Anatomy- The ear Flashcards
what bounds the external ear
pinna
what is the pinna formed from
neural crest cells
what are the functions of the ear
hearing (auditory system, cochlear)
balance (vestibular system, semicircular canals)
which bone holds all the parts of the ear
temporal
what nerves exist in the temporal bone
CN VIII (vesticulococclear) (stays in bone) and CN VII (facial) (passes through bone)
what is the pterion
H shaped structure where frontal, parietal, temporal and sphenoid bones join
thinnest part of the skull
what forms the squamous part of the temporal bone
1st pharyngeal arch from the neural crest
what do the digastric muscle attach to
styloid process
what bone can infection of the middle ear blow out
mastoid process
what does the styloid process form from
2nd arch
what forms the zygomatic arch
zygomatic process of the temporal bone
what can rupture of the pterion cause
epidural haematoma
were does the facial nerve exit the temporal bone
stylomastoid foramen
what nerves could a pathology in the internal accoustic meatus develop
CNs VII and VIII
what nerves come out of the jugular foramen
CN 9, 10 and 11
what are the roles of the facial nerve
motor to face motor to stapedius taste to anterior 2/3rds of tongue secretomotor to salivary glands and lacrimal gland general sensation to external ear
what is the role of the vestibulocochlear nerve
balance
hearing
what is the labyrinthine artery
branch of anterior inferior cerebellar artery from circle of willis
what is in the internal accoustic meatus
CN VII, CN VIII, labyrinthine artery and vein
what is the circle of willis
blood supply to the brain and brain stem
everything supplied by the facial nerve is from what pharyngeal arch
2nd
what makes up the external ear
the auricle to the tympanic membrane (via the external acoustic meatus)
what is the role of the external ear
collects and conveys sound waves to the tympanic membrane
what makes up the middle ear
tympanic membrane to oval window + eustachian tube (aka auditory tube, pharyngotympanic tube)
what is the role of the middle ear
amplifies and conducts sound waves to the internal ear
what makes up the internal ear
oval window to the internal acoustic meatus
what is the role of the internal ear
converts special sensory information into fluid waves, then APs
then conducts APs to the brain
what covers the oval window
the stapes (an ossicle)
what does the eustachian tube do
connects the tympanic cavity (middle ear) to the lateral wall of the nasopharynx
what does the ear cartilage form from
neural crest cells
is the external ear vascular
no gets nutrients from the skin
what type of cartilage in the external ear
elastic
where does the ear canal begin
at the external accoustic meatus
what makes up the ear canal
1/3rd cartilage 2/3rds bone
lined with skin
what does the ear canal produce
ear wax via ceruminous glands
what is the nerve supply to the external ear
outer half= C2,3 spinal nerves and CN VII
superior parts of EAM and most of the tympanic membrane= CN V3
inferior parts of EAM and tympanic membrane = vagus
facial nerve also does sensation (one of few areas where is does) around the concha of the auricle
what is the tragus
external convering of external acoustic meatus
where does the lymph from the lateral surface of the superior half of the auricle drain to (infront of the ear)
parotid
where does the lymph from the cranial surface of superior half (behind the ear)
mastoid lymph nodes (and deep cervical)
where does most of the auricle including the lobe drain its lymph to
superficial cervical lymph nodes
where does all lymph from auricle eventually drain to
deep cervical lymph nodes (in carotid sheath) then thoracic duct/ right lymphatic duct at venous angles
what is the EAM like in children - what does this mean for an otoscopic exams
short and straight
be careful not to damage the tympanic membrane when pulling auricle posteroinferiorly
how and what do you exam in an otoscopic exam
EAM and tympanic membrane
straighten EAM (n adults this is curved)
gently pull auricle posterosuperiorly
what is the umbo
the most inwardly depressed part of the tympanic membrane
where is the cone of light normally
directly anteroinferiorly