Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29465/444/
SCAPULAR REGION. 
434 
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 ffom 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 ossifie 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.
        

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