384 



MUSCLES AND FASCIAE. 



Fig. 239. Front of the Left 

 Forearm. Superficial Muscles. 



deep from the superficial layer of muscles. Numerous apertures exist in the 

 fascia for the passage of vessels and nerves ; one of these, of large size, situated 

 at the front of the elbow, serves for the passage of a communicating branch 

 between the superficial and deep veins. 



The muscles of the forearm may be subdivided into groups corresponding to 

 the region they occupy. One group occupies the inner and anterior aspect of 



the forearm, and comprises the flexor and pro- 

 nator muscles. Another group occupies its outer 

 side ; and a third, its posterior aspect. The two 

 latter groups include all the extensor and supi- 

 nator muscles. 



ANTERIOR BRACHIAL REGION. 



Superficial Layer. 



Pronator Radii Teres. 

 Flexor Carpi Radialis. 

 Palmaris Longus. 

 Flexor Carpi Ulnaris. 

 Flexor Sublimis Digitorum. 



These muscles take origin from the internal 

 condyle of the humerus by a common tendon. 



The Pronator Radii Teres arises by two heads. 

 One, the larger and more superficial, arises from 

 the humerus, immediately above the internal con- 

 dyle, and from the tendon common to the origin 

 of the other muscles ; also from the fascia of the 

 forearm, and intermuscular septum between it and 

 the Flexor Carpi Radialis. The other head is a 

 thin fasciculus, which arises from the inner side of 

 the coronoid process of the ulna, joining the pre- 

 ceding at an acute angle. Between the two heads 

 passes the median nerve. The muscle passes ob- 

 liquely across the forearm from the inner to the 

 outer side, and terminates in a flat tendon, which 

 turns over the outer margin of the radius, and is 

 inserted into a rough ridge at the middle of the 

 outer surface of the shaft of that bone. 



Relations. By its anterior surface, with the deep 

 fascia, the Supinator Longus, and the radial vessels 

 and nerve. By its posterior surface, with the Bra- 

 chialis Anticus, Flexor Sublimis Digitorum, the 

 median nerve, and ulnar artery; the small, or 

 deep, head being interposed between the two lat- 

 ter structures. Its outer border forms the inner 

 boundary of a triangular space, in which is placed 

 the brachial artery, median nerve, and tendon of 

 the Biceps muscle. Its inner border is in contact 

 with the Flexor Carpi Eadialis. 



The Flexor Carpi Eadialis lies on the inner side 

 of the preceding muscle. It arises from the internal 

 condyle by the common tendon, from the fascia of 

 the forearm, and from the intermuscular septa between it and the Pronator 

 Teres, on the outside ; the Palmaris Longus, internally ; and the Flexor Sublimis 

 Digitorum, beneath. Slender and aponeurotic in structure at its commencement, 

 it increases in size, and terminates in a tendon which forms the lower two-thirds 

 of its length. This tendon passes through a canal on the outer side of the 



