250 



THE ARTICULATIONS. 



of the acromion just in front of the articular surface for the clavicle, and by its 

 broad base to the whole length of the outer border of the coracoid process. Its 

 posterior fibres are directed inward, its anterior fibres forward and inward. This 

 ligament completes the vault formed by the coracoid and acromion processes for 

 the protection of the head of the humerus. It is in relation, above, with the 

 clavicle and under surface of the Deltoid ; below, with the tendon of the Supra- 

 spinatus muscle, a bursa being interposed. Its outer border is continuous with 

 a dense lamina that passes beneath the Deltoid upon the tendons of the Supra- 

 and Infraspinatus muscles. This ligament is sometimes described as consisting 

 of two marginal bands and a thinner intervening portion, the two bands being 

 attached respectively to the apex and base of the coracoid process, and joining 

 together at their attachment into the acromion process. When the Pectoralis 

 minor is inserted, as sometimes is the case, into the capsule of the shoulder-joint 

 instead of into the coracoid process, it passes between these two bands, and the 

 intervening portion is then deficient. 



The Transverse or Coracoid (suprascapular) Ligament converts the suprascapu- 

 lar notch into a foramen. It is a thin and flat fasciculus, narrower at the middle 

 than at the extremities, attached by one end to the base of the coracoid process, 

 and by the other to the inner extremity of the scapular notch. The supra- 

 scapular nerve passes through the foramen ; the suprascapular vessels pass over 

 the ligament. 



An additional ligament (the spino-glenoid] is sometimes found on the scapula, 

 stretching from the outer border of the spine to the margin of the glenoid 

 cavity. When present, it forms an arch under which the suprascapular vessels 

 and nerve pass as they enter the infraspinous fossa. 



BICEPS. 

 CORACO-ACROMIAL \ GLENOID LIGAMENT. 



LIGAMENT. 

 DELTOID. 



DELTOID. CUPRA-SPINATUS. 



TERES MAJOR. 



SUB- 



'APULA- 

 RIS. 

 TRICEPS. 



TRICEPS. 



TERES MAJOR. Circumflex vessels. 'Circumflex vessels. SCAPULARIS. 



FIG. 170. -Vertical sections through the shoulder-joint, the arm being vertical and horizontal. (After Henle.j 



Movements of Scapula. The scapula is capable of being moved upward and 

 downward, forward and bacltAvard, or, by a combination of these movements, cir- 

 cumducted on the wall of the chest. The muscles which raise the scapula are the 

 upper fibres of the Trapezius, the Levator anguli scapulae, and the two Rhom- 

 boids ; those which depress it are the lower fibres of the Trapezius, the Pectoralis 

 minor, and, through the clavicle, the Subclavius. The scapula is drawn backward 

 by the Rhomboids and the middle and lower fibres of the Trapezius, and forward 

 by the Serratus magnus and Pectoralis minor, assisted, when the arm is fixed, by 

 the Pectoralis major. The mobility of the scapula is very considerable, and 

 greatly assists the movements of the arm at the shoulder-joint. Thus, in raising 

 the arm from the side the Deltoid and Supraspinatus can only lift it to a right 



