Workbook 2

Question 1

Normal IC pressure

Answer 1

0-10mmHg

Question 2

Monroe Kelli doctrine

Answer 2

Cerebral perfusion= MAP (Diastolic +1/3 (Syst-diastolic) - ICP
If ICP raises then MAP must increase to maintain perfusion

Question 3

Herniations

Answer 3

Uncal herniation associated with CNIII palsy, cerebellar tonsil herniation associated with death due to resp centre compression

Question 4

Inner ear anatomy

Answer 4

Membranous labirythn has endolymph, bony labirynth has perilymph. Scala media has endolymph. Scala vesticuli and
scala typami have perilymph and are continuous with each other at the apex.
Scala media has organ of corti, which is covered by the tectorial membrane and has basilar
membrane at the bottom.Scala media contains endolymph and is
separated from the scala vestibuli superiorly by the vestibular membrane, and from the
scala tympani inferiorly by the basilar membrane. The spiral organ sits on the basilar
membrane (contains the stereocilia) and above that there is the tectorial membrane, and
this moves in response to the oscilations in the perilymph. Endolymph is more viscous than
the CSF-life perilymph.
Semi circular canals are dynamic (head moving, body still), utricles and saccules are for moving body with stationary head - utricles do side to side,saccule does vertical.

Question 5

lateral gaze (automatic)

Answer 5

When the vestibular system is activated, the vestibular part of CNVIII is activated and this
travels through the internal acoustic meatus to the pontinemedullary junction at the
vestibular nuclei. Ascending tracts decussate and synapse with the contralateral abducens
nuclei (CN VI) (activates LR), then decussates and then on to the Trochlear (CN IV) and
occulomotor (CNIII) nuclei (CNIII activates MR in the same side as the original signal).
The right vesticular system will be activated when the head turns to the right, and therefor
the contralateral abducens will be activated (left eye turns to the left) and ipsilateral
occulomotor nerve activated (right eye turns medially to the left).
While this pathway is activated, there is a matching, inhibitory pathway in place to
antagonise the ipsilateral abducens and contralateral Occulomotor.

Question 6

auditory pathway

Answer 6

CNVIII to cochlear nucleus (medulla - enters brainstem at cerebellopontine angle)). Ascend to trapezioid body of superior olivary nucleus, and decussate. Ascend to medial geniculate body of thalamus (remember that music goes to medial and light goes to lateral). Then to primary auditory cortex (superior temporal gyrus, right under the lateral fissure)

Question 7

cold caloric test

Answer 7

COWS: Cold opposite, warm the same. And the nystagmus is usually described in terms of the fast movement as easier to see.
Adding cold water into a left ear will cause eyes to drift slowly to the left and then jerk back to the right.

Question 8

positive Romberg sign

Answer 8

Rombergs sign is the unability to stand still with eyes closed, positive sign if when patient
loses their balance. Balance relies on 2/3 mechanisms working (from vision, proprioception
and vestibular sense). If lose 1, then can maintain upright posture. If lose 2+ then fall over.
By removing vision sense, patient must rely on proprioception and vestibular senses, and if
they fall over then one of those doesn’t work.
Could be vestibular (e.g. schwannoma), could be proprioception (anle fracture not healed). Could also be vitamin deficiency (B12), conditions affecting dorsal tracts in the spinal
cord, neurosyphalis, Friedreich’s ataxia or Meniere’s disease.

Question 9

Vestibulospinal tracts

Answer 9

The medial vestibulospinal tract is bilateral descending tract, and these neurons synapse in
the ventral horn of the spinal cord to inflence neck muscles (for example).
Lateral vestibulospinal tract is an ipsilateral, unilateral descending tract, these synapse with
neurons supplying extensor muscle (e.g. erector spinae muscles and lower limb extensors
to maintain upright posture).
When patient turns head to righ

Question 10

Innervation to the tongue

Answer 10

Motor is largely by CNXII, but also some from CNX (palatoglossus)
General sensory (anterior 2/3) CNVc
Special sensory (ant 2/3) is chorda tympani (CNVII)
General and special posterior 1/3 is CNIX
Very far back is internal laryngeal CNX

Taste in Epiglottis and pharyngeal walls : CNIX

Question 11

Alveolar nerve block

Answer 11

Blocks sensation from teeth, but lingual nerve is nearby and this may be aneasthatised too

Question 12

Sustenacular cells

Answer 12

detoxify

Question 13

Basal olfactory cells

Answer 13

Replace older receptor cells

Question 14

Olfactory pathway

Answer 14

Olfactory epithelium conntect to bipolar mitral cells. These synapse with olfactory nerve that does not relay via the thalamus, but goes to the olfactory cortex

