76 BONES OF THE UPPER LIMB. 



The acromion process, projecting outwards and forwards from the extremity 

 of the spine, is situated above and behind the glenoid cavity, and forms the 

 summit of the shoulder. It is an expanded process, compressed from above 

 downwards. Its superior surface, rough and subcutaneous, is continuous 

 with the prominent border of the spine ; its inferior surface, smooth and 

 concave, is continuous with the superior surface and external border of the 

 spine. On its internal border anteriorly is a narrow oval surface for articula- 

 tion with the clavicle ; and at its extremity it affords attachment to the 

 coraco-acromial ligament. 



The glenoid cavity is a slightly concave surface, looking outwards and a 

 little upwards and forwards. It is ovoid or rather pyriform in shape, with 

 the narrow end uppermost, and gently incurved in front. It is in some 

 degree flattened at its circumference, where, in the recent state, it is covered 

 by a fibrous band, the gleuoid ligament, which deepens its concavity ; and 

 at its upper extremity is a slight roughness, marking the attachment of the 

 long head of the biceps muscle. 



The neck, supporting the glenoid cavity, is most distinct posteriorly, where 

 it forms between the glenoid cavity and the spine the great scapular notch or 

 groove, leading from the supraspinous to the infraspinous fossa. The line 

 of the neck, as described by anatomists, passes superiorly between the glenoid 

 cavity and the coracoid process, but that of the part often named neck by 

 surgeons passes internal to the coracoid process. 



The coracoid process, thick and strong, springs almost vertically from the 

 superior border of the bone, above the glenoid cavity, but, suddenly 

 bending at a right angle, is directed forwards and outwards. Its superior 

 surface, towards the base, is rough and uneven, giving origin to the corac'o- 

 clavicular ligaments ; on its outer border is attached the coraco-acromial 

 ligament, at its extremity the coraco-brachialis muscle and short head of 

 the biceps, and on the inner edge the pectoralis minor. 



The borders or costce of the scapula are three in number. The superior 

 border is the shortest ; it extends from the superior angle outwards and down- 

 wards towards the coracoid process, at the base of which it presents a rounded 

 suprascapular notch (incisuta semilunaris), which is converted into a foramen 

 by a ligament or occasionally a spiculum of bone, and is traversed by the 

 suprascapular nerve, and sometimes also by the accompanying vessels. The 

 external, axillary, or inferior border presents at its upper part, beneath the 

 glenoid cavity, a rough tuberculated ridge, above an inch long, to which the 

 long head of the triceps muscle is attached : a little below this there is 

 usually a slight groove, where the dorsal branch of the subscapular artery 

 passes backwards : and at its lower extremity the border is thick, and 

 rounded over into the space from which the teres major muscle arises. The 

 internal, vertebral, or posterior border, called also the base, is the longest of 

 the three, and is divisible into three parts, viz., a short one opposite the 

 triangular surface of origin of the prominent border of the spine, and the 

 portions above and below that space, both of which incline outwards as they 

 recede from the spine. The upper part gives attachment to the levator 

 anguli scapulae muscle, the middle one to the rhomboideus minor, and the 

 lower to the rhomboideus major muscle. 



Texture. The triangular part of the scapula is in great part thin and 

 translucent, and contains little cancellated tissue. The neck, the coracoid 

 and acromion processes, the prominent border of the spine, and the part 

 near the inferior angle, derive their greater thickness and strength from 

 increased thickness of the compact bony substance in some parts, and 



