Brain stem

Question 1

what are the key landmarks in the skull base (posterior fossa)

Answer 1

Petrous apex, cavernous sinus, orbital apex
Internal acoustic meatus
Jugular foramen
Tentorium hiatus

Question 2

how does trauma cause a 3rd nerve palsy?

Answer 2

Parasympathetic fibres outside of nerve are compressed due to brain pressing over apex of petrous part of temporal fossa
= Fixed dilated pupil

Question 3

how can the oral combiened contraceptive pill lead to strokes?

Answer 3

risk of thrombus in sinus

Question 4

how can a head injury lead to intracranial haemorrage?

Answer 4

Fracture crossing venous sinuses

Question 5

how can a large mass in the posterior fossa lead to hydrocephalus?

Answer 5

squash cerebral aqueduct, back pressure in ventricular system and expand = ICP raised and hydrocephalus

Question 6

what makes up the roof and the floor of the 4th ventricle?

Answer 6

Root of 4th ventricle is cerebellum, floor formed by pons and medulla

Question 7

what are the presentations of cerebellar syndrome?

Answer 7

Ataxia and nystagmus (feel as if drunk)

Deficit on side of cerebellar lesions

Question 8

what surrounds the brain stem?

Answer 8

Superior to brian stem = thalamus (either side of midbrain), internal capsule, 3rd ventricle
Inferior to brain stem = spinal cord

Question 9

where is the circle of willis is relation to the brain stem?

Answer 9

infront of the midbrain

Question 10

what is the blood supply to the brain stem?

Answer 10

Vertebral and basilar arteries supply brain stem

Question 11

what are the brain stem associated neuro structures?

Answer 11

Cranial nerves 3-12
Descending tracts (pyramidal tracts)
Ascending tracts (lemnisci)
Reticular activation 
Cerebellar peduncles

Question 12

describe the spinothalamic tracts

Answer 12

Pain and temperature - c fibres, unmyelinated, slow conduction
Cross at point of entry to spinal cord
Rely to thalamus

Question 13

describe the DCML

Answer 13

Light touch vibration - a fibres, large, myelinated, fast conduction, lots of genes involved 
Ascend in spinal cord 
Cross in medulla 
Relay in thalamus 
Then cortex

Question 14

describe the corticospinal tract

Answer 14

Internal capsule
Crosses in medulla (pyramidal decussation)
Corticospinal tract
LMN

Question 15

what is the reticular activating system?

Answer 15

Periaqueductal grey matter / floor of fourth ventricle
Tumours of 4th ventricle = injury to floor in surgery = paralysis
Alertness
sleep/wake
REM/non REM
Resp
Cardio

Question 16

describe where the cranial nerves come from on the brain stem

Answer 16

3 - 6 - eye movement and face sensation, pupils (midbrain) (6 between pons and medulla, 5 from pons)
Cavernous sinus - Oculomotor nerve (III), Internal Carotid artery, Ophthalmic nerve (V1), Abducens nerve (VI), Trochlear nerve (IV).
7 and 8 - hearing, vertigo, facial motor (top of medulla, pontomedullary junction), internal acoustic meatus
9-12 - from medulla, jugular foramen and hypoglossal canal AND internal jugular vein

Question 17

which cranial nerves control the corneal reflex?

Answer 17

afferent = V1, efferent = VII

Question 18

which cranial nerves control the pupillary light reflex?

Answer 18

afferent = II, efferent = III

Question 19

which cranial nerves control the gag reflex?

Answer 19

afferent = IX, efferent = X

Question 20

why is the tectal plate important in pathology?

Answer 20

Tectum = posterior aspect of midbrain posterior to the cerebral aqueduct
Auditory and visual reflexes
Edinger–Westphal nucleus - pupillary reflex and accommodation, associated with 3rd nerve nucleus
Paranoid syndrome - downward gaze due to hydrocephalus, pressure on tectal plate

Question 21

what is checked when diagnosing and confirming death?

Answer 21

Brainstem death 
Check:
Pupils 
Corneal reflex
Caloric vestibular reflex - water in ear?
Cough reflex 
Gag reflex 
Respirations 
Response to pain