Module 1: Structure And Development Of The Nervous System

Question 1

Dorsal-ventral

Answer 1

Back and belly

Question 2

Cranial-caudal

Answer 2

Head end and tail end

Question 3

Proximal-distal

Answer 3

Close to and far away.
Used to compare the position in structures that have a beginning and an end, eg. The elbow is distal to the shoulder.

Question 4

Anterior-posterior

Answer 4

Front end and back end.
In four legged animals this is the same as cranial-caudal. Same as ventral-dorsal in a biped.

Question 5

Rostral

Answer 5

Means nose or mouth end.
Used interchangeably with cranial and with anterior in quadrupeds.

Question 6

Medial-lateral

Answer 6

Towards the midline or away from it.

Question 7

Superior-inferior

Answer 7

Used to describe position in the vertical axis (closer to head/feet)

Question 8

Cephalic-caudal

Answer 8

Cephalic sometimes used in place of cranial.

Question 9

Sectional planes in the brain

Answer 9

Transverse plane- axial or horizontal
Sagittal plane- longitudinal
Frontal plane- coronal

Question 10

Nervous system
Motor or efferent

Answer 10

These are neurons that carry a signal towards a target tissue or organ to make something happen.
Eg. A motor neuron carries impulses from the spinal cord to skeletal muscle and signals the muscle to contract.

Question 11

Nervous system
Sensory or efferent

Answer 11

Sensory neurons detect change in the environment and carry signals about that change to the central nervous system.
Eg. Neurons in the auditory nerve carries signals generated by sound in the ear to the brain.

Question 12

Autonomic nervous system

Answer 12

• controls involuntary response to the environment
  -sympathetic (fight or flight) and parasympathetic (rest)

Question 13

Why do we have a nervous system

Answer 13

A nervous system allows us to respond to stimulus, process it and make a decision about movement. Response to the environment is what has made animals successful.

Question 14

Invertebrate brains

Answer 14

Eg. Arthropods.
Have a ventral nerve cord which extends along the belly compared to a dorsal cord in vertebrates.

Question 15

Brain divisions common in all vertebrates

Answer 15

Olfactory bulb, cerebral hemispheres, cerebellum, optic tectum, medulla oblongata.

Mammals: neocortex enables us to process complex info

Question 16

Which layer of cells will become the nervous system.
-mesoderm
-ectoderm
-endoderm

Answer 16

Ectoderm forms the nervous system and skin

Question 17

How does the nervous system form from the neural plate?

Answer 17

-the neural plate folds and fuses to form the neural tube.
-CNS develops from the walls of the tube, PNS derives from the neural crest.

Question 18

Where does the notochord derive from?

Answer 18

The mesoderm

Question 19

What happens if the anterior/rostral pore in the neural tube doesn’t close?

Answer 19

The brain wont develop (anencephaly) this condition is incompatible with life.

Question 20

What happens if the posterior end of the neural tube doesn’t close?

Answer 20

Spina bifida, can end up with a gap in the vertebral column and a portion of the spinal cord poking out.
Likely to be paralysed.

Question 21

What does folic acid do for neural tube defects?

Answer 21

Reduces by 90% when supplemented in early pregnancy.

Question 22

How do drugs for Eg. Antiepulepilepsy/ bipolar increase risk of spinal bifida?

Answer 22

Interfere with folate metabolism.

Question 23

Developmental differentiation

Answer 23

3 swellings at the rostral end of the neural tube become the primary vesicles (brain)
Forming the forebrain, midbrain and hindbrain.

Question 24

In the neural tube what are the 3 rostral end swellings called?

Answer 24

-prosencephalon (forebrain)
-mesencephalon (midbrain)
-rhombencephalon (hindbrain)

Question 25

The prosencephalon develops into…..

Answer 25

• The telencephalon which becomes the cerebrum.
• The diencephalon which becomes the thalamus, hypothalamus and epithalamus.
• The eye cup

Question 26

The mesencephalon develops into the……

Answer 26

• Mesencephalon continues to develop into midbrain

Question 27

The rhombencephalon develops into…….

Answer 27

• Metencephalon which becomes the pons and the cerebellum.
• Myelencephalon which becomes the medulla oblongata.

Question 28

When can we see the beginning of structures that are recognisable in the adult brain?

Answer 28

5 weeks

Question 29

The brain is hollow and filled with with cerebrospinal fluid.
- Yes
- No

Answer 29

Yes

Question 30

How many ventricles do we have in our brain and how are they connected?

Answer 30

We have 4 brain ventricles: 2 lateral, 3rd ventricle, 4th ventricle.

Connected by canals:
- Interventricular foramen.
- Cerebral aqueduct.
- Central canal (extends down into the spinal cord)

Question 31

The spinal cord is hollow and filled with fluid.
- Yes
- No

Answer 31

Yes, the spinal cord as well as the brain is hollow and filled with fluid.

Question 32

The spinal cord…

Answer 32

• Protected by spinal column, surrounded by meninges and cerebrospinal fluid CSF
• Primary channel for messages from skin, joints and muscles to brain and from brain to PNS
• Dorsal roots of the spinal cord contain sensory, afferent neurons.
• Ventral roots contain motor, efferent neurons.

Question 33

In the brain what are the gray and white matter?

Answer 33

Grey matter= neuron cell bodies

White matter= myelinated axons

Question 34

The brainstem contain:

Answer 34

• the midbrain
• the hindbrain (pons, medulla, cerebellum)

Question 35

The brainstem is…

Answer 35

The oldest part of the brain, the decision matrix, controls vital functions.

Question 36

Where are the pons and medulla located in the brain, and the function of each?

Answer 36

Both located in the base of the brain.

Pons: swells out from ventral surface of brain stem, important relay between cortex and cerebellum.

Medulla: important in control of blood pressure and respiration.

Question 37

Damage to the brain stem

Answer 37

• hydrocephalus or haemorrhage (build up of fluid)
• pushes brain down as the skull is not elastic
• Severe cases can lead to coning, damage to the medulla causes respiratory arrest.
• Coning is where the brain stem is pushed down the opening at the bottom of the brain.

Question 38

Diencephalon and mesencephalon

Answer 38

Midbrain: linkage between components of the motor systems.

Diencephalon: thalamus (relay and gating roles) in sleep, conscious movement and hypothalamus (homeostasis and reproduction)

Question 39

The cerebellum

Answer 39

Old part of the brain.

Movement control centre.

Extensive connections to cerebrum and spinal cord.

Disease include ataxias - aberrant movement coordination.

Question 40

The cerebral cortex

Answer 40

Clear divisions between two halves along sagittal fissure.
Size related to cognitive ability.
Controls:
- voluntary actions
- cognition
- perception/ awareness

Question 41

The neocortex is…

Answer 41

Unique to mammals and is a more complex 6 layer structure of the cortex.

Question 42

Cortical folding

Answer 42

The cortex is folded as the number of cortical neurons represent processing power on the thin layer at the surface.
But the skull is a confined structure so folding occurs.

The tops of the folds are called gyrus.

The bottoms of the folds are called sulcus.

Question 43

The cortical lobes of the cerebral cortex.

Answer 43

Cortical lobes clockwise from the front (rostral):
- frontal
- parietal
- occipital
- temporal

Question 44

Decussation

Answer 44

Means to be crossed.

Mammalian nervous systems contralateral motor and sensory pathways.

The motor pathways from the cortex to the spinal cord and the sensory pathways from the spinal cord to the cortex decussate at the medulla level.