Week 22 Brain Stem

Question 1

Long-tract findings

Answer 1

Motor or sensory symptoms in the extremities.

Question 2

What do you suspect if your have CN deficits and long-tract findings?

Answer 2

Brainstem lesion

Question 3

Brainstem rule of 4 for latitude

Answer 3

Midbrain/above : I, II, III, IV
Pons: V, VI, VII, VIII
Medulla: IX, X, XI, XII

Question 4

Brainstem rule of 4 for longitude

Answer 4

Mediat tract = MOTOR:
Motor tracts
Medial Lemniscus (not motor, but M)
Median longitudinal fasciculus
Motor nuclei (III, IV, VI, XII)

Side (lateral tract) = SENSORY:
Spinothalamic
Spinocerebellar
Sensory nucleus CN V
Sympathetic pathway

Question 5

What is the pneumonic for ocular mm innervation?

Answer 5

SO4, LR6, all the rest are 3

Question 6

What is the pupil rule for CNIII palsies?

Answer 6

Pupil involvement with other CN III symptoms is usually d/t compressive lesion (aneurysm) rather than ischemia.

Question 7

Alexander’s Law

Answer 7

Tells you the direction the nystagmus will be worse.
Name the nystagmus for the fast phase (eg down beat = fast phase down).
Slow phase is the pathologic portion (eg slow drift upward is pathologic, down beat is corrective saccade).
Therefore when you look in the direction where the problem is, the nystagmus will be worse.

Question 8

Red flags for headaches

Answer 8

S Systemic symptoms
N Neuro symptoms
O Older age
O Onset
P Pattern change, pregnancy, positional, progressive

Question 9

What structures pass through the optic canal?

Answer 9

Optic nerve
Opthalmic artery

Question 10

What structures pass through the superior orbital fissure?

Answer 10

CN III, IV, VI
Nasociliary nerve
Lacrimal nerve
Frontal nerve
Opthalmic vein
**Tendonous ring

Question 11

What structures pass through the inferior orbital fissure?

Answer 11

Infraorbital nerve (branch of CN V2)
Zygomatic nerve

Question 12

What structures pass through the supraorbital fissure?

Answer 12

Supraorbital nerve

Question 13

What structures pass through the infraorbital foramen?

Answer 13

Infraorbital nerve (branch of CN V2)???????

Question 14

What structures are located in the fossa of lacrimal sac?

Answer 14

Nasolacrimal duct

Question 15

Which artery supplies blood to almost all of the structures of the orbit, extraocular mm, and lacrimal gland?

Answer 15

Opthalmic artery

Question 16

How is blood drained from the orbital region?

Answer 16

Through the opthalmic vein to the cavernous sinus.

Question 17

Describe blood flow to the eye from the internal carotid

Answer 17

Internal carotid ->
Opthalmic artery ->
-lacrimal
-central retinal
-posterior ciliary
-supraorbital

Question 18

What are the functions of the fat found within the orbital area?

Answer 18

1. Stabilize position of the eyeball
2. Acts as a socket for eyeball to rotate in.

Question 19

Classic sign of hyperthyroidism

Answer 19

Exopthalmus.
Volume of orbital fat increases, causing eyeball to protrude outward (proptosis).

Question 20

How can starvation affect the appearance of the eye?

Answer 20

Loss of orbital fat causes eye sockets to look hollow.

Question 21

Discuss orbital fracture

Answer 21

Floor of orbit is extremely thin.
Can be fractured by blunt force trauma.
Inferior rectus and orbital fat may prolapse into maxillary sinus.

Question 22

What is the function of Opthalmic nerve/CN V1?

Answer 22

Sensory from upper eyelid, cornea, conjunctiva, forehead, and scalp.

Question 23

What is the pathway of the opthalmic nerve/CN V1?

Answer 23

Branches from the trigeminal ganglia and middle cranial fossa via superior orbital fissure.

Question 24

What does the opthalmic nerve/CN V1 branch into?

