Neuroscience Anat (CNS Organisation)

Question 1

Somato-sensory = sensory from ____ (conscious/subconscious)

Somato-motor = motor innervation for ____ muscles (voluntary/involuntary)

Viscero-sensory = sensory from ____ (conscious/subconscious)

Viscero-motor (ANS) = motor innervation for ____ muscles (voluntary/involuntary)

Answer 1

Somato-sensory = sensory from SKIN/JOINTS (conscious)

Somato-motor = motor innervation for SKELETAL muscles (voluntary)

Viscero-sensory = sensory from ORGANS (subconscious) except visceral pain is conscious

Viscero-motor (ANS) = motor innervation for SMOOTH muscles AND GLANDS (involuntary)

Question 2

In brain parenchyma, white matter inside/outside, grey matter inside/outside

State the contents of white and grey matter in brain

Answer 2

In brain parenchyma, white matter inside, grey matter outside

WHITE MATTER:
- myelinated axons

GREY MATTER:
- cerebral cortex
- thalamus
- basal ganglia

Question 3

State the definition of nuclei and ganglion

Answer 3

nuclei = aggregation of neuronal cell bodies in CNS

ganglion = aggregation of neuronal cell bodies in PNS

Question 4

State the total number of pairs of spinal nerves.

State the number of spinal nerves for each type of vertebrae.

Answer 4

total of 31 pairs

cervical - 8
thoracic - 12
lumbar - 5
saccral - 5
coccygeal - 1

Question 5

State the number of cranial nerves.

Name each cranial nerve

Answer 5

12 pairs of cranial nerves
CN I - olfactory N
CN II - optic N
CN III - oculomotor N
CN IV - trochlear N
CN V - trigeminal N
CN VI - abducens N
CN VII - facial N
CN VIII - vestibulocochlear N
CN IX - glossopharyngeal N
CN X - vagus N
CN XI - spinal accessory N
CN XII - hypoglossal N

Question 6

State the function of nerve cells/neurons

State the flow of neuronal information through nerve.

Answer 6

FUNCTIONS:
1. ability to initiate and conduct electrical impulses
2. ability to secrete and transmit neurotransmitters or modulators

FLOW OF INFORMATION:
dendrites –> cell body –> axons –> synapse

Question 7

State the 2 forms of adaptations the nerve cells/neurons can undergo

Answer 7

1. increased number of mitochondria - supply more energy to facilitate efficient communication
2. increased number of dendrites - facilitate rapid communication due to increased surface area contact with other neurons to receive electrical impulses

Question 8

How do neurons transmit neuronal information so quickly

Answer 8

Signal jumps from node of ranvier to the next across the myelin sheaths (increasing speed of conduction)

Question 9

Recap the 3 types of neuroglial cells in CNS, state the 2 types of glial cells in PNS

Answer 9

NEUROGLIAL CELLS (CNS)
1. ASTROCYTES - control BBB
2. OLIGODENDROCYTES - myelinate CNS axons
3. MICROGLIA - phagocytic function

GLIAL CELLS (PNS)
1. SATELLITE CELLS - support and protect neurons
2. SCHWANN CELLS - myelinates PNS axons

Question 10

State the 2 types of neurons commonly found. State the type of conduction that occurs in each neuron.

Answer 10

1. MYELINATED NEURON
   - saltatory conduction
   - activation in the nodes of Ranvier (faster conduction)
2. NON-MYELINATED NEURON
   - continuous conduction
   - activation along entire length of axon (slower conduction)

activation occurs through voltage-gated sodium channels

Question 11

State the vertebral level where the spinal cord ends.

Name the extension at that level.

State the common presentation of any pathologies related.

Answer 11

Spinal cord ends at cona medullaris (L1-L2) level.

Cauda equina extends from cona medullaris.

Relevant pathology = cauda equina syndrome
- Cauda equina is PNS –> downgoing plantars + absent reflexes
- Lower back pain
- Leg pain
- Paralysis of muscles in thigh and legs
- Incontinence

Question 12

State the relevant horns involved in
1. somato-sensory
2. viscero-sensory
3. somato-motor
4. viscero-motor (ANS)

Answer 12

(1) SOMATO-SENSORY AND (2) VISCERO-SENSORY = dorsal horn via DRG

(3) somato-motor = ventral horn directly to skeletal muscles
(4) viscero-motor = lateral horn to synapse onto autonomic ganglia –> post-synaptic neuron brings information to smooth muscles and glands

Question 13

Dermatomes are the ____ of ____ innervation on the ____ for one particular ____.

