The Skeleton of the Anterior Limb. ,159 



skull and the chain of elements commonly occurring in riiamtei^ls 

 and other vertebrates in this region. In most mammals the term 

 "lesser", as applied to it, is inappropriate. The muscl'e tendon 

 contains near the jugular process a small ossification representing 

 a detached styloid process. This connection, together with the 

 hyoid bone itself, indicates the relation of the embryonic hyoid arch, 

 from which the skeletal structures in question are derived. The 

 greater cornu belongs to the succeeding visceral arch, and is con- 

 nected with the superior cornu of the thyreoid cartilage of the 

 larynx by the lateral hyothyreoid ligament. It is commonly 

 represented in mammals by a small thyreohyal process. 



THE SKELETON OF THE ANTERIOR LIMB. 



The skeleton of the anterior limb is divisible into two portions, 

 namely, a proximal portion, comprising the scapula and the 

 clavicle, and a distal portion, comprising the supports of the 

 free extremity. The scapulae and clavicles of the two sides 

 together form the pectoral girdle. The pectoral girdle is lightly 

 constructed, and, apart from its muscular connections, which 

 constitute its main support, is directly attached to the axial skeleton 

 only through the sternoclavicular ligament. 



The skeleton of the free extremity is divisible into proximal, 

 middle, and distal segments. The proximal segment contains 

 a single bone, the humerus ; the middle segment two elements, the 

 radiusand ulna; while the distal segment comprises, in addition 

 to the accessory sesamoid bones, twenty-eight elements of the 

 regular series, of which nine form the carpus, five the metacarpus, 

 and fourteen the phalanges of the digits. 



THE SCAPULA. 



The scapula (Fig. 66). .is a somewhat triangular plate of bone 

 lying in the natural position oh the lateral surface of the anterior 

 part of the thorax, with its apex directed downward and forward. 

 In the rabbit, as in quadrupedal mammals generally, the main 

 surfaces are respectively .medial and lateral, and differ in this respect 

 from the human condition, in which, from the transverse widening' 



