Week 1 - B - Anatomy of the Ear (and some cranial nerves) Flashcards
What are the three anatomical divisions of the ear?
External ear Middle Ear Inner ear
How does our middle ear connect with the nasopharynx?
Connects via the Eustachian tube
What are the two functional divisions of the ear?
Hearing (Auditory system) Balance (Vestibular system)
What bone do all the anatomical and functional divisions of the ear lie within?
All lie within the temporal bone
What are the two parts of the temporal bone? What are the two process coming off the temporal bone? Which process is sort of like a sinus and why?
Squamous and petrous (rock-like) part The mastoid process and the styloid process The mastoid process is sort of like a sinus as it has air spaces
What is the thinnest part of the skull known as and what four bones of the skull form this structure?
Known as the pterion Formed by the frontal, parietal, sphenoid and temporal bones It is an H-shaped structure
What is the space in the occipital bone for the spinal cord? Which bone of the skull has a butterfly like shape? What is the process of the temporal bone that continues into the cheek?
Formane magnum - for spinal cord Sphenoid bone - unpaired butterfly like shape Zygomatic process of the temporal bone
Name all the cranial nerves and their foramen Not enough space on this slide so leave the three trigeminal foramen naming for the next card
Olfactory - Cribriform plate of ethmoid bone Optic - optic canal Oculomotor - superior orbital fissue Trochlear - suprior orbital fissure Trigeminal (Opthalmic, maxillary, mandibular) Abducent - superior orbital fissure Facial - internal acoustic meatues/ stylomastoid foramen Vestibulocochlear - internal acoustic meatus Glossopharyngeal - jugular foramen Vagus - jugular foramen Spinal accessory - jugular foramen Hypoglossal - hypoglossal canal
Name the three trigeminal nerves and their foramen
Opthalmic division (CN V1) - superior orbital fissure Maxillary division (CN V2) - foramen rotundum Mandibular division (CN V3) - foramen ovale
What foramen is this pointing to? What formina lie either side of the foramen magnum?
Pointing to the internal acoustic meatus Hypoglassal canal lie either side of the foramen magnum
What two nerves pass through the internal acoustic meatus?
The facial nerve (CN VII) and The vestibulocochlear nerve (CN VIII)
What part of the CN VIII allows for balance and hearing?
Cochlear allows for hearing Vestibular nerve allows for balance
Which artery/vein (aka the auditory artery) provides a blood supply to the vestibular and cochlea apparatus? This artery/vein passes through the internal acoustic meatus also What is this artery a branch of?
The labyrinthine artery and vein It is a branch of the anterior inferior cerebellar artery which is from the circle of willis
What muscle attaching to the stapes does the facial nerve provide motor supply to? How does the facial nerve innervate the tongue for taste? Which glands does it provide parasympathetics to?
Facial nerve provides motor supply to the stapedius muscle Innervates the tongue through the chorda tympani branch which innervates the anterior 2/3rds of the tongue for taste Provides parasympathetic supply to the submandibular, sublingual glands
Pathology in the internal acoustic meatus could damage the CN VII and VIII COuld be due to eg an acoustic meatus What is an acoustic meatus also often known as? (due to the nerve on which it arises)
Also known as a vestibular schwannoma - it grows on CN VIII and can also damage the facial nerve
What is a schwannoma?
A schwannoma is a benign nerve sheath tumor composed of Schwann cells, which normally produce the insulating myelin sheath covering peripheral nerves. Schwanna cells produce myelin in the PNS
Schwannomas are a common tumour that causes tinnitus and dizziness What patients usually present with bilateral schwannomas?
Patients with NF 2
Apart from tinnitus (ringing in the ear) and dizziness due to acoutic neuromas, what are other symptoms that may arise?
Pateint could have a dry mouth as it does supply the salivary glands Pateint could have a dry eye as it supplie the orbicularis oculi which is respoble for blinking too move tears across the cornea Hearing loss Patients food may be less pleasurable
What is the function of the external ear? What is the passage that helps with this function?
Collects and conveys sound waves from the auricle to the tympanic membrane via the external acoustic meatus through the ear canal
What division of the ear does the Eustachian tube lie in? Where does the Eustachian tube travel?
Lies in the middle ear Connects the middle ear to the nasopharynx
The external ear ends with the tympanic membrane, what does the middle ear end with?
