译 名：
MEATUS ACUSTICUS EXTERNUS OSSEUS AND AURIS MEDIA OF THE HORSE
摘 要：
The osseous portion of the external acoustic meatus may be subdivided into two parts: (1) The tubular part formed by the exteral acoustic process of the temporal bone. The direction of the acoustic process extends from its origin laterally and upward; (2) The tympanic part representing the medial end of the external acoustic meatus. The Iumen of the tympanic part is diminished to form a slit-like cavity. This part is composed of two walls: The medial wall is formed by the tympanic membrane; the lateral wall is osseous. In the circumference between these walls is the annulus tympanicus. The tympanic membrane of the horse is oval in form, its dorso-ventral diameter (gram) is slightly greater than that of the transversal. The middle and ventral parts of the lateral surface of the membrane are concave. The umbo membrane is in the region between the middle and the ventral third of the membrane. Ossicula auditus: The general structure of the ossieula is very similar to that of man. However, the malleus is somewhat special—the processus muscularis is much developed, the processus longus is smaller and processus brevis is quite indistinct as compared with that of humans. Mm. ossiculorum auditus and their innervations: (1) m. tensor tympanie is somewhat pyramidal in shape and compressed laterally. The dorsal end of the muscle is inserted to the processus museularis of malleus by a short tendon. This musele is innervated by the branch of n. trigeminus; (2) m. stapedius is situated in a recess posterior to fossula fenestre vestibuli and ventral to the n. facialis. The nerve supply is from the facial nerve. We find a small ganglion on the surface of the trunk of the facial nerve, where the n. stapedius arises, and we named this ganglion "G. stapedius."
