Chapter 13 - Central Nervous System (CNS)

Primary brain vesicles

Prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain).

Secondary vesicles of the hindbrain

Metencephalon and myelencephalon.

Adult structures of the metencephalon

Pons and cerebellum.

Adult structure of the myelencephalon

Medulla oblongata.

Function of the pons

Relays information between brain regions and helps regulate breathing.

Function of the cerebellum

Coordinates movement, posture, and balance.

Function of the medulla oblongata

Controls vital autonomic functions like heart rate, blood pressure, and breathing.

Embryonic origin of the diencephalon

Prosencephalon (forebrain).

Three major structures of the diencephalon

Thalamus, hypothalamus, and epithalamus.

Main function of the thalamus

Acts as a sensory relay station.

Main function of the epithalamus

Includes the pineal gland and secretes melatonin.

Cranial nerves associated with the midbrain

CN III and CN IV.

Cranial nerves associated with the pons

CN V, VI, VII, and VIII.

Cranial nerves associated with the medulla

CN IX, X, XI, and XII.

Cranial nerves associated with the forebrain

CN I (olfactory) and CN II (optic).

Location of the hypothalamus

Inferior to the thalamus, forming the floor of the third ventricle.

Hypothalamus role in the ANS

Regulates involuntary activities like heart rate and digestion.

Hypothalamus role in body temperature

Regulates heat production and heat loss.

Hypothalamus role in food and water

Monitors and regulates hunger and thirst.

Hypothalamus role in sleep

Helps control circadian rhythms (sleep-wake cycles).

Hypothalamus role in endocrine system

Controls pituitary hormone secretion.

Hypothalamus role in memory

Mammillary bodies participate in memory processing.

Effect of damage to hypothalamic hunger centers

Abnormal appetite.

Composition of CNS gray matter

Neuron cell bodies, dendrites, and synapses.

Composition of CNS white matter

Primarily axons, many of which are myelinated.

Arrangement of gray matter in the brain

Outer cerebral cortex and deep nuclei.

Arrangement of gray matter in the spinal cord

Central and H-shaped.

Four major brain regions

Cerebrum, diencephalon, brainstem, and cerebellum.

Function of the frontal lobe

Voluntary movement, planning, decision-making, and personality.

Function of the parietal lobe

Touch, pressure, pain, temperature, and spatial awareness.

Function of the temporal lobe

Hearing, memory, and language comprehension.

Function of the occipital lobe

Vision.

Function of the insula

Taste, visceral sensation, and internal body awareness.

Sensory exception to thalamic relay

Olfaction (smell) reaches the cortex without a thalamic relay.

Definition of homunculus

A distorted body map on the cortex showing regional representation.

Location of motor homunculus

Precentral gyrus of the frontal lobe.

Location of sensory homunculus

Postcentral gyrus of the parietal lobe.

Symmetry of most homunculus pathways

Contralateral: left hemisphere controls the right side of the body.

Location of the primary visual cortex

Occipital lobe, along the calcarine sulcus.

Dorsal stream of visual processing

The "where/how" pathway toward the parietal lobe.

Ventral stream of visual processing

The "what" pathway toward the temporal lobe.

Primary cells forming the blood-brain barrier

Endothelial cells of CNS capillaries with tight junctions.

Gyrus vs. sulcus

Gyrus is a raised ridge; sulcus is a groove between gyri.

Fissure

A deep groove separating major brain regions.

Central sulcus

Separates the frontal and parietal lobes.

Lateral sulcus

Separates the temporal lobe from the frontal and parietal lobes.

Longitudinal fissure

Separates the left and right cerebral hemispheres.

Precentral gyrus

Primary motor cortex.

Postcentral gyrus

Primary somatosensory cortex.

Function of the Reticular Activating System

Maintains consciousness, alertness, and arousal.

Pyramids of the medulla

Contain descending motor tracts.

Pyramidal decussation

The site in the medulla where corticospinal fibers cross over.

Dorsal horn of spinal cord

Receives sensory input.

Ventral horn of spinal cord

Contains somatic motor neuron cell bodies.

Location of sensory neuron cell bodies in spinal cord

Dorsal root ganglia, outside the spinal cord.

Ascending vs. descending tracts

Ascending tracts carry sensory info up; descending carry motor commands down.

Cervical spinal cord injury effect

May cause tetraplegia (quadriplegia).

Thoracic or lumbar spinal cord injury effect

May cause paraplegia.

Paresthesia

Abnormal sensations such as tingling or pins and needles.

Anencephaly

Failure of much of the brain and skull to develop.

Spina bifida

Incomplete closure of structures around the spinal cord.