238 CLINICAL APPLIED ANATOMY. 



and placed still in a median position exactly posterior to the 

 tendon of the palmaris longus muscle, if this is present. 



Just above the anterior annular ligament is perhaps the most 

 usual spot for the nerve to be accidentally divided. An incised 

 wound caused by passing the hand through a pane of glass is 

 the common form of injury to cause the division. At the 

 same time the surrounding flexor tendons may be severed. It is 

 very necessary to be able to distinguish between the divided 

 ends of nerve and tendon, for accurate suturing in these cases is 

 highly essential. The following differences may be considered : 



Nerve. Tendon. 



Colour... ... Greyish pink. Dull. ... ... Yellowish white. Shining. 



Cut surf ace ... Round. Tends to be frayed. ... Transversely oval. Clean cut. 



Retraction ... Proximal end not greatly re- Proximal end markedly re- 

 tracted, tracted. 



Action... ... Manipulation of distal end may Pull on distal end will cause 



excite action of short muscles flexion of a digit, 

 of thumb. 



The median nerve gives off the anterior interosseous branch 

 soon after it enters the forearm. 



The main trunk supplies the pronator radii teres (the branch 

 to this muscle may arise just above the flexure of the elbow) the 

 flexor carpi radialis, the palmaris longus and the flexor sublimis 

 digitorum in the forearm. 



The anterior interosseous branch supplies the flexor longus 

 pollicis, the radial half of the flexor profundus digitorum, and 

 the pronator quadratus : all of these muscles will be paralysed 

 if the nerve is cut just above the bend of the elbow, and the loss 

 of power will be easily recognised by the inability to flex the 

 terminal phalanx of the thumb, and the second and third 

 phalanges of the index and middle fingers, and to pronate the 

 hand. 



In the lower third of the forearm the palmar cutaneous branch 

 is given off. 



The median nerve enters the palm of the hand by passing deep 

 to the anterior annular ligament, and immediately gives off a 

 motor branch to the chief muscles of the thenar eminence, viz., 



