The anterior ligament is a broad and membranous layer consisting of three fasciculi, which pass between the lower part of the radius and the scaphoid, semilunar, and cuneiform bone.

The posterior ligament, also thin and loose, passes between the posterior surface of the radius, and the posterior surface of the semilunar and cuneiform bone.

The internal lateral ligament extends from the styloid process of the ulna to the cuneiform and pisiform bone.

The external lateral ligament is attached by one extremity to the styloid process of the radius, and by the other to the side of the scaphoid bone, some of its fibres being prolonged to the trapezium. The radial artery rests on this ligament as it passes backwards to the first metacarpal space.

The synovial membrane of the wrist joint lines the under surface of the radius and interarticular cartilage above, and the first row of bones of the carpus below.

The relations of the wrist joint are the flexor and extensor tendons, by which it is surrounded, and the radial and ulnar artery.

Actions. The movements of the wrist joint are, flexion, extension, adduction, abduction, and circumduction. In these motions the articular surfaces glide upon each other.

8. Articulations between the Carpal Bones. These are amphi-arthrodial joints, with the exception of the conjoined head of the os magnum and unciforme, which is received into a cup formed by the scaphoid, semilunar, and cuneiform bone, and constitutes an enarthrosis. The ligaments are,

The dorsal ligaments are ligamentous bands, that pass transversely and longitudinally from bone to bone on the dorsal surface of the carpus.

The palmar ligaments are fasciculi of the same kind, but stronger than the dorsal, having the like disposition on the palmar surface.

The interosseous ligaments are fibro-cartilaginous lamellæ situated between the adjoining bones in each range: in the upper range they close the upper part of the space between the scaphoid, semilunar, and cuneiform bones; in the lower range they are stronger than in the upper, and connect the os magnum on the one side to the unciforme, on the other to the trapezoides, leaving intervals through which the synovial membrane is continued to the bases of the metacarpal bones.

The proper annular ligament (lig. carpi volare proprium) is a firm ligamentous band, which connects the bones of the two sides of the carpus. It is attached by one extremity to the trapezium and scaphoid, by the other to the unciform process of the unciforme and base of the pisiform bone, and forms an arch over the anterior surface of the carpus, beneath which the tendons of the long flexors and the median nerve pass into the palm of the hand.

The articulation of the pisiform bone with the cuneiform is provided with a separate synovial membrane, protected by fasciculi of ligamentous fibres, which form a kind of capsule around the joint; they are inserted into the cuneiforme, unciforme, and base of the metacarpal bone of the little finger.

Synovial Membranes. There are five synovial membranes entering into the composition of the articulations of the carpus :

The first is situated between the lower end of the ulna and the interarticular fibro-cartilage; it is called sacciform, from forming a sacculus between the ulna and radius.

The second is situated between the lower surface of the radius and interarticular fibro-cartilage above, and the first range of bones of the carpus below.

The third, the most extensive of the synovial membranes of the wrist, is situated between the two rows of carpal bones, and passes between the bones of the second range, to invest the carpal extremities of the four metacarpal bones of the fingers.

The fourth is the synovial membrane of the articulation of the metacarpal bone of the thumb with the trapezium.

The fifth is situated between the pisiform and cuneiform bone.

FIG. 139.

DIAGRAM SHOWING THE DISPOSITION OF THE FIVE SYNOVIAL MEMBRANES OF THE WRIST JOINT. [One of these (2) only, belongs to the wrist joint proper; the others are, more correctly, in relation with it.] 1. Sacciform membrane. 2. Second synovial membrane. 3, 3. Third, or large synovial membrane. 4. Synovial membrane between the pisiform and cuneiform bone. 5. Synovial membrane of the metacarpal articulation of the thumb. 6. Lower extremity of the radius. 7. Lower extremity of the ulna. 8. Interarticular fibro-cartilage. S. Scaphoid bone. L. Semilunare. C. Cuneiforme; interosseous ligaments are seen passing between these three bones and separating the articulation of the wrist (2) from that of the carpal bones (3). P. Pisiforme. T. Trapezium. T 2. Trapezoides. M. Os magnum. U. Unciforme; interosseous ligaments are seen connecting the os magnum with the trapezoides and unciforme. 9. Base of the metacarpal bone of the thumb. 10, 10. Bases of the other metacarpal bones.

Actions.

Very little movement exists between the bones in each range, but more is permitted between the two ranges. The motions of the latter are those of flexion and extension.

