Orbit and the menengies

Question 1

What happens if you damage the frontotemporal division of the the facial nerve?

Answer 1

Inability to use the obicularis oculi, which gives voluntary control of the eye lids. This results in an inability to close the the ipsilateral upper eyelid and the lower eyelid droops. This is associated with corneal ulcers and spillage of tears.

Question 2

Damage to which muscle causes complete ptosis and to which causes incomplete ptosis?

Answer 2

Levator palpebral superosis - complete

Superior tarsal - incomplete

Question 3

What are the three divisions of the opthalamic nerve?

Answer 3

Lacramal, frontal and nasocillary. All run in the superior orbital fissure

Question 4

What is a path for infections to spread from outside to inside the central cavity?

Answer 4

From the facial veins to the opthalamic veins to the cavernous sinus.

SOV ->
Deep facial vein -> pterygoid plexus -> IOV

Not becuase they don’t have valves as the SOV does contain valves.

or from the emissary veins into the dural sagital sinuses

Question 5

What vessels are damaged in a epidural haemorrhage, subdural and subarachnoid haemorrhage?

Answer 5

Epidural - arterial origin - usually the middle meningeal artery. Usually associated with a skull fracture. Blood collects between the dura and the skull.
Subdural - venus origin. BETWEEN THE TWO DURA LAYERS. Damage to the cerebral veins that go from the brain to the superior sagittal sinus. particularly in patients with cerebral atrophy or on anticoagulants.
subarachnoid haemorrhage - bleeding from a ruptured cerebral artery aneurysm of the circle of willis. May be associated with an intracerebral bleed. May cause sudden sever headache, vomiting and loss of consciousness.

Question 6

What are the two dural layers called?

Answer 6

Perosteal and meningeal layer

Question 7

What are the four partitions in the skull?

Answer 7

Diaphragma sellae (over the pititary)

Question 8

What are the different meningeal arteries and where do they come from?

Answer 8

From maxillary division of the external carotid. middle meningeal artery. From ethmoid arteries the anterior meningeal artery.
Also the accessory and posterior meningeal aes.

Middle meningeal artery divides into anterior (behind the pterion) and the posterior meningeal artery.

These run in the periosteal layer of the

Question 9

What innervates the dura?

Answer 9

Three division of the trigemial give sensory info.

Question 10

What structures run within the cavernous sinus?

Answer 10

CN III, IV, V (1 and 2), VI and internal carotid artery

Question 11

What structures run in the cavernous sinus?

Answer 11

CN III, IV, V (1 and 2), VI and internal carotid artery.

Important difference:
ICA and VI run in the sinus and the rest run in the wall.

Question 12

What is the risk of periorital thrombosis?

Answer 12

Infection -> opthalamic -> cavernous sinus causeing cavernous thrombosis and meningitis

Question 13

What are the two regions of obiclaris occuli and what innervates it?

Answer 13

The palpebral on the eye lids and the orbital part, surrounding this. These close the eye lid.

Frontotemporal branch of the Facial nerve.

Question 14

Discuss the orbital septum .

Answer 14

It is an extension of the periosteal dural layer. Deep to obicularis oculi. Surrounds the eye.

Question 15

What does the tarsus do?

Answer 15

Protectes the eye becuase it is dense connective tissue.. It also has tarsal glands that secrete oil to protect the eye from drying out

Question 16

What is horner syndrome?

Answer 16

Ptosis, anyhydrosis and miosis.

Damage to the cervical plexus sympathetic chain - This is what innervates the superior tarsal - partial ptosis

Pupillary constriction due to paralysis of the dilator pupillae muscle

Question 17

What is the blood supply and innervation to the eyelids?

Answer 17

Opthalamic artery, facial artery, and superficial temporal artery

Sensory: CNV (1 and 2)
Motor: CN III, CN VII and sympathetic fibres

Question 18

What is the periosteal layer called in the orbital cavity?

Answer 18

Periorbital

Question 19

What are the parts of the lacrimal apparatus?

Answer 19

The lacrimal gand, the lacrimal canaliculi, lacrimal sac and nasolacrimal duct

Question 20

What is a dacryocystocele?

Answer 20

is an uncommon consequence of congenital nasolacrimal duct obstruction

Question 21

Where do the cerebral arteries run and where can they cause haemorrhage?

Answer 21

They run in the subarachnoid space and cause subdural haemorrhages.

Question 22

How do yo find the pterion?

Answer 22

From the later corner of the eye go up 1 cm to palpate two bumps. This is the frontozygomtic suture. From here go 2.6 cm behind and 1.3 cm above there.

Question 23

What is the blood supply, innervation and lymphatic drainage to the eyelid?

Answer 23

The ophthalmic artery, superior and inferior ophthalmic veins and the parotid gland. Sensory innervated by V1 and V2.
Motor: Facial to the palpebral part of orbicularis oculi muscle
LPS - oculomotor
Superior tarsal to postganglionic sympathetic fibres from the superior cervical plexus.

Question 24

What can increased intracranial pressure in the eye cause?

Answer 24

Blocking if the central retinal vein

Question 25

What are the intrinsic eye muscles?

Answer 25

Ciliary muscle, sphincter pupillae, dilator pupillae