CHAPTER VII. 

 THE FOREARM. 



ANATOMY. LIGATIONOFARTERIES. 



ACTION OF MUSCLES. NERVE STRETCHING. 



LANDMARKS. FRACTURES*. 



AMPUTATION. 



The superficial tissues of the anterior surface of the 

 forearm are supplied by the following nerves : The mus- 

 culo-cutaneous externally and the internal cutaneous in- 

 ternally ; while, on the posterior surface, the musculo-cut- 

 aneous and the radial on the outer aspect, and the poste- 

 rior branch of the internal cutaneous on the inner, together 

 with the lower cutaneous branch of the musculo-spiral, 

 constitute the nerve supply. Beneath the superficial is 

 the deep fascia, strengthened by accessions from the 

 tendons of the biceps and triceps, and attached to the 

 following bony projections, viz.: The olecranon, the con- 

 dyles, the posterior border of the ulna and the outer 

 border of the lower end of the radius. This fascia is 

 composed of fibres which are circular, oblique and longi- 

 tudinal in direction, and is thickest on the posterior 

 surface, thinnest on the upper part of the anterior surface 

 and intermediate on the lower part of the same surface. 



Action of Muscles. Beneath the deep fascia are 

 the following muscles : i. The biceps. This muscle, in- 

 serted into the tuberosity of the radius, flexes the bone 

 and, therefore, the forearm, at the same time rotating out- 

 wards the radius, and with it, the hand. This movement 

 of rotation results from the fact that the tendon is insert- 

 ed into the back part of the tuberosity, so that, when the 

 muscle contracts, the radius is rotated through an axis 

 passing up the centre of the bone. In this movement 

 of rotation, the head of the bone rolls on the articular 



