Flashcards in Anatomy of the Ear Deck (14):
What is the structure of the external ear?
Auricle or Pinna is your "ear," the part outside of your temporal bone.
It has stratified keratinising squamous epithelium (skin)
This flows to the external acoustic meatus
-lateral 1/3 cartilage and skin
-Medial 1/3 bone and skin
The deep parts of the external ear have:
-Ceruminous glands (produce wax)
What is otitis externa?
Inflammation of the external ear
What is the tympanic membrane?
1cm diameter approx
-Outer squamous epithelium
-Middle fibrous connective tissue
-inner columnar ciliated mucous membrane (respiratory)
Perforation by trauma, suppuration
Part of sound conduction
What is the eustachian tube?
Auditory tube or eustachian tube
Connection between middle ear and nasal canal
Keeps equal pressure in inner ear
Holding your nose and breathing out or swallowing will open the tube and let air in
What is the ossicular chain?
KEY role in sound production
-Bony sclerosis (otosclerosis)
Made up of the malleus, incus and stapes
What is otosclerosis and how is it managed?
Thickening or proliferation of bone around the stapes
This prevents it from moving as well as its more fixed
As a result sound isn't conducted
To fix the stapes is bypassed
-Remove stapes (stapedectomy)
-Fix small pole into stapes footplate
-Join to incus by thin fibre
Sound can now be conducted
Give a brief overview of the middle ear
Lined by columnar ciliated epithelium
-mucous, cataarh, glue
-facial nerve and chorda tympani
Two main spaces:
Where does the middle ear connect to?
Mastoid system via aditus
Post-nasal space via eustachian tube
What important relations does the middle ear have?
Internal jugular vein
Internal carotid artery
Discuss the facial nerve
Great importance to surgeon
Cosmetic and functional importance of damage
Medial wall of middle ear - horizontal
Lies in the bony (fallopian) canal
10% dehiscent (isn't covered by fallopian canal- more at risk)
Stylomastoid foramen to parotid
Describe the inner ear
Vestibulo-cochlear organ of balance and hearing
Consists of a bony labyrinth containing:
-Vestibule (in the centre)
Inside this bony labyrinth is a membranous labyrinth of sensory epithelium
There are two types of fluid in the inner ear:
Describe the nerve pathway of hearing
Cochlear fibres form the cochlear nerve
The cochlear nerve joins with the vestibular nerve to form the vestibulo-cochlear nerve.
This travels through the internal auditory meatus
Joins brainstem at junction of pons and medulla
Describe the innervation of the ear
Mixed innervation to the ear:
-Cervical nerve root branches
-5th nerve (Trigeminal Nerve)
-9th Nerve (Glossopharyngeal Nerve)
-10th Nerve (Vagus nerve)
This mixture of nerves gives common referred pain of the ear