Ear

Question 1

What two structures make up the external ear?

Answer 1

Auricle( pinna) and external auditory meatus

Question 2

Describe the middle ear.

Answer 2

The tympanic cavity- a small-hour glass shaped cavity embedded in the petrous temporal bone
Roof: tegmen tympani
Contains 3 ossicles for sound transmission

Question 3

Describe the internal ear.

Answer 3

Forms a series of interconnected fluid-filled membranous tubes (ducts) and sacs, which are suspended in corresponding bony canals and cavities of the petrous temporal bone

Question 4

Sound vibration are conveyed to the inner ear via ______ and the _______?

Answer 4

Ossicles and fenestra vestibuli

Question 5

Air transmission are preformed by the __________?

Answer 5

External auditory meatus

Question 6

What are the 3 mechanisms that protect the inner ear from trauma?

Answer 6

1. Pound sounds cause the footplate of the stapes to rock side-to-side rather than depress directly into the fenestra vestibuli
2. Continuous loud sound causes the contraction of the stapedius and tensor tympani muscles and attenuation of vibrations
3. The cochlear pathway in the CNS is capable of filtering, focusing, and attenuating sound

Question 7

The pinna is innervated by _________?

Answer 7

Auriculotemporal (V3): GSA fibers
Lesser Occipital (C2-3)
Greater auricular (C2-3)

Question 8

Blood supply to the auricle is via _________ and ________?

Answer 8

Superficial temporal a.

Posterior auricular a.

Question 9

Trauma to the pinna may cause hemorrhaging in the _________ tissue resulting in an _________ hematoma?

Answer 9

Subcutaneous tissue

Auricular hematoma

If not evacuated and bandaged the subsequent scar tissue may grossly deform the auricle, cauliflower ear

Question 10

The external auditory meatus end as it bind to __________?

Answer 10

Tympanic membrane

Question 11

The skin lining the out 1/3 of the external auditory meatus contains __________ and ________ glands which secrete _______?

Answer 11

Sebaceous and ceruminous glands which secrete cerumen

Question 12

What problems may occur when removing cerumen?

Answer 12

The cerumen may be firmly adherent to the epithelia of the EAM and/or tympanic membrane and ossicles, thus causal removal of a mass of ear wax may avulse the TM/ and/or ossicles

Question 13

Describe the position of the tympanic Membrane at the medial end of the EAM.

Answer 13

Circular drum-like disk that is tilted forward, and lateral and downward in the canal

Divides the external from the middle ear

Question 14

What are the 3 layers of the Tympanic Membrane?

Answer 14

Outer epidermis or skin
Middle fibrous layer
Inner mucous membrane

Question 15

What is the outer epidermis or skin layer of the TM innervated by?

Answer 15

GSA of the trigeminal nerve

Question 16

The middle fibrous layer form the __________?

Answer 16

Pars tensa

The absence of this layer in the anterior-superior quadrant of the TM forms the pars flaccida

Question 17

The inner mucous membrane is innervated by __________?

Answer 17

GVA fibers of the glossopharyngeal nerve via the the tympanic plexus

Question 18

The center also concavity of the tympanic membrane is called the ______?

Answer 18

Umbo

Question 19

The ______ and ________ ________ Folds are v-shaped folds formed by the inner mucous membrane on the borders of the pars flaccida?

Answer 19

Anterior and posterior mallear folds

The chorda tympani nerve course through theses folds

Question 20

Describe the path of the Facial nerve.

Answer 20

After leaving the brainstem, VII travels laterally in the IAM before entering the fanciful canal.. Within the canal, the geniculate ganglion is located just above and medial to the promontory of the middle ear cavity

At the level of the ganglion, the nerve turns sharply posteriorly as it forms the external genu

Then courses downward, sends a branch to the stapedius muscle, and exits the stylomastoid foreman

Question 21

What are the 3 ossicle?

Answer 21

Malleus
Incus
Stapes

Question 22

What is otosclerosis?

Answer 22

Is ossification or scarring of the small ossicular joints that prevent the transmission of sound from the tympanic membrane to the fenestra vestibuli

Hearing impairment
Clinically: tests for bone conduction are normal, but nerve conduction is reduced

Question 23

What are the muscles of the middle ear cavity?

Answer 23

Tensor Tympani muscle

Stapedius muscle

Question 24

What is the function and what innervates the tensor tympani m.?

Answer 24

Function: tightens the TM and attenuated its vibrations
Innervation: mandibular n of V

Question 25

What is the function and innervation of the Stapedius m.?

Answer 25

Function: pulls stapes out of the fenestra vestibuli, protective mechanism to prevent excessive movement of the stapes due to loud sounds Innervation: facial nerve

Question 26

What is the blood supply to the middle ear?

Answer 26

Stylomastoid branch of the posterior auricular a and the anterior tympanic a.

Question 27

What is the sensory innervation to the middle ear?

Answer 27

Epithelial (mucosal lining) of the middle ear is innnervated by GVA sensory branches of the IX via the tympanic plexus

Question 28

What is the function of the internal ear?

Answer 28

Functions of the inner ear: Cochlear receptor for hearing Receptors in the semicircular ducts: detect angular acceleration REceptors in the sacculus and utricle: detect linear acceleration

Question 29

What are the receptors of the inner ear innervated by?

Answer 29

Divisions of VIII Cochlear division: organ of Corti(spiral organ) and coveys auditory input Vestibular division: macular utricle and saccule, and the crystal ampullaris of the semicircular ducts and conveys static and dynamic position-sense information for equilibrium

Question 30

What is the blood supply for the inner ear?

Answer 30

Labyrinthine artery, a branch of the anterior inferior cerebellar artery Arteriosclerosis of the labyrnthine artery may result in vertigo, nausea and other inner ear abnormalities

Question 31

Describe the Cochlea

Answer 31

Cochlea is a helical-shaped bone tube in a shape to the shell of a snail t The basal turn of the cochlea forms an eminence in the middle ear cavity called the promontory

Question 32

The bony core of the cochlea is referred to as the __________, and ________ nerve passes through it.

Answer 32

Modiolus Cochlear division of VIII

Question 33

The ________ _____ projects from the modiolus like the threads of a screw.

Answer 33

Spiral lamina The cochlear duct is attached to the spiral lamina

Question 34

_______ communicate with each other at the helicotrema?

Answer 34

Scala vestibuli and Scala tympani Scala vestibuli extends from the vestibuli to the helicotrema and is separated from the cochlear duct by the vestibular membrane Scala tympani extends from the helicotrema to the 2nd tympanic membrane (round window)

Question 35

_________ is anchored along the length of the bony cochlea at the spiral lamina and spiral ligament

Answer 35

Cochlear duct

Question 36

The walls of the cochlear duct are formed by the _____ and ________ membranes

Answer 36

Basilar and vestibular membranes, which separates the duct from the scalar tympani and vestibuli respectively

Question 37

The cochlear duct contains the _____ __ _____?

Answer 37

Organ of Corti which is located along the entire length of the basilar membrane The spiral organ contains the receptors for hearing

Question 38

What are the tiny blood vessels in the area of the spiral ligament which supply the organ of Corti?

Answer 38

Stria vascularis Prolonged exposure to excessive amounts of noise and/or music may lead to the partial destruction of the organ of Corti Ischemic necrosis may be one the the mechanisms