Tympanic membrane to the oval window
What is the function of the middle ear? (as in what does it do to the sound before it reaches the internal ear)
Amplifies and conducts sound waves to the internal ear
The internal ear begins with the opening of the oval window What does it end with? (what does the inner ear convert special sensory information to)
Ends with the internal acoustic meatus, the internal ear converts special sensory information into fluid waves then action potentials that are carried along the internal acoustic meatus and to the brainstem
The ear canal begins at the external acoustic meatus, what produces the ear wax in the ear canal?
The ceruminous glands
What does the skeleton of the external ear contains that prevents it from being rigid?
Elastic cartilage
What is the visible part of the ear known as? What is the outer curvature of the ear known as? What is the inner curvature of the ear known as?
Known as the auricle (or pinna) Outer curvature known as the helix Inner curvature known as the anti-helix
What nerve innnervates the inferior part of the external acoustic meatus and the tympanic membrane?
The vagus nerve CN X
An examination of the ear (external acoustic meatus and tympanic membrane) begins by straightening out the external acoustic meatus How is this done in children and adults? This examination is known as an otoscopic examination
In a child – EAM is short and straight. Careful not to damage tympanic membrane when gently pull auricle posteroinferiorly In an adult – EAM is curved. Gently pull auricle posterosuperiorly
What is the membrane commonly known as the eardrum that separtes the external and middle ear?
The tympanic membrane - the malleus sits againts the tympanic membrane
What is the most inwardly depressed part of the tympanic membrane? What does this connect to?
The umbo Connects to the handle of the malleus
What provides sensory innervation to the Eustachian tube, the tonsils and the naso/oro pharynx?
The glossopharyngeal nerve (CN IX)
Which three bones (the ossicles) and which two muscles does the middle ear contain?
The three bones are the smallest in your body The malleus (hammer), incus (anvil) and stapes (stirrup) Contains the stapedius muscle and tensor tympani muscle
How do the auditory ossicles articulate? What nerve supplies the stapedius muslce and what supplies the tensor tympani? What do both the muscles attach to?
Articulate via synovial joints Facial nerve supplies the stapedius muscle CN V3 Supplies the tensor tympani muscle Tensor tympani is attached to the handle of the hammer Stapedius muscle is attached to the stapes
What is the function of both the tensor tympani and the stapedius muscle?
Both muscles contract to dampen the noise of sound
What connection with the inner ear does the base of the stapes fit into? What structures pass through the internal acoutsic meatus?
Fits into the oval window The facial nerve, vestibulocochlear nerve, the labyrinthine artery + vein
What connects anterior wall of the middle ear cavity to the lateral wall of the nasopharynx ? What tonsil liess below the soft palate? What can tonsilitis and pharyngitis often mimic?
The Eustachian tube The palatine tonsil They can mimic earache due to common snesory nerve supply CN IX
What does the facial canal connect? What is the smallest muscle in the body and is supplied by the facial nerve
Facial canal cnnects internal acoustic meatus to stylomastoid foramen - facial nerve travels through this Smallest muscle in the body is the stapedius muscle
What does the chorda tympani nerve connect with on route to supplying the tongue?
CN V3 - maxillary division of the trigeminal nerve
What is the pad in the side of the cheek that is lost in illness giving the appearance of a sunken face? It is lost in illness What is the border of the lips line representing the change in skin epithelium (highly keratinized) to the less keratinized mucous membrane of lips? What is the condition that causes paralyisis of one side of the face?
The buccal fat pad The border of the lips is the vermillion border Bells palsy
What are the canals in the vestibular labyrinth known as? How many turns dows the cochlea have? and what is the apex of the cochlea known as?
Canals are known as semicircular canals Cochlea has 2.5 turns and the apex is known as the cupula
Cochlear duct: A long balloon-like structure within the cochlea filled with endolymph: APs conducted to the brainstem in the cochlear nerve What are the semicircular ducts? How are the action potentials from the semicircular ducts conducted to the brainstem?
Inter-linked ballon like structures within the semi-circular canals filled with endolymph Conducted to the brainstem vvia the vestibular nerve
Semicircular ducts detect angular movement change Utricle and saccule detect linear movement change Which of the utricle and sacule detect horizontal and vertical?
Utricle detects the horizontal change Sacule detects the verticle change
What ligament suspends the cochlear duct? The cochlear duct separates the cochlear canal into two parts, which part is above and which is below?
The spiral ligament The scala vestibuli is above The scala typmani is below