Question 15

Main general sensory tracts of spinal cord

Answer 15

Posteriormedially, fasciculus gracilis, laterally the fasciculus cuneatus ((dorsal columns)
Lateral from lateral horn area, anterior and posterior spinocerebral tracts. Medial to this is the lateral spinothalamic tract. Anteriomedally on the cord is the anterior spinothalamic tract.
Fasciculus gracilis and fasciculus cuneatis are part of the dorsal column median
lemniscus pathway - these receive fine touch, vibration and conscious propriception,
with FG from lower limbs and FC from upper limbs. The lateral and anterior
spinothalamic tracts deal with pain, pressure, crude touch and temperature.
Posterior and anterior cerebellar tracts deal with unconscious propriception (ipsilateral,
anterior crosses twice and posterior doesn’t cross).
Consider anterior and posterior spinal arteries

Question 16

Lateral, medial and anterior thalamus

Answer 16

Lateral has specific nuclei, medial is mood/amygdala/hypothalamus, anterior receives from mammillary body and projects to limbic system

Question 17

internal capsule vulnerable in vascular problems?

Answer 17

End arties, not much anastamoses so lacunar infacts around the internal capsule can be very damaging.

Question 18

Motor pathways

Answer 18

Anterior to the dorsal horn is the lateral corticospinal tract. Anterior to this is the rubrospinal tract (medially) and the lateral (medullary) reticulispinal tract.
Anterior to the ventral horn is the medial/pontine reticulospinal tract (laterally) and the lateral vestibulospinal tract (medially)
At the medial anterior section is the ventral corticospinal tract (medially) and the medial vestibuloispinal tract (laterally)
Tectospinal (S/C of midbrain level) is involved in head movement
Vestibulospinal (pons vestibular nuclei) involved in posture - receives input from labyrinthine system, and acts to
extend torso/neck and arms, flex legs. This is normally inhibited by CST. Medially tract is
invovled in head movement and gaze fixation, and lateral tract is to do with posture. Lateral
is uncrossed, medial decussates and is shorter.
Rubrospinal (red nucleus of midbrain, S/C level)- flexor muscle tone in upper limbs, inhibits extensor muscles (supplements
CST) and is thought to be able to take over some CST function if injured. Thought to not
go below cervical level of spinal cord.
Reticulospinal (nuclei scattered throughout midbrain/pons/medulla)- major alternative to CST. Cortical neurons can control motor function.
Supplies paravertebral and limb extensors. It is activated in response to noxious stimuli.
Medial RST is to do with posture, steering head/neck. Lateral RST is to do with pain
perception as well as motor control. Unknown if fibres cross.

Question 19

sympathetic pathway

Answer 19

lateral horn to ventral rami, then into mixed rami, then white rami - can synapse or carry on, but exit through gray rami.

Question 20

Motor and sensory nulcei of the brainstem

Answer 20

Generally, motor are bilaterally innervated, sensory are ipsi or contrallateral

Question 21

Branches of CNVII supplying face

Answer 21

Temporalis, zygomaticus, buccinator, marginal mandibular and cervical

Question 22

Location of trigeminal ganglion, and sensory pathway

Answer 22

Meckel’s cave, behind cavernous sinus. CSF filled and lined with dura mater. Medial to the ganglion in Meckel cave is the internal carotid artery in the posterior portion of the cavernous sinus.
Pseuounipolar sensory neurons (first order), run from face/tongue to trigmenial ganglion (cell bodies) and on to trigeminal nuclei :
- touch/pressure/vibration to chief in pons (some decussate/some remain ipsi), then synapse in thalamus
-pain/temp to spinal nucleus in medulla (decussates), then synapse in thalamus
-Proprioception from mastication muscles go into CNS (unique) to mesencephalic nucleus (midbrain), and either relay back for reflex (via motor nucleus) or go to cerebellum.

Question 23

Muscles derived from 1st pharyngeal arch, and innervation

Answer 23

Muscles of mastication - > masseter, temporalis, medial pterygoid and lateral pterygoid (lateral opens jaw).
mylohyoid, anterior belly of digastric (assists with jaw movement), tensor veli palatani and tensor tympani (elevates soft palate to block food going to nose)(connects to malleus to dampen sound)
Special visceral efferent from CNV (from trigemnial motor nucleus in pons), and this receives bilateral innervation from first order neurons in the somatomotor cortex.
Exits with CNVC.

