162 



SKELETON OF THE DOG 



BONES OF THORACIC LIMB 



The clavicle is a small, thin, irregularly-triangular bony or cartilaginous plate. 

 It is embedded in the mastoido-humeralis muscle in front of the shoulder-joint 

 and forms no articulation with the rest of the skeleton. (It is nearly an inch long 

 in a large cat and is a slender curved rod.) 



The scapula is relatively long and narrow. The spine increases gradually 

 in height from above downward and divides the external surface into two nearly 

 equal fossae. Its free edge is thick and rough above, and at the lower part is thin 

 and bent backward. The acromion is short and blunt and is opposite the rim of 

 the glenoid cavity. The subscapular fossa is very shallow and is marked by rough 

 lines. The rough area alcove it for the attachment of the serratus magnus is large 

 and quadrilateral in front, narrow and marginal behind. The anterior liorder is 

 thin, strongly convex, and sinuous. The posterior border is straight and thick. 

 The vertebral border is convex and thick and bears a band of cartilage. The 

 cervical angle is rounded. The dorsal angle is thick and square. The neck is well 

 defined and bears a rough eminence posteriorly. The glenoid cavity is continued 



Fig. 128. — Right Scapula of Dog, External View. 

 a, Supraspinous fossa; h, infraspinous fossa; 

 c, spine; d, upper broad end of spine; e, acromion; 

 /, glenoid cavity; y, tuberosity; h, vertebral border; 

 i, posterior angle; k, scapular notch. (Ellenberger- 

 Baum, Anat. d. Ilundes.) 



Fig. 129. — Left Scapula of Dog, Costal Surface. 

 a, Subscapular fossa; h, b, b, muscular lines; 

 c, c, limiting line between subscapular fossa and serra- 

 tus area; d, glenoid cavity; e, f, tuberosity; g, nutri- 

 ent foramen. (Ellenberger-Baum, Anat. d. Hundes.) 



forward upon the lower face of the scapular tuberosity, which is blunt and bears 

 no distinct coracoid process. There is a rough eminence on the posterior surface 

 of the neck, from which the long head of the triceps arises. The cervical angle is 

 opposite the first thoracic spine, the dorsal angle lies above the vertebral end of 

 the fourth rib, and the articular angle at a point just in front of the sternal end 

 of the first rib in the ordinary standing position. The shoulder has a great range 

 of movement on the chest wall. 



The humerus is relatively very long, rather slender, and has a slight spiral 

 twist. The shaft is somewhat c()mi:)ressed laterally, especially in its upper t^^'o- 

 thirds; this part is curved in varying degree, convex in front. The deltoid tuber- 

 osity has the form of a low ridge, and it is continued by a crest which runs upward 

 and backward and l)ears a tubercle on its upper part. Another line runs frojn it 

 down the anterior aspect and forms the inner boundary of the very shallow musculo- 

 spiral groove. The nutrient foramen is about in the middle of the posterior 

 surface. A slight elevation on the proximal third of the inner surface represents 

 the teres tubercle. The head is long and strongly curved from before backward. 



