Anatomy · Short notes

Nervous System Anatomy: Short Notes & Cheat Sheet

Divisions of the nervous system, brain regions and their functions, meninges and CSF, the spinal cord, cranial nerves, neurons and glia.

Attempt Nervous System Anatomy MCQs

Short notes

Read these before you attempt the topic's MCQs.

Brain regions and what they do

Link each region to one headline function first; details can come later.

Organisation

The central nervous system is the brain and spinal cord. The peripheral nervous system is 12 pairs of cranial nerves and 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal).
Neurons have dendrites, a cell body and an axon. Myelin is made by Schwann cells in the PNS and oligodendrocytes in the CNS; nodes of Ranvier allow saltatory conduction.
Glial cells: astrocytes (support, blood–brain barrier), microglia (immune defence), ependymal cells (line ventricles, help make CSF).

The brain

Frontal lobe: movement, planning, personality, and Broca's area (speech production, usually left).
Parietal lobe: body sensation. Temporal lobe: hearing, memory and Wernicke's area (understanding speech). Occipital lobe: vision.
Cerebellum: coordination and balance. Brainstem (midbrain, pons, medulla): cranial nerve nuclei and vital centres for breathing and circulation.
Thalamus relays sensory information. Hypothalamus controls temperature, hunger, thirst and the pituitary.
Basal ganglia control movement (the substantia nigra degenerates in Parkinson's disease). The limbic system (hippocampus, amygdala) handles memory and emotion.

Meninges, CSF and spinal cord

Meninges from outside in: dura mater, arachnoid mater, pia mater. CSF flows in the subarachnoid space.
CSF is made by the choroid plexus (about 500 mL a day; about 150 mL present at any time) and absorbed by arachnoid granulations.
In adults the spinal cord ends at about L1–L2, so lumbar puncture is done at L3–L4 or L4–L5, below the cord.
The largest cranial nerve is the trigeminal (V); the longest and most widely distributed is the vagus (X).

Cheat sheet

High-yield facts in one place. Cover the right-hand column and test yourself.

Cranial nerves

Nerve	Main function
I Olfactory	Smell
II Optic	Vision
III Oculomotor	Most eye movements, pupil constriction
IV Trochlear	Superior oblique muscle
V Trigeminal	Face sensation, chewing
VI Abducens	Lateral rectus
VII Facial	Facial expression, taste (front 2/3)
VIII Vestibulocochlear	Hearing and balance
IX Glossopharyngeal	Taste (back 1/3), swallowing
X Vagus	Parasympathetic to thorax and abdomen
XI Accessory	Sternocleidomastoid, trapezius
XII Hypoglossal	Tongue movement

Brain region → function

Region	Function
Broca's area	Speech production
Wernicke's area	Speech comprehension
Cerebellum	Coordination, balance
Medulla	Breathing and cardiovascular centres
Hypothalamus	Temperature, hunger, pituitary control
Hippocampus	Memory formation

Memory aids

Some Say Marry Money But My Brother Says Big Brains Matter More: Cranial nerves I–XII are Sensory, Motor or Both, in order.
DAP from outside in: Dura, Arachnoid, Pia mater.

Exam traps

Lumbar puncture is done below L2 because the adult spinal cord ends at about L1–L2.
There are 31 pairs of spinal nerves but 33 vertebrae.
Myelin in the CNS comes from oligodendrocytes, not Schwann cells.
Broca's area produces speech; Wernicke's area understands it.

Revised? Now test yourself.

Attempt the Nervous System Anatomy MCQs while the notes are fresh. Anything you get wrong is saved to your incorrect list for the next revision round.