74 LABORATORY MANUAL OF HUMAN ANATOMY 



(c) Follow the medial margin (mar go medialis) downward to the medial 



epicondyle (epicondylus medialis), and the lateral margin (mar go 

 later alis) downward to the lateral epicondyle (epicondylus later- 

 alis). Note that, though the margo lateralis is more salient than 

 the margo medialis, the epicondylus medialis is more prominent 

 than 'the epicondylus lateralis. Feel through the skin behind the 

 medial epicondyle for the groove for the ulnar nerve (sulcus N. 

 ulnaris). Press upon the nerve in your own arm (" funny bone," 

 or " crazy bone"). Whence does the sensation seem to come? 



(d) Observe the prominence due to the olecranon (1) when the forearm 



is extended, (2) when the forearm is flexed. Standing in front of 

 a living body, take the two elbow-joints in the palms of the two 

 hands, with the -forefinger resting on the tip of the olecranon, the 

 thumb on the lateral epicondyle, and the middle finger on the 

 medial epicondyle. Ask the person to flex and extend the fore- 

 arms, and notice changes in relative position of bony points. Note 

 the relative distance between the level of the olecranon and the 

 epicondyles. The olecranon is a little nearer to the medial than 

 to the lateral epicondyle, especially in children. Observe the free 

 movement of the skin over the olecranon, due to a subcutaneous 

 bursa. To what extent is the posterior surface of the ulna sub- 

 cutaneous? Feel for the margins of the semilunar notch (incisura 

 semilunaris) . 



(e) Extend the forearm. Place the thumb of the left hand on the lateral 



epicondyle of the humerus; seize the hand with your right hand 

 and rotate gently. Feel the rounded head of the radius (capitulum 

 radii) rotating immediately below the epicondyle. 

 (/) In the forearm palpate 



(fa) Dorsal margin of ulna (margo dorsalis ulnae). 



(fb) Styloid process of ulna (processus styloideus ulnae). 



(fc) Rounded head of ulna (capitulum ulnae). 



(fd) Styloid process of radius (processus styloideus radii). 



(fe) Radial artery (A. radialis). 



(ff) The tendons about the wrist. 



Skin and Superficial Fascia. 



Cut through the skin in the middle line of the anterior sur- 

 face of the upper arm and the volar surface of the forearm as 

 far as the wrist. Make a circular incision around the forearm 

 just proximal to the wrist- joint. Remove the skin, dissecting 

 lateralward and medialward, but take none of the fat of the 

 superficial fascia with it. Preserve the skin, as it makes the 

 best primary wrapping for the extremity in the intervals between 

 dissection-periods. In the superficial fascia dissect out carefully 

 the following : 



Nerves. (Cf. Fig. 20, and Spalteholz, Figs. 792 and 793.) 



(a) Intercostobrachial nerves (Nn. intercostobrachiales) (0. T. inter- 

 costohumeral). 



