Exam 7 Ear Special Senses 74X Flashcards
What are the three regions in which the ear is divided?
- External Ear: Collects sound wave and funnels inward
- Middle Ear: Conveys sound vibrations to oval window
- Inner/Internal Ear: Receptors hearing and Equilibrium
What does the External Ear Consist of?
Auricle
External Auditory Canal
Eardrum
The auricle portions of the ear, Superior Rim and inferior portion are referred to as?
Rim: Helix
Inferior: Lobule
The external auditory canal lies in which bone and leads to what?
Temporal Bone
Leads to Eardrum
What are the specialized sebaceous glands in the ear called, that in combination with hairs prevent dust and foreign objects from entering the ear?
Ceruminous Glands (secrete cerumen)
Describe the Middle Ear?
Air filled-space separated from external by TM and Internal ear by the oval window and round window
What is contained in the middle ear?
Auditory Ossicles (connected by synovial joints)
The Auditory Ossicles transmit what?
Vibratory motions of the TM to the oval window
What are the names of the Auditory Ossicles?
Malleus (hammer)
Incus (Anvil)
Stapes (Stirrup)
What portions of which Auditory ossicles produce bulges which can be seen when viewing the Tympanic Membrane?
Malleus: Handle and Lateral Process
Incus: Long Limb
What are the muscles that attach to the Auditory Ossicles?
Tensor Tympani Muscle
Stapedius Muscle
Which muscle of the middle ear arises from the wall of the auditory tube and inserts into the handle of the malleus? What does this muscle limit and is innervated by which nerve?
- Tensor Tympani muscle
- Limits: Movement and increases tension on the TM to prevent damage from loud noises
- Innervated by: Trigeminal Nerve (CN-V)
Which muscle of the middle ear originates from the posterior wall of the middle ear cavity and inserts into the stapes? What purpose does it serve and what innervates it?
- Stapedius Muscle
- Purpose: Dampens large vibrations of stapes due to loud noises
- Innervated by: Facial Nerve (CN-VII)
- Smallest muscle of the body
What is the term used to describe the reflection from the otoscope’s illuminator?
Light Reflex (Cone of Light): Radiating Anteroinferiorly
What branch of the facial nerve (CN-VII) serves taste buds in the anterior 2/3 of the tongue and runs through the middle ear and carries taste messages to the brain and exerts an inhibitory influence on other taste nerves as well as pain fibers in the tongue?
Chorda Tympani Nerve
What structure of the ear is also termed the auditory tube or pharyngotympanic tube, consists of bone and cartilage and connects middle ear with nasopharynx?
Eustachian tube
The inner ear is also called what and what are the two main divisions?
Labyrinth:
- Bony Labyrinth (outer)
- Membranous Labyrinth (Inner)
The bony labyrinth is a series of cavities in what portion of the temporal bone and is comprised of what three areas?
Petrous Portion Comprised: -Semicircular Canals -Vestibule -Chochlea
What portion of the inner ear is a series of sacs and tubes inside the bony labyrinth?
Membranous Labyrinth
What fluid of the inner ear is chemically similar to CSF and surrounds the membranous labyrinth?
Perilymph
What fluid of the inner ear is within the membranous labyrinth and has high levels of potassium ions? What role does this fluid serve?
Endolymph
Role: Generation of Auditory Signals
What portion of the inner ear is the oval central portion of the bony labyrinth and part of the membranous labyrinth is within it?
Vestibule
What is the vestibule composed of and what does it contain?
Composed: Utricle sac and Saccule sac
Contains: Oval Window (Vestibular Window)
The three semicircular canals are bony structures named according to position, what are the names and orientation?
Anterior (Vertical)
Posterior (Vertical)
Lateral (Horizontal)
What is the swollen enlargement at one end of each canal called?
Ampulla
The part of the membranous labyrinth inside the semicircular canals are called what and what do they connect to?
Semicircular Ducts
Connect to Utricle of Vestibule
What disease is caused by increased amount of endolymph which enlarges the membranous labyrinth and includes symptoms of fluctuating hearing loss (distortion of basilar membrane), roaring tinnitus, whirling vertigo?
Meniere’s Disease
What are the three nerves that innervate the semicircular canals? What are these branches of?
Utricular Nerve
Saccular Nerve
Ampullary Nerve
Branches of: Vestibular Branch of Vestibulocochlear nerve (CN-VIII)
The Utricular, Saccular, and Ampullary nerves synapse with receptors for what reason? These nerves are?
Equilibrium
- First Order sensory and Motor Neurons
- Sensory: carry sensory information from receptors
- Motor: Carry feedback signal to receptors to modify sensitivity
The cell bodies of the sensory neurons for the Semicircular nerves are located where?
Vestibular Ganglia
The cell bodies of the motor neurons are located where and project where?
Pons
Project: to the semicircular canals, saccule, and utricle
What is the bony spiral of the inner ear called?
Cochlea
The central supporting core of the cochlea is called?
Modiolus
The Y-shaped partition of the Cochlea forms three channels, what are they called?
- Scala Media (Cochlear Duct): in the forks of the Y
- Scala Vestibuli: ends at oval window, one side
- Scala Tympani: ends at round window, other side
What do the Scala Vestibuli and Scala Tympani contain?
Perilymph
The Scala Vestibuli and Scala Tympani are separated by the stem of the “Y” except at what part of the Cochlea? What is the name of this opening?
Apex
-Helicotrema (hole in the spiral)
What portion of the Cochlea opens into the Vestibule?
Scala Vestibuli
