THE UPPER LIMB 415 



border of the muscle near its centre. In cleaning this border the relation to it 

 of the deep fascia over the infraspinatus is to be observed. The deltoid having 

 been fully dissected, and twigs of the circumflex nerve which pierce it having 

 been noted, the muscle is to be divided about i inch below its origin. In 

 turning it down the subacromial bursa and the circumflex nerve and posterior 

 circumflex artery are to be shown, the latter two entering its deep surface. 



The infraspinatus, teres minor, teres major, and long head of the triceps are 

 then to be dissected, and the gangUform enlargement on the branch of the 

 circumflex nerve to the teres minor is to be observed. The quadrangular and 

 triangular muscular spaces, ^^ith their contents, are to be exposed, and the 

 substitution of the subscapularis as a boundary in front for the teres minor 

 behind is to be noted. The dorsaUs scapulae artery- is to be shown winding 

 round the axiUary border of the scapula through the origin of the teres 

 minor. The supraspinatus is next to be dissected, and, to follow the muscle 

 to its insertion, the acromion process may be sa\\Ti through. At the upper 

 border of the muscle will be found the posterior belly of the omo-hyoid and the 

 suprascapular nerve and artery. The subscapularis is to be cleaned, and at 

 this stage the upper or short subscapular nerve will be fully seen. 



The supraspinatus, infraspinatus, and teres minor are to be stripped carefuUy 

 from the bone and dissected up to their insertions, in doing which the intimate 

 connection between their tendons and the upper and back parts of the capsule 

 of the shoulder- joint will arrest attention. Between the infraspinatus tendon and 

 the capsule a small bursa may be found. The careful removal of these muscles 

 will allow the dissector to follow out the suprascapular artery and nerve, and 

 the dorsaUs scapulae artery. The subscapularis is also to be stripped from the 

 bone and dissected to its insertion, to do which the muscle must be raised 

 from beneath the coraco-brachiaUs and short head of the biceps. The close 

 connection between its tendon and the front of the capsule is to be noted, as 

 well as the opening in the capsule through which the sjTiovial membrane 

 protrudes to form the subscapular bursa. The teres major and latissimus 

 dorsi are to be followed to their insertions, the varjdng relations between the 

 two are to be made clear, the intervening bursa shown, and in some cases a 

 small bursa behind the tendon of the teres major close to the bone. Before 

 leaving this region the dissector should carefully study the scapular anasto- 

 moses of arteries, the muscular relations of the capsule of the shoulder-joint, 

 and the actions of the scapular muscles, with their ner\'e-supply. 



Cataneoas Nerves and Veins of the Arm and Forearm. — The skin should be 

 at once reflected as low as the wrist by a median incision down the front of 

 the hmb, and transverse incisions at the elbow and wrist. In reflecting it 

 from over the back of the olecranon process the subcutaneous bursa, there 

 situated, is to be attended to. The following cutaneous nerves are to be fol- 

 lowed out to their distribution, care being taken to preserve the cutaneous 

 veins : (i) the in tercos to-humeral to the inner and back part of the arm in 

 its upper half ; (2) the internal cutaneous of the musculo-spiral to the back of 

 the arm ; (3) the nerve of Wrisberg to the lower half of the arm on its inner 

 aspect ; (4) twigs of the internal cutaneous to the front of the arm in its upper 

 part ; and (5) the upper external cutaneous branch of the musculo-spiral 

 (which appears a Uttle below the centre of the outer side of the arm) to the 

 outer side and front of the arm over about its lower half. At the junction of 

 the upper two-thirds and lower third of the arm on its iimer side the internal 

 cutaneous nerve will be found piercing the deep fascia in two divisions, separ- 

 ately or conjointly, and from this point the two divisions, anterior and 

 posterior, are to be followed downwards along the inner part of the forearm, 

 as low as the wrist in the case of the anterior. The lower external cutaneous 

 branch of the musculo-spiral is to be followed from the outer side of the arm, 

 a little below the centre, down the back of the outer side of the forearm as low 

 as the wrist. The cutaneous part of the musculo-cutaneous wiU be found at 

 the outer border of the biceps a httle above the elbow, and it is to be traced 

 down the outer side of the forearm as low as the wrist in two divisions, anterior 

 and posterior. 



In front of the forearm, just below the centre and internal to the middle line. 



