 Section 9 of Gray's Anatomy Part 2. 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 2 by Henry Gray. Articulations of the upper extremity. Sternoclavicular articulation. The sternoclavicular articulation is a double-arthrodial joint. The parts entering into its formation are the sternal end of the clavicle, the upper and lateral part of the manubrium sterni, and the cartilage of the first rib. The articular surface of the clavicle is much larger than that of the sternum, and is invested with a layer of cartilage, which is considerably thicker than that on the ladder bone. Footnote. According to Brooke, the sternal end of the clavicle is covered by a tissue which is fibrous rather than cartilaginous in structure. End of footnote. The ligaments of this joint are the articular capsule, the anterior sternoclavicular, the posterior sternoclavicular, the interclavicular, the costoclavicular, the articular disc. The articular capsule, capsular articularis, capsular ligament. The articular capsule surrounds the articulation and varies in thickness and strength. In front and behind, it is of considerable thickness, and forms the anterior and posterior sternoclavicular ligaments. But above, and especially below, it is thin and partakes more of the character of areolar than of true fibrous tissue. The anterior sternoclavicular ligament, ligamentum sternoclaviculari anterior. The anterior sternoclavicular ligament is a broad band of fibers covering the anterior surface of the articulation. It is attached above to the upper and front part of the sternal end of the clavicle, and passing obliquely downward and medial word is attached below to the front of the upper part of the manubrium sterni. The sternocleidomastoidius and the intugument behind, it is in relation with the capsule, the articular disc, and the two synovial membranes. The posterior sternoclavicular ligament, ligamentum sternoclaviculari posterioris. The posterior sternoclavicular ligament is a similar band of fibers covering the posterior surface of the articulation. It is attached above to the upper and back part of the sternal end of the clavicle, and passing obliquely downward and medial word is fixed below to the back of the upper part of the manubrium sterni. It is in relation, in front, with the articular disc and synovial membranes, behind, with the sternohiodeus and sternothiodeus. The interclavicular ligament, ligamentum interclaviculari. This ligament is a flattened band which varies considerably in form and size in different individuals. It passes in a curved direction from the upper part of the sternal end of one clavicle to that of the other, and is also attached to the upper margin of the sternum. It is in relation, in front, with the intugument and sternocleidomastoidii behind, with the sternothiodeus. The castoclavicular ligament, ligamentum castoclavicularae rhomboid ligament. This ligament is short, flat, strong, and rhomboid in form. Attached below to the upper and medial part of the cartilage of the first rib, it ascends obliquely downward and lateralward, and is fixed above to the costal tuberosity on the undersurface of the clavicle. It is in relation, in front, with the tendon of origin of the subclavius behind, with the subclavian vein. The articular disc, discus articularis. The articular disc is flat and nearly circular, interposed between the articulating surfaces of the sternum and clavicle. It is attached above to the upper and posterior border of the articular surface of the clavicle, below to the cartilage of the first rib, near its junction with the sternum, and by its circumference to the interclavicular and anterior and posterior sternoclavicular ligaments. It is thicker at the circumference, especially its upper and back part than at its center. It divides the joint into two cavities, each of which is furnished with a synovial membrane. Synovial Membranes Of the two synovial membranes found in this articulation, the lateral is reflected from the sternal end of the clavicle over the adjacent surface of the articular disc, and around the margin of the facet on the cartilage of the first rib. The medial is attached to the margin of the articular surface of the sternum and closed the adjacent surface of the articular disc. The latter is the larger of the two. Movements This articulation admits of a limited amount of motion in nearly every direction, upward, downward, backward, forward, as well as circumduction. When these movements take place in the joint, the clavicle in its motion carries the scapula with it, this bone gliding on the outer surface of the chest. This joint therefore forms the center from which all movements of the supporting arch of the shoulder originate, and is the only point of articulation of the shoulder girdle with the trunk. The movements attendant on elevation and depression of the shoulder take place between the clavicle and the articular disc, the bone rotating upon the ligament on an axis drawn from before backward through its own articular facet. When the shoulder is moved forward and backward, the clavicle with the articular disc rolls to and fro on the articular surface of the sternum, revolving with a sliding movement around an axis drawn nearly vertically through the sternum. In the circumduction of the shoulder, which is compounded of these two movements, the clavicle revolves upon the articular disc and the latter with the clavicle rolls upon the sternum. Elevation of the shoulder is limited principally by the costoclavicular ligament, depression by the interclavicular ligament and articular disc. The muscles which raise the shoulder are the upper fibers of the trapezius, the levator scapulae, and the clavicular head of the sternum cleodomastoidius, assisted to a certain extent by the rhomboidiae, which pull the vertebral border of the scapula backward and upward, and so raise the shoulder. The depression of the shoulder is principally affected by gravity, assisted by the subclavius, pectoralis minor, and lower fibers of the trapezius. The shoulder is drawn backward by the rhomboidiae and the middle and lower fibers of the trapezius and forward by the suritus anterior and pectoralis minor. End of section 9 Section 10 of Grey's Anatomy Part 2 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 Laurie Ann Walden. Anatomy of the Human Body Part 2 by Henry Gray Acromioclavicular articulation Caracoacromial superior and inferior transverse Articulatioacromioclavicularis Scapuloclavicular articulation The acromioclavicular articulation is an arthrodial joint between the acromial end of the clavicle and the medial margin of the acromion of the scapula. Its ligaments are The articular capsule The superior acromioclavicular The inferior acromioclavicular The articular disc The caracoaclavicular trapezoid and conoid The articular capsule Capsular articularis Capsular ligament The articular capsule completely surrounds the articular margins and is strengthened above and below by the superior and inferior acromioclavicular ligaments. The superior acromioclavicular ligament Ligamentum acromioclaviculare This ligament is a quadrilateral band covering the superior part of the articulation and extending between the upper part of the acromial end of the clavicle and the adjoining part of the upper surface of the acromion. It is composed of parallel fibers which interlace with the aponeuroses of the trapezius and deltoidius. Below it is in contact with the articular disc when this is present. The inferior acromioclavicular ligament This ligament is somewhat thinner than the preceding. It covers the under part of the articulation and is attached to the adjoining surfaces of the two bones. It is in relation above in rare cases with the articular disc. Below with the tendon of the supraspinatus. The articular disc discus articularis The articular disc is frequently absent in this articulation. When present it generally only partially separates the articular surfaces and occupies the upper part of the articulation. More rarely it completely divides the joint into two cavities. The synovial membrane There is usually only one synovial membrane in this articulation, but when a complete articular disc is present there are two. The coracoclavicular ligament Ligamentum coracoclaviculari This ligament serves to connect the clavicle with the corcoid process of the scapula. It does not properly belong to this articulation, but is usually described with it since it forms a most efficient means of retaining the clavicle in contact with the acromion. It consists of two fasciculi called the trapezoid and conoid ligaments. The trapezoid ligament, ligamentum trapezoidium, the anterior and lateral fasciculus, is broad, thin, and quadrilateral. It is placed obliquely between the coracoid process and the clavicle. It is attached below to the upper surface of the coracoid process, above to the oblique ridge on the under surface of the clavicle. Its anterior border is free. Its posterior border is joined with the conoid ligament. The two forming, by their junction, an angle projecting backward. The conoid ligament, ligamentum conoidium, the posterior and medial fasciculus, is a dense band of fibers, conical in form, with its base directed upward. It is attached by its apex to a rough impression at the base of the coracoid process, medial to the trapezoid ligament, above by its expanded base to the coracoid tuberosity on the under surface of the clavicle, and to a line proceeding medialward from it for 1.25 centimeters. These ligaments are in relation, in front, with a subclavius and deltoidius, behind, with a trapezius. Movements. The movements of this articulation are of two kinds. One, a gliding motion of the articular end