anatomy Flashcards
action + innervation of lateral rectus muscle
ONLY aBduct eyeball
CN VI (abducent)
–> brings line of gaze into same plane as superior rectus + inferior rectus
action + innervation of superior rectus muscle
when in aBduction, can ONLY elevate
CN III (oculomotor)
action + innervation of inferior rectus
when in abduction, can ONLY depress
CN III (oculomotor)
action + innervation of medial rectus muscle
aDduct only
CN III (oculomotor)
–> same plane as superior + inferior obliques
action + innervation of internal oblique muscle
when in aDduction can only elevate
CN III (oculomotor)
action + innervation of superior oblique
when in aDduction, only depress
CN IV (trochlear)
innervation of the extraocular muscles
LR6 SO4 AO3
lateral rectus CNVI (abducent)
superior oblique CNIV (trochlear)
all others CNIII (oculomotor)
sympathetic reflexes of the eye
opens eyes wider - more light
focus on far objects
emotional lacrimation
parasympathetic reflexes of the eye
less light in
focus on near objects
reflex lacrmation - wash away stimulant foreign body
sensory + motor limbs of the corneal reflex (blink)
sensory = CNV1 (cornea, V1, trigeminal ganglion, pons)
motor = CN VII (facial –> orbicularis oculi)
which nerves are being tested in the corneal reflex (blink)
facial + trigeminal (ophthalimic)
V1 = sensory/afferent facial = mottor/efferent
what muscle is responsible for opening eyes wider? how is this innervated?
levator palpebrae superioris
skeletal muscle PLUS smooth muscle (Muellers muscle)
SYMMPATHETIC innervation
the tendon of which extraocularmuscle passes through the trochlea?
superior oblique
what is the somatic motor innervation of the lateral rectus muscle?
abducens
what is the action of the levator palpebrae superioris?
elevate upper eyelid
where to sympathetics leave spinal cord
T1-L2`
postsynaptic sympathetic fibres reach the orbit by travelling on the surface of which artery?
ophthalamic
a parasympathetic ganglia thats associated with the eyeball
cilliary
the ciliary ganglion is associated with which cranial nerve?
CN III oculomotor
what muscle is responsible for parasympathetic response of constricting pupil?
sphincter pupillae
dilator pupillae (radially arranged) pulls on sphincter pupillae to stretch + widen pupil
class of drugs used to induce pupil dilation
mydriatic
special sensory + motor CNs responsible for the pupillary light reflex
special sensory (afferent) = ipsilateral CN II
motor (efferent) = CN III
normal response to pupillary light reflex
constriction in stimulated eye (direct)
a consensual constriction will also occur in non stimulated eye
location of cell bodies of parasympathetic axons of CN III
Edinger-Westphal (EW) nucleus
involved in the pupillary light reflex pathway, synapses with ciliary ganglion via CN III
which muscle controls the shape of the lens?
ciliary muscle
smooth muscle like a sphincter around circumference
muscular and vascular
what effect does relaxation of the ciliary muscle have on the vision of the eye? shape of the lens?
ciliary muscle relaxes in “far vision”
–> ligament TIGHTENS + lens FLATTENS to focus on object in distance
NO parasympathetics
what effect does contraction of the ciliary muscle have on the vision of the eye? shape of the lens?
ciliary muscle contracts in “near vision”
–> ligament contracts+ lens becomes MORE SPHERICAL to focus on near objects
PARASYMPATHETIC
when is the lens accommodation reflex used?
in response to “near”
3 components of the lens accommodation reflex?
- bilateral pupilllary constriction - parasympathetic constriction of sphincter pupillae
- convergence of both eyes towards midline - medial rectus
- bilateral relaxation of lens - contraction of ciliary muscles (more spherical)
CN responsible for lens accommodation reflex
CN III
3 reflexes of lacrimation
basal tears - corneal health
reflex tears - mechanical or chemical stimulation
emotional tears
enzyme contained in basal tears
lysozyme - hydrolyses bacterial cell walls
CN involved in reflex tears
afferent = CN V1 from cornea/conjunctiva
efferent = parasympathetic axons originating from CN VII
splanchnic nerves
supplies sympathetic innervation to organs
pathways of presynaptic SYMPATHETIC axons from CNS to head + neck
exit spinl cord in T1
ascend within sympathetic chain
synapse in SUPERIOR CERVICAL SYMPATHETIC GANGLION
pathway of postsynaptic sympathetic axons of head + neck
enter internal + external carotid nerves
travel to organs on surface of internal + external carotid arteries
(ophthalmic artery carries sympathetic axons into orbit)
which CN do parasympathetics axons leave the CNS via?
ALL PARAsympathetic axons leave CNS via -
III, VII, IX + X
+ sacral spinal nerves
which muscles of the eye have secondary movement?
all bar medial + lateral rectus
