fine transverse filaments that lie in planes parallel to the sagittal plane. The trabeculi of the transverse system are somewhat lighter in structure than those of the longitudinal system and consist of numerous trabeculi at right angles to the latter. As the distal end of the femur is approached, the shaft gradually becomes thinner until the articular surface is reached, where there remains only a thin shell of compact bone. With the gradual thinning of the compact bone of the shaft, there is a simultaneous increase in the amount of the spongy bone and a gradual flaring of the femur which gives this portion of the bone a gradually increasing gross area of cross section. There is a marked thickening of the shell of bone in the region of the interconduloid fossa, where the anterior and posterior crucial ligaments are attached. The thickened area is about 0.4 inch in diameter and consists of compact bone from which a number of thick trabeculi pass at right angles to the main longitudinal system. The inner structure of the bone is here evidently adapted to the efficient distribution of the stresses arising from this ligamentary attachment. Near the distal end of the femur, the longitudinal trabeculi gradually assume curved paths and end perpendicularly to the articular surface at every point. Such a structure is in accordance with the principles of mechanics, as stresses can be communicated through a frictionless joint only in a direction perpendicular to the joint surface at every point. With practically no increase in the amount of bony material used, there is a greatly increased stability produced by the expansion of the lower femur from a hollow shaft of compact bone to a structure of much larger cross section almost entirely composed of spongy bone. Significance of the inner architecture of the distal part of the femur. The function of the lower end of the femur is to transmit through a hinged joint the loads carried by the femur. For stability, the width of the bearing on which the hinge action occurs should be relatively large. For economy of material, the expansion of the end bearing should be as lightly constructed as is consistent with proper strength. In accordance with the principles of mechanics, the most efficient manner in which stresses are transmitted is by the arrangement of the resisting material in lines parallel to the direction in which the stresses occur and in the paths taken by the stresses. Theoretically the most efficient manner to attain these objects would be to prolong the innermost filaments of the bone as straight lines parallel to the longitudinal axis of the bone, and gradually to flare the outer shell of compact bone outward, and continuing to give off filaments of bone parallel to the longitudinal axis as the distal end of the femur is approached. These filaments should be well braced transversely, and each should carry its proportionate part of the total load parallel to the longitudinal axis, transmitting it eventually to the articular surface and in a direction perpendicular to that surface. Referring to figure 249, it is seen that the large expansion of the bone is produced by the gradual transition of the hollow shaft of compact bone to cancelated bone, resulting in the production of a much larger volume. The trabeculi are given off from the shaft in lines parallel to the longitudinal axis, and are braced transversely by two series of trabeculi at right angles to each other in the same manner as required theoretically for economy. Although the action of the muscles exerts an appreciable effect on the stresses in the femur, it is relatively small and very complex to analyse, and has not been considered in the above analysis. The femur is ossified from five centres, one for the body, one for the head, one for each trochanter, and one for the lower extremity. Of all the long bones except the clavicle, it is the first to show traces of ossification. This commences in the middle of the body at about the seventh week of fetal life, and rapidly extends upward and downward. The centres in the epiphyces appear in the following order. In the lower end of the bone, at the ninth month of fetal life, from this centre the contiles and epicontiles are formed, in the head. At the end of the first year after birth, in the greater trochanter, during the fourth year, and in the lesser trochanter between the thirteenth and fourteenth years. The order in which the epiphyces are joined to the body is the reverse of that of their appearance. They are not united until after puberty, the lesser trochanter being first joined, then the greater, then the head, and lastly the inferior extremity, which is not united until the twentieth year. End of section number 46 Section 47 of Gray's Anatomy Part 1 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 Steve Foreman Anatomy of the Human Body Part 1 by Henry Gray The patella The patella is a flat triangular bone situated on the front of the knee joint. It is usually regarded as a sesamoid bone, developed in the tendon of the quadriceps femoris, and resembles these bones, one, in being developed in a tendon, two, in its centre of ossification, presenting a knotty or tuberculated outline, three, in being composed mainly of dense, cancerless tissue. It serves to protect the front of the joint and increases the leverage of the quadriceps femoris by making it act at a greater angle. It has an anterior and a posterior surface, three borders, and an apex. Surfaces The anterior surface is convex, perforated by small apertures for a passage of nutrient vessels and marked by numerous rough longitudinal striate. This surface is covered, in the recent state, by an expansion from the tendon of the quadriceps femoris, which is continuous below with the superficial fibres of the ligament and patella. It is separated from the integument by a bursa. The posterior surface presents above a smooth