Orbit & Scalp

Question 1

Layers of scalp: name + describe

Answer 1

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

Question 2

Sensory innervation of scalp

Answer 2

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

Question 3

Blood supply of scalp

Answer 3

Ant. + sup aspects:

• ophthalmic = br. ICA
• supra-orbital
• supratochlear

Post. + lat. = rest:

• ECA
• superficial temporal
• posterior auricular
• occipital

Question 4

Orbit: name bones

Answer 4

Frontal
Sphenoid
Ethmoid
Lacrimal
Maxilla
Zygomatic
Palatine

Question 5

Orbit: roof

Answer 5

Mainly = orbital plate of frontal

Lesser wing sphenoid

Question 6

Orbit: medial wall

Answer 6

Ethmoid, lacrimal, maxilla + sphenoid
Junction roof + medial = ethmoidal foramina (ant. + post.)
Lacrimal + frontal process maxilla = lacrimal goove
Sphenoid = part of optic canal

Question 7

Orbit: floor

Answer 7

Orbital surface maxilla, zygomatic + palatine

IOF

Question 8

Orbit: lateral wall

Answer 8

Zygomatic ant. + greater wing sphenoid post.

SOF = btw. wings forming roof

Question 9

Common tendinous ring: location

Answer 9

Apex of orbit

Ant. SOF - divides regions

Question 10

Fissures + foramina of orbit:

Answer 10

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.

Question 11

Extra-ocular muscles: name

Answer 11

Levator palpebrae superioris
Sup. rectus
Inf. rectus
Med. rectus
Lat. rectus
Sup. oblique
Inf. oblique

Question 12

Levator palpebrae superioris: action + innervation

Answer 12

Raises upper eyelid

Sup. br. oculomotor

Question 13

Superior rectus: action + innervation

Answer 13

Elevate, adduct + int. rotates

Sup. br. oculomotor

Question 14

Inferior rectus: action + innervation

Answer 14

Depress, adduct + ext. rotate

Inf. br. oculomotor

Question 15

Medial rectus: action + innervation

Answer 15

Adducts

Inf. br. oculomotor

Question 16

Lateral rectus: action + innervation

Answer 16

Abducts

Abducent n.

Question 17

Superior oblique: action + innervation

Answer 17

Depress, abduct + int. rotates

Trochlear n.

Question 18

Inferior oblique: action + innervation

Answer 18

Elevate, abduct + ext. rotates

Inf. br. oculomotor

Question 19

Testing extraocular muscles: superior + inferior rectus

Answer 19

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

Question 20

Testing extraocular muscles: lateral + medial rectus

Answer 20

Track lat. or med.

Question 21

Testing extraocular muscles: superior + inferior oblique

Answer 21

Track med. = bring axis of muscle into alignment with eyeball
Sup. = down + inf. = up
Extreme adduction = only obliques can elevate/depress

Question 22

Paralysis to trochlear nerve

Answer 22

Sup. oblique = paralysed
Can’t look down + in
Double vision + head tilt away from side of lesion

Question 23

Paralysis to abducent nerve

Answer 23

Lat. rectus = paralysed
Cannot abduct past midline
Strabismus = squint

Question 24

Paralysis to oculomotor nerve

Answer 24

Dense ptosis = drooping eyelid - paralysis of LPS

Only LR + SO = unaffected - eye rests down + out

Question 25

Pupillary light reflex: afferent limb

Answer 25

Fibres run in optic n. | Retina, optic n. + pretectal nucleus

Question 26

Pupillary light reflex: efferent limb

Answer 26

2 = ipsilateral - controls direct + contralateral - controls consensual Fibres run in oculomotor n. Motor output = pretectal nucleus to cilialry spinchter muscle of iris

Question 27

Pupillary light reflex: describe

Answer 27

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

Question 28

Pupillary light reflex: direct vs consensual

Answer 28

``` Direct = light in 1, constriction in 1 Consensual = light in 1, constriction in both ```

Question 29

Corneal reflex: afferent limb

Answer 29

Fibres of nasociliary n. of ophthalmic division of trigeminal n.

Question 30

Corneal reflex: efferent limb

Answer 30

Fibres of br. of facial n.

Question 31

Corneal reflex: describe

Answer 31

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

Question 32

Orbicularis oculi: parts, action + innervation

Answer 32

Orbital part Palpebral part = anchored by med. + lat. ligaments Med. fibres attach deeply to post. lacrimal crest = Lacrimal part Closes eyelids Facial n.

Question 33

Orbital septum: structure

Answer 33

Deep palpebral part Extension periosteum into eyelids Attaches to tendon of LPS + inferior tarsus

Question 34

Sensory innervation of eyelids

Answer 34

Branches trigeminal: * supra-orbital, supratrochlear, infratrochlear + lacrimal br. of ophthalmic division * infra-orbital br. of maxillary division

Question 35

Motor innervation of eyelids

Answer 35

Palpebral part orbicularis oculi = facial n. | LPS = oculomotor n.

Question 36

Blood supply of eyelids

Answer 36

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

Question 37

Lacrimal apparatus: function + parts

Answer 37

``` Production, movement + drainage of tears Consists of: *gland + ducts *sac *canaliculi *nasolacrimal duct ```

Question 38

Lacrimal apparatus: production of fluid

Answer 38

Lacrimal gland + ducts

Question 39

Lacrimal apparatus: movement of fluid

Answer 39

Across eyeball, lat. to med. after blink

Question 40

Lacrimal apparatus: drainage of fluid

Answer 40

Accumulates lacrimal lake, drained by canaliculi Punctum = opening of canaliculi Lacrimal sac = ant. lacrimal part Contraction of oculi dilates sac + draws fluid in

Question 41

Lacrimal apparatus: secretomotor/parasympathetic innervation

Answer 41

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

Question 42

Lacrimal apparatus: sympathetic innervation

Answer 42

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