Anatomy of Special Sense Organs Flashcards
What may cause narrowing of the internal acoustic meatus?
Acoustic neuroma
Mastoiditis
Paget’s disease
Where will tumours be located that impinge on CN VII and CN VIII?
Internal acoustic meatus
Cerebellopontine angle
What connects the middle ear to the pharynx?
Pharyngotympanic tube / auditory tube
Which bone houses the vestibulocochlear apparatus?
Petrous temporal bone
What is the external acoustic meatus composed of?
Cartilage - lateral 1/3
Bone - medial 2/3
Name the structure that secretes ear wax
Ceruminous glands
Which nerve supplies the middle ear and tympanic membrane?
CN IX
What causes the umbo to be concave?
Attachment of the tip of the handle of malleus
Where does tensor tympani attach?
Handle of malleus
What is the function of the middle ear muscles?
Prevent excessive movement of the ossicles
Why may swelling of the tubal tonsil cause otitis media?
Situated at the opening of pharyngotympanic tube so may block it
Which muscles pull the auditory tube open for pressure equalisation?
Tensor palati
Levator palati
What attaches to the pyramidal eminence?
Stapedius
Which nerves make up the tympanic plexus?
PNS from CN IX
SNS from carotid plexus
Where is the tympanic plexus?
Promontory in middle ear
What is the function of the vestibular and cochlear aqueducts?
Allow membranous labyrinth to connect with subarachnoid space for reabsorption of endolymph and perilymph
Which parts of the eye contain aqueous humour?
Anterior and posterior chambers
What does the choroid continue as anteriorly?
Ciliary body
What happens when the ciliary muscle contracts?
Support ring shrinks
Suspensory ligaments relax
Lens becomes rounded
Where is aqueous humour reabsorbed by?
Scleral venous sinus i.e. canal of Schlemm
What in the arrangement of the pupil constrictor and dilator?
Constrictor internal
Dilator external
What is the significance of the retinal artery being a terminal vessel?
Blockage will cause blindness
What is retinal detachment?
When the inner neural layer separates from the rest of th retina
How can raised ICP cause papilloedema?
CN II lies in a sheath of meninges in the optic canal, filled with CSF
Raised ICP transmitted along optic canal causing papilloedema
What may cause anosmia?
Tumours in frontal lobe
Trauma causing brain to move and tear nerves
What is the striate cortex?
Primary visual area in the occipital lobe
