Anatomy; Ear Flashcards
List the ways the ear can be divided
Anatomical Divisions:
- External ear
- Middle ear
- Inner ear (pretty sure both functional divisions are found here)
OR
Functional Divisions:
- Hearing (auditory system)
- Balance (vestibular system)
all in the temporal bone
What does the temporal bone contain?
Temporal bone contains:
- organs of hearing and balance (special sensory)
- facial nerve (CN VII)
- vestibulocochlear nerve (CN VIII)
List the ‘processes’ found on the temporal bone
- zygomatic process
- mastoid process
- styloid process
There is a meatus found on the temporal bone, name it
the external acoustic meatus
What are the 2 parts of the temporal bone
the temporal (squamous) part
and
the petrous part
What is the thinnest part of the skull?
The pterion
(frontal, parietal, temporal and sphenoid all join)
Briefly describe the anatomy and function of the external ear (3 points)
The External Ear
- auricle to tympanic membrane
- via external acoustic meatus
- collects & conveys sound waves to the tympanic membrane
Briefly describe the anatomy and function of the middle ear (3 points)
Middle Ear
- Tympanic membrane to oval window
- Also Eustachian tube
- amplifies and conducts sound waves to the internal ear
Briefly describe the anatomy and function of the internal ear (2 points)
Internal Ear
- Oval window to internal acoustic meatus
-
converts special sensory information
- into fluid waves
- then APs
- conduct APs to brain
Describe the sensory nerve supply of the ear
- Tympanic membrane
- external surface: mostly CN V3
- internal surface: CN IX
- Glossopharyngeal nerve (CN IX) provides sensory innervation to:
- middle ear cavity
- Eustachian tube
- Nasopharynx
- Oropharynx
- Tonsils
Using clinical terms describe the parts of the auricle
Describe the innervation of the auricle
Describe the components of the external ear skeleton
- Skeleton
- temporal bone
- elastic cartilage
- avascular and gets nutrients from skin
- Ear canal
- begins at external acoustic meatus
- composed of 1/3 cartilage, 2/3 bony
- lined with skin
- produces earwax via ceruminous glands
Describe the anatomy of the middle ear in regard to its bones, muscles and innervation
The middle ear contains…
- 3 bones:
- malleus
- incus
- stapes
- 2 muscles
- stapedius
- tensor tympani
- Nerve branches from:
- facial nerve
- glossopharyngeal nerve
State the function of the ossicles
Auditory ossicles articulate via synovial joints
When sound waves make tympanic membrane vibrate the vibrations are transmitted through ossicles
Describe the anatomical course of CN VII from brainstem to muscles of facial expression
- Brainstem at pontomedullary junction
- Into internal acoustic meatus in the posterior cranial fossa
- Runs through stylomastoid foramen
- Supplies muscles of facial expression
Briefly describe/draw the inner ear labyrinths
The endolymph-containing membranous labyrinth “floats” within the perilymph contained in the bony labyrinth
Where does the otic capsule sit?
The dense otic capsule sits in temporal bone
Describe the cochlear duct
- A long balloon-like structure within the cochlea filled with endolymph:
- APs conducted to the brainstem in the cochlear nerve
Describe the semicircular ducts
- inter-linked balloon-like structures within the semicircular canals filled with endolymph
- APs conducted to the brainstem in the vestibular nerve
How does the vestibular apparatus function?
Hair cells are stimulated by the movement of endolymph
Clusters of hair cells are in regions called maculae
- Semicircular ducts detect angular movement change
-
Utricle and saccule detect linear movement change
- Utricle (horizontal)
- Saccule (vertical)
Remember: the brain looks for changes in fluid velocity