of the clavicle on the acromion. Two, rotation of the scapula forward and backward upon the clavicle. The extent of this rotation is limited by the two portions of the coraco-clavicular ligament, the trapezoid limiting rotation forward and the conoid backward. The acromioclavicular joint has important functions in the movements of the upper extremity. It has been well pointed out by Humphrey that if there had been no joint between the clavicle and scapula, the circular movement of the scapula on the ribs, as in throwing the shoulders backward or forward, would have been attended with a greater alteration in the direction of the shoulder than is consistent with the free use of the arm in such positions. And it would have been impossible to give a blow straightforward with the full force of the arm. That is to say, with the combined force of the scapula arm and forearm. This joint, as he happily says, is so adjusted as to enable either bone to turn in a hinge-like manner upon a vertical axis drawn through the other. And it permits the surfaces of the scapula, like the baskets in a roundabout swing, to look the same way in every position, or nearly so. Again, when the whole arch formed by the clavicle and scapula rises and falls in elevation or depression of the shoulder, the joint between these two bones enables the scapula still to maintain its lower part in contact with the ribs. The ligaments of the scapula. The ligaments of the scapula are the caracochromial ligament, ligamentum caracochromiali. This ligament is a strong triangular band extending between the caracoid process and the acromion. It is attached by its apex to the summit of the acromion just in front of the articular surface for the clavicle, and by its broad base to the whole length of the lateral border of the caracoid process. This ligament, together with the caracoid process and the acromion, forms a vault for the protection of the head of the humerus. It is in relation above with the clavicle and under surface of the deltoidius, below with the tendon of the supraspinatus, a bursa being interposed. Its lateral border is continuous with a dense lamina that passes beneath the deltoidius upon the tendons of the supraspinatus and infraspinatus. The ligament is sometimes described as consisting of two marginal bands and a thinner intervening portion, the two bands being attached respectively to the apex and the base of the caracoid process and joining together at the acromion. When the pectoralis minor is inserted, as occasionally is the case, into the capsule of the shoulder joint instead of into the caracoid process, it passes between these two bands and the intervening portion of the ligament is then deficient. The superior transverse ligament, ligamentum transversum scapulae superius, transverse or suprascapular ligament. This ligament converts the scapular notch into a foramen. It is a thin and flat fasciculus, narrower at the middle than at the extremities, attached by one end to the base of the caracoid process and by the other to the medial end of the scapular notch. The suprascapular nerve runs through the foramen. The transverse scapular vessels cross over the ligament. The ligament is sometimes ossified. The inferior transverse ligament, ligamentum transversum scapulae inferius spina glenoid ligament. This ligament is a weak membranous band situated behind the neck of the scapula and stretching from the lateral border of the spine to the margin of the glenoid cavity. It forms an arch under which the transverse scapular vessels and suprascapular nerve enter the infraspinatus fossa. End of Section 10 Section 11 of Gray's Anatomy Part 2 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 2 by Henry Gray. Section 11 Humeral Articulation or Shoulder Joint Articulatio humeri. The shoulder joint is an anarthrodial or ball and socket joint. The bones entering into its formation are the hemispherical head of the humerus and the shallow glenoid cavity of the scapula, an arrangement which permits a very considerable movement while the joint itself is protected against displacement by the tendons which surround it. The ligaments do not maintain the joint surfaces in that position because when they alone remain, the humerus can be separated to a considerable extent from the glenoid cavity. Their use therefore is to limit the amount of movement. The joint is protected above by an arch formed by the coracoid process, the acromion, and the coracoachromial ligament. The articular cartilage on the head of the humerus is thicker at the center than at the circumference, the reverse being the case with the articular cartilage of the glenoid cavity. The ligaments of the shoulder are the articular capsule, the coracohumeral, the glenohumeral, the transverse humeral, the glenoidal labrum. Footnote. The long tendon of origin of the biceps brachii also acts as one of the ligaments of this joint. See the observations on page 287 on the function of the muscles passing over more than one joint. End of footnote. The articular capsule. Capsula articularis. Capsular ligament. The articular capsule completely encircles the joint, being attached above to the circumference of the glenoid cavity beyond the glenoid labrum, below to the anatomical neck of the humerus, approaching nearer to the articular cartilage above than in the rest of its extent. It is thicker above and below than elsewhere, remarkably loose and lax, that it has no action in keeping the bones in contact, but allows them to be separated from each other more than 2.5 cm, an evident provision for that extreme freedom of movement which is peculiar to this articulation. It is strengthened above by the supraspinatus, below by the long head of the triceps brachii, behind by the tendons of the infraspinatus and pterus minor, and in front by the tendon of the subscapularis. There are usually three openings in the capsule. One anteriorly, below the coracoid process, establishes a communication between the joint and a bursa beneath the tendon of the subscapularis. The second, which is not constant, is at the posterior part, where an opening sometimes exists between the joint and a bursal sac under the tendon of the infraspinatus. The third is between the tubercles of the humerus, and the passage of the long tendon of the biceps brachii. The coracohumeral ligament, ligamentum coracohumorale. This ligament is a broad band which strengthens the upper part of the capsule. It arises from the lateral border of the coracoid process and passes obliquely downward and lateralward to the front of the greater tubercle of the humerus, blending with the tendon of the supraspinatus. This ligament is intimately united to the capsule by its hinder and lower border, but its anterior and upper border presents a free edge, which overlaps the capsule. Glenohumeral ligaments. In addition to the coracohumeral ligament, three supplemental bands, which are named the Glenohumeral ligaments, strengthen the capsule. These may be best seen by opening the capsule at the back of the joint and removing the head of the humerus. One on the medial side of the joint passes from the medial edge of the glenoid cavity to the lower part of the lesser tubercle of the humerus. A second at the lower part of the joint extends from the under edge of the glenoid cavity to the under part of the anatomical neck of the humerus. A third at the upper part of the joint is fixed above to the apex of the glenoid cavity close to the root of the coracoid process and passing downward along the medial edge of the tendon of the biceps brachii is attached below to a small depression in the lesser tubercle of the humerus. In addition to these, the capsule is strengthened in front by two bands derived from the tendons of the pectoralis major and the teres major respectively. The transverse humeral ligament is a broad band passing from the lesser to the greater tubercle of the humerus and always limited to that portion of the bone which lies above the epiphyseal line. It converts the intertubercular groove into a canal and is the homologue of the strong process of bone which connects the summits of the two tubercles in the muscox. The glenoidal labrum labrium glenoidole glenoid ligament is a fibrocartilaginous rim attached around the margin of the glenoid cavity. It is triangular on section, the base being fixed to the circumference of the cavity while the free edge is thin and sharp. It is continuous above with the tendon of the long head of the biceps brachii to blend with the fibrous tissue of the labrum. It deepens the articular cavity and protects the edges of the bone. Synovial membrane The synovial membrane is reflected from the margin of the glenoid cavity over the labrum. It is then reflected over the inner surface of the capsule and covers the lower part and sides of the anatomical neck of the humerus as far as the articular cartilage on the head of the bone. The tendon of the long head of the biceps brachii passes through the capsule and is enclosed in a tubular sheath of synovial membrane which is reflected upon it from the summit of the glenoid cavity and is continued around the tendon into the intertubercular groove as far as the surgical neck of the humerus. The tendon thus traverses the articulation, but is not contained within the synovial cavity. Bursi The bursi in the neighborhood of the shoulder joint are the following. One, a constant bursa is situated between the tendon of the subscapularis muscle and the capsule. It communicates with the synovial cavity through an opening in the front of the capsule. Two, a bursa which occasionally communicates with the joint is sometimes found between the tendon of the infraspinatus and the capsule. Three, a large