LO1 + LO2

Question 1

Name parts of the CNS

Answer 1

2 major structures: brain + spinal cord.

• Brain plays most integral role in movements, awareness, cognition, speech, memory etc.
• Spinal cord lies cadually to the brain and is involved in some reflex movements.

Question 2

Explain the formation of the NS

Answer 2

• Ectoderm: will form all the packaging of the organism = sensory organs, hair, skin, nails, whole NS (CNS + PNS)
  Thickening of the ectoderm leads to the development of the neural plate
  A neural groove begins to develop at 20 days
  By 22 days the neural groove closes along the length of the embryo making the neural tube. This becomes the CNS. The closure begins in the center and ends are initially left open

Question 3

Name the stages in human development

Answer 3

Pre-embryonic stage (zygote)  
Embryonic stage (embryo)  
Fetal stage (fetus); from 8th week + until birth = 32 weeks to 42 weeks

Question 4

Name the layers of the embryo

Answer 4

ENDOderm
MESOderm
ECTOderm

Question 5

How do we get from a tube to the brain?

Answer 5

Following closure of the top end of the neural tube the major regions of the brain begin to develop (cerebral hemisphere, midbrain, hindbrain (pons and medulla, cerebellum), diencephalon.

Question 6

Why is learning about the NS important?

Answer 6

• NS development is an ongoing process
• Issues in development can lead to major diseases (genetic mutations etc)
• The NS is adaptable

Question 7

What is the ventricular system?

Answer 7

Th lumen of the original neural tube becomes a fluid filled system, of cavities (ventricles which follow convolutions that the brain made during development) lying in centre of CNS.

Question 8

Briefly discuss 2 development disorders that relate to timing and effect

Answer 8

1. Anencephaly: neural tube defect, failure to develop major CNS structures (cerebral hemispheres + cerebellum)
2. Spina Bifida: neural tube defect (spinal end) - varies: affects spinal cord + body vertebral canal

Question 9

Briefly discuss 2 developmental disorders that relate to genetics and the environment

Answer 9

1. Fetal alcohol spectrum disorder (enviro): damage to neuron maturation, migration + organisation. Damage to cerebellum, cerebral nuclei, corpus callosum, neural tube - learning and memory deficits, impulsivity, lack of inhibition, EXPRESSIVE + RECEPTIVE IMPAIRMENTS + MISARTICULATION
2. Down syndrome (genetic): abnormalities in chromo 21 =higher risk of health conditions, hypotonia, speech difficulties, intellectual disability

Question 10

Discuss neural classification

Answer 10

• Structural: grouped by number of processes

- Functional: according to direction in which impulses are transmitted (sensory - Afferent, motor = efferent).

Question 11

What is the diencephalon?

Answer 11

• Small part of the brain that is mostly by the cerebral hemispheres
• Can be found just ABOVE the brainstem
• Between the cerebral hemispheres
• Has the 3rd ventricle between the left and right sides
• It has the internal capsule lying superficial to it
• Divided into 4 parts: epithalamus, thalamus, sub thalamus, hypothalamus

Question 12

Discuss the thalamus

Answer 12

(largest dorsal nuclear mass)  
Relay center  
Largest part  
Shape of 2 small eggs stuck together  
Internal capsule at lateral aspect  
Connections to lobes/functional areas  
Motor part  
Sensory part

Question 13

Discuss the hypothalamus.

Answer 13

(ventral and rostral to thalamus)
Regulation of autonomic/endocrine functions
Pituitary gland

Question 14

Discuss the subthalamus

Answer 14

(immediately ventral to thalamus)

Related to movement of control/basal ganglia

Question 15

Discuss the epithalamus

Answer 15

(caudal to thalamus)

Circadian rhythm and sexual reproduction cycles

Question 16

Name the parts of the brainstem and discuss its main function

Answer 16

midbrain, pons, medulla oblongta

The stalk of the brain and connects the CNS to the spinal cord

Question 17

Extrapolate on the function of the brainstem

Answer 17

Relay center: areas of grey matter where neurons travelling from one destination to another SYNAPSE, receives/sorts/stores/sends info
Throughfare: areas of white matter where axons of nerve fibres pass through; passageway for ascending and descending tracts
Integration Centre: Special functions = pain, breathing, reticular formation

The brainstem centers regulate vomiting, coughing, breathing rate, heart rate
Pain modulation
TRACTS: travel vertically through brainstem and continue through without alteration, some begin

Question 18

Discuss features and function of the midbrain

Answer 18

• Uppermost part of brainstem between diencephalon and pons, joins 3+4 ventricle.
• Houses CN nuclei: CN III, IV (for eye movement)
• Houses special nuclei
• Substantia nigra (involved in movement control)
• Periaquaductal grey (for pain perception)
• Colliculi (involved in hearing & vision

Question 19

Discuss features and function of pons

Answer 19

sits between midbrain and medulla, has a 4th vent dorsally, passage for motor info from cerebral cortex into cerebellum, contains cranial nerve nuclei (CN V and CN VII)

Question 20

Discuss features and function of medulla oblongta

Answer 20

Lowest section of brainstem, contains many cranial nuclei important for speech and swallowing. Decussactio

Question 21

What are the effects of disorders to the brainstem?

Answer 21

• An isolated brainstem lesion may cause a mix of
ipsilateral and contralateral signs because:
• cranial nerves supply the ipsilateral face and neck;
• many vertical tracts decussate [X] in the brainstem to
supply the contralateral body.
• Lesions in the brainstem may also interfere with vital
functions and consciousness.
States of altered consciousness may occur with lesions to the brainstem

Question 22

What is the structure and function of the spinal cord?

Answer 22

• segments of the spinal cord exchange information with other spinal cord segments, peripheral nerves and the brain.
  Info conveyed by a motor tract to a motor neuron is only one of many influences on that motor neuron
• Continues from the brainstem
  Different regions (cervical. Thoracic, lumbar, sacral)
  Composed of white and grey matter

Question 23

Link spinal cord to spinal nerves

Answer 23

Dorsal root; contains sensory axons bringing info into spinal cord
Ventral root; contains motor axons taking info from the spinal cord to the body/limb segments
Internal structure of SC:
The gray matter is composed of cell bodies:
• Dorsal horn processes sensory information
• Lateral horn processes autonomic information
• Ventral horn processes motor information
White matter is composed of travelling axons