Fig. 89. Right Forearm, Deep Layer: Anterior Aspect. 



The Fasciae of the Anteciibital Space and of the anterior aspect of the forearm 



are removed, including the Bicipital Fascia, e. g. of the Sii/)erficial Flexors, 



only their origin and insertion are left. The Deep Head of the Pronator 



Radii Teres is intact, and the Brachio-Radialis is drawn outwards. 



The Brachial Artery divides into Radial and Ulnar usually in front of 

 the line of the Joint. The Ulnar Artery runs downwards and inwards, under 

 cover of the muscles which arise from the Inner Condyle of the Humerus; below 

 the middle (or near the middle) of the forearm, it meets the Ulnar Nerve, which 

 runs along its inner (ulnar) side. 



The Median Nerve, as a rule, leaves the vessels in the antecubital space, 

 pierces the Pronator Radii Teres and runs downwards between the Superficial 

 and Deep Flexors. Near the wrist, the Nerve emerges at the outer border of 

 the Flexor Sublimis Digitorum (or Palmaris Longus, if present), and comes to lie 

 just under the Fascia. 



The Musculo-Spiral Nerve lies at the inner border of the Brachio-Radialis, 

 and divides into (i) the Posterior Interosseous, which supplies the Extensors of the 

 forearm (cf. Fig. 90) and (2) the Radial Nerve, which accompanies the Radial Artery 

 in the upper 2/3rds of the forearm, and then passes to the posterior aspect (cf. Fig. 93). 



The Ulnar Ner\-e having pierced the Flexor Carpi Ulnaris, runs, to the 

 hand, along that muscle. At the junction of the middle and lower i/3rd of the 

 forearm, it gives off the Dorsal Cutaneous Branch for the hand (cf. Fig. 93). The 

 Ulnar Artery and Nerve only accompany each other in the lower i/3rd of the forearm. 



The Anterior Interosseous Artery, the Radial and Ulnar Recurrent 

 Arteries are shown in the figure; these latter are important for carrying on the 

 collateral circulation on the outer and inner sides of the arm respectively. 



We make special mention of the Lymphatic Glands in this region about 

 which so little is known; in the Antecubital Space: Superficial, Deep, Posterior 

 Cubital Glands; on the forearm: Radial and Ulnar Glands. 



When the Palmaris Longus is absent — and in some cases also where 

 it is present — one can make the following observation. When the hand is 

 flexed upon the forearm, the tendons recede, and thus the Median Nerve comes 

 to lie directly under the fascia, where it can be seen, felt and rolled about. The 

 Ulnar Artery becomes at the same time more deepl}' placed, owing to the relax- 

 ation of the Flexor Carpi Ulnaris Muscle. When the hand is extended (dorsi- 

 flexed) the Median Nerve slides back into position and the Flexor Carpi Ulnaris 

 presses the Ulnar Artery to the surface. The pulse can now be readily felt by 

 placing the finger on the outer side of the tendon of that muscle. 



The position of the hand and the fingers at the moment of injury, trau- 

 matism, etc. is therefore most important. In Flexion, there is more danger for 

 the Median Nerve. In Extension the Ulnar Artery (and even the Ulnar Nerve) 

 is in greater peril, even when no muscle or tendon is injured. 



