Ear - Anatomy & Physiology Flashcards
what is Jacobsons nerve and what does it supply?
Tympanic branch of the glossopharyngeal nerve CN IX
- sensation to middle ear
What is arnolds nerve and what does it supply?
Auricular branch of the vagus nerve CN X
- sensation to posterior half of the external auditory canal
what part of the ear does the vagus nerve supply?
posterior half of the EAC
what nerve supplies the pinna?
upper half = CN V3
lower half = greater auricular nerve (C2/C3)
what part of the ear does the facial nerve supply?
the anterior half of EAC
what nerve supplies the inner ear?
vestibulocohlear nerve (CN VIII)
WHAT IS THE LENTGH OF THE EXTERNAL EAR CANAL?
4cm
what is the medial and lateral 1/3rd of the EAC made of?
medial third made of skin and bone
lateral third made of skin and cartilage
what does the skin contain in the lateral 1/3rd of the EAC?
ceruminous and sebaceous glands which produce wax
what are 2 characteristics of the medial 1/3rd of the EAC?
no hairs or cilia
doesn’t produce wax (don’t have ceruminous or sebaceous glands in the skin)
where does the skin of the EAC grow from?
grows from the umbo of the tympani membrane outwards
what type of skin and what type of cartilage is found in the EAC?
Stratified keratinised epithelium
Elastic cartilage
why does minimal hearing loss occur with damage to the EAC?
the pinna isn’t good at sound localisation so if there is wax or disruption this can cause minimal hearing loss
what are the 3 layers of the tympanic membrane?
outer layer - continuous with skin of EAC
middle - fibrous layer
inner layer = respiratory epithelium (ciliated columnar epithelium with goblet cells)
what plays an important role in sound conduction?
ear ossicles found in the middle ear
what does the ossicles attach to?
connects to mastoid system via audits
connects to nasopharynx via eustachian tube
the middle ear receives sensation from the tympanic branch of glossopharyngeal nerve but what nerve runs through the middle ear?
chords tympani - branch of facial nerve