bursa exists between the under surface of the deltoidius and the capsule but does not communicate with the joint. This bursa is prolonged under the acromion and intervenes between these structures and the capsule. Four, a large bursa is situated on the summit of the acromion. Five, a bursa is frequently found between the coracoid process and the capsule. Six, a bursa exists beneath the coracobrachialis. Seven, one lies between the teres major and the long head of the triceps brachii. Eight, one is placed in front of and another behind the tendon of the latissimus dorsi. The muscles in relation with the joint are above the supraspinatus below the long head of the triceps brachii in front the subscapularis behind the infraspinatus and teres minor within the tendon of the long head of the biceps brachii. The deltoidius covers the articulation in front, behind, and laterally. The arteries supplying the joint are articular branches of the anterior and posterior humoral circumflex and transverse scapular. The nerves are derived from the axillary and suprascapular. The shoulder joint is capable of every variety of movement. Flexion, extension, abduction, adduction, circumduction, and rotation. The humerus is flexed, drawn forward by the pectoralis major anterior fibers of the deltoidius, and when the forearm is flexed by the biceps brachii. Extended, drawn backward by the latissimus dorsi teres major posterior fibers of the deltoidius and, when the forearm is extended by the triceps brachii. It is abducted by the deltoidius and supraspinatus. It is abducted by the subscapularis pectoralis major latissimus dorsi and teres major the limb. It is rotated outward by the infraspinatus and teres minor, and it is rotated inward by the subscapularis latissimus dorsi teres major pectoralis major and the anterior fibers of the deltoidius. The most striking peculiarities in this joint are 1. The large size of the head of the humerus in comparison with the depth of the glenoid cavity even when this ladder is supplemented by the glenoid labrum. 2. The looseness of the capsule of the joint. 3. The intimate connection of the capsule with the muscles attached to the head of the humerus. 4. The peculiar relation of the tendon of the long head of the biceps brachii to the joint. It is in consequence of the relative sizes of the two articular surfaces and the looseness of the articular capsule that the joint enjoys such free movement in all directions. When these movements of the arm are arrested in the shoulder joint by the contact of the bony surfaces and by the tension of the fibers of the capsule together with that of the muscles acting as accessory ligaments the arm can be carried considerably farther by the movements of the scapula involving of course motion of the acromio and sternoclavicular joints. These joints are therefore to be regarded as accessory structures to the shoulder joint. The extent of the scapular movements is very considerable especially in extreme elevation of the arm a movement best accomplished when the arm is thrown somewhat forward and outward because the margin of the head of the humerus is by no means a true circle. Its greatest diameter is from the intertubricular groove downward medial word and backward and the greatest elevation of the arm can be obtained by rolling its articular surface in the direction of this measurement. The great width of the central portion of the humeral head also allows a very free horizontal movement when the arm is raised to a right angle in which movement the arch formed by the acromion, the coracoid process, and the coracoacromial ligament constitutes a sort of supplemental articular cavity for the head of the bone. The looseness of the capsule is so great that the arm will fall about 2.5 centimeters from the scapula when the muscles are dissected from the capsule and an opening made in it to counteract the atmospheric pressure. The movements of the joint therefore are not regulated by the capsule so much as by the surrounding muscles and by the pressure of the atmosphere. An arrangement which renders the movements of the joint much more easy than they would otherwise have been and permits a swinging pendulum-like vibration of the limb when the muscles are at rest. Humphry. The fact also that in all ordinary positions of the joint the capsule is not put on the stretch enables the arm to move freely in all directions. Extreme movements are checked by the tension of appropriate portions of the capsule as well as by the interlocking of the bones. Thus it is said that abduction is checked by the contact of the great tuberosity with the upper edge of the glenoid cavity by the tension of the coraco-humeral ligament. Boni-e Bouchard. Cleveland maintains that the limitations of movement at the shoulder joint are due to the structure of the joint itself. The glenoidal fibrum fitting in different positions of the elevated arm into the anatomical neck of the humerus. The scapula is capable of being moved upward and downward, forward and backward, or by a combination of these movements circumducted on the wall of the chest. The muscles which raise the scapula are the upper fibers of the trapezius, the levator scapulae and the rhombordii. Those which depress it are the lower fibers of the trapezius, the pectoralis minor and through the clavicle, the subclavius. The scapula is drawn backward by the rhombordii and the middle and lower fibers of the trapezius and forward by the serratus anterior and pectoralis minor, assisted when the arm is fixed by the pectoralis major. The mobility of the scapula is very considerable and greatly assists the movements of the arm at the shoulder joint. Thus in raising the arm from the side the deltoidius and supraspinatus can only lift it to a right angle with the trunk, the further elevation of the limb being affected by the trapezius and the serratus anterior moving the scapula on the wall of the chest. This mobility is of special importance and ankylosis of the shoulder joint, the movements of this bone compensating to a very great extent for the immobility of the joint. Cascart has pointed out that in abducting the arm and raising it to the head, the scapula rotates through the whole movement with the exception of a short space at the beginning and at the end that the humerus moves on the scapula not only while passing from the hanging to the horizontal position but also in traveling upward as it approaches the vertical above. That the clavicle moves not only during the second half of the movement but in the first as well though to a less extent. That is, the scapula and clavicle are concerned in the first stage as well as in the second and that the humerus is partly involved in the second as well as chiefly in the first. The intimate union of the tendons of the supraspinatus, infraspinatus, teresminer and subscapularis with the capsule converts these muscles into elastic and spontaneously acting ligaments of the joint. The peculiar relations of the tendon of the long head of the biceps brachii to the shoulder joint appear to be of various purposes. In the first place, by its connection with both the shoulder and elbow the muscle harmonizes the action of the two joints and acts as an elastic ligament in all positions in the manner previously discussed. It strengthens the upper part of the articular cavity and prevents the head of the humerus from being pressed up against the acromion. When the deltoidius contracts it thus fixes the head of the humerus as the center of motion in the glenoid cavity. By its passage along the intertubercular groove it assists in studying the head of the humerus in the various movements of the arm. When the arm is raised from the side it assists the supraspinatus and infraspinatus in rotating the head of the humerus in the glenoid cavity. It also holds the head of the bone firmly in contact with the glenoid cavity and prevents it slipping over its lower edge or being displaced by the action of the latissimus dorsi and pectoralis major as in climbing in many other movements. End of section 11. Section 12 of Gray's Anatomy Part 2 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 2 by Henry Gray Section 12 Elbow Joint Articulatio Cubidi The elbow joint is a ginglimus or hinge joint. The trochlea of the humerus is received into the semi-lunar notch of the ulna and the capitulum of the humerus articulates with a phobia on the head of the radius. The articular surfaces are connected together by a capsule which is thickened medially and laterally and to a less extent in front and behind. These sections are usually described as distinct ligaments under the following names. The anterior, the posterior, the ulnar collateral, the radial collateral. The anterior ligament The anterior ligament is a broad and thin fibrous layer covering the anterior surface of the joint. It is attached to the front of the medial epicondyle and to the front of the humerus immediately above the coronoid and radial fossey below. The anterior surface of the coronoid process of the ulna and to the annular ligament being continuous on either side with the collateral ligaments. Its superficial fibers pass obliquely from the medial epicondyle of the humerus to the annular ligament. The middle fibers, vertical in direction pass from the upper part of the coronoid depression and become partly blended with the proceeding but are inserted mainly into the anterior surface of the coronoid process. The deep or transverse set intersects these at right angles. This ligament is in relation in front with the brachialis except at its most lateral part. The posterior ligament This posterior ligament is thin in membranous and consists of transverse and oblique fibers. Above