Internal acoustic opening - Porus acusticus internus
The internal acoustic opening is a large orifice near the center of posterior surface of petrous part, its size varies considerably; its margins are smooth and rounded, and it leads into a short canal, the internal acoustic meatus, about 1 cm. in length, which runs lateralward. It transmits the facial and acoustic nerves and the internal auditory branch of the basilar artery.
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).
General Anatomy > Bones; Skeletal system > Axial skeleton > Cranium > Temporal bone > Petrous part > Posterior surface of petrous part > Internal acoustic opening