14.FLOOR OF MIDDLE EAR RELATED WITH

A.INTERNAL CAROTID ARTERY
B.INTERNAL JUGULAR VEIN
C.ROUND WINDOW
D.

ANS:INTERNAL JUGULAR VEIN

Floor: The floor is much narrow. Infact it is narrower than the roof of the middle ear cavity. This portion of the middle ear cavity lies in close relationship with the jugular bulb. The middle ear cavity is separated from the jugular bulb by a thin piece of bone. Rarely, the floor may be deficient and the jugular bulb in these patients is separated from the middle ear cavity only by fibrous tissue and mucous membrane. At the junction of the floor and the medial wall of the middle ear there is a small opening which allows the entry of tympanic branch of glossopharyngeal nerve to pass into the middle ear. This nerve takes an important part in the formation of tympanic plexus.

Middle ear cavity 

1. canal for tensor tympani muscle
2. auditory tube
3. internal carotid artery
4. facial nerve
5. geniculate ganglion
6. greater petrosal nerve
7. lesser petrosal nerve
8. promontory formed by 1st turn of cochlea
9. tympanic plexus
10. round window
11. lateral semicircular canal
12. facial canal and facial nerve
13. oval window for stapes
14. tympanic nerve from IX
15. jugular vein
16. opening to mastoid air cells (aditus ad antrum)
17. tendon of stapedius muscle
18. malleus
19. tympanic membrane
20. chorda tympani
21. stylomastoid foramen