9. Carpo-metacarpal Articulations. The second row of bones of the carpus articulates with the metacarpal bones of the four fingers by dorsal and palmar ligaments; and the metacarpal bone of the thumb with the trapezium by a capsular ligament. There is also in the carpo-metacarpal articulation a thin interosscous band, which passes from the ulnar edge of the os magnum to the bases of the third and fourth metacarpal bones at their point of connexion.

of

The dorsal ligaments are strong fasciculi which pass from the second range carpal to the metacarpal bones; with the exception of the little finger there are two fasciculi to each bone, namely, to the index finger, one each from the trapezium and trapezoides; to the middle finger, one each from the trapezoides and os magnum; to the ring finger, one each from the os magnum and unciforme; and to the little finger, one from the unciforme.

The palmar ligaments are thin fasciculi arranged according to the same plan on the palmar surface.

The synovial membrane is a continuation of the great synovial membrane of the two rows of carpal bones.

The capsular ligament of the thumb is one of the three true capsular ligaments of the skeleton; the other two belong to the shoulder joint and hip joint. The articulation has a proper synovial membrane.

The metacarpal bones of the four fingers are firmly connected at their bases by means of dorsal and palmar ligaments, which extend transversely from one bone to the other, and by interosseous ligaments which pass between their contiguous surfaces. Their lateral articular facets are lined by a reflection of the great synovial membrane of the two rows of carpal bones.

Actions. The movements of the metacarpal on the carpal bones are restricted to a slight degree of sliding motion, with the exception of the articulation of the metacarpal bone of the thumb with the trapezium. In the latter, the movements are flexion, extension, adduction, abduction, and circumduction.

10. Metacarpophalangeal Articulation. The metacarpo-phalangeal articulation is a ginglymoid joint; and its ligaments four in number,

Anterior,

Two lateral,

Transverse.

The anterior ligaments, thick and fibro-cartilaginous, form part of the articulating surface of the joints. They are grooved externally for the lodgment of the flexor tendons, and by their internal aspect form part of the articular surface for the head of the metacarpal bone. At each side they are continuous with the lateral ligaments.

The lateral ligaments are strong narrow fasciculi, holding the bones together at each side.

The transverse ligament is a strong ligamentous band passing across the heads of the metacarpal bones of the four fingers, and connected with the anterior ligaments.

The expansion of the extensor tendon over the back of the fingers takes the place and performs the office of a posterior ligament.

Actions.. This articulation admits of movement in four different directions, viz., flexion, extension, adduction, and abduction; it is also capable of circumduction.

11. Articulation of the Phalanges.-These articulations are ginglymoid joints; and furnished with three ligaments,

The anterior ligament, firm and fibro-cartilaginous, forms part of the articular surface for the head of the phalanges; while externally it is grooved for the reception of the flexor tendons.

The lateral ligaments are very strong; and the principal bond of connexion between the bones.

The extensor tendon takes the place and performs the office of a posterior ligament.

Actions.-The movements of the phalangeal joints are flexion and extension, these movements being more free between the first and second, than between the second and third.

In connexion with the phalanges it will be proper to examine certain fibrous bands termed thecæ or vaginal ligaments, which serve to retain the tendons of the flexor muscles against the flat surface of the bones. These fibrous bands are attached at each side to the lateral margins of the phalanges; they are thick in the interspaces of the joints, thin where the tendons lie upon the joints, and are lined on their inner surface by synovial membrane.

LIGAMENTS OF THE LOWER EXTREMITY.

The ligaments of the lower extremity, like those of the upper, may be arranged in the order of the joints to which they belong; these are,

5. Articulation of the tarsal bones.
6. Tarso-metatarsal articulation.
7. Metatarso-phalangeal articulation.
8. Articulation of the phalanges.

1. Hip Joint. - The articulation of the head of the femur with the acetabulum constitutes an enarthrosis, or ball-and-socket joint. The articular surfaces are, the cup-shaped cavity of the acetabulum and the rounded head of the femur; the ligaments are five in number, viz.,

The capsular ligament (membrana capsularis, fig. 129, 8) is a strong ligamentous capsule, embracing the acetabulum superiorly, the neck of the femur below, and connecting the two bones firmly together. It is much thicker on the upper part of the joint, where more resistance is required, than on the under part, and extends further along the neck of the femur on the anterior and superior than on the posterior and inferior side, being attached to the intertrochanteric line in front, to the base of the great trochanter above, and to the middle of the neck of the femur behind.