it is attached to the humerus immediately behind the capitulum and close to the medial margin of the trochlea, to the margins of the ulacranon fossa to the back of the lateral epicondyle some little distance from the trochlea. Below it is fixed to the upper and lateral margins of the ulacranon, to the posterior part of the annular ligament and to the ulna behind the radial notch. The transverse fibers form a strong band which bridges across the ulacranon fossa under cover of this band a pouch of synovial membrane and a pad of fat project into the upper part of the fossa where the ulna point is extended. In the fat are a few scattered fibrous bundles which pass from the deep surface of the transverse band to the upper part of the fossa. This ligament is in relation behind with the tendon of the triceps brachii and the anchoneus. The ulnar collateral ligament ligamentum collateralae ulnarae internal lateral ligament This ligament is a thick triangular band consisting of two portions of the anterior and posterior united by a thinner intermediate portion. The anterior portion directed obliquely forward is attached above by its apex to the front part of the medial epicondyle of the humerus and below by its broad base to the medial margin of the coronoid process. The posterior portion also of triangular form is attached above by its apex to the lower and back part of the medial epicondyle to the medial margin of the olacranon. Between these two bands a few intermediate fibers descend from the medial epicondyle to blend with the transverse band which bridges across the notch between the olacranon and the coronoid process. This ligament is in relation with the triceps brachii and flexor carpi ulnaris and the ulnar nerve and gives origin to part of the flexor digitorum sublimus. The radial collateral ligament ligamentum collaterali radialii external lateral ligament. This ligament is a short and narrow fibrous band less distinct than the ulnar collateral attached above to a depression below the lateral epicondyle of the humerus below to the annular ligament some of its most posterior fibers passing over that ligament to be inserted into the lateral margin of the ulna. It is intimately blended with the tendon of origin of the supinator. Synovial membrane The synovial membrane is very extensive. It extends from the margin of the articular surface of the humerus and lines the coronoid, radial and olacranyl fossey on that bone. It is reflected over the deep surface of the capsule and forms a pouch between the radial notch, the deep surface of the annular ligament and the circumference of the head of the radius. Projecting between the radius and ulna into the cavity is a crescentic fold of synovial membrane suggesting the division of the joint into two one of the humeral radial the other the humeral ulnar. Between the capsule and the synovial membrane are three masses of fat. The largest over the olacranon fossa is pressed into the fossa by the triceps brachii during the flexion the second over the coronoid fossa and the third over the radial fossa are pressed by the brachialis the respective fossey during extension the muscles in relation with the joint are in front the brachialis behind the triceps brachii and anconius laterally the supinator and the common tendon of origin of the extensor muscles medially the common tendon of origin of the flexor muscles and the flexor carpi ulnaris the artery supplying the joint are derived from the anastomosis between the profunda and superior ulnar collateral branches of the brachial with the anterior, posterior and inter oceosis recurrent branches of the ulnar and the recurrent branch of the radial these vessels form a complete anastomotic network around the joint the nerves of the joint are a twig from the ulnar as it passes between the medial condyle and olacranon a filament from the musculocutaneous and two from the median movements the elbow joint comprises three different portions namely the joint between the ulnar and humerus that between the head of the radius and the humerus and the proximal radial ulnar articulation described below all these articular surfaces are enveloped by a common synovial membrane and the movements of the whole joint should be studied together the combination of the movements of flexion and extension of the forearm with those of pronation and supination of the hand which is ensured the two being performed at the same joint is essential to the accuracy of the various minute movements of the hand the portion of the joint between the ulnar and the humerus is a simple hinge joint and allows of movements of flexion and extension only owing to the obliquity of the trochella of the humerus this movement does not take place in the anterior posterior plane of the body of the humerus when the forearm is extended and supinated the axes of the arm and forearm are not in the same line the arm forms an obtuse angle with the forearm the hand and forearm being directed lateral during flexion however the forearm and the hand tend to approach the middle line of the body and thus enable the hand to be easily carried to the face the accurate adaptation of the trochella of the humerus with its prominences and depressions to the semi-lunar notch of the ulnar prevents any lateral movement extension is produced by the action of the biceps brachii and brachialis assisted by the brachioradialis and the muscles arising from the medial condyle of the humerus extension by the triceps brachii and anconius assisted by the extensors of the wrist the extensor digitorum communes and the extensor digiti quinti propius the joint between the head of the radius and the capitulum of the humerus is an arthrodial joint the bony surfaces would of themselves constitute an anarthrosis and allow of movement in all directions were it not for the annular ligament by which the head of the radius is bound to the radial notch of the ulnar and which prevents any separation of the two bones laterally it is to the same ligament that the head of the radius owes its security from dislocation which would otherwise tend to occur from the shallowness of the cup-like surface on the head of the radius in fact, but for this ligament the tendon of the biceps brachii would be liable to pull the head of the radius out of the joint the head of the radius is not in complete contact with the capitulum of the humerus in all positions of the joint the capitulum occupies only the anterior and inferior surfaces of the lower end of the humerus so that in complete extension a part of the radial head can be plainly felt projecting at the back of the articulation the full flexion, the movement of the radial head is hampered by the compression of the surrounding soft parts so that the freest rotary movement of the radius on the humerus pronation and supination takes place in semi-flexion in which position the two articular surfaces are in most intimate contact flexion and extension of the elbow joint are limited by the tension of the structures on the front and back of the joint the limitation of flexion is also aided by the soft structures of the arm and forearm coming into contact in any position, a flexion or extension the radius carrying the hand with it can be rotated in the proximal radial ulnar joint the hand is directly articulated to the lower surface of the radius only and the ulnar notch on the lower end of the radius travels around the lower end of the ulna the latter bone is excluded from the wrist joint by the articular disc rotation of the head of the radius around an axis passing through the center of the radial head of the humerus in parts circular motion to the hand through a very considerable arc end of section 12 section 13 of the grace anatomy part 2 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 2 by Henry Gray radio ulnar articulation articulatio radio ulnaris the articulation of the radius with the ulna is affected by ligaments which connect together the extremities as well as the bodies of these bones the ligaments may consequently be subdivided into three sets one those of the proximal radio ulnar articulation two the middle radio ulnar ligaments three those of the distal radio ulnar articulation proximal radio ulnar articulation articulatio radio ulnaris proximalis superior radio ulnar joint this articulation is a trochoid or pivot joint between the circumference of the head of the radius and the ring formed by the radial notch of the ulnar and the annular ligament annular ligament ligamentum annular radii orbicular ligament this ligament is a strong band of fibres which encircles the head of the radius and retains it in contact with the radial notch of the ulnar it forms about four fifths of the osteo fibrous ring and is attached to the anterior and posterior margins of the radial notch a few of its lower fibres are continued around below the cavity and form at this level a complete fibrous ring its upper border blends with the anterior and posterior ligaments of the elbow while from its lower border a thin loose membrane passes to be attached to the neck of the radius a thickened band which extends from the inferior border of the annular ligament below the radial notch to the neck of the radius as known as the straight ligament the superficial surface of the annular ligament is strengthened by the radial collateral ligament of the elbow and efforts origin to part of the supinator its deep surface is smooth and lined by a synovial membrane which is continuous with that of the elbow joint movements the movements allowed in this articulation related to the rotatory movements of the head of the radius within the ring formed by the annular ligament and the radial notch of the ulna rotation forward