THE MUSCLES OF THE HEAD. 103 
lis (c). The aponeurosis is united with the caudoventral angle 
of the scutiform cartilage and with the ventral edge of the 
cranial margin of the auricular cartilage. 
This muscle is united at its cranial end with the orbicularis 
oris (2); throughout its length more or less with the platysma 
(@, a’); at its caudodorsal end with the corrugator supercilii 
lateralis (£) on its medial side, and with the submentalis (¢) on 
its lateral side. 
Relations.—Outer surface with the integument and the 
platysma (a’). Inner surface with the masseter, temporal, 
frontoscutularis, and adductor auris inferior (¢). 
Action.—Draws the angle of the mouth dorsocaudad; the 
external ear ventrocraniad. 
M. submentalis (Fig. 64, c).—A flat band, similar to the 
last, and closely connected for some distance to its caudal 
border. 
It arises as scattered fibres near the ventral middle line at 
about the level of the larynx, the fibres of the opposite muscles 
crossing the middle line and intermingling. The fibres pass 
dorsad, converging so as to form a narrower band, which 
unites dorsad with the zygomaticus (d), to be inserted with it 
into the tendinous aponeurosis above described. 
Relations.—Outer surface with the integument and _ pla- 
tysma (a’). Inner surface with the muscles of the hyoid, the 
digastricus, the parotid gland, the masseter, the zygomatic arch 
and the temporal muscle. 
Action.—Draws the external ear ventrad. 
M. depressor conche (Fig. 64, 4).—A thin band of fibres, 
caudad of the last and parallel with it. The muscle arises as 
scattered fibres on the ventral surface of the neck, one or 
two centimeters craniad of the manubrium, the fibres of the 
muscles of opposite sides crossing the middle line and inter- 
digitating. They pass dorsad, gathering together to form a 
narrow band which is inserted into the summit of the antitragus. 
Relations. —Outer surface with the skin at the ventral end, 
and with the platysma (a@’) further dorsad. Inner surface with 
the deep muscles of the neck and with the parotid gland. 
Action.—Draws the external ear ventrad. 
