Lab 9: Inner Ear, Auditory Pathways Flashcards

Question

Foramen lacerum

Answer 1

Visible on dried skull only Between the apex of the petrous temporal bone and the sphenoid bone

Answer 2

Visible on skull only Between the petrous temporal bone and sphenoid bones

Answer 3

Tympanic membrane Epitympanic Recess: a small area that's superior to the level of the tympanic membrane

Answer 4

The mastoid air cells: the aditus leads to the antrum and the air cells of the mastoid process -a route for the spread of infection

Answer 5

Auditory tube: which leads to the nasopharynx. Note the cardioid canal passes anterior to the tympanic cavity and inferior to the auditory tube

Answer 6

Floor of the tympanic cavity | This floor is related to the superior jugular bulb

Answer 7

The inner ear

Answer 8

The tegmen tympani or thin roof formed by a plate of the petrous temporal bone that separates the middle ear from the middle cranial fossa

Answer 9

Connect the tympanic membrane with the inner ear and transmit vibrations of the tympanic membrane to the inner ear. Of the ossicles, the MALLEUS and INCUS act as an angular lever and the STAPES titles to enable the footplate of the stapes to transmit the vibration produced by sound waves to fluid in the inner ear

Answer 10

Influence by the tensor tympani muscle: innervated by CN V and is activated by sudden contact in the facial region. This reflex may stabilize the ossicles during head impact The stapedius muslce which is innervated by CN VII and is activated by loud sound to reflexively protect the hair cells from damage due to excessive vibrations

Answer 11

A branch of the facial nerve in the facial canal that carries parasympathetic and taste fibers to the oral region; it loops anteriorly between the malleus and the incus, medial to the tympanic membrane and exits the skull between the petrous and tympanic parts of the temporal bone at the petrotympanic fissure

Answer 12

Leads to antrum and mastoid air cells

Answer 13

For the facial nerve (CN VII); trace the facial nerve through the petrous part of the temporal bone as it bends posteriorly, then turns and proceeds inferiorly to reach the stylomastoid foramen

Answer 14

Embedded in the petrous part of the temporal bone

Answer 15

Embedded in the petrous part of the temporal bone

Answer 16

Formed by the basal turn of the cochlea; has openings called the oval and round windows -in life, the promontory is covered by mucous membrane

Answer 17

Fibers that are located deep to the mucous membrane of the promontory. This plexus contains fibers of the glossopharyngela nerve (CN IX) that provide sensory supply to the mucous membrane of the middle ear, mastoid cells, and auditory tube. In addition,this plexus gives rise to the LESSER PETROSAL NERVE, which brings preganglionic parasympathetics to the otic ganglion

Answer 18

Small elevation of bone which houses the stapedius muscle

Answer 19

Stapes Footplate of stapes Oval window

Answer 20

Derived from the tympanic plexus This nerve is the visceral motor component of the glossopharyngeal nerve and brings preganglionic parasympathetic fibers to the optic ganglion. It leaves the petrous temporal bone via a hiatus for the lesser petrosal nerve in the floor of the middle cranial fossa. It exits the middle cranial fossa into the infratemporal fossa through the foramen oval and synapses with postganglionic parasympathetic neurons in the otic ganglion Postganglionic parasympathetic fibers travel with the auriculotemporal nerve to innervate the parotid gland

Answer 21

A branch that will bring parasympathetic fibers to deep structures of the head It branches from the facial nerve at the bend, then gravels to the anterior surface of the petrous temporal bone through the hiatus for the greater petrosal nerve. The groove for the greater petrosal nerve can be seen on a skull The temporal bone specimen has a string-like bulge representing the greater petrous all nerve in the upper area of the medial view of the middle ear cavity traveling anteriorly from the facial nerve to the area of the carotid canal

Answer 22

A branch from the facial nerve in the facial canal It loops anteriorly, medial to the tympanic membrane between the malleus and incus and exits the skull between the petrous and tympanic parts of the temporal bone through the petrotympanic fissure It enters the infratemporal fossa and travels to structures of the oral cavity

Answer 23

This branch leaves the facial nerve in the facial canal and immediately enters the muscle with the same name Imagine this branch exciting from the facial nerve in the facial canal and traveling to the stapedius muscle

Answer 24

The bony roof and floor of the middle ear cavity can be very thin. Infection can easily erode them away If infection spreads through the roof, there can be involvement of the meninges and brain (meningitis, cerebral abscess in the temporal lobes) If infection spreads through the floor into the jugular vein there can be jugular thrombosis

Answer 25

Vestibulocochlear Nerve at cerebellopontine angle Flocculus and facial nerve: near VIIIth cranial nerve Inferior colliculus: nucleus for synapse in auditory pathway Brachium of inferior colliculus: path for fibers from the inferior colliculus to the thalamus (medial geniculate nucleus or body) Medial geniculate body: thalamic nucleus for hearing

Answer 26

Transverse Temporal Gyri (of Heschl): primary auditory cortex Auditory association cortex: peripheral to the primary auditory cortex in the superior Temporal gyrus Wernicke's Area: usually on the left side; the planum temporale (posterior part of the superior Temporal gyrus and parts of the inferior parietal lobule)

Answer 27

- Located lateral and dorsal to the inferior cerebellar peduncle - contain cell bodies of second order neurons in the auditory pathway - receive fibers from the cochlear nerve - send axons into the acoustic stria