Question 24

Tongue innervation

Answer 24

Motor by CNXII
GSA of anterior 2/3 by CNVC
GSA of posterior 1/3 by CNIX
SVA of posterior 1/3 by CNIX
SVA of anterior 2/3 by CNVII (chorda tympani)

Question 25

Which blood vessel often causes compression in trigmenial neuralgia

Answer 25

superior cerebellar artery

Question 26

pseudobulbar palsy

Answer 26

This is an UMN lesion that is bilateral, and affects both tracts. If it was a unilateral UMN lesion then no effect would be seen due to the bilateral motor innervation that CN normally have. Often due to demyelination. CNV motor lesions can be unilateral or bilateral - depends on cause

Question 27

Causes of locked in syndrome

Answer 27

Locked in syndrome is where all the voluntary muscles of the body are paralysed except th eye muscles. Causes include damage to nerve cells (osmotic demyelination syndrome (central pontine myelinolysis) due to rapid correction of hyponatraemia - but can also be seen with re-feeding during anorexia nervosa, dialysis treatment and burn vixtems)). Can also be seen in cases of alcoholism. Pathophysiology is due to rapid correction of tonicity which leads to water being driven out of cells, leading to dysfunction. Other causes (most common) is ischaemic pontine lesion, but can also be tumours or infection.

Question 28

Muscles of the second pharyngeal arch, and innervation (and other innervations - nervus intermedius)

Answer 28

facial expression (big branches are temporalis, zygomatic, buccinator, marginal mandibular and cervical), stapedius, stylohyoid, platysma and the posterior belly of digastric. CNVII. Also has secretomotor parasympathetic to glands (including submandibular, sublingual, lacrimal and minor mucusal in nasal/oral cavities) GSA is small, and is part of external ear and EAM. Special sensory is from ant 2/3 of tongue

Question 29

geniculate ganglion

Answer 29

Sensory ganglion for the facial nerve, located in the facial canal and receives motor, sensory and parasympathetic components of the facial nerve. It is lateral to the IAM

Question 30

Facial nerve nuclei

Answer 30

Facial nerve nuclei are in pons. Separate nuclei for motor, salivatory (parasympathetic), solitarius (taste) and trigemnial nuclei (sensation) (There is no separate sensory nucleus for CVII, and CNV sensory nucleus also receives sensory information coming from CNVII, IX and X as well as that from CNV)

Question 31

How is CNVII motor unusual?

Answer 31

Upper face has UMN bilateral innervation, lower face has unilateral contralateral UMN innervation. Therefore, a stroke on left side of brain could cause facial issues on right lower side, but be forehead sparing. A left sided LMN lesion would cause paralysis of the whole right side.

Question 32

subthalamic nucleus

Answer 32

part of indirect pathway. Inhibits thalamus, but in indirect pathway it is inhibited, and therefore thalamus is disinhibited.

Question 33

substantia nigra

Answer 33

(in midbrain at cerebral peduncles) - pars compacta lies medially and pars reticula lies laterally. Pars compacta has black, dopaminergic neurons and is densely packed.

Question 34

Lentiform nucleus, Striatum

Answer 34

``` Putamen and globus pallidus (lentiform), caudate nucleus and putamen (striatum ```

Question 35

Direct Pathway

Answer 35

``` Activation promotes movement -D1 receptors Cortex excited (glutamate) striatum. Striatum inhibits (GABA) GPi and SNr. These send inhib (GABA) to thalamus - but less so since they are inhibited. Excitatory thalamic (glut) signals go to cortex - > movement ```

Question 36

Indirect Pathway

Answer 36

D2 mediated, allows moveement. Cortex excited striatum (glut) sends GABA to GPe, which normrally inhibits subthalamic nucleus. Since disinhibited, sends glut to thalamus and promotes movement.

Question 37

Cerebellar blood supply

Answer 37

SCA does anterior lobe, deep cerebellar nuclei, superior peduncle AICA does middle cerebral peduncle (along with pontine arteries) and ventral posterior lobe pICA does inferior peduncle, deep nuclei, , inferior vermis, most of posterior lobe

Question 38

Deep nuclei of the cerebellum

Answer 38

4 pairs : Don't Eat Greasy Food dentate, emboliform, globose, and fastigial Emboliform and globose are interposed nuclei. Dentate is lateral hemisphere,, interposed are in paravermal region, and fastigial is in vermis.

Question 39

Premotor and supplementary motor cortex

Answer 39

Premotor cortex is anterior to the primary motor cortex. Supplementary motor cortex is lateral to this (on the side). PRe motor cortex is involved in coordinating movements that need visual guidance. The supplementary motor cortex is involved in planning movement (esp mentally picturing movements) and gets thalamic input

Question 40

athetosis definition, MND definition Supranuclear palsy definition

Answer 40

Athetosis is writing movements, seen in HD, Wilsons, cerebral palsy, strokes and jaundice. Often basal ganglia lesion. MND can be UMN/LMN or both. LArgely affects anterior horn of spinal cord Supranuclear palsy is associated with tau buildup, causing rapid motor decline. Causes PD symptoms, but often fall back than forward, posture is erect than stooped and patients are wide eyed. As disease progresses, voluntary eye movement is affected.