being called pronation rotation backward supination supination is performed by the biceps brachii and supinator assisted to a slight extent by the extensor muzzles of the thumb pronation is performed by the pronator terrace and pronator quadratus middle radial annular union the shafts of the radius and ulna are connected by the oblique cord and the interosseous membrane the oblique cord corda oblica oblique ligament the oblique cord is a small flattened band extending downward and lateral from the lateral surface of the tubercle of the ulna at the base of the coronoid process to the radius a little below the radial tuberosity its fibers run in the opposite direction to those of the interosseous membrane it is sometimes wanting the interosseous membrane membrana, interossea and tibracae the interosseous membrane is a broad and thin plane of fibrous tissue descending oblique downward and medial from the interosseous crest of the radius to that of the ulna the lower part of the membrane is attached to the posterior of the two lines into which the interosseous crest of the radius divides it is deficient above about 2.5 cm beneath the tuberosity of the radius is broader in the middle than at either end and presence and ovular aperture are little above its lower margin for the passage of the volar interosseous vessels to the back of the forearm this membrane serves to connect the bones and to increase the extent of surface for the attachment of the deep muscles between its upper border and the oblique cord is a gap through which the dorsal interosseous vessels pass two or three fibrous bands are occasionally found on the dorsal surface of this membrane they descend oblique from the ulna towards the radius and have consequently a direction contrary to that of the other fibres the membrane is in relation in front by its upper three fourths with the flexor policies longest on the radial side and with the flexor digitorum profundus on the ulna lying in the interval between which other volar interosseous vessels extend the nerve by its lower fourth with the pronator quadratus behind with the supineator abductor policies longest extensor policies brevis extensor policies longest extensor interosseous and near the rest dorsal interosseous nerve distal radial articulation articulatio radial distalus inferior radial joint is a pivot joint formed between the head of the ulna and the ulna notch on the lower end of the radius the articulator surfaces are connected together by the following ligaments the volar radial ulnar the dorsal radial ulnar the articular disc the volar radial ulnar ligament anterior radial ulnar ligament this ligament is a narrow band of fibres extending from the anterior margin of the ulnar notch of the radius to the front of the head of the ulna dorsal radial ulnar ligament posterior radial ulnar ligament this ligament extends between corresponding surfaces on the dorsal aspect of the articulation the articular disc discuss articularis triangular fibrocartilage the articular disc is triangular in shape and is placed transversely beneath the head ulnar binding the lower ends of the ulnar radius firmly together its periphery is thicker than its center which is occasionally perforated it is attached by its apex to a depression between the styloid process and the head of the ulnar and by its base which is thin to the prominent edge of the radius which separates the ulnar notch from the carpal articular surface its margins are united to the ligaments of the wrist joint its upper surface smooth and concave articulates with the head of the ulna forming a a trial joint its under surface also concave and smooth forms part of the wrist joint and articulates with the triangular bone and medial part of the lunate both surfaces are clothed by synovial membrane the upper by that of the distal radial ulnar articulation the under by that of the wrist synovial membrane the synovial membrane of this articulation is extremely loose and extends upward as a recess recesses saciformis between the radius and the ulna movements the movements in the distal radial ulnar articulation consist of rotation of the lower end of the radius around an axis which passes through the center of the head of the ulna when the radius rotates forward pronation of the forearm and when backward supination it will thus be seen that in pronation and supination the radius describes the segment of a cone the axis of which extends from the center of the head of the radius to the middle of the head of the ulna in this movement the head of the ulna is not stationary but describes a curve in a direction to that taken by the head of the radius this however is not to be regarded as a rotation of the ulna the curve which the head of this bone describes is due to a combined anterior posterior and rotatory movement the former taking place almost entirely at the elbow joint the later at the shoulder joint radial carpal articulation or wrist joint articulate your radial carpal the wrist joint is a condyloid articulation the parts forming it are the lower end of the radius and under surface of the articular disc above and the navicular lunate and triangular bones below the articular surface of the radius and the under surface of the articular disc form together a transversely elliptical concave surface the receiving cavity the superior articular surfaces of the navicular lunate and triangular form a smooth convex surface the condyle which is received into the concavity the joint is surrounded by a capsule strengthened by the following ligaments the volar radiocarpal the dorsal radiocarpal the ulnar collateral the radial collateral the volar radiocarpal ligament ligamentum radiocarpium volare anterior ligament this ligament is a broad membranous band attached above to the anterior margin of the lower end of the radius to its styloid process and to the front of the lower end of the ulnar its fibres pass downward and medial to be inserted into the volar surfaces of the navicular lunate and triangular bones some being continued to the capitate in addition to this broad membrane there is a rounded fasciculus superficial to the rest which reaches from the base of the styloid process of the ulnar to the lunate and triangular bones the ligament is perforated by a purchase of vessels and is in relation in front with the tendons of the flexor digitorum profundus and flexor policies longus behind it is closely to the anterior border of the articular disc of the distal radial ulnar articulation the dorsal radiocarpal ligament radiocarpium dorsal posterior ligament the dorsal radiocarpal ligament less thick and strong than the volar is attached above to the posterior border of the lower end of the radius its fibres are directed obliquely downward and medial and are fixed to the dorsal surfaces of the navicular, lunate and triangular being continuous with those of the dorsal intercarpal ligaments it is in relation behind with the extensor tendons of the fingers in front it is blended with the articular disc the ulnar collateral ligament the latium collateral carpi ulnar internal lateral ligament the ulnar collateral ligament is a rounded chord attached above to the end of the styloid process of the ulnar and dividing below into two fasciculi one of which is attached to the medial side of the triangular bone to the pissy form and transverse couple ligament the radial collateral ligament ligamentum collateral carpi radial external lateral ligament the radial collateral ligament extends from the tip of the styloid process of the radius to the radial side of the navicular some of its fibres being prolonged to the greater multangular bone and the transverse carpi ligament it is in relation with the radial artery which separates the ligament from the tendons of the abductor policies longest and extensor policies brevis synovial membrane the synovial membrane lines of the ligaments above the scribe extending from the margin of the lower end of the radius and articular disc above to the margins of the articular surfaces of the carpal bones below it is loose and lax and presents numerous folds especially behind the wrist joint is covered in front of the flexor and behind by the extensor tendons the arteries supplying the joint are the volar and dorsal carpal branches of the radial and ulnar the volar and dorsal metacarpals and some ascending branches from the deep volar arch the nerves are derived from the ulnar and dorsal interosseous movements the movements permitted in this joint are flexion extension abduction adduction and circumduction they will be studied with those of the carpers with which they are combined end of section 13 section 14 of epitome part 2 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 2 by Henry Gray intercarpal articulations articulations intercarpe articulations of the carpers these articulations may be some divided into 3 sets number 1 the articulations of the proximal row of carpal bones number 2 the articulations of the distal row of carpal bones number 3 the articulations of the 2 rows with each other articulations of the proximal row of carpal bones these are athroidal joints navicular, lunate and triangular are connected by dorsal, volar and interosseous ligaments the dorsal ligaments ligamenta, intercarpe, dorsalia the dorsal ligaments 2 in number are placed transversely behind the bones of the first row they connect the navicular and lunate and the lunate and triangular the volar ligaments ligamenta intercarpe volaria palmar ligaments the volar ligaments also 2 connect the navicular and lunate and the lunate and triangular they are less strong than the dorsal and placed very deeply behind the flexor tendons and the volar raducarpal ligament the