Promontory of tympanic cavity
| Promontory of tympanic cavity | |
|---|---|
 View of the inner wall of the tympanum. (Promontory visible near center.) | |
| Details | |
| Identifiers | |
| Latin | promontorium tympani |
| TA98 | A15.3.02.011 |
| TA2 | 6899 |
| FMA | 77694 |
| Anatomical terminology | |
The promontory of the tympanic cavity, also known as the cochlear promontory or petrosal promontorium, is a rounded hollow prominence upon - and most prominent feature of - the medial wall of the tympanic cavity formed by the underlying first turn of the cochlea. The surface of the promontory is furrowed by fine grooves that accommodate to the strands of the tympanic plexus.[1]
The oval window is situated superoposteriorly to the promontory, and the round window inferoposteriorly to it.[1]
A minute spicule of bone frequently connects the promontory to the pyramidal eminence.
Evolution
In non-mammalian synapsids, the promontorium was not present. During the evolution of mammals, the shrinking and displacement of the basisphenoid allowed for the enlargement of the petrosal, of which the promontorium is a part. This is a major apomorphy by which the earliest mammals can be distinguished from their closest relatives.[2]
Additional images
Coronal section of right temporal bone.
The medial wall and part of the posterior and anterior walls of the right tympanic cavity, lateral view.
References
This article incorporates text in the public domain from page 1042 of the 20th edition of Gray's Anatomy (1918)
- 1 2 Sinnatamby, Chummy S. (2011). Last's Anatomy (12th ed.). p. 415. ISBN 978-0-7295-3752-0.
- ↑ Luo, Zhexi; Crompton, Alfred W.; Lucas, Spencer G. (1995-03-14). "Evolutionary Origins of The Mammalian Promontorium and Cochlea". Journal of Vertebrate Paleontology. 15 (1): 113–121. doi:10.1080/02724634.1995.10011211. ISSN 0272-4634.
External links
- lesson3 at The Anatomy Lesson by Wesley Norman (Georgetown University)