236 ANCONEUS. 



the interossei, forms a broad aponeurosis, which covers the whole of the 

 posterior aspect of the finger. At the first phalangeal joint, the aponeu- 

 osis divides into three slips. The middle slip is inserted into the base 

 .if the second phalanx, and the two lateral portions are continued onwards 

 on each side of the joint, to be inserted into the last. Little oblique ten- 

 dinous slips connect the tendons of the middle, ring, and little finger, as 

 they cross the back of the hand. 



Relations. By its superficial surface, with the fascia of the fore-arm 

 and back of the hand, and with the posterior annular ligament. By its 

 deep surface, with the supinator brevis, extensor ossis metacarpi pollicis, 

 extensor primi internodii, extensor secundi internodii, extensor indicis, 

 posterior interosseous artery and nerve, wrist joint, metacarpal bones and 

 interossei muscles, and phalanges. By its radial border, with the extensor 

 carpi radialis longior and brevior. By the ulnar border, with the extensor 

 minimi digiti, and extensor carpi ulnaris. 



The EXTENSOR MINIMI DIGITI (auricularis) is an offset from the extensor 

 communis, with which it is connected by means of a tendinous slip. 

 Passing down to the inferior extremity of the ulna, it traverses a distinct 

 fibrous sheath, and at the rnetacarpo-phalangeal articulation unites with 

 the tendon derived from the common extensor. The common tendon 

 then spreads out into a broad expansion, which divides into three slips, 

 to be inserted, as in the other fingers, into the last two phalanges. It is 

 to this muscle that the little finger owes its power of separate extension ; 

 and from being called into action when the point of the finger is intro- 

 duced into the meatus of the ear, for the purpose of removing unpleasant 

 sensations or producing titillation, the muscle was called by the old 

 writers "auricularis." 



The EXTENSOR CARPI ULNARIS arises from the external condyle and 

 from the upper two-thirds of the border of the ulna. Its tendon passes 

 through the posterior groove, in the lower extremity of the ulna, to be 

 inserted into the base of the metacarpal bone of the little finger. 



Relations. By its superficial surface, with the fascia of the fore-arm, 

 and posterior annular ligament. By its deep surface, with the supinator 

 brevis, extensor ossis metacarpi pollicis, extensor secundi internodii r ex- 

 tensor indicis, ulna, and wrist joint. By its radial border, it is in relation 

 with the extensor communis digitorum, and extensor minimi digiti: and 

 by the ulnar border, with the anconeus. 



The ANCONEUS is a small triangular muscle, having the appearance of 

 being a continuation of the triceps ; it arises from the outer condyle, and 

 ts inserted into the olecranon and triangular surface on the upper extremity 

 of the ulna. 



Relations. By its superficial surface with a strong tendinous aponeu- 

 rosis derived from the triceps. By its deep surface with the elbow joint, 

 orbicular ligament, and slightly with the supinator brevis. 



Deep Layer. 



Supinator brevis, 

 Extensor ossis metacarpi pollicis, 

 Extensor primi internodii pollicis, 

 Extensor secundi internodii pollicis, 

 Extensor indicis. 