interosseous ligaments ligamenta intercarpe interossea the interosseous ligaments are 2 narrow bundles 1 connecting the lunate with the navicular the other joining it to the triangular they are on a level with the superior surfaces of these bones and their upper surfaces are smooth and form which connects articular surface of the wrist joint the ligaments connecting the pisiform bone are the articular capsule and the 2 volar ligaments the articular capsule is a 10 membrane which connects the pisiform to the triangular it is lined by synovial membrane the 2 volar ligaments are strong fibrous bands 1 the pisor hamate ligament connects the pisiform to the hamate the other the pisor metacarpal ligament joins the pisiform to the base of the 5th metacarpal bone these ligaments are in reality prolongations of the tendon of the flexor carpi ulnaris articulations of the distal row of carpal bones these also are arthritis joints the bones are connected by dorsal volar and interosseous ligaments the dorsal ligaments ligamenta intercarpe dorsalia the dorsal ligaments 3 number extend transversely from one bone to other of the dorsal surface connecting the greater with the lesser multangular the lesser multangular with the capitate and the capitate with the hamate the volar ligaments ligamenta intercarpe volaria parmore ligaments the volar ligaments also 3 have a similar arrangement on the volar surface the interosseous ligaments ligamenta intercarpe interossea the 3 interosseous ligaments are much thicker than those the first row 1 is placed between the capitate and the hamate 2 between the capitate and the lesser multangular and 3 between the greater and lesser multangular the first is much the strongest and the third is sometimes wanting articulations of the 2 rows of carpal bones with each other the joint between an avicular lunit and triangular on the one hand and the second row of carpal bones on the other is named the midcarpal joint and is made up of 3 distinct portions in the centre the head of the capitate and the superior surface of the hamate articulate with the deep cup shaped cavity formed by the mlamicular and lunit and constitute a sort of ball like a joint on the radial side the greater and lesser multangular articulate with the navicular and on the ulnar side the hamate articulates with the triangular forming gliding joints the ligaments are volar, dorsal, ulnar and radial collator the volar ligaments ligamenta intercarpe volaria anthesia opalmer ligaments the volar ligaments consist of short fibres which pass for the most part from the volar surface of the bones of the first row to the front of the capitate the dorsal ligaments ligamenta intercarpe dorsalia posterior ligaments the dorsal ligaments consist of short irregular bundles passing between the dorsal surfaces of the bones of the first and second rows the collatoral ligaments the collatoral ligaments are very short one is placed on the radial the other on the ulnar side of the corpus the former the stronger and more distinct connects the navicular and greater multangular the later the triangular and hamate they are continuous with the collatoral ligaments of the wrist joint in addition to these ligaments a slender interosseous band sometimes connects the capitate and the navicular synovial membrane the synovial membrane of the corpus is very extensive and bounds a synovial cavity of very irregular shape the upper portion of the cavity intervenes between the undersurfaces of the navicular and triangular bones and the upper surfaces of the bones of the second row it sends two prolongations upward between the navicular and lunate and the lunate and triangular and three prolongations downward between the four bones of the second row the prolongation between a greater and lesser multangulars or that between the lesser navicular and capitate is owing to the absence of the interosseous ligament often continuous with the cavity of the carpo metagarpal joints sometimes of the second, third, fourth and fifth metagarpal bones sometimes of the second and third only in the later condition the joint between the hamate and the fourth and fifth metagarpal bones has a separate synovial membrane the synovial cavities of these joints are prolonged for a short distance between the basis of the metagarpal bones there is a separate synovial membrane between the pissy form and triangular movements the articulation of the hand and wrist considered as a hole involves four articular surfaces a the inferior surfaces of the radius and the articular disc B the superior surfaces of the navicular lunate and triangular the pissy form having no essential part in the movement of the hand C the S shaped surface formed by the interior surfaces of the navicular lunate and triangular D the reciprocal surface formed by the upper surfaces of the bones in the second row these four surfaces form two joints one a proximal the wrist joint proper and two a distal the mid-carpal joint one the wrist joint proper is a true condyloid articulation and therefore all movements but rotation are permitted flexion and extension are the most free and of these a greater amount of extension than a flexion is permitted since the articulating surfaces extend farther on the dorsal than on the volar surfaces of the carpal bones in this movement the carpal bones rotate on a transverse axis drawn between the tip of the styloid processes of the radius and ulnar a certain amount of adduction or ulnar flexion and abduction or radial flexion is also permitted the former is considerably greater in extent than the later on a count of the sharpness of the styloid process of the ulnar abduction being soon limited by the contact of the styloid process of the radius with the greater multangular in this movement the carpal bones revolve upon an anterior posterior axis drawn through the center of the wrist footnote H. M. Johnston Journal of Anatomy and Physiology Volume 41 maintains that ulnar and radial flexion only slight lateral movement occurs at the radial carpal joint and that incomplete flexion and extension of the hand there is a small degree of ulnar flexion at the radial carpal joint and footnote finally circumduction is permitted by the combined and consecutive movements of adduction extension abduction and flexion no rotation is possible but the effect of rotation is obtained by the pronation and supination of the radius from the ulnar the movement of flexion is performed by the flexor carpi radialis the flexor carpi ulnaris and the palmaris longus extension by the extensors carpi radialis longus and brevis and the extensor carpi ulnaris adduction ulnar flexion by the flexor carpi ulnaris and the extensor carpi ulnaris abduction radial flexion by the abductor palmaris longus the extensors of the thumb and the extensors carpi radialis longus and brevis and the flexor carpi radialis when the fingers are extended flexion of the wrist is performed by the flexor carpi radialis and ulnaris and extension is aided by the extensor digitorum communus when the fingers are flexed flexion of the wrist is aided by the flexors digitorum sublimus and profundus and extension is performed by the extensor carpi radialis and ulnaris number 2 the chief movements permitted in the mid-carpel joint are flexion and extension and a slight amount of rotation in the flexion and extension which are the movements most freely enjoyed the greater and lesser multangulars on the radial side and the hammit on the ulnar side glide forward and backward on the navicular and triangular respectively while the head of the capitate and the superior surface of the hammit rotate in the cup shaped cavity of the navicular and lunate flexion at this joint is freer than extension a very trifling amount of rotation is also permitted the head of the capitate rotating around a vertical axis drawn through its own center while at the same time a slight gliding movement takes place in the lateral and medial portions of the joint end of section 14 section 15 of grace anatomy part 2 this is a LibriVox recording all LibriVox recordings are in the bubbling domain for more information or to volunteer please visit LibriVox.org recording by anatomy of the human body part 2 by Henry Gray carpo metacarpal articulations articulations carpo metacarpi carpo metacarpal articulation of the thumb articulatio carpo metacarpi carpo metacarpi follices this is a joint of reciprocal reception between the first metacarpal and the greater multangular it enjoys great freedom of movement on account of the configuration of its articula surfaces which are saddle shaped the joint is surrounded by a capsule which is thick but loose from the circumference of the base of the metacarpal bone to the rough edge bounding the articula surface of the greater multangular it is thickest laterally and dorsally and is lined by synovial membrane movements in this articulation the movements permitted a flexion and extension in the plane of the hand adduction and abduction in a plane at right angles to the thumb, circumduction and opposition it is by the movement of opposition that the tip of the thumb is brought into contact with the volar surfaces of the slightly flexed fingers this movement is affected through the medium of a small open facet on the anterior lip of the saddle shaped articula surface of the greater multangular the flexure muscles pull the corresponding part of the articula surface of the metacarpal bone on to this facet and the movement of opposition is then carried out by the adductors flexion of this joint is produced by the exaurus policies longus and brevis assisted by oponence policies and adductor policies extension is affected mainly by the abductor policies longus assisted by