Special senses Flashcards
What 3 sets of air sinuses are in close proximity to the orbit of the eye?
frontal, ethmoid and maxillary
What are the main contents of the orbit?
eyeball, extrinsic ocular muscles, ligaments supporting the eye, optic nerve, branches of opthalmic artery, the lacrimal apparatus and fat
What are the components of the outer fibrous layer of the eye?
sclera and cornea
Is the fibrous layer of the eye complete or incomplete?
complete
What are the components of the middle vascular layer of the eye?
iris, ciliary body and choroid
Is the vascular layer of the eye complete or incomplete?
it is incomplete anteriorly (aperture is the pupil)
What is the structure composing of the inner sensory layer of the eye?
the retina
Is the sensory layer of the eye complete or incomplete?
incomplete, only present posteriorly
Apart from the 3 layers, what else does the eye contain?
the lens, aqueous humour and vitreous humour
Where in the lens is the aqueous humour?
the anterior segment
Where in the lens is the vitreous humour?
the posterior segment
What part of the eye secretes aqueous humour?
ciliary epithelium (in the ciliary body)
What are the 3 intrinsic muscles of the eye?
Ciliaris, iris sphincter and iris dilator
What action does the ciliaris muscle perform?
accomodation
What action does the iris sphincter perform?
pupillary constriction
What action does the iris dilator perform?
pupillary dilation
What type of innervation do the intrinsic muscles of the eye recieve?
ciliaris and iris sphincter - parasympathetic
iris dilator - sympathetic
What type of muscles perform eye movements? How many are there?
extrinsic muscles- there are 6
What are the 6 extrinsic muscles of the eye?
superior and inferior obliques
superior, inferior, lateral and medial recti
What is the only muscle that doesn’t arise from the posterior aspect of the orbit?
inferior oblique
What branch of the internal carotid artery supplies the orbit and the eye?
opthalmic artery
What fissure do the opthalmic veins pass through to enter the cranial cavity?
superior orbital fissure
What 4 cranial nerves pass through the superior orbital fissure?
opthalmic (V1), oculomotor , abducens and trochlear
What cranial nerve passes through the optic foramen?
optic
What impulses does the optic nerve carry?
visual
What muscles does the oculomotor nerve supply?
the medial, inferior, and superior recti, the inferior oblique, and levator palpebrae
What muscle does the abducens nerve supply?
lateral rectus
What muscle does the trochlear nerve supply?
superior oblique
How is aqueous humour drained?
drained by draining apparatus in the angle of the anterior chamber of the eye
What type of joints are found between the ear ossicles?
synovial
What are the three bones termed the ‘ossicles’ of the ear?
malleus, incus and stapes
Which ossicle is in contact with the tympanic membrane?
malleus
Which ossicle is in contact with the oval window?
stapes
What are the 2 muscles related to the ossicles?
tensor tympani and stapedius
What is the action of the tensor tympani?
pulls handle of malleus medially, tensing tympanic membrane and reducing amplitude of vibrations
What is the action of the stapedius?
pulls the stapes posteriorly and tilts its base in the oval widow, reducing oscillatory range
Within which part of the temporal bone do the middle and inner ear lie?
petrous part
Name 2 areas with which the caivty of the middle ear communicates
pharyngotympanic tube and mastoid antrum
What is the fluid that lies within the bony labyrinth?
perilymph
What chambers lie within the bony labyrinth?
membranous chambers
What is the fluid that lies within the mebranous labyrinth?
endolymph
What is the function of the cochlea?
transforms sound into neural messages
What is the function of the semicircular canals?
it is a motion sensor, movements of the cilia are communicated to the brain
Through which foramen does the facial (VII) nerve exit the posterior cranial fossa?
internal acoustic meatus
What other cranial nerve exits through the internal acoustic meatus?
vestibulocochlear (VIII)
