THE ALIMENTARY CANAL. 233 
uous with the circular fibres of the cesophagus. The cranial 
fibres may pass as far as the base of the sphenoid. 
Action.—Constrictor of the pharynx. 
M. constrictor pharyngis medius (7). —A thin sheet which 
covers the middle part of the lateral surface of the pharynx. 
Origin. —The ventral two pieces of the cranial horn and 
the whole of the caudal horn of the hyoid. The fibres diverge, 
passing dorsad. 
Jnsertion into the median dorsal raphe of the pharynx. 
The cranial fibres are inserted into the basé of the sphenoid 
bone. The muscle covers part of the stylopharyngeus (/) and 
the superior constrictor (Fig. 66, 7, page 112) and is partly 
covered by the glossopharyngeus (Fig. 96, z). 
Action.—Constrictor of the pharynx. 
M. stylopharyngeus (/). 
Origin from the tip of the mastoid process of the temporal 
bone and from the inner surface of the cartilaginous piece 
between the tympanohyal and the stylohyal bones. The 
parallel fibres form a flat band which passes ventrocaudad over 
the outer surface of the constrictor superior. 
Insertion.—The ventral fibres pass beneath the middle con- 
strictor (7) at its cranial border and, continuing toward the 
middle line of the pharynx, gradually lose themselves among 
the fibres of the superior constrictor. The dorsal fibres pass 
onto the outer surface of the middle constrictor and are lost- 
among its fibres. 
Action.—Constrictor of the pharynx. 
M. constrictor pharyngis superior or pterygopharyngeus 
(Fig. 66, 7, page 112).—A flat, triangular sheet beneath the 
constrictor medius., 
Origin.—The tip of the hamular process of the pterygoid 
bone. The muscle passes caudad, the fibres diverging, and 
dips beneath the cranial border of the constrictor medius. 
Insertion into the median dorsal raphe of the pharynx. 
The dorsal fibres are inserted into the base of the sphenoid. 
The ventral fibres pass lengthwise of the pharynx, closely 
connected with those of the stylopharyngeus (Fig. 96, /), and 
finally reach the level of the larynx. 
