

COXAL ARTICULATION OR HIP- JOINT 33J 



each is attached by one extremity to the posterior tubercle and adjacent depres- 

 sion on the side of the head of the metacarpal bone, and by the other to the 

 contiguous extremity of the phalanx. 



The dorsal surfaces of these joints are covered by the expansions of the Extensor 

 tendons, together with some loose areolar 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. 



XI. Articulations of the Digits (Articulationes Digitorum Manus ; Interphalangeal 



Joints) (Figs. 337, 338). 



The interphalangeal articulations t are hinge-joints; each has a volar and two 

 collateral ligaments. The arrangement of these ligaments is similar to those in 

 the metacarpophalangeal 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 metacarpophalangeal joints of the 

 fingers is effected by the Flexores digitorum sublimis and profundus, Lumbricales, and Interossei, 

 assisted in the case of the little finger by the Flexor digiti quinti brevis. Extension is produced 

 by the Extensor digitorum communis, Extensor indicis proprius, and Extensor digiti quinti pro- 

 prius. 



Flexion of the interphalangeal joints of the fingers is accomplished by the Flexor digitorum 

 profundus acting on the proximal and distal joints and by the Flexor digitorum sublimis acting 

 on the proximal joints. Extension is effected mainly by the Lumbricales and Interossei, the 

 long Extensors having little or no action upon these joints. 



Flexion of the metacarpophalangeal joint of the thumb is effected by the Flexores pollicis 

 longus and brevis; extension by the Extensores pollicis longus and brevis. Flexion of the inter- 

 phalangeal joint is accomplished by the Flexor pollicis longus, and extension by the Extensor 

 pollicis longus. 



ARTICULATIONS OF THE LOWER EXTREMITY. 



The articulations of the Lower Extremity comprise the following: 

 I. Hip. V. Intertarsal. 



T 



II. Knee. VI. Tarsometatarsal. 



III. Tibiofibular. VII. Intermetatarsal. 



IV. Ankle. VIII. Metatarsophalangeal. 



IX. Articulations of the Digits. 



I. Coxal Articulation or Hip-joint Articulatio Coxee . 





'his articulation is an enarthrodial or 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 center than at the 

 circumference, covers the entire surface with the exception of the fovea capitis 

 femoris, to which the ligamentum teres is attached ; that on the acetabulum forms 

 an incomplete 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 Pubocapsular. 



The Iliofemoral. The Ligamentum Teres Femoris. 



The Ischiocapsular. The Glenoidal Labrum. 



The Transverse Acetabular 



