A&P Final

What is the tragus and where is it located?

Small cartilaginous projection that extends from the external ear towards the cheek. It's located above the earlobe and below the helix.

Where is the lobule located?

The lobule is also known as the ear lobe and is located at the bottom of the outer ear. It is the soft fleshy part.

Where is the helix located?

It is located at the pinna and it is the curled margin (close to the middle, above the tragus

Cartilaginous meatus

Has hairs that point toward the opening of the ear canal . Within the hair follicles are glands which secrete cerumen which is a waxy substance.

Why do we need the outer ear?

It is the collector of sound

It shapes the frequency components of sound

Outer Ear

The outermost part of the ear, which includes the pinna and the ear canal. Its main function is to collect and direct sound waves towards the middle ear.

Middle Ear

The part of the ear responsible for transmitting acoustic energy. It includes three small bones - the malleus, incus, and stapes - that amplify the sound waves.

Inner Ear

Part of the ear responsible for balance and hearing. Contains the cochlea, vestibule, and semicircular canals. Converts sound waves and head movements into electrical signals for the brain to interpret.

Antihelix

Curved cartilage ridge of ear's outer rim, parallel to the helix.

What structure seperates the middle and outer ear?

Tympanic Membrane (eardrum)

What does the eardrum have contact with?

the ossicles

Which part of the eardrum does not vibrate with sound?

Pars flaccida (anterior)

Why does the umbo matter?

Only bone that touches the tympanic membrane

Malleus

Largest of the ossicles and provides a point of attachment with the tympanic membrane. The bulk of this bone is the head or caput.

Incus

Anvil shaped bone that provides intermediate link of the ossicular chain. It articulates with the malleus by the means of a saddle joint

Stapes (stirrup)

The third bone in the ossicular chain that helps to transmit sound vibrations from the eardrum to the oval window. Articulates with the incus and stapes by the means of a ball and socket joint

Stapedius Muscle

This muscle is embedded in the posterior wall of the middle ear and pulls the stapes posteriorly. Pulls stapes away from the inner ear. The contraction of this muscle stiffens the ossicluar chain

Tensor Tympani

The muscles inserts into the upper mandibular malli and pulls the malleus anteromedially. Pulls malleus away from the tympanic membrane. The contraction of this muscle stiffens the ossicular chain.

What portion of the tympanic membrane is responsible for sound?

pars tensa

What portion of the tympanic membrane is not responsible for sound?

Pars flaccida

What does the stapedius attach to?

the oval window

What is the side where the eustachican tube located?

lateral wall

What wall can see the oval window and the round window?

medial wall

What are the three parts of the inner ear?

cochlea, vestibule, semicircular canal

What is the strongest bone in the body?

the temporal bone

The external auditory meatus is how long and what is its diameter?

7 mm in diameter and 2.5 cm long

EAM cross section forms a slight _____ across its length

s curve

What does the cross section of the EAM do?

enhances sound energy nearly 3000 hz

Pinna of the outer ear…

localizes sound

Where is the umbo located?

the cone of light

What is the umbo?

point of attachment for malleus, middle ear bone

What structures are found on the medial wall in the middle ear?

The round and oval window

What is found at the back and top of the middle ear?

aditus

What is found at the front of the middle ear?

the opening of the Eustachian tube

Oval Window

(fenestra \n ovalis)- footplate of \n stapes is embedded in \n it

Round Window

entrance into scala \n tympani of the cochlea

Promontory

a prominence on the cochlea

Eustachian Tube

* Responsible for aeration of \n middle ear \n • Maintains equilibrium \n between atmospheric \n pressure and middle ear \n pressure \n • 36 mm in length

Middle Ear Mechanism

Acts to overcome impedence because impedence is resitant to the flow of energy

What is the middle ear designed as?

an impedance matching device. It increases pressure of the signal arriving at the cochlea

Osseous (bony labyrinth)

Contains the inner ear structures: osseous vestibule, osseous semicircular canals, osseous cochlear labyrinth

osseous vestibule

\-Embedded within petrous portion of temporal bone

\-epithelial lining secretes perilymph

osseous semicircular canals

These are three bony, fluid-filled loops in the inner ear responsible for detecting rotational movement and maintaining balance.

osseous cochlear labyrinth

This structure is a bony, spiral-shaped canal located in the inner ear. It contains the sensory cells responsible for hearing and is essential for auditory function.

perilymph

fluid found within the superficial cavities of the labyrinth

Ampulla

expanded region of semicircular canals near one opening to the vestibule

Macula (inner ear)

A small sensory organ in the vestibule of the inner ear that helps detect head position and acceleration. Dysfunction of the macula can lead to balance disorders and vertigo.

