CHAPTER 4

ANATOMY OF THE NERVOUS SYSTEM

A. The vertebrate nervous system is comprised of the central nervous system and the peripheral nervous system.

B. Central nervous system (CNS): brain and spinal cord

C. Peripheral nervous system (PNS):

1. Somatic nervous system: nerves that convey messages from the sense organs to CNS and from CNS to the muscles and glands.

2. Autonomic nervous system: neurons that control the heart, the intestines,

and other organs. Consists of parasympathetic and sympathetic

D. Some Terminology

1. Anatomical Terms Referring to Direction

Dorsal: towards the back

Ventral: towards the stomach

Anterior: toward the front end

Posterior: toward the rear end

Superior: above another part

Inferior: below another part

Lateral: toward the side, away from the midline

Medial: toward the midline, away from the side

Proximal: toward the point of origin or attachment

Distal: away from point of origin or attachment

Ipsilateral: on same side of the body

Contralateral: on opposite side of the body

Coronal plane: plane that shows the brain structures as seen from the front Sagittal plane: plane that shows the brain structures as seen from the side Horizontal plane: plane that show brain structures as seen from above

2. Terms Referring to Parts of the Nervous System

Lamina: row or layer of cell bodies separated from other cell bodies by a layer

of axons and dendrites

Column: set of cells perpendicular to the surface of the cortex, with similar

properties

Tract: a set of axons with the CNS, also know as a projection.

Nerve: a set of axons in the periphery, either from the CNS to a muscle or gland or

from a sensory organ to the CNS

Ganglion: a cluster of neuron cell bodies, usually outside the CNS

Gyrus (pl. gyri): protuberance on surface of the brain

Sulcus: (pl. sulci): fold or groove that separates one gyrus from another Fissure: a long deep sulcus

1. Bell-Magendie law: Dorsal roots enter the spinal cord carrying information from sensory organs (e.g., skin); ventral roots exit the spinal cord carrying motor information to muscles and glands.

2. Dorsal root ganglia: clusters of sensory neuron cell bodies located outside the spinal cord.

3. The gray matter lies in the center of the spinal cord, packed with cell bodies and dendrites.

4. The white matter lies in the periphery of the spinal cord, comprised mainly of myelinated axons.

F. The Autonomic Nervous System (ANS)

1. Sympathetic nervous system: "Fight or Flight" system (prepares body for action by increasing heart rate, blood pressure, etc.). The ganglia near the spinal cord. Short preganglionic fibers/ Long postganglionic.

2. Parasympathetic nervous system: Relaxation system (parasympathetic activities are generally opposite of sympathetic activities). Aka craniosacral system. Ganglia are not close to the spinal cord.

Long preganglionic fibers/ Short postganglionic.

3. Parasympathetic postganglionic fibers release ACh, most sympathetic

postganglionic fibers release norepinephrine, although a few sympathetic

postganglionic fibers use acetylcholine.

G. Hindbrain: Posterior brain: medulla, pons, cerebellum.

1. Medulla (medulla oblongata): Controls breathing, heart rate, vomiting, coughing, and other vital reflexes through cranial nerves

2. Pons ("bridge"): Axons in the pons cross from one side of the brain to the other at the pons

(Reticular Formation and Raphe System in both the pons and medulla; involved in arousal, attention)

3.Cerebellum: Organizes sensory information which guides movement

H. Midbrain: Middle of the brain

1. Tectum (Latin for "roof"): superior colliculus and inferior

colliculus; both are involved in pathways for sensory information

2. Tegmentum (Latin for "covering") includes III and IV cranial nerve nuclei, part of the reticular formation, and many important pathways.

3. Substantia Nigra: Midbrain structure that contains dopamine neurons which

degenerate in Parkinson's Disease.

I. Forebrain: Cerebral cortex and several subcortical areas:

1. Limbic System: Comprised of the olfactory bulb, hypothalamus, hippocampus, amygdala, and cingulate gyms. The limbic system is involved in our motivational and emotional behaviors.

2. Thalamus: The thalamus and the hypothalamus together form the diencephalon. The thalamus provides the main source of information to the cerebral cortex. Most sensory information is first processed in the thalamus before going to the cerebral cortex. The one exception is olfactory information.

3. Hypothalamus: Sends messages to the pituitary gland altering its release of hormone. Important for motivated behavior (i.e, eating, drinking, etc.).

4. Pituitary Gland: Endocrine (hormone-producing) gland

5. Basal Ganglia: caudate, putamen, and the globus pallidus. Deterioration prominent in Parkinson's and Huntington's disease.

7. Hippocampus: between thalamus and cerebral cortex. Important for new memory storage.

8. Fornix: A major axon tract;links hippocampus with hypothalamus and

J. Ventricles: Four fluid-filled cavities within the brain.

2 lateral ventricles, one third and one forth ventricle.

Central Canal: Fluid-filled channel in center of spinal cord.

Cerebrospinal fluid (CSF): clear fluid in ventricles and central canal. Formed by choroid plexus

K. Meninges: Membranes surrounding brain and spinal cord. CSF flows through the spaces between the brain and the meninges.

A. Two hemispheres connected by Corpus callosum and anterior commissure:

B. 6 distinct laminae

C. Arranged in columns

D. 4 lobes (named after skull bones)

E. Occipital Lobe: Posterior. Primary Visual Cortex (Striate cortex)

F. Parietal Lobe: Between occipital lobe and central sulcus. Contains postcentral Gyrus or Primary Somatosensory Cortex

G. Temporal Lobe: Near the temples; auditory cortex; emotional and motivated behaviors. Left: comprehension of spoken language.

1. Kluver-Bucy syndrome: temporal lobe damage: failure to show normal fear or anxiety.

H. Frontal Lobe: anterior of central sulcus. primary motor cortex (Precentral Gyrus) and prefrontal cortex.

1. Prefrontal Cortex: most anterior portion of frontal lobe. Receives information from all of our senses. Damage leads to deficits in Delayed-Response Task

Prefrontal lobotomy: Disconnecting the prefrontal cortex from the rest of the brain to control psychological disorders.

I. The Binding Problem: How does sensory information combine in brain to produce a unified perception of an object?

Hypotheses: