78 BONES OF THE UPPER LIMB. 



Texture. The interior of the clavicle contains coarse cancellated tissue 

 in its whole extent. It almost always presents a foramen for a medullary 

 artery on its posterior surface, and sometimes others. 



THE HUMERUS. 



The humerus or arm-bone extends from the scapula to the bones of the 

 forearm, with each of which it is articulated. It hangs nearly vertically 

 from the shoulder, with an inclination inwards towards the lower end. It 

 is divisible into a superior extremity, including the head, neck, and greater 

 and smaller tuberosities ; the shaft ; and the in- 

 Fig. 69. ferior extremity, including the external and internal 



supracondyloid eminences, and the inferior articular 

 surface. In general form it is subcylindrical and 

 slightly twisted. 



The superior extremity is the thickest part of 

 the bone. The . head is a large hemispherical 

 articular elevation, directed inwards, upwards, and 

 somewhat backwards. The neck, as described by 

 anatomists, is the ring of bone which supports the 

 head ; iuferiorly, it passes into the shaft ; superiorly, 

 it is a mere groove between the head and the great 

 tuberosity. The neck, as often described by sur- 

 geons, is the part of the shaft immediately below 

 the tuberosities. The great tuberosity is a thick 

 projection, continued upwards from the external 

 I ,;'| part of the shaft, and reaching nearly to the level 



of the upper margin of the head ; it is sur- 

 mounted by three flat surfaces, the uppermost of 

 which gives attachment to the supraspinatus 

 muscle, the lowest to the teres minor, and the 

 intermediate one to the infraspinatus muscle. 

 Separated from the great tuberosity by the com' 

 mencement of the bicipital groove, the small 

 tuberosity, rounded and prominent, looks directly 

 forwards and gives attachment to the subscapularis 

 muscle. 



Fig. 69. RIGHT HUMERUS PROM BEFORE. 



1, the articular head ; 2, lesser tuberosity ; 3, greater 

 tuberosity ; 4, neck of anatomists ; 5, bicipital groove ; 

 6, inner bicipital ridge, and mark of the attachment of the 

 latissimus dorsi and teres major muscles; 7, outer bicipital 

 ridge, and rough surface of insertion of the pectoralis major, 

 running down into 7', the triangular mark of the insertion 

 of the deltoid ; 8, spiral groove ; 9, inner ridge of the 

 humerus; 10, trochlear articular surface; 11, capitellum, 

 or radial condyle ; 12, epitrochlear or internal supracondy- 

 loid eminence ; 13, capitellar or external supracondyloid 

 eminence; 14, coronoid depression or fossa. 

 iv 



The shaft or body, thick and cylindrical supe- 

 riorly, becomes somewhat thinner as it descends, and in the lower third 

 is expanded transversely and becomes somewhat three-sided. Superiorly on 

 its anterior aspect is the bicipital groove, so named from lodging the long 



