2S8 ARTICULATIONS. 



Its posterior fibres are directed obliquely backwards and outwards, its anterior 

 fibres transversely. 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 Supraspinatus muscle, a bursa being interposed. Its anterior 

 border is continuous with a dense cellular lamina that passes beneath the 

 Deltoid upon the tendons of the Supraspinatus and Infraspinatus muscles. 



The Transverse or Coracoid Ligament converts the suprascapular 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 suprascapular 

 nerve passes through the foramen; the suprascapular vessels above it. 



IV. SHOULDER-JOINT. (Fio. 198.) 



The shoulder is an enarthrodial or ball-and-socket joint. The bones entering 

 into its formation are the large globular head of the hujnerus, received into 

 the shallow glenoid cavity of the scapula, an arrangement which permits of 

 very considerable movement, whilst the joint itself is protected against dis- 

 placement by the strong ligaments and tendons which surround it, and above 

 by an arched vault, formed by the under surface of the coracoid and acromion 

 processes, and the coraco-acromial ligament. The articular surfaces are covered 

 by a layer of cartilage ; that on the head of the humerus is thicker at the centre 

 than at the circumference, the reverse being the case in the glenoid cavity. The 

 ligaments of the shoulder are, the 



Capsular. Coraco- humeral. 



Glenoid. 1 



The Capsular Ligament completely encircles the articulation ; being attached, 

 above, to the circumference of the glenoid cavity beyond the glenoid ligament ; 

 below, to the anatomical neck of the humerus, approaching nearer to the articular 

 cartilage above than in the rest of its extent. It is thicker above than below, 

 remarkably loose and lax, and much larger and longer than is necessary to 

 keep the bones in contact, allowing them to be separated from each other more 

 than an inch, an evident provision for that extreme freedom of movement which 

 is peculiar to this articulation. Its external surface is strengthened, above, by the 

 Supraspiuatus ; above and internally, by the coraco -humeral ligament; below, 

 by the long head of the Triceps ; externally, by the tendons of the Infraspinatus 

 and Teres minor; and internally, by the tendon of the Subscapularis. The 

 capsular ligament usually presents three openings : one at its inner side, below 

 the coracoid process, partially filled up by the tendon of the Subscapularis; it 

 establishes a communication between the synovial membrane of the joint and 

 a bursa beneath the tendon of that muscle. The second, which is not constant, 

 is at the outer part, where a communication sometimes exists between the joint 

 and a bursal sac belonging to the Infraspinatus muscle. The third is seen in 

 the lower border of the ligament, between the two tuberosities, for the passage 

 of the long tendon of the Biceps muscle. 



The Coraco-humeral or Accessory Ligament is a broad band which strengthens 

 the upper and inner part of the capsular ligament. It arises from the outer 

 border of the coracoid process, and passes obliquely downwards and outwards 

 to the front of the great tuberosity of the humerus, being blended with the 

 tendon of the Supraspinatus muscle. This ligament is intimately united to the 

 capsular in the greater part of its extent. 



The Glenoid Ligament is a firm fibrous band attached round the margin of the 

 glenoid cavity. It is triangular on section, the thickest portion being fixed to 



1 The long tendon of origin of the Biceps muscle also acts as one of the ligaments of this joint. 



