MUSCLES OF THE BODY. 115 
bone through their insertion into the tendon of the stylo- 
hyoid (@). 
Relations. —Outer surface with the submentalis (Fig. 64, c) 
and the digastric (Fig. 65, 4). Lateral edge with the masseter 
(a), the digastric (4), and the mandibula. Caudal border with 
the stylohyoid (@). Inner (dorsal) surface with the geniohyoid 
(Fig. 67, g), the hyoglossus (Fig. 67, %), and the genioglossus 
(Fig. 67, f). 
Action.—Raises the floor of the mouth and thus brings the 
hyoid forward. 
M. ceratohyoideus. 
Origin, the two proximal pieces of the cranial horn of the 
hyoid. The fibres pass caudad parallel to one another and 
within the middle constrictor of the pharynx. 
Insertion into the whole length of the caudal cornu of the 
hyoid bone. 
Relations.—Outer surface with the middle constrictor of the 
pharynx. Inner surface with the pharynx. 
Action.—Draws craniad the body of the hyoid by bringing 
its cornua together and bending the joint between the two 
pieces of the cranial cornua. 
The muscles connecting the hyoid and the tongue are 
described in connection with the description of the tongue. 
III. MUSCLES OF THE BODY. 
1. Muscles of the Back. 
A. MUSCLES OF THE SHOULDER (connecting the forelimb 
with the back) (Fig. 68). 
M. trapezius.—The trapezius muscle is divided in the cat 
into three portions, the spinotrapezius, the acromiotrapezius, 
and the clavotrapezius. 
M. spinotrapezius, or trapezius inferior (Fig. 68, 7).—The 
spinotrapezius (caudal part of the human trapezius) is a flat 
triangular muscle. 
Origin from the tips of the spinous processes of all or 
nearly all the thoracic vertebrae and from the intervening 
supraspinous ligament. The origin may extend from a point 
anywhere between the first and fourth spines to any point 
between the eleventh and thirteenth. 
