Intro to CNS, neurotransmitters and BBB

Question 1

Describe the main features of the spinal cord.

Answer 1

• continuous with brain stem
• extends from foramen magnum to conus medullaris at L1-L2 in adults
• ends at cauda equina
• surrounded by dura mater + other meningeal layers
• cervical and lumbrosacral enlargements
• differing amounts of grey matter corresponds to axons innervating lower + upper limbs

Question 2

What are the 5 major embryological divisions of the brain?

Answer 2

Forebrain

• telencephalon (becomes cerebral hemispheres)
• diencephalon

Midbrain
- mesencephalon

Hindbrain

• metencephalon (becomes cerebellum + pons)
• myelencephalon (becomes medulla oblongata)

Question 3

Which regions make up the brain stem?

Answer 3

Midbrain and hindbrain

Question 4

What are the 3 functions of the brain stem?

Answer 4

1. Conduit for ascending and descending tracts for spinal cord, connecting them to higher centres
2. contains important reflex centres
3. contains important nuclei of CN III to XII

Question 5

What is found in the midbrain?

Answer 5

• nuclei for CN III and CN IV
• Edinger-Westphal nucleus responsible for pupillary diameter, accommodation of lens, convergence of eyes
• neurons that are responsible for control of reflex movements of eyes, head and neck in response to visual and auditory signals

Question 6

What is found in the pons?

Answer 6

Motor nucleus for CN V - muscles of mastication
Nucleus for CN VI - eye movement (lateral rectus muscle)
Sensory nucleus for CN V - face, scalp, mouth, nose
Nuclei for CN VIII - hearing + equilibrium
Nuclei involved in respiration

Question 7

What is found in the medulla oblongata?

Answer 7

Motor nuclei for CN XI - muscles of neck
Motor nuclei for CN XII - muscles of tongue
Nuclei involved in respiration via CN X, control of blood pressure (CNX + CN IV), HR and digestion (CN X)

Question 8

Where is the diencephalon found?

Answer 8

Either side of 3rd ventricle

Question 9

Which structures make up the diencephalon?

Answer 9

• Thalamus - largest - sensory switchboard
• Hypothalamus - controls homeostatic, autonomic and endocrine functions
• Epithalamus - pineal body (produces melatonin and maintain circadian rhythm) + Habenular nucleus (regulates CNS neurotransmitters such as dopamine + serotonin, role in behaviour of addiction and motivation)
• Subthalamus

Question 10

What is the cerebellum and responsible for?

Answer 10

• receives peripheral info regarding proprioception, muscle tone, position of head in space, visual and auditory info
• compares and integrates info with info from cortex
• modulates ongoing movement patterns
• coordinator and predictor of movement

Question 11

What are the lobes of the cerebrum?

Answer 11

Frontal, parietal, occipital, temporal

Question 12

What is the frontal lobe responsible for?

Answer 12

• Primary motor cortex housed in precentral gyrus
• Regulating voluntary motor behaviour but also initiating it
• Expressive motor aspects of language processed on lateral surface in Broca’s motor speech area

Question 13

What is the prefrontal area responsible for?

Answer 13

• Part of frontal lobe
• Not involved with movement
• Connections with parietal, temporal and occipital lobes via fasciculi - access to sensory processing and memory
• Monitors behaviours and controls higher processes
• Prefrontal association areas involved with emotion, motivation, personality, initiative, judgement, concentration, social inhibitions