Anterior canals

sense movement of head toward the shoulder

Posterior Canals

sense movement of head when nodding “yes”

Lateral semicircular

sense movement of head when shaking head “no”

Scala Vestibuli

a part of the cochlea in the inner ear responsible for detecting high-frequency sounds.

Scala tympani

scala tympani ends at the round window, a structure that provides a pressure relief for movement of the cochlear fluid

What do the scala vestibuli and scala tympani contain?

perilymph

What does the round window communicate between?

scala tympani and middle ear

What does the oval window communicate between?

the scala vestibuli and middle ear space

What is the cochlear duct referred to as?

scala media

Where is the cochlear duct located?

between the scala vestibuli and scala tympani

Reissner’s membrane

thin seperation of perilymph of the scala vestibuli and the endolymph of the scala media

Does the scala media have perilymph or endolymph?

endolymph

Basilar Membrane

“floor” of the scala media that separates the scala media from the scala tympani

Where is the organ of corti located?

on the membranous labyrinth

Organ of Corti

Sensory organ of hearing within the inner ear. Has four rows of hair cells

How many outer hair cells does the organ of corti have?

Three rows or 12000 cells

How many inner hair cells does the organ of corti have?

3,500 cells or 1 row

Stereocilia

protrude from the surface of hair cells

Tectorial membrane

Arises from the spiral limbus, overlays hair cells, and processes acoustic stimuli

What is the stria vascularis?

a dense layer of tissue in the cochlea with a rich capillary network

What is the source of endolymph in the cochlea?

vascular tissue spirals along the outside of the cochlea within the scala media secrete endolymph into the scala media

Spiral Limbus

seperates the osseous cochlear labyrinth into the scala vestibuli and scala tympani

Hensen’s cells

keeps regulation of ion metabloism and homestosis and endolymph and perilymph, regenerates hair cells, and prevents cochlea damage

Reticular lamina

vibrations interact with the basilar membrane traveling through the cochlear fluid to enhance hearing sensitivity

Inner Phalangeal Cells

The inner hair cells are supported and enclosed by this

Delters Cell

supporting cells for the sensory-motor outer hair cells 

Heliotrema

allows fluid exchange between SV and ST

Afferent innervation Type 1

large myelinated fibers make up 95% of VIII nerve and innervate inner hair cells

Afferent innervation type 2

small myelinated and unmyelinated innervate outer hair cells

Efferent innervation

inhibitory, reducing output by hair cell stimulation \n Helps detect signals in background noise

The inner ear preforms ___ __and__ ______ analysis on ongoing acoustic signal

temporal and spectral

stereocilia

minute cilia protruding from surface of hair cells

During the electrical events of the cochlea, when the __ __is displaced toward__ _____, the hair cells are__ ________

basilar membrane; scala vestibuli; activated

During the electrical events of the cochlea, when the __ __is displaced toward__ _____, the hair cells are__ ________

basilar membrane; scala tympani; inhibited

What happens during the excitation of hair cells?

they are displaced as traveling waves move along the basilar membrane

Excitation of outer hair cells

\-Result of shearing effect on cilia \n • Important for coding intensity in intensity less than 40 dB

Excitation of inner hair cells

• Results from fluid flow and endolymph turbulence \n • Essential for coding frequency

What are resting or standing potentials?

Voltage potential differences that can be measured from the cochlea at rest

Scala media is ____ more positive

80 mV

Heschl’s gyrus

primary reception area of the temporal lobe

The central nervous system consists of the following:

• Includes the brain \n • Cerebrum (cerebral \n cortex) \n • Cerebellum \n • Subcortical structures \n • Brainstem \n • Spinal cord

Peripheral nervous system includes

• Peripheral nervous \n system (PNS) \n • Twelve pairs of cranial \n nerves \n • Thirty-one pairs of \n spinal nerves \n • Sensory receptors \n • Most components are \n outside of bone

Telencephalon

cerebral hemispheres, white matter, \n basal ganglia, olfactory tract

Diencephalon

thalamus, hypothalamus, pituitary \n gland and optic tract

Mesencephalon

midbrain

Metencephalon

pons and cerebellum

Myelencephalon

medulla oblongata

Dendrite

Transmits information toward \n soma

receives information as well

Axon

Transmits information away \n from soma

Myelin sheath

• fatty wrapping covering \n neuron \n • Speeds neural \n transmission \n • Made up of Schwann cells \n in PNS; oligodendrocytes \n in CNS

Neurotransmitters activate…

next neuron in chain after \n being released in the synaptic \n cleft (gap between neurons)

synaptic vesicles

uptake, storage and stimulus-dependent release of neurotransmitter

neurotransmitters

transmit messages between neurons, or from neurons to muscles