Myotome is the ____ that one particular ____ supplies.

Answer 13

Dermatomes are the AREAS of SENSORY innervation on the SKIN for one particular SPINAL ROOT/SPINAL NERVE.

Myotome is the MUSCLES (MOTOR INNERVATION) that one particular SPINAL ROOT/SPINAL NERVE supplies.

Question 14

State the steps involved in the reflex arc.

Answer 14

1. receptors respond to stimulus
2. afferent sensory neuron carries impulses to the CNS
3. integration of information in CNS (monosynaptic / polysynaptic)
4. efferent motor neuron carries impulses to effector

Question 15

Name the cranial nerves that have parasympathetic (ANS) function.

Answer 15

3,7,9,10

CN III - oculomotor N –> IOM (ciliary muscles and sphincter pupillae)
CN VII - facial N –> glands of face except parotid gland (lacrimal, submandibular, sublingual)
CN IX - glossopharyngeal N –> parotid gland
CN X - vagus N –> to distant organs

Question 16

State the pathways affected by anterior cord syndrome. State the common causes of this syndrome.

State the resultant impact of the syndrome.

Answer 16

AFFECTED PATHWAYS
1. spinothalamic tract

COMMON CAUSES
1. anterior spinal artery occlusion –> spinal infarct

RESULT:
1. loss of pain pathways
2. loss of temperature

Question 17

State the pathways affected by posterior cord syndrome. State the common causes of this syndrome.

State the resultant impact of the syndrome.

Answer 17

AFFECTED PATHWAYS:
1. dorsal column medial lemniscus

COMMON CAUSES:
1. b12 deficiency
2. syphillis - tabes dorsalis

RESULT:
1. loss of proprioception
2. loss of vibrations

Question 18

State the common causes of
1. anterior cord syndrome
2. posterior cord syndrome
3. entire cord syndrome

Answer 18

1. anterior cord syndrome - anterior spinal artery occlusion leading to spinal infarct
2. posterior cord syndrome - b12 deficiency, syphillis (tabes dorsalis)
3. entire cord - transverse myelitis

Question 19

State the function of each ascending (somato-sensory) pathway

Answer 19

(1) SPINOTHALAMIC
- crude touch and pressure
- pain and temperature

(2) DORSAL COLUMN MEDIAL LEMNISCUS
- fine touch
- vibrations
- pressure
- conscious proprioception

(3) SPINOCEREBELLAR
- unconscious proprioception

Question 20

State the function of each descending (somato-motor) pathway

Answer 20

(1) CORTICOSPINAL (PYRAMIDAL) TRACT
- voluntary, discrete and skilled movements

(2) EXTRAPYRAMIDAL SYSTEM (POSTURAL PATHWAYS)
- muscle tone
- posture and movement

Question 21

State the common presentations of UMN and LMN lesions.

Answer 21

UMN LESION
- hyperreflexia (brisk reflexes)
- hypertonia
- spasticitiy
- rigid paralysis
- babinski’s sign
- upgoing plantars

LMN LESION
- hyporeflexia / areflexia (absent reflexes)
- hypotonia
- flaccid paralysis
- muscular atrophy
- fasciculations

Question 22

State the 2 spinal (visceral-motor) pathways

Answer 22

1. sympathetic - thoracolumbar outflow
2. parasympathetic - craniosacral outflow

Question 23

Recap the 4 cranial nerves that have parasympathetic supply. State the post-synaptic ganglion for each cranial nerve.

Answer 23

CN III (oculomotor N) - ciliary G -> IOM (sphincter pupillae, ciliary body)

CN VII (facial N) - pterygopalatine G + submandibular G -> glands of face (lacrimal, submandibular, sublingual)

CN IX (glossopharyngeal N) - otic G - parotid gland

CN X (vagus N) -> distal organs of the body

Question 24

State the structures that make up the limbic system.

State the functions it supports.

Answer 24

STRUCTURES:
- hippocampus
- amygdala
- anteiror thalamic nuclei
- limbic cortex (cingulate gyrus)

FUNCTIONS
- emotion
- behaviour
- long term memory
- olfaction