Nervous System Anatomy

Breakdown:

Central Nervous System (CNS)

• Brain• Spinal Cord

Peripheral Nervous System (PNS)

• Somatic Nervous System

• Autonomic Nervous System– Sympathetic N.S.–Parasympathetic

N.S.

Function of the CNS:

• Spinal Cord– Conducts sensory information to the brain– Conducts motor information to the brain• Skeletal Muscle• Cardiac Muscle• Smooth Muscle• Glands

– Minor reflex center

Functions of the CNS:• Brain– Receives sensory input from Spinal Cord and own

nerves (e.g. olfactory/optical nerves)– Process information– Generates and coordinates appropriate responses

Functions of the PNS:Somatic Nervous System–Regulate body

movement• Control of skeletal

muscle• Reception of

external stimuli (i.e. the senses!!)

Summary: RECEIVE and REACT to the WORLD around us!!!

Functions of the PNS:

Autonomic Nervous System• Innervates:

– Cardiac Muscle– Smooth Muscle– Glands

• Regulates hormone levels• Homeostasis!!

Functions of the PNS:

Sympathetic Nervous System

• Localized adjustments and reflex adjustments of cardiovascular system

• Whole system response: Fight or Flight

Parasympathetic Nervous System

• Returns body to normal after Sympathetic response

• Vagus Nerve – originates in Medulla Oblongata, can play a role in controlling inflammation

The Brain

Major Divisions

• The brain of all vertebrates develops from three swellings at the anterior end of the neural tube of the embryo. From front to back these develop into the:– Forebrain (Prosencephalon)

• Cerebral Hemispheres: Telencephalon and Diencephalon

– Midbrain (Mesencephalon)• Substantia nigra, Ventral tegmental area (VTA)

– Hindbrain (Rhombencephalon)• Medulla oblongata, Pons, Cerebellum

Structures of the Hindbrain

Medulla Oblongata

• Rhythmic stimulation of intercostals and diaphragm

• Regulate heartbeat• Regulate bloodflow

(diameter of arterioles)

Pons

• Relays information from eyes, ears, and touch receptors from cortex to cerebellum

Cerebellum

• Functions:– Coordination of voluntary

movement– Motor-learning– Balance– Reflex memory– Posture– Timing

• Contains as many neurons as rest of brain combined!

• Associated with Damage:– Loss of fine coordination– Tremor– Inability to walk– Dizziness (vertigo)– Slurred speech

Cerebellum

Midbrain

• Substantia Nigra:– Helps “smooth” out

body motions

• Ventral Tegmental Area (VTA):– One of the pleasure

centers of the brain (dopamine releasing neurons)

Brain Stem

• Midbrain• Pons• Medulla oblongata

Forebrain: Telencephalon

• Cerebrum–4 lobes• Frontal• Parietal • Occipital• Temporal

Frontal Lobe

• Higher cognitive functions– Attention– Conscious thought– Voluntary movement– Decision making– Language– Planning– Problem-solving– Many more!

• Associated with damage:– Paralysis– Loss of spontaneity – Mood changes– Inability to express

language– Atypical social skills and

personality traits

Parietal Lobe

• Perception/Integration of somatosensory information (e.g. touch, pressure, temperature, pain)

• Visuospatial processing• Spatial attention• Spatial mapping• Number representation

• Associated with Damage:– Inability to locate and

recognize objects, events, and parts of the body

– Difficulty in discriminating between sensory information

– Disorientation– Lack of coordination

Parietal Lobe

Occipital Lobe

• Vision! • Associated with Damage:– Hallucinations– Blindness– Inability to see color,

motion, or orientation– synesthesia

Occipital Lobe

Temporal Lobe

• Recognition• Perception (hearing,

vision, smell)• Understanding language• Learning and Memory

• Associated with Damage:– Difficulty understanding

speech, faces, objects– Inability to attend to

sensory input– Persistent talking– Long and short-term

memory loss– aggression

Temporal Lobe

Forebrain: Diencephalon

• Thalamus• Hypothalamus• Pituitary Gland

Hypothalamus

– Hunger– Thirst– Body temperature– Arousal– Parenting– Perspiration– Blood pressure– Beart rrate– Shivering– Pupil dilation– Circadian rhythms

• Aggression• Chronic stress• Hypothermia• Hypersomnia• Lethargy• Self-mutilitation• Weight gain/loss

Hypothalamus

Thalamus

• Relaying motor/sensory information

• Memory• Alertness• Consciousness• Contributes to

perception and cognition

• Associated with Damage:– Amnesia– Apathy– Coma– Dementia– Difficulty speaking– Loss of alertness and activitaion– Sleepiness– Impaired processing of sensory

information– Inattention– Impaired movements/posture– pain

Thalamus

Thalamus

Pituitary Gland

• Secretes hormones

• Referred to as the “master gland”

• Associated with Damage:– Loss of hormonal

regulation in many areas of the body

Pituitary Gland

Crossing Over

• “Impulses reaching the spinal cord from the left side of the body eventually pass over to tracts running up to the right side of the brain and vice versa. In some cases this crossing over occurs as soon as the impulses enter the cord. In other cases, it does not take place until the tracts enter the brain itself.”

• How is this possible???– Corpus Callosum!!

Corpus Callosum

• Connects right and left hemisphere and allows information to pass between them

• Associated cognitive disorders:– Coma or vegetative state– Schizophrenia– Psychotic episodes– Memory impairment– Split-brain syndrome

Corpus Callosum