ANATOMY IN A NUTSHELL. 69 



The nutrient artery comes from the brachial about the middle of the fore- 

 arm; it pierces the tendon of the Coraco-brachialis to enter the nutrient canal 

 which is below the insertion of the Coraco-brachialis; It is directed towards 

 the elbow (page 19. Lesson 1.) A branch from the musculo-cutaneous 

 nerve enters the bone with this artery. The artery may be a branch of the 

 superior profunda. 



The muscular branches are three or four in number and arise from the outer 

 >ide of the artery and supply the Bicep-. Coraco-brachialis, and Brachialis 

 amicus. The same muscles are supplied by the musculo-cutaneous nerve. 



The anastomotica magna arises two inches above the elbow-joint, passing 

 inward over the Brachialis anticus to pierce the internal intermuscular septum 

 to pass to the back of the internal and external condyles. It anastomoses in 

 front of the internal condyle with a branch from the inferior profunda and an- 

 terior ulnar recurrent. It anastomoses behind the internal condyle with the 

 sterior branch of the inferior profunda and the posterior ulnar recurrent. 

 It anastomoses behind the external condyle with the posterior branch of the 

 superior profunda and the interosseous recurrent. 



The vasa aberrantia are collateral branches which connect the brachial 

 or axillary artery with the arteries of the forearm, generally with the radial. 



Forearm. — There are twenty muscles in the forearm, eight in the anterior 

 (radio-ulnar) region arranged in four layers: in the first layer there are four — 

 I Plate XXIX) — The Pronator radii teres. Flexor carpi radialis, Palmaris longus, 

 and Flexor carpi ulnaris. The first three of these are supplied by the median 

 nerve, which conies from the outer and inner cords of the brachial plexus. The 

 Flexor carpi ulnaris is supplied by the ulnar nerve, which comes from the inner 

 cord. (Plate VI.) In the second layer there is one muscle, the Flexor sublimis 

 digitorum. (Plate XXX.) It is supplied by the median nerve. In the third 

 layer there are two muscles. (Plate XXXI.) Flexor longus pollicis and the Flexor 

 profundus digitorum. The first is supplied by the anterior interosseous,, which 

 is a branch of the median; the second one by the anterior interosseous and the 

 ulnar. In the fourth layer there is one muscle, the Pronator quadratus, which 

 is supplied by the anterior interosseous nerve. 



In the radial region there are threemuscles (Plate XXXII) Brachio-radialis 

 (Supinator longus,) Extensor carpi radialis longior, and the Extensor carpi 

 radialis brevior. The first two are supplied by the musculo-spiral nerve: the 

 last one by theposterior interosseous aervewhich Lsa branch of the musculo- 

 spiral nerve. 



In the posterior radio-ulnar region there are nine muscles, Plate XXXII,) 

 four in the superficial layer andfive in the deep layer. Thefour in the superficial 

 layer are the Extensor communis digitorum, Extensor minimi digiti, Extensor 

 carpi ulnaris, and Anconeus. The fust three are supplied by the posterior in- 

 terosseous nerve; theAnconeus by the musculo-spiral nerve. (Plate XXXIII). 

 The five muscles in the deep layer are the Supinator brevis, Extensor ossis meta- 

 carpi pollicis. Extensor brevis pollicis. Extensor longus pollicis, and the Exten- 

 sor indicis; they are all supplied by the posterior interosseous nerve. 



The bones of the forearm are the radius and ulna: the radius has nine mus- 



