Page 192 - Clinical Anatomy

ECA3 7/18/06 6:45 PM Page 177

The bones and joints of the upper limb 177

Fig. 129◊The shoulder
joint—the same view as
in Fig. 128—but now with
the addition of the
surrounding muscles.

3◊◊the more distantly related long muscles of the shoulder; the deltoid,
long head of triceps, pectoralis major, latissimus dorsi and teres major.

Movements of the shoulder girdle

The movements of the shoulder joint itself cannot be divorced from those of
the whole shoulder girdle. Even if the shoulder joint is fused, a wide range
of movement is still possible by elevation, depression, rotation and protrac-
tion of the scapula, leverage occurring at the sternoclavicular joint, the
pivot being the costoclavicular ligament.
Abduction of the shoulder is initiated by the supraspinatus; the deltoid
can then abduct to 90°. Further movement to 180° (elevation) is brought
about by rotation of the scapula upwards by the trapezius and serratus
anterior. Shoulder and shoulder girdle movements combine into one
smooth action. As soon as abduction commences at the shoulder joint, so
rotation of the scapula begins. Test this on yourself or on a colleague by pal-
pating the lower pole of the scapula. This will be felt to swing outwards on
initiation of shoulder abduction. Movements of the scapula occur with reci-
procal movements at the sternoclavicular joint. Place a finger on this joint;
elevate the shoulder and the joint will be felt to depress, swing the shoulder
forwards and it will be felt to move backwards, and so on.
Rotator cuff (Fig. 130) is the name given to the sheath of tendons of the
short muscles of the shoulder which covers and blends with all but the infe-
rior aspect of that joint. The muscles are the supraspinatus, infraspinatus
and teres minor, which are inserted from above down into the humeral
greater tubercle, and the subscapularis, which is inserted into the lesser
tubercle. All originate from the scapula.
Of these muscles, the supraspinatus is of the greatest practical impor-
tance. It passes over the apex of the shoulder beneath the acromion
process and coracoacromial ligament, from which it is separated by the