7. Temporal bone and external ear (workbook) Flashcards
what does the temporal bone constitute of?
a large portion of the lateral area of the skull
what does the temporal bone house?
the cavities of the ear
what are the different components of the temporal bone?
squamous part pretromastoid part tympanic plate styloid process (zygomatic part)
what does the external acoustic meatus consist mostly of?
the tympanic plate
what do the free outer border of the external acoustic meatus provide?
attachment for the cartilage of the external ear
what does the EAM fuse with medially?
petrous part of temporal bone
which part of the skull contains the middle and inner ear?
petromastoid part of temporal bone
what does the upper surface of the temporal bone form?
part of the floor of the middle and posterior cranial fossae
what happens to the part of the temporal bone forming the front of the posterior cranial fossa floor?
pierced by the internal acoustic meatus
transmitting the facial and vestibulocochlear nerves
what does the inferior surface of the temporal bone appear and what does it contain?
inferior surface = irregular
contains carotid canal for the internal carotid artery
what is the mastoid process and what does it attach?
mastoid process is a large palpable landmark
attaches to several muscles
what is the cavity of the mastoid antrum?
a prolongation of the cavity of the middle ear
where does the cavity of the mastoid antrum extend?
into the mastoid process by intercommunicating mastoid air cells
what can spread via the route of mastoid antrum cavity into mastoid process via mastoid air cells?
middle ear disease can spread causing mastoiditis
what does the external ear consist of?
pinna / auricle + external acoustic meatus (ear canal)
what is the auricle?
cartilaginous and covered with skin
how are the elastic cartilages of the external ear arranged?
in a number of curved ridges that include the outer rim (helix) and a small flap (tragus) guarding the external acoustic meatus
what is the earlobe?
a fatty structure
what is the external acoustic meatus?
a cartilaginous tube laterally and a bony canal medially lying within the temporal bone
what is the EAM lined by?
skin secreting cerumen (modified sebum) that affords protection for the delicate meatal skin
what forms wax?
the discarded cells of the skin together with cerumen (modified sebum)
what is the ear drum?
fibrous tympanic membrane
how is the fibrous tympanic membrane arranged?
as a shallow cone with its apex pointing medially
how does the fibrous tympanic membrane appear?
translucent allowing visualisation of some structures within the middle ear
what attaches to the apex of the eardrum?
malleus (middle ear ossicle)
