Breakdown of the Nervous System
A. Central Nervous System (CNS)
1. Functions
A) Acts as command center
B) Interprets sensory information and dictates response based on past experience,
reflexes, and current body conditions
B. Peripheral Nervous System (PNS)
1. Functions
A) Conveys information to and from CNS
2. Components
A) Somatic sensory (afferent) neurons
1) Carry impulses from receptors in skin, skeletal muscle, and joints to the CNS
B) Visceral sensory neurons
1) Carry impulses from receptors within the visceral organs to the CNS
C) Somatic motor (efferent) neurons
1) Carry impulses from the CNS to skeletal muscles
D) Visceral motor neurons
1) Carry impulses from the CNS to smooth muscle, cardiac muscle, and glands
C. Divisions of PNS
1. Somatic NS
A) Consists of somatic sensory neurons and somatic motor neurons
B) Voluntary nervous system
2. Autonomic NS
A) Consists of visceral sensory neurons and visceral motor neurons
B) Involuntary nervous system
C) 2 branches
1) Sympathetic – fight-or-flight system
a) Stimulates most effectors
2) Parasympathetic – energy restoration/conservation system
a) Inhibits most effectors
The Central Nervous System
A. Structures of the CNS
1. Cerebrum
A) Divided into 2 hemispheres
1) Each consists of gyri (elevated areas), sulci (shallow depressions) and fissures
B) 5 lobes
1) Frontal, parietal, occipital, temporal, and insula
C) Important structures
1) Longitudinal fissure (right & left hemispheres)
2) Transverse fissure (cerebrum & cerebellum)
3) Central sulcus (frontal & parietal lobes)
a) Precentral gyrus (within frontal lobe)
b) Postcentral gyrus (within parietal lobe)
, 4) Parieto-occipital sulcus (parietal & occiptal lobes)
5) Lateral sulcus (temporal & frontal/parietal lobes)
D) Cerebral cortex – "conscious mind"
1) Composed of gray matter
2) Involved with memory, reasoning, intelligence, etc...
3) Contrilateral
4) Exhibits hemisphere dominance
a) Left hemisphere – most functions; 90% of population
b) Right hemisphere – artistic & musical qualities; left-handed
5) 3 main functional areas
a) Motor areas
i) Primary motor cortex
(a) Found in precentral gyrus
(b) Responsible for conscious movement of skeletal muscles
ii) Premotor cortex
(a) Lies anterior to primary motor cortex
(b) Responsible for learned motor skills that are repeated or patterned
(ex. typing)
iii) Broca’s area
(a) Lies anterior & inferior to premotor cortex
(b) Involved in speech production
(c) Only in one hemisphere (usually left)
iv) Frontal eye field
(a) Lies anterior to premotor cortex and superior to Broca’s area
(b) Responsible for voluntary eye movements
b) Sensory areas
i) Primary somatosensory cortex
(a) Lies in postcentral gyrus
(b) Allows for spatial discrimination
ii) Somatosensory association cortex
(a) Lies posterior to primary somatosensory cortex
(b) Integrates and analyzes somatic sensory inputs (i.e. pain, touch, temp,
etc.) to produce an understanding of what is being felt
iii) Visual area
(a) Located within occipital lobes
iv) Auditory area
(a) Found in temporal lobes
v) Olfactory area
(a) Found in temporal lobes in regions known as the uncus
vi) Gustatory area
(a) Found in parietal lobe
A. Central Nervous System (CNS)
1. Functions
A) Acts as command center
B) Interprets sensory information and dictates response based on past experience,
reflexes, and current body conditions
B. Peripheral Nervous System (PNS)
1. Functions
A) Conveys information to and from CNS
2. Components
A) Somatic sensory (afferent) neurons
1) Carry impulses from receptors in skin, skeletal muscle, and joints to the CNS
B) Visceral sensory neurons
1) Carry impulses from receptors within the visceral organs to the CNS
C) Somatic motor (efferent) neurons
1) Carry impulses from the CNS to skeletal muscles
D) Visceral motor neurons
1) Carry impulses from the CNS to smooth muscle, cardiac muscle, and glands
C. Divisions of PNS
1. Somatic NS
A) Consists of somatic sensory neurons and somatic motor neurons
B) Voluntary nervous system
2. Autonomic NS
A) Consists of visceral sensory neurons and visceral motor neurons
B) Involuntary nervous system
C) 2 branches
1) Sympathetic – fight-or-flight system
a) Stimulates most effectors
2) Parasympathetic – energy restoration/conservation system
a) Inhibits most effectors
The Central Nervous System
A. Structures of the CNS
1. Cerebrum
A) Divided into 2 hemispheres
1) Each consists of gyri (elevated areas), sulci (shallow depressions) and fissures
B) 5 lobes
1) Frontal, parietal, occipital, temporal, and insula
C) Important structures
1) Longitudinal fissure (right & left hemispheres)
2) Transverse fissure (cerebrum & cerebellum)
3) Central sulcus (frontal & parietal lobes)
a) Precentral gyrus (within frontal lobe)
b) Postcentral gyrus (within parietal lobe)
, 4) Parieto-occipital sulcus (parietal & occiptal lobes)
5) Lateral sulcus (temporal & frontal/parietal lobes)
D) Cerebral cortex – "conscious mind"
1) Composed of gray matter
2) Involved with memory, reasoning, intelligence, etc...
3) Contrilateral
4) Exhibits hemisphere dominance
a) Left hemisphere – most functions; 90% of population
b) Right hemisphere – artistic & musical qualities; left-handed
5) 3 main functional areas
a) Motor areas
i) Primary motor cortex
(a) Found in precentral gyrus
(b) Responsible for conscious movement of skeletal muscles
ii) Premotor cortex
(a) Lies anterior to primary motor cortex
(b) Responsible for learned motor skills that are repeated or patterned
(ex. typing)
iii) Broca’s area
(a) Lies anterior & inferior to premotor cortex
(b) Involved in speech production
(c) Only in one hemisphere (usually left)
iv) Frontal eye field
(a) Lies anterior to premotor cortex and superior to Broca’s area
(b) Responsible for voluntary eye movements
b) Sensory areas
i) Primary somatosensory cortex
(a) Lies in postcentral gyrus
(b) Allows for spatial discrimination
ii) Somatosensory association cortex
(a) Lies posterior to primary somatosensory cortex
(b) Integrates and analyzes somatic sensory inputs (i.e. pain, touch, temp,
etc.) to produce an understanding of what is being felt
iii) Visual area
(a) Located within occipital lobes
iv) Auditory area
(a) Found in temporal lobes
v) Olfactory area
(a) Found in temporal lobes in regions known as the uncus
vi) Gustatory area
(a) Found in parietal lobe