The ilio-femoral ligament (fig. 129, ) is an accessory and radiating band, which descends obliquely from the anterior inferior spinous process of the ilium to the anterior intertrochanteric line, and strengthens the anterior portion of the capsular ligament.

The ligamentum teres, [interarticular ligament] (fig. 130, 7), triangular in shape, is attached by a round apex to the depression just below the middle of the head of the femur, and by its base, which separates into two fasciculi, into the borders of the notch of the acetabulum. It is formed by a fasciculus of fibres of variable size, surrounded by synovial membrane; sometimes the synovial membrane is present without the fibres, or the ligament is wholly absent. [Its only use seems to be to support the vessels which pass to and from the head of the femur.]

The cotyloid ligament (fig. 130, 6) is a prismoid cord of fibro-cartilage, attached around the margin of the acetabulum, and serving to deepen that cavity and protect its edges. It is thicker at the upper and posterior border of the acetabulum than in front, is inclined inwards towards the acetabulum, and consists of fibres which arise from the whole circumference of the brim, and interlace with each other at acute angles.

The transverse ligament is a strong fasciculus of ligamentous fibres, continuous with the cotyloid ligament, and stretching across the notch of the acetabulum. It converts the notch into a foramen, through which the articular branches of the internal circumflex and obturator artery enter the joint.

The fossa at the bottom of the acetabulum is filled with a mass of fat, covered by synovial membrane, which serves as an elastic cushion for the head of the bone during its movements. This was described by Havers as the synovial gland.

The synovial membrane is extensive; it invests the head of the femur, and is continued around the ligamentum teres into the acetabulum, whence it is reflected on the inner surface of the capsular ligament back to the head of the bone.

The muscles immediately surrounding and in contact with the hip joint ae, in front, psoas and iliacus, separated from the capsular ligament by a large synovial bursa; above, short head of the rectus and gluteus minimus; behind, pyriformis, gemellus superior, obturator internus, gemellus inferior, and quadratus femoris; and at the inner side, obturator externus and pectineus.

Actions.

-The movements of the hip joint are very extensive; they are flexion, extension, adduction, abduction, circumduction, and rotation.

2. Knee Joint. The knee [formed by the condyles of the femur, the glenoid cavities of the tibia, and the posterior surface of the patella] is a ginglymoid articulation of large size, and provided with numerous ligaments; the latter are thirteen in number, namely:

The first five are external to the articulation; the next five are internal; the remaining three are mere folds of synovial membrane, and have no title to the name of ligaments. In addition to the ligaments, there are two fibro-cartilages, and a synovial membrane.

The anterior ligament, or ligamentum patellæ, is the prolongation of the tendon of the extensor muscles of [the leg, which are placed upon] the thigh, down

FIG. 140.

5

ANTERIOR VIEW OF THE LIGAMENTS OF THE KNEE

JOINT. 1. Tendon of the quadriceps extensor muscle of the leg. 2. Patella. 3. Anterior ligament, or ligamentum patellæ, near its inser

tion. 4, 4. Synovial mem

brane. 5. Internal lateral

ligament. 6. Long external

lateral ligament. 7. Anterosuperior tibio-fibular liga

ment.

wards to the tubercle of the tibia. It is, therefore, no ligament; and, as the patella is simply a sesamoid bone developed in the tendon of the extensor muscles for the defence of the front of the knee joint, the ligamentum patellæ has no title to consideration, either as a ligament of the knee joint or as a ligament of the patella.

A small bursa mucosa is situated between the ligamentum patellæ near its insertion and the front of the tibia; and another of larger size between the anterior surface of the patella and fascia lata. It is the latter which is enlarged in housemaid's knee.

The posterior ligament, ligamentum posticum Winslowii, is a broad expansion of ligamentous fibres, which covers the whole of the posterior aspect of the joint. It is divisible into two lateral portions, which invest the condyles of the femur, and a central portion which is depressed, and formed by the interlacement of fasciculi passing in different directions. The strongest of these fasciculi is derived from the tendon of the semi-membranosus, and passes obliquely upwards and outwards from the posterior part of the inner tuberosity of the tibia to the external condyle of the femur. Other accessory fasciculi are given off by the tendon of the popliteus and heads of the gastrocnemius. The middle portion of the ligament supports the popliteal artery and vein, and is perforated by several openings for the passage of branches of the azygos articular artery and the nerves of the joint.

The internal lateral ligament is a broad and trapezoid layer of ligamentous fibres, attached above to the tubercle on the internal