What is the pterion?
H-shaped suture on the lateral aspect of the skull
Which bone contains the organs of hearing and balance?
Temporal bone
Which structures does the petrous part of the temporal bone contain?
The organs of hearing and balance
The facial nerve (CN VII)
The vestibulocochlear nerve (CN VIII)
What forms the skeleton of the external ear?
Temporal bone and elastic cartilidge
What is the function of the external ear?
Collect and convey soundwaves to the tympanic membrane
What does the middle ear consist of?
Tympanic membrane to oval window
Includes the Eustachian tube
What is the function of the middle ear?
Amplifies and conducts sound waves to the internal ear
What is the function of the internal ear?
Converts special sensory information on sound/balance into fluid waves then into action potentials and conducts the action potentials towards the brainstem
What is the ear canal lined with?
Ceruminous glands that produce ear wax
Which bony structures are being indicated here?
Which nerve gives general sensory supply to the inferior parts of the EAM and the tympanic membrane?
Vagus nerve
Which nerve gives general sensory nerve supply to the superior part of the EAM and most of the tympanic membrane?
CN V3
What is the general sensory nerve supply of most of the tympanic membrane?
CN V3 (mandibular nerve)
Which nerves supply general sensation to most of the auricle?
Spinal nerve C2, 3
What is the name of the group of pre-auricular lymph nodes?
Parotid nodes
What is the name of the group of post-auricular lymph nodes?
Mastoid nodes
(behind the ear)
Where do the parotid and the mastoid lymph nodes drain into?
Deep cervical chain lymph nodes
Lymphatic duct/thoracic duct
Venous angle
What is the umbo?
The most inwardly depressed part of the tympanic membrane
What is the pars flaccida?
The thin part of the tympanic membrane that lies superiorly
What is the pars tensa?
The thick part part of the tympanic membrane that lies posteroinferiorly
Which middle ear structure can be seen through the tympanic membrane here?
Handle of the malleus
What is the structure being indicated here?
Umbo
The opening into which tube is being shown here?
Eustachian tube
What is the shared general sensory nerve supply to the eustachian tube, tonsils, middle ear cavity, nasopharynx and oropharynx?
CN IX
What is the eustachian tube?
A tube that connects the tympanic cavity to the lateral wall of the nasopharynx
Which cavities are being shown here?
Which part of which middle ear bone inserts into the oval window?
Footplate/base of the stapes
What are the middle ear bones?
Stapes
Incus
Malleus
What kind of joints are between the middle ear bones?
Synovial joints
What is the promontry?
A bony swelling on the medial wall of the middle ear caused by the cochlea of the internal ear
What structure is being outlined here that lies deep to the bone?
Facial canal
Where is this arrow pointing?
Into the aditus
What can cause mastoiditis?
Spread of infection from the middle ear cavity via the aditus
What the smallest muscle in the body and what is it's function?
Stapedius
Reduces movement of the stapes to protect inner ear from excessive noise
Which ossicle is this?
Incus
Which bone is this?
Incus
Which bone is this?
Malleus
Which nerve supplies the stapedius?
Facial nerve CN VII
What is the action of the tensor tympani muscle?
Pulls on the mandle of the malleus to tense the tympanic membrane
Which nerve supplies the tensor tympani?
CN V3
Which cranial nerve is the chorda tympani a branch of?
Facial nerve
What are the three parts of the bony labrinth?
Cochlea
Vestibule
Semicircular canals
What is the fluid that fills the bony labrinth?
Perilymph
Which structure can be found floating in the perilymph of the bony labrinth?
Membranous labrinth
What is the fluid that fills the membranous labrinth?
Endolymph