Answer 24

Frontal nerve
Nasociliary nerve
Lacrimal nerve

Question 25

Ciliary ganglion, CN III, and CN V

Answer 25

CN V1 sympathetic fibers -> ciliary ganglion **Synapse-> short ciliary nerves. CN III parasympathetic fibers -> ciliary ganglion **Synapse -> short ciliary nerves. Sensory fibers from eyeball through ciliary ganglion into CN V1 **No synapse.

Question 26

Corneal blink reflex

Answer 26

Poke eye Opthalmic nerve -> Trigeminal sensory nucleus -> Facial motor nucleus -> Facial nerve -> Orbicularis oculi muscle.

Question 27

What does sympathetic innervation to the head result in?

Answer 27

Dilator pupillae. Superior tarsal mm in eye. Sweating when in hot environment. Dilation of vessels in skin when in hot environment/emotion. Constriction of vessels inside the skull.

Question 28

Horner Syndrome

Answer 28

Loss of sympathetic innervation to the head: Miosis (pupillary ctx) Ptosis Anhidrosis Absence of flushing Conjunctival injection (dilation of the vessels in the conjuctiva.

Question 29

Components of the lacrimal apparatus

Answer 29

Lacrimal glands Lacrimal ducts Lacrimal canaliculi Lacrimal sac Nasolacrimal duct

Question 30

What are the 4 supranuclear gaze systems?

Answer 30

Saccadic Pursuit Vergence Non-optic reflex

Question 31

Saccadic movements

Answer 31

Fast voluntary mvmts. Contralateral frontal cortex. Projects via internal capsule to brain stem gaze centres. Commonly affected (MCA stroke), Bilateral lesions = vertical gaze impairment. Clinical: movement between targets on command.

Question 32

Pursuit movements

Answer 32

Slow, involuntary mvmts. Occipital-parietal cortex. Tracks a moving object. Project via internal capsule to brain stem. Impairment results in "cogwheel" pursuit. Clinical: tracking a slowly moving target.

Question 33

Vergence

Answer 33

Slow disconjugate mvmts. Occipital-parietal to mid brain pre-tectum. Allows near focus. Clinical: shift from distant to near.

Question 34

Non-optic reflex

Answer 34

Slow eye mvmts. Vestibular nuclei in medulla. Inputs from labyrinth and neck. Maintains fixation w/head mvmt. Clinical: oculocephalic reflex and caloric responses.

Question 35

Supranuclear anatomy

Answer 35

Frontal gaze centre. Occipital gaze centre. Descending pathways to brain stem. Vergence centre. Vertical gaze centre. Horizontal gaze centre. MLF.

Question 36

Oculomotor nuclei

Answer 36

CN III oculomotor complex CN IV trochlear nucleus CN VI abducens nucleus

Question 37

Oculomotor complex

Answer 37

CN III Superior, medial, inferior, inferior oblique mm. Levator palpabrae. Parasympathetics to pupil and ciliary ganglion.

Question 38

When is a CN III palsy never nuclear?

Answer 38

Unilateral ptosis and mydriasis (dilation).

Question 39

Trochlear nuclei

Answer 39

Superior oblique. Depresses and abducted eye. Intorsion of abducted eye.

Question 40

Abducens nuclei

Answer 40

Lateral rectus. Abducts eye.

Question 41

Infranuclear nerves

Answer 41

III, IV, VI

Question 42

Progressive supranuclear palsy

Answer 42

Gradual impariment of supranuclear gaze. Vertical > Horizontal. Voluntary > Pursuit > Reflex. Axial dystonia. Dementia.

Question 43

Dorsal midbrain syndrome

Answer 43

Vertical gaze palsy. Light near dissociated pupils. Lid retraction or ptosis. Convergence-retraction nystagmus.

Question 44

INO

Answer 44

Ipsilateral adduction weakness. Contralateral abduction nystagmus. MLF

Question 45

Third nerve palsy/Oculomotor nerve palsy

Answer 45

Double vision d/t affected eye lacking adduction. Ptosis. Relative afferent pupillary defect.