extensors policies longus and brevis adduction is carried out by the adductor abduction mainly by the abductor policies longus and brevis assisted by the extensors articulations of the other four metacarpal bones with the corpus articulations carpo metacarpae the joints between the corpus and the second third fourth and fifth metacarpal bones are arthritis the bones are united by dorsal, volar and interosseous ligaments the dorsal ligaments ligamenta carpo metacarpae dorsalia the dorsal ligaments the strongest and most distinct connect the carpal and metacarpal bones on their dorsal surfaces the second metacarpal bone receives two fascinite one from the greater the other from the lesser multangular the third metacarpal receives two one each from the lesser multangular and capitate the fourth two one each from the capitate and the hamate the fifth receives a single fasciculus from the hamate and this is continuous with a similar ligament on the volar surface forming an incomplete capsule the volar ligaments ligamenta carpo metacarpae volaria the volar ligaments have a somewhat similar arrangement with the exception of those of the third metacarpal which are three in number are lateral one from the greater multangular situated superficial to the sheath of the tendon of the flexure carpi radialis an intermediate one from the capitate and a medial one from the hamate interosseous ligaments the interosseous ligaments consist of short thick fibres and are limited to one part of the carpo metacarpal articulation they connect the contiguous inferior angles of the capitate and hamate with the adjacent surfaces of the third metacarpal bones synovial membrane the synovial membrane is a continuation of that of the intercarpal joints occasionally the joint between the hamate and the fourth and fifth metacarpal bones has a separate synovial membrane the synovial membranes of the wrist and carpus are thus seen to be five in number the first passes from the lower end of the ulnar to ulnar notch of the radius and lines the upper surface of the articular disc the second passes from the articular disc and the lower end of the radius above to the bones of the first row below the third the most extensive passes between the contiguous margins of the two rows of carpal bones and sometimes in the event of one of the interosseous ligaments being absent between the bones of the second row to the carpal extremities of the second, third, fourth and fifth metacarpal bones the fourth extends from the margin of the great multangular to the metacarpal bone of the thumb the fifth runs between the adjacent margins of the triangular and busy form bones occasionally the fourth and fifth metacarpal joints have a separate synovial membrane movements the movements permitted in the carpal metacarpal articulations of the fingers are limited to slight gliding of the articular surfaces upon each other the extent of which varies in joints the metacarpal bone of the little finger is most movable than that of the ring finger the metacarpal bones of the index and middle fingers are almost immovable inter metacarpal articulations articulations intercarpe articulations of the metacarpal bones with each other the basis of the second third fourth and fifth metacarpal bones articulate with one another by small surfaces covered with cartilage and are connected together by dorsal volar and interosseous ligaments the dorsal ligamenta basium osseous metacarp dorsalia and volar ligaments ligamenta basium osseous metacarp volaria palmar ligaments pass transversely from one bone to another on the dorsal and volar surfaces the interosseous ligaments ligamenta basium osseo metacarp interossea connect the contiguous surfaces just distant to their collateral surfaces the synoval membrane for these joints is continuous with that of the carpo metacarpal articulations the transverse metacarpal ligamenta ligamentum capitullarium osseo metacarpalium transversum this ligament is a narrow fibrous band which runs across the carpo surfaces of the heads of the second, third, fourth and fifth metacarpal bones connecting them together it is blended with the volar glenoid ligaments of the metacarpal palangial articulations its volar surface is concave where the flexor tendons pass over it behind it the tendons of the interosseae pass to their insertions metacarpal palangial articulations articulations metacarpal palangio metacarpal palangial joints these articulations are of condy-like kind formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the first phalanges with the exception of that of thumb which presents more of the characters of a ginglamoid joint each joint has a volar and two collateral ligaments the volar ligaments glenoid ligaments of cruella parmal or vaginal ligaments are thick, dense fibrocatellational structures placed upon the volar surfaces of the joints in the intervals between the collateral ligaments to which they are connected they are loosely related to the metacarpal bones but are very firmly attached to the basis of the first phalanges their volar surfaces are intimately blended with the transverse metacarpal ligament and present grooves for the passage of the flexor tendons the sheets surrounding which are connected to the sides of the grooves the deep surfaces form parts of the articular facets for the heads of the metacarpal bones and are lined by synovial membranes the collateral ligaments the collateral ligaments the collateral ligaments are strong grounded cuts placed on the sides of the joints each is attached by one extremity to the posterior tubercle and adjacent depression on the side of the head of the metacarpal bone and by the other he is extremity of the phalanges that also surface of these joints are covered by the expansions of the extensor tendons together with some loose azural tissue which connects the deep surfaces of the tendons to the bones movements the movements which occur in these joints are flexion extension, adduction, abduction and circumduction the movements of abduction and adduction are very limited and cannot be performed when the fingers are flexed articulations of the digits articulations digitalum manus interphalangeal joints the interphalangeal articulations are hinge joints each has a volar and two collateral ligaments the arrangement of these ligaments is similar to those in the metacarpal phalangeal articulations the extensor tendons supply the place of posterior ligaments movements the only movements permitted in the interphalangeal joints are flexion and extension these movements are more extensive between the first and second phalanges than between the second and third the amount of flexion is very considerable but extension is limited by the volar and collateral ligaments muscles acting on the joints of the digits flexion of the metacarpal phalangeal joints of the fingers is affected by the flexors digitalum sublimus and profanus lubricants and interosci assisted in the case of the little finger by the flexor digitai quintai brevis extension is produced by the extensor digitalum communus extensor indices proprious and extensor digitai quintai proprious flexion of the interphalangeal joints of the fingers is accomplished by the flexor digitalum profanus acting on the proximal and distal joints and by the flexor digitalum sublimus acting on the proximal joints extension is mainly affected by the lubricates and interosci the long extensors having little or no action upon these joints flexion of the metacarpal phalangeal joint of the thumb is affected by the flexor's polisus lungus and brevis extension by the extensor's polisus lungus and brevis flexion of the interphalangeal joint is accomplished by the flexor's polisus lungus and extension by the extensor's polisus lungus End of section 15 by Ruth Golding Anatomy of the Human Body Part 2 by Henry Gray 7. Articulations of the lower extremity a. coxal articulation or hip joint the articulations of the lower extremity comprise the following 1. hip 2. knee 3. tibio fibula 4. ankle 5. intertarsal 6. tarso metatarsal 7. intermetatarsal 8. metatarsal phalangeal 9. articulations of the digits coxal articulation or hip joint articulatio coxie this articulation is an n-arthrodial ball and socket joint formed by the reception of the head of the femur into the cup-shaped cavity of the acetabulum the articular cartilage on the head of the femur thicker at the centre than at the circumference covers the entire surface with the exception of the fovea capitis femoris to which the ligamentum teres is attached the complete marginal ring the lunate surface within the lunate surface there is a circular depression devoid of cartilage occupied in the fresh state by a mass of fat covered by synovial membrane the ligaments of the joint are the articular capsule the iliofemoral the ischiocapsula the pubocapsula the ligamentum teres femoris the glenoidal labrum the transverse acetabula the articular capsule capsular articularis capsular ligament the articular capsule is strong and dense above it is attached to the margin of the acetabulum 5 to 6 millimetres beyond the glenoidal labrum behind but in front it is attached to the outer margin of the labrum and opposite to the notch where the margin of the cavity is deficient it is connected to the transverse ligament and by a few fibres to the edge of the obturator foramen it surrounds the neck of the femur and is attached in front to the intertrochanteric line to the base of the neck behind to the neck about 1.25 centimetres above the intertrochanteric crest below to the lower part of the neck close to the lesser trochanter from its femoral attachment some of the fibres are reflected upward along the neck as longitudinal bands termed retinacula