286 FASCIAE OF THE UPPER EXTREMITY. 



the compressor urethras muscle, Cowper's glands, the internal pudic 

 and bulbous arteries, and a plexus of veins. Mr. Tyrrell considers 

 the anterior lamella alone as the deep perinea! fascia, and the posterior 

 lamella as a distinct layer of fascia covering in a considerable plexus 

 of veins. 



FASCLE OF THE UPPER EXTREMITY. 



The superficial fascia of the upper extremity contains between 

 its layers the superficial veins and lymphatics, and the superficial 

 nerves. 



The deep fascia is thin over the deltoid and pectoralis major 

 muscles, and in the axillary space, but thick upon the dorsum of the 

 scapula, where it binds down the infra- spinatus muscle. It is attach- 

 ed to the clavicle, acromion process, and spine of the scapula. In the 

 upper arm it is somewhat stronger, and is inserted into the condyloid 

 ridges, forming the intermuscular septa. In the fore-arm it is very 

 strong, and at the bend of the elbow its thickness is augmented by a 

 broad band, which is given off from the inner side of the tendon of 

 the biceps. It is firmly attached to the olecranon process, to the ulna, 

 and to the prominent points about the wrist. Upon the front of the 

 wrist it is continuous with the anterior annular ligament, which is 

 considered by some anatomists to be formed by the deep fascia, but 

 which I am more disposed to regard as a ligament of the wrist. On 

 the posterior aspect of this joint it forms a strong transverse band, the 

 posterior annular ligament, beneath which the tendons of the extensor 

 muscles pass, in distinct sheaths. The attachments of the posterior 

 annular ligament are, the radius on one side, and the ulna and pisiform 

 bone on the opposite side of the joint. 



The tendons, as they pass beneath the annular ligaments, are sur- 

 rounded by synovial bursae. The dorsum of the hand is invested by 

 a thin fascia, which is continuous with the posterior annular liga- 

 ment. 



The palmar fascia is divided into three portions. A central portion, 

 which occupies the middle of the palm, and two lateral portions, which 

 spread out over the sides of the hand, and are continuous with the 

 dorsal fascia. The central portion is strong and tendinous : it is 

 narrow at the wrist, where it is attached to the annular ligament, and 

 broad over the heads of the metacarpal bones, where it divides into 

 eight slips, which are inserted into the sides of the base of the first 

 phalanx of each finger. The fascia is strengthened at its point of 

 division into slips by strong fasciculi of transverse fibres, and the 

 arched interval left between the slips gives passage to the tendons of the 

 flexor muscles. The arches between the fingers transmit the digital 

 vessels and nerves, and lumbricales muscles. 