Answer 28

Passage of fibers from the cochlear nucleus across the midline into the auditory stria (dorsal acoustic stria, intermediate acoustic stria, and ventral acoustic stria) These projections will gather into the pathway called lateral lemniscus

Answer 29

- The auditory info from the cochlear nuclei will ascend through the brainstem bilaterally - consequently, a lesion of the ascending pathways distal to the cochlear nucleus will result in virtually no loss of hearing - the deficit that the patient will experience is an impairment of the ability to localize the direction and distance of sounds

Answer 30

- Some of the ascending fibers of the central auditory pathway will synapse in the superior olivary nuclei in the ventrolateral tegmentum of the caudal pons - This nuclear complex receives bilateral impulses from the cochlear nuclei and is involved in auditory processing related to sound localization - the SON will send axons into the lateral lemniscus

Answer 31

- Lateral to the superior cerebellar peduncle - contains fibers from the acoustic stria and superior olivary nucleus - contains ascending acoustic fibers that are both crossed and uncrossed

Answer 32

-tract and dark rim below the inferior colliculus

Answer 33

Nuclei which receive terminals from lateral lemniscus fibers

Answer 34

Reflex center for visual system

Answer 35

Ventral to the medial geniculate Nucleus | -fibers that travel from the inferior colliculus to the medial geniculate Nucleus

Answer 36

The thalamic nucleus for hearing | -receives fibers from the brachium of the inferior colliculus

Answer 37

Dorsal to the medial geniculate Nucleus | -fibers from the optic tract en route to the superior colliculus and pretectal area

Answer 38

Located medial to the lateral geniculate nucleus - the thalamic Nucleus for hearing - receives fibers for hearing from the inferior colliculus - sends axons to the primary auditory cortex - it sends auditory radiations to the primary auditory cortex (transverse temporal or Heschl's gyri) via fibers that pass BELOW the caudal part of the lenticular nucleus - in this part of the radiations, they're called "sublenticular fibers" or the "sublenticular part of the internal capsule"

Answer 39

-should know that they're located in the ventral (caudal pons) and then lateral (rostral pons) reticular formation until they reach the inferior colliculi (roof of midbrain) Paths and nuclei from the inferior colliculi to the auditory cortex are difficult to locate in most clinical scans

Answer 40

A marker for the general position of the termination of cochlear nerve fibers

Answer 41

General position of the cochlear nuclei are along the lateral surface of the inferior cerebellar peduncle

Answer 42

-general position of auditory nuclei such as the superior olivary nuclei along the ventral edge of the tegmentum (along the horizontal reference line between the tegmentum and the base)

Answer 43

Due to damage of the cochlea, cochlear receptors, or the cochlear nerve - damage to the cochlear nerve cannot usually be corrected - however, cochlear implants have been successful in restoring some ability to detect sounds in patients with cochlear nerve deafness

Answer 44

Due to damage of middle ear structures such as the tympanic membrane or ear ossicles -can often be corrected with surgery or hearing aids

Answer 45

- compares the efficiency of the conduction of sound vibrates through bone vs. air 1. Places a faintly vibrating tuning fork on the "patient's" mastoid process. Just after the sound disappear as, move the fork over the patient's external auditory canal. He/she should be able to hear the sound again, because normally air conduction is more efficient than bone 2. If you press your fingertip in your ear while holding the tuning fork besides the external auditory canal, the sound will be blocked, but press your finger hard into your hear to occlude the canal. Then hold the tuning fork on your mastoid process. The sound gets louder. This test shows that a mechanical impediment in the auditory canal can cause an apparent increase in bone conduction 3. If anything impedes the conduction of sound vibrations through the external auditory canal or ossicles, the PT has a CONDUCTION hearing loss. Contrarily, a reduction of hearing by a lesion of the organ of Corti or the auditory nerve is called a NUEROSENSORY hearing loss. Conduction loss refers to loss of mechanical conduction of sound vibrations through the external and middle ear, not a loss of conduction of nerve impulses through the 8th nerve. Application of the vibrating tuning fork to the mastoid process causes bone conduction to the inner ear to excite auditory impulses, bypassing the air conductance channels of the external and middle ear. Bone conduction tests the integrity of the nerve even though air conduction of sound vibration through the external and middle ear is blocked. Characteristically, neurosensory losses cause a decrease in both bone conduction and air conduction. In other words, nerve lesions block hearing by either channel (air or bone), whereas mechanical lesions block only the sounds transmitted through the ear

Answer 46

A. Consists of placing a vibrating tuning fork on the middle of the forehead or the vertex of the skull. Try this test. The sound seems to come from the center and is equal in both ears if you're normal. B. With the vibrating fork in place on the vertex of your head, press your fingertip in one ear and then the other. The sound lateralizes to the occluded side. If a mechanical impediment blocks sound conduction in one ear, the vertex sound localized to the same side as the block If the pt has an auditory nerve lesion on one side, the vertex vibration sounds loudest on the OPPOSITE SIDE OF THE LESION -only a consistent lateralization to one side is considered significant

Answer 47

If your screening suggests loss of hearing, refer the patient for electronic tests. These may include pure tone audiometry, speech discrimination batteries, and a loudness discrimination test. Brainstem auditory evoked responses (BAER) do not require conscious responses and objectively tests for the integrity of the auditory pathways in conscious or unconscious patients. The commonest causes of delayed speech are mental retardation and deafness. Always investigate every infant or young kid thoroughly with bedside and electronics tests if a child doesn't appear to hear or has delayed speech