Question 41

Waters Xray

Answer 41

Allows view of all sinuses (Except ethmoid)

Question 42

MRI scans

Answer 42

No radiation but not suitable for those with metal implants. Also has issues with claustrophobia. Time consuming and expensive. Similar resolution to CT, but allows better resolution of similar structures compared to CT T1 weighted has water/fluid dark, fat is bright T2 weighted has fat dark, water is bright Since damaged tissue often has oedema, T2 can pick this up better T2 can also be converted to Fluid Attenuated Inversion Recovery (FLAIR) sequence - free water is now dark but oedematous tissue is bright. This is very sensitive for assessing demylinating diseases (MS). gadolinium often used as MRI contrast

Question 43

CT scan

Answer 43

``` Fat tissues (e.g. heavily myelinated) have a low density and therefore appear darker gray on CT scan. Fresh blood shows as white (high density). ```

Question 44

EEG and MEG

Answer 44

EEG:measures brain electrical activity. Can be used for epilepsy, coma, encephalopathies and depth of anaesthesia. Also used in clinical research. It is a mobile technique, and it allows millisecond range temporal resolution (not possible with CT/PET/MRI). MEG is similar but with magnetic brain waves are measured instead.

Question 45

Glossopharyngeal nerve

Answer 45

Passes through jugular foramen. Taste (post 1/3 of tongue) - > pseudounipolar neurons bring taste through jugular foramen and synapses in solitary nucleus GVA from carotid body, carotid sinus, parotid gland, pharynx -> pseudounipolar to solitary nucleus General sensation from middle ear, oropharynx (sensory limb of gag reflex), post 1/3 of tongue - > pseudounipolar through internal jugular formane to spinal trigeminal tract/nucleus. LMNs go from nucleus ambiguus - > skeletomuscle (stylopharyngeus) Parasympathetic supply: starts at inferior salivatory nucleus - > otic ganglion - > travels with CNVc to parotid gland Main points: gag reflex (sensory limb), parotid gland, post1/3 of tongue (taste + gen sensation), baroreceptors (control of mean arterial pressure).

Question 46

Vagus nerve

Answer 46

Has both sensory and motor functions, and passes through jugular foramen. Taste - > receptors from epiglottis/palate. Pseudounipolar neurons go through jugular foramen to synapse in solitary nucleus GVA sensation from viscera/medulla (pharynx, base of tongue, thoracic organs, oesophagus, intestine - > splenic flexure). Pseudounipolar tract through jugular foramen to solitary nucleus. General sensory neurons from external ear, larynx, laryngopharynx - > pseudounipolar. Synapses in spinal trigeminal tract/nucleus LMNs, cell bodies in nucleus ambiguus. Run through jugular foramen and go to instrinsic muscles of pharynx and larynx.gives motor limb of gag reflex. Parasympathetic supply: Pre ganglionic cell bodies in motor nucleus of the vagus - > passes through jugular foramen and travels to intramural ganglia - > supplies smooth muscle, glandular epithelium of gut/cardiac muscle. Main points: vagus is very vital - motor limb of gag reflex, main parasympathetic supply to thorax, foregut and midgut. GVAs from pharynx, thorax, foregut and midgut

Question 47

Accessory nerve

Answer 47

Cell bodies of LMNs come from rootlets formed from C1-C5, exit from spinal cord and join together as they ascend. They enter into the skull through the foramen magnum. Then exit almost immediately through jugular foramen. Supple trapezius (shrug shoulders, stabilises scapula during arm abduction) muscle and sternocleidomastoid muscle (neck turning, neck side flex). This spinal part is purely motor There is a cranial part of the accessory nerve, but this travels with the vagus and can be considered part of it - supplies muscles in pharynx and larynx. Main points: if damaged, can’t shrug shoulders, can’t turn head and can’t raise arm more than 90 degrees

Question 48

Hypoglossal nerve

Answer 48

Hypoglossal nerve comes from hypoglossal nucleus. It provides motor only function - supplies intrinsic tongue muscles, styloglossus, hypoglossus, genioglossus (extrinsic) (apart from palatoglossus?) Each side of the tongue has its own hypoglossal supply (right and left). Nerve goes through the hypoglossal canal (inferior to the jugular foramen). It runs inferior to the mandible to run underneath the tongue. Main point: Unilateral LMN lesion will result in tongue pointing to side of lesion due to unopposed action. Will also see ipsilateral muscle atrophy and fasciculations. Also see eating, speaking, swallowing problems.