oval articular area divided into two facets by a vertical ridge. The ridge corresponds to the groove on the patella surface of the femur, and the facets to the medial and lateral parts of the same surface. The lateral facet is the broader and deeper. Below the articular surface is a rough, convex, non-articular area, the lower half of which gives attachment to the ligament and patella. The upper half is separated from the head of the tibia by adipose tissue. Borders The base or superior border is thick and sloped from behind downward and forward. It gives attachment to that portion of the quadriceps femoris, which is derived from the rectus femoris and vastus intermedius. The medial and lateral borders are thinner and converge below. They give attachment to those portions of the quadriceps femoris, which are derived from the vasti lateralis and medialis. Apex The apex is pointed and gives attachment to the ligament and patella. Structure The patella consists of nearly uniform, dense, cancerous tissue covered by a thin, compact lamina. The cancilii, immediately beneath the anterior surface, are arranged parallel with it. In the rest of the bone, they radiate from the articular surface toward the other parts of the bone. Osification The patella is ossified from a single center, which usually makes its appearance in the second or third year, but may be delayed until the sixth year. More rarely, the bone is developed by two centers, placed side by side. Osification is completed about the age of puberty. Articulation The patella articulates with the femur. The tibia The tibia is situated at the medial side of the leg, and accepting the femur is the longest bone of the skeleton. It is prismoid in form, expanded above, where it enters into the knee joint, contracted in the lower third, and again enlarged, but to a lesser extent below. In the male, its direction is vertical, and parallel with the bone of the opposite side. But in the female, it has a slightly oblique direction downward and lateralward, to compensate for the greater obliquity of the femur. It has a body and two extremities. The upper extremity The upper extremity is large and expanded into two immenences, the medial and lateral condyles. The superior articular surface presents two smooth articular facets. The medial facet, oval in shape, is slightly concave from side to side, and from before backward. The lateral, nearly circular, is concave from side to side, but slightly convex from before backward. Especially at its posterior part, where it is prolonged onto the posterior surface for a short distance. The central portions of these facets articulate with the condyles of the femur, while their peripheral portions support the menisci of the knee joint, which here intervene between the two bones. Between the articular facets, but nearer the posterior than the anterior aspect of the bone, is the intercondyloid eminence, or spine of tibia. Surmounted on either side by a prominent tubercle onto the sides of which the articular facets are prolonged. In front of and behind the intercondyloid eminence are rough depressions for the attachment of the anterior and posterior cruciate ligaments and the menisci. The anterior surfaces of the condyle are continuous with one another, forming a large, somewhat flattened area. This area is triangular, broad above, and perforated by large vascular foramina, narrow below where it ends, in the large oblong elevation, the tuberosity of the tibia, which gives attachment to the ligamentous patella. A bursa intervenes between the deep surface of the ligament and the part of the bone immediately above the tuberosity. Posteriorly, the condyles are separated from each other by a shallow depression, the posterior intercondyloid fossa, which gives attachment to part of the posterior cruciate ligament of the knee joint. The medial condyle presents posteriorly a deep transverse groove for the insertion of the tendon of the semi-membinosis. Its medial surface is convex, rough, and prominent. It gives attachment to the tibial collateral ligament. The lateral condyle presents posteriorly a flat, articular facet, nearly circular in form, directed downward, backward, and lateralward for articulation with the head of the fibula. Its lateral surface is convex, rough, and prominent in front. On it is an eminence situated on a level with the upper border of the tuberosity and at the junction of its anterior and lateral surfaces for the attachment of the iliotibial band. Just below this is a part of the extensor digitorum longus takes off, and a slip from the tendon of the biceps femoris is inserted. The body or shaft. The body has three borders and three surfaces. Borders. The anterior crest or border, the most prominent of the three, commences above at the tuberosity and ends below at the anterior margin of the medial malleolus. It's sinuous and prominent in the upper two thirds of its extent, but smooth and rounded below. It gives attachment to the deep fascia of the leg. The medial border is smooth and rounded above and below, but more prominent in the center. It begins at the back part of the medial condyle and ends at the posterior border of the medial malleolus. Its upper part gives attachment to the tibial collateral ligament of the knee joint to the extent of about five centimeters, an insertion to some fibers of the popliteus from the middle third of some fibers of the soleus and flexor digitorum longus take origin. The interosseous crest or lateral border is thin and prominent, especially its central part, and gives attachment to the interosseous membrane. It commences above in front of the fibular articular facet and bifurcates below to form the boundaries of a triangular rough surface for the attachment of the interosseous ligament connecting the tibia and fibula. Surfaces. The medial surface is smooth, convex, and broader above than below. Its upper third, directed