Orbit and the Meninges

Question 1

Two layers of the dura

Answer 1

Periosteal and meningeal

Question 2

What innervates the dura? Different sections?

Answer 2

Trigeminal Nerve

V1: Falx cerebri and tentorium cerebelli
V2: Medial part, deep
V3: Medial superficial

Question 3

What does the sigmoid sinus travel through?

Answer 3

The jugular foramen

Question 4

Sinus tracts

Answer 4

Sup+ inf sagittal sinus
(INF) to straight sinus
Confluence of sinuses
Transverse sinus (left and right)
Sigmoid sinus (Cavernous and lesser petrosal drain into here)
IJV

Question 5

Structures passing through cavernous sinus

Answer 5

Middle: Internal carotid and Abducens (CN6)

Wall/Edge: CN3, CN4, V1, V2

Question 6

Periorbital Cellulitis and Cavernous sinus

Answer 6

Opthalmic veins drain to CS, so must check for CN function and be aware of CS thrombosis

Question 7

Cerebral veins

Answer 7

Emissary (from scalp to sinus)
Diploic (cranium to sinus)
Cerebral (cerberum to sinus)

Question 8

Arachnoid Mater

____ membrane
Trabeculae and Subarachnoid space
Does not project into grooves except longitudinal fissure
____ drain CSF into sinus

Answer 8

Avascular membrane
Trabeculae and Subarachnoid space
Does not project into grooves except longitudinal fissure
Granulations drain CSF into sinus

Question 9

Intracranial haemorrhages, causes and blood supply

Answer 9

Extradural: From head trauma, skull fracture. Almost always arterial (MMA pterion). Between periosteal dura and bone

Subdural: Between periosteal and meningeal layer of dura. Elderly patients, cerebral vein damage. Venous

Subarachnoid: usually arterial origin (cerebral artery). Maybe veins. Associated with severe headache

Question 10

Orbital bones

Answer 10

Palatine, Ethmoid, Lacrimal, Maxillary, Zygomatic, Frontal, Sphenoid

Question 11

Eyelid layers

Answer 11

Skin; sunbcutaneous tissue, Orbicularis oculi; orbital septum, Conjunctiva, tarsus

Question 12

Racoon eyes

Answer 12

Periosteal layer of skull damages, causing blood to run into potential eye spaces of subcutaneous tissue. No eye problem. Maybe base of skull fracture

Question 13

Two tarsal muscles

Answer 13

Levator palpebrae superioris: Innervated by CN3, occulomotor, superior part
Superior tarsal: Sympathetic fibres (superior cervical ganglion)

PTOSIS, e.g in Horner syndrome (symp problem)

Question 14

Tarsus glands and eyelash glands

Answer 14

Tarsus: Chalazion

Eyelash sweat gland: Stye

Question 15

Optic canal contents

Answer 15

Optic nerve; Opthalmic artery

Question 16

Superior Orbital Fissure

Answer 16

Lacrimal nerve (V1); Frontal nerve (V1), trochlear nerve; CTR also sup opthalmic vein

IN THE CTR: Sup CN3; Nasociliary (V1) nerve, CN6; INFCN3

Question 17

Inferior Orbital fissure

Answer 17

Inf opthlamic vein, Infra orbital vein and artery

Question 18

Lacrimal apparatus

Answer 18

Lacrimal Gland: Lateral upper eye lid
Puncta with lacrimal cancaliculi MEDIALLY
Draining to Nasolacrimal duct

Question 19

Orbital fracture, nerves effected

Answer 19

Abducen: Eye is medial
Trochlear: Can not look down or in, trochlea ligament in medial orbit, could be damaged

Question 20

Danger Triangle research

Answer 20

Idea that some facial veins, and suproptic veins that drain into the sup and inf opthalmic veins, have no valves, and can lead to septic cavernous thrombosis

Opthalmic veins (particulalrly sup) had veins, as did some facial veins. But no relation so communication between facial veins and cavernous sinus is the important spread of infection

Question 21

Horner syndorme

Answer 21

ptosis, miosis, anhidrosis