10 - Brainstem & Cranial Nerves II

Question 1

What is the function of the midbrain?

Answer 1

CN III, IV, V
Visual (superior colliculus, pretectal nuclei) and auditor (inferior colluculi) reflex centre
Subcortical motor centres - substantia nigra and red nuclei
Reticular formation functions - arousal

Question 2

What is the function of the pons?

Answer 2

CN V, VI, VII, VIII nuclei
Cerebral relays to the cerebellum and vestibulospinal tract
Pontine respiratory centres
Reticular formation functions

Question 3

What is the function of the medulla?

Answer 3

CN IX, X, XI, XII nuclei
Visceral nuclei for control of heart rate, blood vessel diameter, respiration
Inferior olivary nuclei - relay sensorimotor information to cerebellum
2nd order neurons of the dorsal column medial lemniscal system and sensory decussation
Decussation of the pyramids
Reticular formation functions

Question 4

What is the blood supply to the brain? - Draw out the anterior and posterior circulation

Answer 4

https://upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Circle_of_Willis_en.svg/1200px-Circle_of_Willis_en.svg.png

Question 5

What supplies the medial brainstem with blood?

Answer 5

Medulla - vertebral and spinal branches

Pons/midbrain - basilar arteries

Question 6

What supplies the lateral brainstem with blood?

Answer 6

Longer cerebellar e.g PICA - rostral medulla, AICA - pons, SCA - midbrain
Posterior cerebral also supplies lateral aspects of midbrain

Question 7

Fill in the table on the google document

Answer 7

See google doc

Question 8

What does damage in the brainstem result in?

Answer 8

Whole body sensorimotor dysfunction + abnormalities in cranial nerve function

Question 9

How can you locate the level of a lesion?

Answer 9

Dysfunction of specific cranial nerves + specific ascending/descending tracts
Ask: LATERAL or MEDIAL? What is the LEVEL of the lesion?

Question 10

What are the altering symptoms of brainstem lesions?

Answer 10

• Ipsilateral sensorimotor involvement of a cranial nerve

- contralateral sensorimotor involvement of the body functions with respect to the site of a lesion

Question 11

What are common symptoms of damage to Medulla in a Unilateral medial lesion ?

Answer 11

Common symptoms + CN XII damage ipsilateral weakness & wasting of the tongue muscles

Question 12

What are common symptoms of damage to Pons Unilateral medial lesion?

Answer 12

Common symptoms + CN VI damage  medial deviation of the eye (adduction paralysis)
Pontine RF (gaze center)  ipsilateral gaze paralysis

Question 13

What are common symptoms of damage to Midbrain Unilateral medial lesion?

Answer 13

Common symptoms + CN III damage ophthalmoplegia

Red Nucleus contralateral cerebellar ataxia

Question 14

What are common symptoms of unilateral lateral brainstem lesions?

Answer 14

• Contralateral loss of pain/thermal sensation of body
• Ipsilateral loss of facial skin sensation
• Horner’s syndrome (miosis, ptosis and impaired sweating)
• Nystagmus, vertigo, nausea and vomiting
• Ipsilateral limb ataxia
• Hiccups

Question 15

What are common symptoms of a unilateral lateral lesion in the medulla?

Answer 15

Dysarthria, dysphagia, hoarseness, ipsilateral vocal cord paralysis (CN IX, X)
Ipsilateral loss of gag reflex (CN X)
Loss of Taste sensation (CN IX).

Question 16

What are common symptoms of a unilateral lateral lesion in the pons?

Answer 16

Deafness or tinnitis (CN VIII).
Loss of taste sensation, Complete ipsilateral facial muscle paralysis, can’t shut eyes, impaired salivation/ lacrimation, and hyperacuisis (all CN VII)
Rostral pons - jaw deviation during opening (Vmo)

Question 17

What are common symptoms of a unilateral lateral lesion in the midbrain?

Answer 17

Contralateral hemianaesthesia (ascending tracts)
 Lateral tegmentum  intention tremor (superior cerebellar peduncle fibres)

Question 18

What can raised intracranial pressure cause?

Answer 18

• Haemorrhage
• Tumour
• Swelling of the brain
• Berry aneurysm
  Symptoms - headache, nausea, vomiting, unconsciousness

Question 19

What are the 3 different types of brain tissue herniation?

Answer 19

Subfalcine
Uncal
Tonsillar