MYOLOGY 



medial epicondyle of the humerus by the common tendon; the ulnar head 

 arises from the medial margin of the olecranon and from the upper two-thirds 

 of the dorsal border of the ulna by an aponeurosis, common to it and the Extensor 

 carpi ulnaris and Flexor digitorum prof undus ; and from the intermuscular septum 

 between it and the Flexor digitorum sublimis. The fibers end in a tendon, which 

 occupies the anterior part of the lower half of the muscle and is inserted into the 

 pisiform bone, and is prolonged from this to the hamate and fifth metacarpal 

 bones by the pisohamate and pisometacarpal ligaments; it is also attached by a 

 few fibers to the transverse carpal ligament. The ulnar vessels and nerve lie on 

 the lateral side of the tendon of this muscle, in the lower two-thirds of the forearm- 



Variations. Slips of origin from the coronoid. The Epitrochleo-anconceus, a small muscle often 

 present runs from the back of the inner condyle to the olecranon, over the ulnar nerve. 



The Flexor digitonun sublimis is placed beneath the previous muscle; it is 

 the largest of the muscles of the superficial group, and arises by three heads 

 humeral, ulnar, and radial. The humeral head arises from the medial epicondyle 

 of the humerus by the common tendon, from the ulnar collateral ligament of the 

 elbow-joint, and from the intermuscular septa between it and the preceding 

 muscles. The ulnar head arises from the medial side of the coronoid process, 

 above the ulnar origin of the Pronator teres (see Fig. 213, page 216). The radial 

 head arises from the oblique line of the radius, extending from the radial tuberosity 

 to the insertion of the Pronator teres. The muscle speedily separates into two 

 planes of muscular fibers, superficial and deep: the superficial plane divides into 

 two parts which end in tendons for the middle and ring fingers; the deep plane 

 gives off a muscular slip to join the portion of the superficial plane which is asso- 

 ciated with the tendon of the ring finger, and then divides into two parts, which 

 end in tendons for the index and little fingers. As the four tendons thus formed 

 pass beneath the transverse carpal ligament into the palm of the hand, they are 

 arranged in pairs, the superficial pair going to the middle and ring fingers, the deep 

 pair to the index and little fingers. The tendons diverge from one another in the 

 palm and form dorsal relations to the superficial volar arch and digital branches 

 of the median and ulnar nerves. Opposite the bases of the first phalanges each 

 tendon divides into two slips to allow of the passage of the corresponding tendon 

 of the Flexor digitorum prof undus; the two slips then reunite and form a grooved 

 channel for the reception of the accompanying tendon of the Flexor digitorum 

 profundus. Finally the tendon divides and is inserted into the sides of the second 

 phalanx about its middle. 



Variations. Absence of radial head, of little finger portion; accessory slips from ulnar tuberosity 

 to the index and middle finger portions; from the inner head to the Flexor profundus; from the 

 ulnar or annular ligament to the little finger. 



The Deep Group (Fig. 415). 



Flexor digitorum profundus. Flexor pollicis longus. 



Pronator quadratus. 



The Flexor digitorum profundus is situated on the ulnar side of the forearm, 

 immediately beneath the superficial Flexors. It arises from the upper three- 

 fourths of the volar and medial surfaces of the body of the ulna, embracing the 

 insertion of the Brachialis above, and extending below to within a short distance 

 of the Pronator quadratus. It also arises from a depression on the medial side of 

 the coronoid process; by an aponeurosis from the upper three-fourths of the dorsal 

 border of the ulna, in common with the Flexor and Extensor carpi ulnaris; and 

 from the ulnar half of the interosseous membrane. The muscle ends in four tendons 

 which run under the transverse carpal ligament dorsal to the tendons of the Flexor 





