10. Ear Anatomy (Keim) Flashcards
What nerves innervate the tympanic membrane?
External surface: Auriculotemporal nerve and Auricular branch of the vagus.
Internal surface: Glossopharyngeal (CN IX)
What would be affected in an erosion through the medial wall of the middle ear?
The inner ear, the oval and round windows, the promontory of the labyrinthine wall, and the nerve plexus thereof (tympanic and lesser petrosal nerves).
Greater and lesser petrosal nerves carry what type of nerve fibers?
Parasympathetic (general visceral efferent) fibers.
What cranial nerve does the tympanic nerve come off of?
The glossopharyngeal (CN IX)
Which portion of the tympanic membrane is more vascular?
The superior portion.
What is a myringotomy, and where is it performed?
Myringotomy: lesion to open up the eardrum. Made in the posterior inferior quadrant to avoid vasculature.
The tympanic plexus primarily contains fibers from which cranial nerve?
Glossopharyngeal, via the tympanic branch.
What is the blood supply to the auricle of the ear?
Posterior auricular A and superficial temporal A.
What would be affected in an erosion through the posterior wall of the middle ear?
Mastoid antrum (containing mastoid air cells) and facial canal (containing facial nerve).
Where are the heads of the incus and malleus found?
In the epitympanic recess.
What would be affected in an erosion through the anterior wall of the middle ear?
Internal carotid artery, opening for the pharyngotympanic tube, and the canal for the tensor tympani.
What would be affected in an erosion through the lateral wall of the middle ear?
Tympanic membrane and external ear.
What are the respective functions of the greater and lesser petrosal nerves?
Greater petrosal: parasympathetics to the eye from facial N.
Lesser petrosal: parasympathetics to the parotid gland from glossopharyngeal N.
List the nerves that innervate the represented parts of the auricle of the ear.
What would be affected in an erosion through the roof of the middle ear?
The tegmen tympani (bone) and the dura of the middle cranial fossa.
What is the bony labyrinth filled with?
What is the membranous labyrinth filled with?
Bony labyrinth: perilymph.
Membranous labyrinth: endolymph.
What nerve gives rise to the greater petrosal nerve?
Facial nerve.
What would be affected in an erosion through the floor of the middle ear?
Bulb of the internal jugular vein.
Which of these spaces contain endolymph, and which contain perilymph?
The scala vestibuli and the scala tympani are filled with perilymph. The cochlear duct is filled with endolymph.
What nerve gives rise to the lesser petrosal nerve?
The tympanic nerve - a branch of the glossopharyngeal nerve.
Note that “malleolus” is actually “malleus.” This slide has a typo.
Which is more anterior, the cochlea or the vestibular apparatus?
The cochlea.
