Orbit & Scalp Flashcards
Layers of scalp: name + describe
Skin
Connective tissue (dense) = v, a + n’s supplying scalp, hold cut vessel open - profuse bleeding
Aponeurotic layer = occipitofrontalis + aponeurotic tendon connecting bellies
Loose connective tissue
Pericranium = periosteum on outer surface calvaria
Sensory innervation of scalp
Ant. ears + vertex:
- trigeminal
- supra-orbital
- supratrochlear
- zygomaticotemporal
- auriculotemporal
Post. ears + vertex:
- cervical n. C2+3
- greater auricular = ant. rami C2+3
- lesser occipital = ant. ramus C2
- greater occipital = post. ramus C2
- third occipital = post. ramus C3
Blood supply of scalp
Ant. + sup aspects:
- ophthalmic = br. ICA
- supra-orbital
- supratochlear
Post. + lat. = rest:
- ECA
- superficial temporal
- posterior auricular
- occipital
Orbit: name bones
Frontal Sphenoid Ethmoid Lacrimal Maxilla Zygomatic Palatine
Orbit: roof
Mainly = orbital plate of frontal
Lesser wing sphenoid
Orbit: medial wall
Ethmoid, lacrimal, maxilla + sphenoid
Junction roof + medial = ethmoidal foramina (ant. + post.)
Lacrimal + frontal process maxilla = lacrimal goove
Sphenoid = part of optic canal
Orbit: floor
Orbital surface maxilla, zygomatic + palatine
IOF
Orbit: lateral wall
Zygomatic ant. + greater wing sphenoid post.
SOF = btw. wings forming roof
Common tendinous ring: location
Apex of orbit
Ant. SOF - divides regions
Fissures + foramina of orbit:
SOF:
- lacrimal n.
- frontal n.
- trochlear n.
- sup. ophthalmic v.
SOF + ring:
- sup. br. oculomotor n.
- abducent n.
- nasociliary n.
- inf. br. oculomotor n.
Optic canal:
- optic n.
- ophthalmic a.
IOF:
*inf. ophthalmic v.
Extra-ocular muscles: name
Levator palpebrae superioris Sup. rectus Inf. rectus Med. rectus Lat. rectus Sup. oblique Inf. oblique
Levator palpebrae superioris: action + innervation
Raises upper eyelid
Sup. br. oculomotor
Superior rectus: action + innervation
Elevate, adduct + int. rotates
Sup. br. oculomotor
Inferior rectus: action + innervation
Depress, adduct + ext. rotate
Inf. br. oculomotor
Medial rectus: action + innervation
Adducts
Inf. br. oculomotor
Lateral rectus: action + innervation
Abducts
Abducent n.
Superior oblique: action + innervation
Depress, abduct + int. rotates
Trochlear n.
Inferior oblique: action + innervation
Elevate, abduct + ext. rotates
Inf. br. oculomotor
Testing extraocular muscles: superior + inferior rectus
Track lat. = brings axis of m. into alignment with eyeball
The up/down
Sup. = up + inf. = down
Extreme abduction - only sup./inf. rectus can elevate/depress
Testing extraocular muscles: lateral + medial rectus
Track lat. or med.
Testing extraocular muscles: superior + inferior oblique
Track med. = bring axis of muscle into alignment with eyeball
Sup. = down + inf. = up
Extreme adduction = only obliques can elevate/depress
Paralysis to trochlear nerve
Sup. oblique = paralysed
Can’t look down + in
Double vision + head tilt away from side of lesion
Paralysis to abducent nerve
Lat. rectus = paralysed
Cannot abduct past midline
Strabismus = squint
Paralysis to oculomotor nerve
Dense ptosis = drooping eyelid - paralysis of LPS
Only LR + SO = unaffected - eye rests down + out
Pupillary light reflex: afferent limb
Fibres run in optic n.
Retina, optic n. + pretectal nucleus
Pupillary light reflex: efferent limb
2 = ipsilateral - controls direct + contralateral - controls consensual
Fibres run in oculomotor n.
Motor output = pretectal nucleus to cilialry spinchter muscle of iris
Pupillary light reflex: describe
Shine light
Retinal ganglion cells generate impulse + optic n. picks up
EWN = axons of optic n. synapse
Fibres of EWN leave in oculomotor n. + synapse in ciliary ganglion
Postganglionic cells leave + innervate sphincter muscles
Pupillary light reflex: direct vs consensual
Direct = light in 1, constriction in 1 Consensual = light in 1, constriction in both
Corneal reflex: afferent limb
Fibres of nasociliary n. of ophthalmic division of trigeminal n.
Corneal reflex: efferent limb
Fibres of br. of facial n.
Corneal reflex: describe
Afferent impulses from cornea/conjunctiva travel through ophthalmic division of trigeminal
In sensory nucleus of trigeminal - synapse with interneurons
Synapse with motor neurons of facial n.
Br. of facial supply orbicularis oculi
Eyelids close
Orbicularis oculi: parts, action + innervation
Orbital part
Palpebral part = anchored by med. + lat. ligaments
Med. fibres attach deeply to post. lacrimal crest = Lacrimal part
Closes eyelids
Facial n.
Orbital septum: structure
Deep palpebral part
Extension periosteum into eyelids
Attaches to tendon of LPS + inferior tarsus
Sensory innervation of eyelids
Branches trigeminal:
- supra-orbital, supratrochlear, infratrochlear + lacrimal br. of ophthalmic division
- infra-orbital br. of maxillary division
Motor innervation of eyelids
Palpebral part orbicularis oculi = facial n.
LPS = oculomotor n.
Blood supply of eyelids
Ophthalmic a. = supra-orbital, supratrochlear, lacrimal + dorsal nasal
Facial a. = angular a.
Superficial temporal a. = transverse facial a.
Central retinal = end a., from ophthalmic - if occluded, retina dies
Lacrimal apparatus: function + parts
Production, movement + drainage of tears Consists of: *gland + ducts *sac *canaliculi *nasolacrimal duct
Lacrimal apparatus: production of fluid
Lacrimal gland + ducts
Lacrimal apparatus: movement of fluid
Across eyeball, lat. to med. after blink
Lacrimal apparatus: drainage of fluid
Accumulates lacrimal lake, drained by canaliculi
Punctum = opening of canaliculi
Lacrimal sac = ant. lacrimal part
Contraction of oculi dilates sac + draws fluid in
Lacrimal apparatus: secretomotor/parasympathetic innervation
Pregang. parasymp. neurons leave CNS via greater petrosal n. = br. of facial n.
Join deep petrosal n. - form nerve of pterygoid canal
Pterygopalatine ganglion - synapse with postganglionic parasymp. fibres
Join maxillary, travel with until zygomatic, zygomaticotemporal then eventually join lacrimal Lacrimal n. = ophthalmic division + innervates gland
Lacrimal apparatus: sympathetic innervation
Postgang. symp. fibres originate in sup. cervical ganglion + travel along int. carotid plexus
Leave plexus as deep petrosal n. + join greater petrosal n. - form nerve of pterygoid canal
Pterygopalatine ganglion - do not synapse
Join maxillary, travel with until zygomatic, zygomaticotemporal then eventually join lacrimal Lacrimal n. = ophthalmic division + innervates gland
