Important Reflexes of the Orbital Region Flashcards
Opthalmic nerve
CN V1 - upper eyelid cornea conjunctiva skin of the root/bridge/tip of the nose
Maxillary Nerve
CN V2 - skin of lower eyelid skin over the maxilla skin of the alla of the nose skin/mucosa of the upper lip
Mandibular nerve
CN V3 -
Skin over the mandible and temperomandibular joint
angle of mandible supplied by C2,3 spinal nerves
Blink (corneal) reflex
Sensory @ CNV1 @ cornea > trigeminal ganglion > CNV > Pons > CNVII > motor function (eyelid part of orbicularis oculi)
Route of sympathetic axons
passes down spinal cord
Exits @ T1-L2 spinal nerves
Passes into spinal nerves (anterior and posterior rami)
Passes into splanchnic nerves to supply organs
Parasympathetic outlfow
CN III, VII, IX + X
Sacral Spinal Nerves
Parasympathetic innervation of eye
Iris + ciliary muscles
Lacrimal Gland
Occulomotor nerve supplies somatic motor to:
CNIII
Superior, Medial + Inferior Rectus
Inferior Oblique
Levator Palpebrae Superioris
Occulomotor Nerve supplies presynaptic parasympathetic axons to ….
ciliary ganglion
Ciliary ganglion
branches into ciliary nerves that supply autonomic axons to control diameter of iris and refractive shape of lens
Fight or flight
maximal eyelid elevation/ wide eye opening
Light reflex
Pupillary dilation/ constriction adjusting light entry
Accomodation reflex
focussing lens for far and near vision
Vestibulo-ocular reflex
Turns eye in opposite direction of head movement.
CNVIII [balance] and CNs III, IV + VI
Oculocardiac reflex
reflex bradycardia in response to tension on extraocular muscles or pressur eon eye (CNV1 + CNX)
Sympathetic function of eye
Open eyes wider
more light into eyes
focus on distant objects
emotional lacrimation
Parasympathetic function of eye
allow orbicularis to work
get less light into eye
focus on near objects
reflex lacrimation (wash away stimulant/ clean the cornea)
levator palpebrae superioris
located in upper eyelid
contains both skeletal and smooth muscle.
So open wide in fight or flight
Drugs that induce dilation of pupil
mydriatic
sympathetics do what to the pupil?
dilate (e.g. dim light, fight or flight)
Parasympathetics do what to the pupil?
constrict the pupil (e.g. bright light, ‘rest & digest’)
radially arranged fibres for pupillary dilatation
dilator pupillae
fibres that encircle pupil for constriction
sphincter pupillae
In far vision what does the ciliary muscle do?
it relaxes - ligaments tighten so lens flattens
In near vision what does the ciliary muscle do?
it contracts - lens becomes squeezed into spherical shape
Symptoms of Horners Syndrome
Miosis (constriction of pupil)
Ptosis (drooping of upper eyelid)
Reduced Sweating
Increased warmth and redness
Cause of Horner’s Syndrome
Compression of cervical parts of the sympathetic trunk
