Special topics final

What are the two major divisions of the nervous system?

Central nervous system (brain & spinal cord) and peripheral nervous system (cranial & spinal nerves).

What is resting membrane potential?

The electrical charge of a neuron at rest (–70 mV), maintained by the sodium-potassium pump.

What happens at the excitation threshold during an action potential?

A large sudden depolarization occurs when threshold is reached.

What occurs after depolarization in an action potential?

Repolarization followed by a brief hyperpolarization.

What is the refractory period?

A period after an action potential when no new depolarization can occur.

What does the central sulcus separate?

The frontal and parietal lobes; motor cortex from somatosensory cortex.

What does the lateral (Sylvian) sulcus separate?

The temporal lobe from the frontal and parietal lobes.

What does the parieto-occipital sulcus separate?

The parietal lobe from the occipital lobe.

Where is the primary motor cortex located?

Precentral gyrus of the frontal lobe.

Where is the primary somatosensory cortex located?

Postcentral gyrus of the parietal lobe.

Functions of the frontal lobe

Motor control, executive functions, speech production (Broca’s), personality, eye movements.

Functions of the parietal lobe

Somatosensory processing, spatial awareness, body schema, reading and writing processing.

Functions of the temporal lobe

Hearing, language comprehension (Wernicke’s), memory, emotion, object recognition.

Functions of the occipital lobe

Primary and higher-order visual processing.

Function of the insular cortex

Articulatory control.

Deep brain structures

Cerebrum, limbic system, thalamus, basal ganglia, brainstem.

Components of the basal ganglia

Caudate nucleus, putamen, globus pallidus, substantia nigra, subthalamic nucleus.

Functions of the cerebellum

Posture, learning new motor acts, coordinating articulation.

Meninges in order (outer to inner)

Dura mater → arachnoid mater → pia mater.

Major blood supplies of the brain

Internal carotid and vertebral arteries → ACA, MCA, PCA.

Purpose of the Circle of Willis

Provides collateral blood flow to the brain.

Pathway from retina to primary visual cortex

Optic nerve → optic chiasm → optic tract → LGN → optic radiations → V1.

How is visual field represented?

Left visual field → right hemisphere; right visual field → left hemisphere.

Major parts of the ear

Outer: pinna, canal. Middle: ossicles. Inner: cochlea, vestibular organs.

Ascending auditory pathway

Cochlea → CN VIII → cochlear nucleus → superior olivary complex → lateral lemniscus → inferior colliculus → MGB → auditory cortex.

What is an upper motor neuron?

Neuron from motor cortex to spinal cord.

What is a lower motor neuron?

Neuron from anterior horn to muscle.

Pyramidal system

Voluntary movement (corticospinal & corticobulbar tracts).

Extrapyramidal system

Posture, tone, coordination involving basal ganglia and cerebellum.

How many cranial nerves are there?

12 pairs.

Origin of CN I & II

Olfactory I: telencephalon; Optic II: diencephalon.

Origin of CN III & IV

Oculomotor III and Trochlear IV: midbrain.

Origin of CN V, VI, VII

Trigeminal V, Abducens VI, Facial VII: pons.

Origin of CN VIII, IX, X, XII

Vestibulocochlear VIII, Glossopharyngeal IX, Vagus X, Hypoglossal XII: medulla.

Where does CN XI originate?

Spinal cord (spinal accessory nerve).