A4 - ear Flashcards
what is the ear divided into?
external, middle and inner ear
what separates the external and middle ear?
tympanic membrane
what joins the middle ear to the nasopharynx?
pharyngotympanic tube
where is much of the ear housed?
in the petrous part of the temporal bone
what does the lobule of the auricle consist of?
fibrous tissue, fat and blood vessels
what is the arterial supply to the auricle derived mainly from?
the posterior auricular and superficial temporal arteries (branches of the external carotid artery?
what is the function of the auricle?
capture and direct sound waves towards the external auditory meatus
what is the only part of the auricle not supported by cartilage?
lobule
what divides the 2 crura of the auricle?
the anti helix
what forms the skeleton of the external ear?
elastic cartilage
describe the external auditory meatus
= a sigmoid shaped tube that extends from the deep part of the concha to the tympanic membrane
- the walls of the external 1/3 are formed by cartilage, whereas the inner 2/3 are formed by the temporal bone
- the ceruminous and sebaceous glands in the subcutaneous tissue of the cartilaginous part of the meatus produce cerumen (earwax)
describe the tympanic membrane
- lies at the distal end of the external acoustic meatus
- it is a connective tissue structure, covered with skin on the outside and a mucous membrane on the inside
- the membrane is connected to the surrounding temporal bone by a fibrocartilaginous ring
what attaches to the inner surface of the membrane at a point called the umbo of the tympanic membrane?
the handle of malleus
describe the tympanic membrane superior to the lateral process of the malleus
the membrane is thin and is called the pars flaccida — lacks the radial and circular fibres present in the remainder of the membrane (pars tensa)
what does the pars tensa of the tympanic membrane form?
the lateral walls of the superior recess of the tympanic cavity
the parts of the tympanic membrane moving away from the lateral process are called the what?
the anterior and posterior malleolar folds
label the tympanic membrane
what innervates the skin of the auricle?
greater auricular nerve (branch of cervical plexus) and the lesser occipital nerve (branch of cervical plexus)
what innervates the skin of the auricle and the external auditory meatus?
auriculotemporal nerve
what is the auriculotemporal nerve a branch of?
mandibular division of CN V
what innervates the deeper aspect of the auricle and external auditory meatus?
branches of facial and vagus nerves
what 2 nerves provide sensory innervation to the external ear?
greater auricular (C2,3) and auriculotemporal (branch of V3) nerves
coughing when cleaning the ears is due to stimulation of what?
the auricular branch of the vagus nerve (vagus nerve responsible for cough reflex)
lymphatics of external ear
superficial parotid, mastoid, upper deep cervical and superficial cervical nodes