Ear and Eye Flashcards
Lecture 5
bones forming the orbit are
frontal
zygomatic
maxilla
lacrimal
sphenoid
ethmoid
palatine
bony orbit protects the
eyes, the sensory organs for vision
muscles that move the eyeball (extraocular muscles)
four rectus muscles: superior rectus, inferior rectus, medial rectus, lateral rectus
two oblique muscles: superior oblique, inferior oblique
superior rectus
moves the eyeball up
inferior rectus
moves the eyeball down
medial rectus
moves the eyeball medially
lateral rectus
moves the eyeball laterally
superior oblique
moves the eyeball laterally and down
inferior oblique
moves the eyeball laterally and up
all eye muscles originate from
a common tendinous ring around optic foramen
the inferior oblique originates from
the floor of the orbit
all muscles of the eye are innervated by
CN III (Oculomotor nerve)
all eye muscles are innervated by CN III except
lateral rectus muscle (CN VI) and superior oblique muscle (CN IV)
intraocular muscles and their functions
constrictor pupillae muscle: constricts the pupil
dilator pupillae muscle: dilates the pupil
intraocular muscles receive ______ innervation
autonomic innervation
parasympathetic fibres of the intraocular muscles
from CN III —> constrictor pupillae muscle
sympathetic fibres of the intraocular muscles
from sympathetic chain —> dilator pupillae muscle
lacrimal gland lies in the
anterolateral part of the roof of the orbit
tears pass across the surface of the eye and collect in the
lacrimal sac
from the lacrimal sac tears drain via _______ duct into the nose
nasolacrimal
lacrimal gland innervation
parasympathetic fibres from facial nerve (CN VII)
cranial nerves in the orbit
CN II
CN III
CN IV
CN V
CN VI
CN II
optic nerve
special sensory fibers for vision
CN III
oculomotor nerve
motor fibers: to most, 4 out of 6, extraocular muscles
parasympathetic fibers: to muscles that constrict pupil
CN IV
trochlear nerve
motor nerve to superior oblique muscle
CN V
trigeminal nerve
V1 branch; sensory nerve to the eyeball, skin on forehead, upper eyelid
CN VI
abducens nerve
motor nerve to lateral rectus muscle
the ear canal of the external ear is separated from the middle ear by the
eardrum
the middle ear is filled with and contains
air-filled and contains three small bones (ossicles)
the middle ear is involved in
the transmission of sound
the middle ear is connected to the throat via
the Eustachian tube
the inner ear contains the
vestibular system (for balance)
cochlea (for hearing)
external ear (pinna) is made of
elastic yellow fibrocartilage covered by skin
pinna is shaped into
helix, the outer fold, and antihelix, the inner fold
external auditory meatus extends from
the opening of the meatus to the tympanic membrane
approximately 25 mm long
flap over the opening of the meatus is the _____ and the opposite fold is the
tragus
antitragus
external auditory meatus structure
is enclosed in cartilage for the first 1/3 of its length, and in bone for the remaining 2/3s of its length
external auditory meatus is lined by ______ which includes
epithelium which includes sebaceous and ceruminous glands and hair follicles
inner wall of the meatus is formed by the
tympanic membrane
tympanic membrane
a thin, cone-shaped, membrane
transmits sound from the air to the middle ear ossicles
malleus
one of the ossicles
is attached to the inner surface of the tympanic membrane at umbo, the most depressed part of the cone
tympanic membrane is innervated by
sensory branches of CN V, IX and X nerves
malleus is one of the… and is attached to
is one of the three auditory ossicles and its handle is attached to the inner surface of the tympanic membrane
tensor tympani muscle
attaches to the handle of malleus
role is to dampen the sounds and protect against hearing loss
innervated by the V3 branch of CN V
the 3 middle ear ossicles are… are they articulate with one another by
malleus, incus, stapes
synovial joints
malleus is attached to the
inner surface of the eardrum
the head of malleus makes a joint with
incus
incus makes a joint with
stapes
the footplate of stapes inserts into the
oval window - the entrance to the cochlea of the inner ear
stapedius muscle attaches
to the stapes and draws stapes backward
stapedius muscle is innervated by
facial nerve (CN VII)
function of the three ossicles
transmit sound vibrations from the eardrum to the fluid in cochlea
middle ear is the
space between the external auditory meatus and the wall of the inner ear
often described as a box, with the roof, floor, anterior, posterior, medial and lateral walls
the roof of the middle ear is formed by
tegmen tympani, part of the petrous temporal bone
separates the middle ear cavity from middle cranial fossa
the floor of the middle ear is formed by
a thin layer of bone separating cavity from internal jugular vein
the lateral wall of the middle ear is formed by
the inner surface of the tympanic membrane
chorda tympani nerve passes between the
handle of malleus and the incus
the medial wall of the middle ear separates
the middle ear from the inner
the medial wall contains the
oval window and round window, the two openings that communicate with cochlea of the inner ear
stapes attaches to the oval window
stapedius muscle attaches to the stapes; dampens the sounds
anterior wall of the middle ear
eustachian tube opens here, the tube connects middle ear with nasopharynx
canal for tensor tympani muscle above tube, internal carotid artery passes below tube
facial nerves arises from the brain and enters the
internal acoustic meatus in the petrous temporal bone together with the vestibulocochlear nerve (CN VIII)
the three functional components of facial nerve
motor root: innervates muscles of facial expression
sensory fibers: provide taste to anterior 2/3s of the tongue
autonomic fibers: innervate lacrimal, submandibular and sublingual glands
the motor root of the facial nerve exits skull via
stylomastoid foramen
the motor root of the facial nerve gives
5 motor branches to the face that supply muscles of facial expression
greater petrosal nerve
reaches the pterygopalatine ganglion and via the ganglion carries parasympathetic fibres to the lacrimal gland to activate tear production
chorda tympani
passes through the middle ear, carries special sensory fibres of taste to the tongue, and parasympathetic fibres to submandibular and sublingual salivary glands
