434 



SCAPULAR REGION. 



divides the scapular region into two distinct 

 parts, termed by anatomists the supra- and 

 infra-spinal fossae ; and in this article we shall 

 describe, seriatim, the anatomical relations of 

 the structures which occupy these two fossae 

 respectively. 



The subcutaneous layer of areolar tissue, 

 throughout the whole of the scapular region, 

 is dense, and much more closely connected to 

 the integument than to the aponeurosis be- 

 neath. Very free motion of the skin on the 

 deeper seated structures is thus allowed. In 

 this layer, superiorly, we find some of the 

 superficial descending branches of the cervical 

 plexus of nerves passing towards the region 

 of the shoulder, where they become lost in 

 the integument. Beneath the skin, sub- 

 cutaneous areolar tissue, and superficial layer 

 of fascia, the trapezius muscle covers all that 

 portion of the scapular region which corre- 

 sponds to the supra- spinal fossa. The fibres 

 of this muscle take a direction downwards, 

 outwards, and forwards, across this region, to 

 the upper edge of the spinous process, and 

 angle of junction between the acromion pro- 

 cess and clavicle, into which they are inserted ; 

 the more posterior fibres are oblique ; the an- 

 terior, coming from the superior crest on the 

 occipital bone, descend more perpendicularly. 

 This muscle acts powerfully as an elevator of 

 the shoulder joint, its anterior fibres drawing 

 the entire scapula upwards and backwards, 

 and with it the upper extremity, whilst its 

 posterior fibres effect the same purpose by 

 producing a motion of rotation in the scapula, 

 in virtue of which the posterior angle of that 

 bone is depressed, and the anterior, or acro- 

 mial extremity, proportionately elevated. In 

 cutting through the trapezius muscle, the 

 anatomist will probably meet with some of 

 the terminal branches of the spinal accessory 

 nerve distributed to this muscle ; as also 

 descending branches of the supra-scapular 

 artery, which, becoming superficial, maintain 

 around the acromion process an anastomosis 

 with the ascending (inferior acromial) branches 

 of the acromial axis, and the circumflex 

 branches of the axillary trunk. 



Beneath the trapezius muscle, and sepa- 

 rating it from the fascia which covers the 

 supra-spinatus muscle, a layer of fatty areolar 

 tissue is always placed, which varies, however, 

 in its amount, in different persons. In chronic 

 disease of the shoulder joint, such as ulcera- 

 tion of the articular cartilage, and, in fact, in 

 all cases where inflammatory action has ex- 

 isted in the articulation for any considerable 

 length of time, this intermuscular fatty stra- 

 tum becomes absorbed ; and to this circum- 

 stance, as also probably in some degree, to 

 atrophy of the muscular fibres, is due the pe- 

 culiar flattening, or even the depression, so 

 constantly observed above the spine of the 

 scapula in such cases ; appearances analogous 

 to the flattening of the gluteal region, which 

 is one of the most remarkable external fea- 

 tures of " morbus coxae." 



Deeper still is placed an aponeurosis of 

 great strength, which forms, with the smooth 



concave surface of the supra-spinal fossa, an 

 osteo-fibrous canal, containing the fleshy por- 

 tion of the supra-spinatus muscle. This 

 fascia is stretched between the superior costa 

 and the spine of the scapula ; by its under 

 surface, posteriorly, it affords attachment to 

 the fibres of the supra-spinatus ; whilst ante- 

 riorly it accompanies the tendon of that 

 muscle, under the acromial end of the cla- 

 vicle and the triangular ligament, losing itself 

 on the capsular ligament of the shoulder joint. 

 By the removal of this fascia, we bring into 

 view the supra-spinatus muscle, filling accu- 

 rately the fossa from which it derives its 

 name, and from nearly the entire of which it 

 derives its origin ; anteriorly, however, the 

 muscular fibres have no ossific attachment. 

 They here glide over the smooth, pulley-like 

 surface presented by the bone, and then, 

 bending downwards and outwards, they form 

 the tendon of the muscle, which is inserted 

 further on into the upper facette of the great 

 tuberosity of the humerus, becoming also in- 

 corporated with the capsular ligament. In 

 this part of their course the supra-spinatus 

 muscle and tendon are concealed by the acro- 

 mio-clavicular articulation, and more exter- 

 nally by the coraco-acromial, or triangular li- 

 gament, which is stretched in the form of an 

 arch above them ; a bursa of large size inter- 

 venes between the under-surface of the liga- 

 ment and the superficial, or upper aspect of 

 the tendon. By the removal of the trapezius 

 muscle we are also enabled to see the attach- 

 ments of several muscles to the edges of the 

 supra-spinal fossa ; thus the insertion of the 

 levator anguli scapulae into the posterior su- 

 perior angle of the scapula becomes apparent ; 

 also the attachment of the upper fibres of the 

 serratus magnus anticus to its superior costa; 

 and that of the omo-hyoid muscle to " the 

 ligament of the notch," and the base of the 

 coracoid process. In this situation also the 

 supra-scapular nerve and artery enter the 

 supra-spinal fossa, usually separated from 

 one another by " the ligament of the notch." 

 The nerve, in the majority of instances, being 

 beneath, and the artery above, the ligament, 

 the nerve is transmitted through a foramen, 

 formed by the notch in the upper edge of the 

 scapula and the ligament of the notch, whilst 

 the artery enters the fossa through a small 

 triangular interval, the respective sides of 

 which are constituted by the ligament of the 

 notch, coracoid process, and the posterior 

 belly of the omo-hyoid muscle. 



The supra-scapular nerve is a branch from 

 the upper division of the brachial plexus : in 

 the neck it follows the course of the omo- 

 hyoid muscle to the scapula, passes beneath 

 the origin of that muscle and through the 

 foramen above described ; after which it 

 enters the supra-spinal fossa, and is distri- 

 buted, firstly, to the supra-spinatus muscle ; 

 secondly, to the infra-spinatus and teres minor 

 muscles, by a branch which passes beneath the 

 acromion process ; and, thirdly, by a few 

 twigs to the exterior of the capsule of the 

 shoulder joint. 