forward and medialward, is covered by the aponeurosis derived from the tendon of the sartorius, and by the tendons of the gracilis and semi-tendinosis, all of which are inserted nearly as far forward as the anterior crest. In the rest of its extent it is subcutaneous. The lateral surface is narrower than the medial. Its upper two-thirds present a shallow groove for the origin of the tibialis anterior. Its lower third is smooth, convex, curves gradually forward to the anterior aspect of the bone, and is covered by the tendons of the tibialis anterior. Extensor halicus longus and the extensor digitorum longus, arranged in this order from the medial side. The posterior surface presents, at its upper part, a prominent ridge, the popliteal line, which extends obliquely downward from the back part of the articular facet for the fibula to the medial border. At the junction of its upper and middle thirds, it marks the lower limit of the insertion of the popliteus, serves for the attachment of the fascia covering this muscle, and gives origin to part of the soleus, flexor digitorum longus, and tibialis posterior. The triangular area above this line gives insertion to the popliteus. The middle third of the posterior surface is divided by a vertical ridge into two parts. The ridge begins at the popliteal line and is well marked above, but indistinct below. The medial and broader portion gives origin to the flexor digitorum longus, the lateral and narrower to part of the tibialis posterior. The remaining part of the posterior surface is smooth and covered by the tibialis posterior, flexor digitorum longus, and the flexor halicus longus. Immediately below the popliteal line is the nutrient foramen, which is large and directed obliquely downward. The lower extremity. The lower extremity is much smaller than the upper, presents five surfaces. It is prolonged downward on the medial side as a strong process, the medial malleolus. Surfaces. The inferior articular surface is quadrilateral and smooth for articulation with the talus. It is concave from before backward, broader in front than behind, and traversed from before backward by a slight elevation separating two depressions. It is continuous with that on the medial malleolus. The anterior surface of the lower extremity is smooth and rounded above, and covered by the tendons of the extensor muscles. Its lower margin presents a rough transverse depression for the attachment of the articular capsule of the ankle joint. The posterior surface is traversed by a shallow groove directed obliquely downward and medialward, continuous with a similar groove on the posterior surface of the talus, and serving for the passage of the tendon of the flexor halicus longus. The lateral surface presents a triangular rough depression for the attachment of the inferior interosseous ligament connecting it with the fibula. The lower part of this depression is smooth, covered with cartilage in the fresh state, and articulates with the fibula. The surface is bounded by two prominent borders, continuous above with the interosseous crest. They afford attachment to the anterior and posterior ligaments of the lateral malleolus. The medial surface is prolonged downward to form a strong pyramidal process, flattened from without inward, the medial malleolus. The medial surface of this process is convex and subcutaneous. Its lateral or articular surface is smooth and slightly concave, and articulates with the talus. Its anterior border is rough for the attachment of the anterior fibres of the deltoid ligament of the ankle joint. Its posterior border presents a broad groove, the malleolar sulcus, directed obliquely downward and medialward, and occasionally double. This sulcus lodges the tendons of the tibialis posterior and flexor digitorum longus. The summit of the medial malleolus is marked by a rough depression behind for the attachment of the deltoid ligament. The structure of the tibia is like that of the other long bones. The compact wall of the body is thickest at the junction of the middle and lower thirds of the bone. Ausification The tibia is ossified from three centers, one for the body and one for either extremity. Ausification begins in the center of the body about the seventh week of fetal life and gradually extends towards the extremities. The center for the upper epiphysis appears before or shortly after birth. It is flattened in form and has a thin, tongue-shaped process in front which forms the tuberosity. That for the lower epiphysis appears in the second year. The lower epiphysis joins the body at about the eighteenth, and the upper one joins about the twentieth year. Two additional centers occasionally exist, one for the tongue-shaped process of the upper epiphysis which forms the tuberosity, and one for the medial malleolus. End of section forty-seven. Section forty-eight of Gray's Anatomy, part one. 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 Leanne Howlett. Anatomy of the Human Body, part one by Henry Gray, the fibula. Six C, part six, the fibula, calf bone. The fibula is placed on the lateral side of the tibia, with which it is connected above and below. It is the smaller of the two bones, and in proportion to its length, the most slender of all the long bones. Its upper extremity is small, placed toward the back of the head of the tibia, below the level of the knee joint, and excluded from the formation of this joint. Its lower extremity inclines a little forward, so as to be on a plane anterior to that of the upper end. It projects below the tibia, and forms the lateral part of the ankle joint. The bone has a body and two extremities. The upper extremity, or head, capitulum fibuli, proximal extremity. The upper extremity is of an irregular, quadrate form, presenting above a flattened, articular surface, directed upward, forward, and medial word, for articulation with a corresponding surface on