Part 13

The three phalanges are all provided with capsular ligaments, or ligamenta capsularia, which bind together the several phalanges.

The small or third finger is connected to the metacarpus by a capsular ligament, the ligamentum capsulare, and by an interosseous ligament, or ligamentum interosseum digitorum, to the first phalanx of the second finger.

=Ligaments of the Pelvis.=—The obturator foramen, formed by the ilium and the ischium, is covered by a broad membranous ligament (Fig. 4, No. 29).

The oblong foramen, or foramen oblongum, and the foramen ischiadicum, formed by the ischium and the pubis are covered by broad membranous ligaments (Fig. 4, Nos. 29 and 60).

Poupart’s ligament or ligamentum Poupartii, quite small in fowls, extends from the anterior lower rim of the ilium to the pelvic cavity, and is inserted at the bottom of the acetabulum.

Another broad ligament originates from the posterior rim of the ischium and is attached to the square surface of the first coccygeal vertebra.

The ilio-pubic ligament extends from the pubic spine to the last rudimentary rib.

=Ligaments of the Hip-joint= (Fig. 25, F).—The hip-joint is made up of the ilium, ischium, pubis and femur and is a deep ball-and-socket joint. The cavity or acetabulum is called a cotyloid cavity.

The hip-joint is provided with three ligaments.

The ligamentum capsulare femoris is attached around the rim of the cotyloid cavity and around the rim of the articular head of the femur (Fig. 25, No. F, 4).

The ligamentum teres, or round ligament, is a very short ligament which closes the hole at the floor of the cotyloid cavity, at which point it is attached. It is also attached to the head of the femur.

The ligamentum ilio-sacrale strengthens the hip-joint capsule. It passes from the lower anterior rim of the os ilii, extending over the capsule to the neck of the femur to which it is attached.

=The Ligaments of the Knee-joint= (Figs. 16 and 17).—The knee-joint is made up of the femur, patella, tibia and fibula, and is provided with the following ligaments:

The ligamentum extero-laterale genu is a strong ligament extending from the condylus externus femoris, or external femoral condyle to the outer surface of the head of the fibula, or capitulum fibulæ. From this head there passes inward, a strong ligament to a point between the femur and fibula (Fig. 25, No. D, 4).

FIG. 16.—Ligaments and muscles of the hind extremity.

A. A transverse section through the tibial or tarsal cartilage, front view. 1, Gastrocnemius tendon. 2, Flexor perforatus annularis primus pedis. 3, Flexor perforans digitorum profundus. 4, Flexor perforatus indicis secundi pedis. 5, Extensor longus hallucis. 6, The articular surface. 7, Ligamentum capsulare ossis tarsi. 8, Flexor perforatus medius secundus pedis. 9, Flexor perforatus indicis secundus pedis. 10, Tendons of the extensor muscles.

B. Knee-joint. Inside view of femoro-tibial articulation. 1, Anterior ligamentum cruciatum. 2, Internal ligamentum laterale genu. 3, Anterior patellar ligament. 4, Patella. 5, Distal end of femur. 6, Proximal end of tibia. 7, Location of meniscus or pad of fibrocartilage.

C. Anterior view of tibio-tarsal articulation. 1, Distal end of tibia. 2, Its articular surface. 3, Ligamentum anticum. 4, Proximal end of metacarpus. 6, Pad of fibrocartilage.

D. The dorsal surface of the coccyx. 1, The bilobate oil gland. 2, Its duct. 3, Levator coccygis.

E. Inside view of pelvis and thigh. 1, Obturator internus. 2, Ambiens. 3, Vastus internus. 4, Internal ligamentum laterale genu. 5, Tibialis anticus. 6, Loop through which the tibialis anticus passes. 7, Adductors of the thigh. 8, Loop for the extensor tendon. ]

The ligamentum intero-laterale genu extends from the outer surface of the internal condyle of the tibia, or condylus internus tibiæ. It gives off a thin ligamentous slip which enters the joint and is attached to the inner half-moon shaped pad of fibrous cartilage, or meniscus, which it draws backward by the flexion of the knee (Fig. 16, No. B, 2).

The ligamentum popliteum arises from the fossa poplitea of the distal extremity of the femur and extends downward to the posterior rim of the head of the tibia.

The anterior ligamentum cruciatum genu originates from the fossa poplitea and extends outward antero-laterally to the rim of the head of the tibia (Fig. 25, No. 6).

The posterior ligamentum cruciatum genu is a short, strong ligament which originates from the cavity of the internal condyle of the femur, or condylus internus femoris, and inserts into the internal glenoid cavity of the tibia (Fig. 25, No. 1) or cavitas glenoidalis interna.

The meniscus of the femoro-tibial articulation is divided into four parts, as follows: first, the internal adhesio cornu antici cartilaginis lunatæ; second, the posterior adhesio cornu antici cartilaginis lunatæ; third, the external cornu cartilaginis lunatæ; fourth, the anterior cornu antici cartilaginis lunatæ. The latter originates between the condyles and passes around the ligamentum cruciatum genu posticum (Fig. 16, No. B, 7).

The inner semi-lunar fibrous cartilage is well developed and is joined by two ligaments between the femoral and the tibial surfaces (Fig. 25, No. 1).

The external semi-lunar cartilage lies in a cavity between the external femoral condyle and the head of the fibula (Fig. 25, No. 2).

The fibrous cartilages are bound posteriorly by a ligament, and by a second ligament to the head of the fibula, or capitulum fibulæ. Both pads of fibrous cartilage are connected by a transverse ligament called the ligamentum transversale commune (Fig. 25, No. 5).