the capsule is much thicker at the upper and four part of the joint where the greatest amount of resistance is required behind and below it is thin and loose it consists of two sets of fibres circular and longitudinal the circular fibres zona orbicularis are most abundant at the lower and back part of the capsule and form a sling or collar around the neck of the femur anteriorly they blend with the deep surface of the iliofemoral ligament and gain an attachment to the anterior inferior iliac spine the longitudinal fibres are greatest in amount at the upper and front part of the capsule where they are reinforced by distinct bands or accessory ligaments of which the most important is the iliofemoral ligament the other accessory bands are known as the pubocapsula and the ischiocapsula ligaments the external surface of the capsule is rough covered by numerous muscles and separated in front from the psoas major and iliacus by a bursa which not infrequently communicates by a circular aperture with the cavity of the joint the iliofemoral ligament ligamentum iliofemorale why ligament ligament of bigelow the iliofemoral ligament is a band of great strength which lies in front of the joint it is intimately connected with the capsule and serves to strengthen it in this situation it is attached above to the lower part of the anterior inferior iliac spine below it divides into two bands one of which passes downward and is fixed to the lower part of the intertrochanteric line the other is directed downward and lateral wood and is attached to the upper part of the same line between the two bands is a thinner part of the capsule in some cases there is no division and the ligament spreads out into a flat triangular band which is attached to the whole length of the intertrochanteric line this ligament is frequently called the wise shaped ligament of bigelow and it's upper band is sometimes named the ilio trochanteric ligament the pubocapsular ligament ligamentum pubocapsulare pubofemoral ligament this ligament is attached above to the obturator crest and the superior ramus of the pubis below it blends with the capsule and with the deep surface of the vertical band of the ilio femoral ligament the ischiocapsular ligament ligamentum ischiocapsulare ischiocapsular band ligament of Bertin the ischiocapsular ligament consists of a triangular band of strong fibres which spring from the ischium below and behind the acetabulum and blend with the circular fibres of the capsule the ligamentum teres femoris the ligamentum teres femoris is a triangular, somewhat flattened band implanted by its apex into the anterosuperior part of the phobia capitis femoris its base is attached by two bands one into either side of the acetabular notch and between these bony attachments it blends with the transverse ligament it is in sheathed by the membrane and varies greatly in strength in different subjects occasionally only the synovial fold exists and in rare cases even this is absent the ligament is made tense when the thigh is semi-flexed and the limb then adducted or rotated outward it is on the other hand relaxed when the limb is abducted it has however little influence as a ligament the glenoidal labrum labrum glenoidalae cotyloid ligament the glenoidal labrum is a fibrocartilaginous rim attached to the margin of the acetabulum the cavity of which it deepens at the same time it protects the edge of the bone and fills up the inequalities of its surface it bridges over the notch as the transverse ligament and thus forms a complete circle which closely surrounds the head of the femur and assists in holding it in its place it is triangular on section its base being attached to the margin of the acetabulum while its opposite edge is free and sharp its two surfaces are invested by synovial membrane external one being in contact with the capsule the internal one being inclined inward so as to narrow the acetabulum and embrace the cartilaginous surface of the head of the femur it is much thicker above and behind than below and in front and consists of compact fibres the transverse acetabular ligament ligamentum transversum to lye transverse ligament this ligament is in reality a portion of the glenoidal labrum though differing from it in having no cartilage cells among its fibres it consists of strong flattened fibres which cross the acetabular notch and convert it into a ferraman through which the nutrient vessels enter the joint synovial membrane the synovial membrane is very extensive commencing at the margin of the cartilaginous surface of the head of the femur it covers the portion of the neck which is contained within the joint from the neck it is reflected on the internal surface of the capsule covers both surfaces of the glenoidal labrum and the mass of fat contained in the depression at the bottom of the acetabulum and in sheaths the ligamentum teres as far as the head of the femur the joint cavity sometimes communicates through a hole in the capsule between the vertical band of the ileofemoral ligament and the pubocapsular ligament with a bursa situated on the deep surfaces of the psoas major and iliocus the muscles in relation with the joint are the psoas major and iliocus separated from the capsule by a bursa above the reflected head of the rectus femoris and gluteus minimus the latter being closely adherent to the capsule immediately the obturator externus and pectinus behind the piriformis gemellus superior obturator internus anterior obturator externus and quadratus femoris the arteries supplying the joint are derived from the obturator medial femoral circumflex and superior and inferior gluteals the nerves are articulate branches from the sacral plexus sciatic obturator accessory obturator and the filament from the branch of the femoral supplying the rectus femoris movements the movements of the hip are very extensive and consist of flexion extension, adduction abduction, circumduction and rotation the length of the neck of the femur and its inclinations to the body of the bone have the effect of converting the angular movements of flexion, extension adduction and abduction partially into rotatory movements in the joint thus when the thigh is flexed or extended the head of the femur on account of the medial inclination of the neck rotates within the acetabulum with only a slight amount of gliding to and fro the forward slope of the neck similarly affects the movements of adduction and abduction conversely rotation of the thigh which is permitted by the upward inclination of the neck is not a simple rotation of the head of the femur in the acetabulum but is accompanied by a certain amount of gliding the hip joint presents a very striking contrast to the shoulder joint in the much more complete mechanical arrangements for its security and for the limitation of its movements in the shoulder as has been seen the head of the humerus is not adapted at all in size to the glenoid cavity and is hardly restrained in any of its ordinary movements by the capsule in the hip joint on the contrary the head of the femur is closely fitted to the acetabulum for an area extending over nearly half a sphere and at the margin of the bony cup it is still more closely embraced by the glenoidal labrum so that the head of the femur is held in its place by that ligament even when the fibres of the capsule have been quite divided the iliofemoral ligament is the strongest of all the ligaments in the body and is put on the stretch of any attempt to extend the femur beyond a straight line with the trunk that is to say this ligament is the chief agent in maintaining the erect position without muscular fatigue for a vertical line passing through the centre of gravity of the trunk falls behind the centres of rotation in the hip joints and therefore the pelvis tends to fall backward but is prevented by the tension of the iliofemoral ligaments the security of the joint may be provided for also by the two bones being directly united through the ligament and teres but it is doubtful whether this ligament has much influence upon the mechanism of the joint when the knee is flexed flexion of the hip joint is arrested by the soft parts of the thigh and abdomen being brought into contact and when the knee is extended by the action of the hamstring muscles extension is checked by the tension of the iliofemoral ligament adduction by the thighs coming into contact adduction with flexion by the lateral band of the iliofemoral ligament and the lateral part of the capsule abduction by the medial band of the iliofemoral ligament and the pubocapsular ligament rotation outward by the lateral band of the iliofemoral ligament and rotation inward by the ischiocapsular ligament and the hind a part of the capsule the muscles which flex the femur on the pelvis are the psoas major iliacus rectus femoris pectinus aductoris longus bravis and the anterior fibres of the glutei medius and minimus extension is mainly performed by the gluteus maximus assisted by the hamstring muscles and the ischial head of the aductor magnus the thigh is adducted by the aductoris magnus longus and bravis the pectinus the gracilis and lower part of the gluteus maximus and abducted by the glutei medius and minimus and the upper part of the gluteus maximus the muscles which rotate the thigh inward are the gluteus minimus and the anterior fibres of the gluteus medius the tensor fascielate and the iliacus and psoas major while those which rotate it outward are the posterior fibres of the gluteus medius the piriformis obturatoris externus and internus gemelli superior and inferior quadratus femoris gluteus maximus the aductoris longus bravis and magnus the pectinus and the sartorius end of section 16 recording by Ruth Golding