the lateral condyle of the tibia. On the lateral side is the thick and rough prominence continued behind into a pointed eminence, the apex, styloid process, which projects upward from the posterior part of the head. The prominence at its upper and lateral part gives attachment to the tendon of the biceps femoris, and to the fibular collateral ligament of the knee joint, the ligament dividing the tendon into two parts. The remaining part of the circumference of the head is rough for the attachment of muscles and ligaments. It presents in front a tubercle for the origin of the upper and interior fibers of the peronius longus, and a surface for the attachment of the anterior ligament of the head, and behind another tubercle for the attachment of the posterior ligament of the head, and the origin of the upper fibers of the soleus. The body or shaft, corpus fibuli. The body presents four borders, the anterior lateral, the anterior medial, the posterior lateral, and the posterior medial, and four surfaces, anterior, posterior, medial, and lateral. Borders. The anterolateral border begins above in front of the head, runs vertically downward to a little below the middle of the bone, and then curving somewhat lateral word, bifurcates so as to embrace a triangular subcutaneous surface immediately above the lateral malleolus. This border gives attachment to an intramuscular septum which separates the extensor muscles on the anterior surface of the leg from the peronii longus and brevis on the lateral surface. The antero-medial border, or enterosius crest, is situated close to the medial side of the preceding and runs nearly parallel with it in the upper third of its extent, but diverges from it in the lower two-thirds. It begins above just beneath the head of the bone, sometimes it is quite indistinct for about 2.5 cm below the head, and ends at the apex of a rough triangular surface immediately above the articular facet of the lateral malleolus. It serves for the attachment of the enterosius membrane which separates the extensor muscles in front from the flexor muscles behind. The posterior lateral border is prominent. It begins above at the apex and ends below in the posterior border of the lateral malleolus. It is directed lateral word above, backward in the middle of its course, backward in a little medial word below, and gives attachment to an aponeurosis which separates the peronii on the lateral surface from the flexor muscles on the posterior surface. The posterior medial border, sometimes called the oblique line, begins above at the medial side of the head, and ends by becoming continuous with the enterosius crest at the lower fourth of the bone. It is well marked and prominent at the upper and middle parts of the bone. It gives attachment to an aponeurosis which separates the tibialis posterior from the soleus and flexor halusus longus. Surfaces. The anterior surface is the interval between the enterolateral and enteromedial borders. It is extremely narrow and flat in the upper third of its extent. Broader and grooved longitudinally in its lower third, it serves for the origin of three muscles, the extensor digitorum longus, extensor halusus longus, and peronius tertius. The posterior surface is the space included below the postural lateral and the postural medial borders. It is continuous below with the triangular area above the articular surface of the lateral malleolus. It is directed backward above, backward in medial word at its middle, directly medial word below. Its upper third is rough for the origin of the soleus, its lower part presents a triangular surface connected to the tibia by a strong enterosius ligament. The intervening part of the surface is covered by the fibers of origin of the flexor halusus longus. Near the middle of this surface is the nutrient foramen, which is directed downward. The medial surface is the interval included between the enteromedial and the postural medial borders. It is grooved for the origin of the tibiaeolus posterior. The lateral surface is the space between the enterolateral and postural lateral borders. It is broad and often deeply grooved. It is directed lateral word in the upper two thirds of its course, backward in the lower third, where it is continuous with the posterior border of the lateral malleolus. This surface gives origin to the peroniii longus and brevis. The lower extremity are lateral malleolus, malleolus lateralus, distal extremity, external malleolus. The lower extremity is of a pyramidal form and somewhat flattened from side to side. It descends to a lower level than the medial malleolus. The lateral surface is convex, subcutaneous, and continuous with the triangular, subcutaneous surface on the lateral side of the body. The medial surface presents in front a smooth triangular surface, convex from above downward, which articulates with a corresponding surface on the lateral side of the talus. Behind and beneath the articular surface is a rough depression, which gives attachment to the posterior talofibular ligament. The anterior border is thick and rough and marked below by a depression for the attachment of the anterior talofibular ligament. The posterior border is broad and presents the shallow malleolus sulcus for the passage of the tendons of the perionii longus and brevis. The summit is rounded and give attachment to the clicanofibular ligament. Osification. The fibula is ossified from three centers, one for the body and one for either end. Osification begins in the body about the eighth week of fetal life and extends toward the extremities. At birth, the ends are cartilaginous. Osification commences in the lower end in the second year and in the upper about the fourth year. The lower epiphysis, the first to ossify, unites with the body about the twentieth year. The upper epiphysis joins about the twenty-fifth year. End of section forty-eight, recording by Leanne Howlett.