The muscle passes lateroventrad lying beneath the abductor longus (m) as a flat band 6 to 8 millimeters wide which is inserted into the medial surface of the most proximal portion of the concha, just distad of its junction with the cartilaginous auditory meatus.
Relations.—Outer surface with the abductor longus (m), a small strand of the platysma and the concha. Inner surface with the temporal muscle (n).
Action.—Pulls the concha caudad.
M. epicranius (or occipitofrontalis) ([Fig. 63], h and h′).
Origin on the sagittal crest or suture, just craniad of the origin of the levator longus auris, to the inner surface of which this muscle is closely united. From the origin the fibres pass craniad forming a band (h) about 8 or 10 millimeters in width, the two muscles lying close to one another and partly united in the middle line. About two centimeters craniad of their origin the fibres of both muscles end in a tendinous sheet, the galea aponeurotica, which covers the surface of the skull in the region between the ears and eyes, and is formed by the inner surface of the intermedius scutulorum (a) and other muscles of this region. The galea aponeurotica passes craniad onto the surface of the nose, where it gives origin again to a thin sheet of muscle-fibres (h′) which are inserted into the integument near the cranial ends of the nasal bones.
M. epicranius is thus formed of two muscular portions (h and h′), connected by a long tendinous sheet. The caudal portion is frequently distinguished as the occipital muscle (M. occipitalis, h), the cranial portion, on the nose, as the frontal muscle (M. frontalis, h′).
Relations.—Outer surface of the occipitalis (h) with the intermedius scutulorum (a), the levator auris longus (g), and the integument; inner surface with the auricularis superior (h), the abductor auris longus, and the bone. Outer surface of the frontalis (h′) with the integument; inner surface with the bones of the skull.
Action.—Moves the integument of the dorsal surface of the head and of the nose.
Ventrad of the external ear the following three differentiated portions of the platysma may be distinguished.
M. zygomaticus (major) ([Fig. 64], d).—A slender band connecting the angle of the mouth with the scutiform cartilage of the ear.