Nervous System Overview

Nervous System Function

• Detect change in internal and external environments 

• Plan and execute appropriate responses in muscles, organs, and glands

• Capacity for learning, memory, cognition, self-awareness, intellect and personality

Anatomical Planes and Directions

axis of the forebrain- rostral to caudal

axis of the brainstem- rostral (toward the cerebrum) to caudal (toward the cauda equina)

Anatomical Organization of NS

CNS- brain, SC, and cranial nerve 1 and 2

PNS- cranial nerves, spinal nerves, plexuses, peripheral nerves

Somatic NS

• Detecting changes in external environment

• Control of movement

  • without sensation, complex/coordinated/adapted movement is impossible (but reflexes and simple movement is possible)

Autonomic NS

• Detect changes and controls activity in viscera

• Sympathetic- fight or flight

• Parasympathetic - feed, breed, rest, digest

• pupil constriction/dilation, saliva, digestion, heart rate, bronchi constriction/dilation, sweat, genitalia/reproduction

Sensory System

somatosensation- proprioception, tactile

special senses- vision, vestibular, gustatory, olfactory, auditory

interoception- visceral

pain- tactile, visceral

Motor System

Motor output

• reflexes- long/short loop

• triggered responses- CPG/equilibrium responses

• volitional movement- cortically/subcortically driven

Motor learning

Motor control

Motor coordination

Limbic System

executive function, emotional regulation, motivation/behavior

• includes prefrontal cortex, amygdala, anterior cingulate cortex, hippocampus

Cerebral Hemisphere

• Left and right hemispheres divided by the longitudinal fissure

• Lateralization of function

  • Left: logic, analytical, language

  • Right: spatial, creative, visual comprehension

Frontal- planning, goal directed behavior, motor function, social behavior, cognition

Parietal- sensory, awareness, and processing

Temporal- declarative memory, auditory processing

Occipital- vision

Limbic System/Lobe- motivation, emotion, learning, memory

Surface Anatomy

Gyri- hills

• precentral gyrus (M1)

• postcentral gyrus (S1)

Sulci- vallies

• Longitudinal fissure- separates L and R hemisphere

• Central sulcus- separates frontal and parietal lobe

• Parietal-occipital sulcus- on the medial surface

• Lateral sulcus (sylvian fissure)- separates temporal and frontal lobes

surface of the cerebral cortex is mostly gray matter (cell bodies where info is processed)

deeper in the cerebral cortex is mostly cortical white matter (axons that transmit info)

Precentral and Postcentral Gyrus

gyrus right next to the central sulcus

Internal anatomy

corpus collosum- connects L and R hemisphere

corpus radiata- connects cortex to brain stem and thalamus

internal capsule- conduit of axons connecting cerebral cortex to other brain areas and spinal cord

Subcortical gray matter- Basal Ganglia

3 nuclei (caudate, putamen, globus pallidus), social and goal-oriented behavior, movement, emotions

• gray/light tan space between thalamus/hypothalamus and basal ganglia is the internal capsule

Subcortical gray matter- Amygdala

emotions and motivation

Subcortical gray matter- hippocampus

declarative memory

diencephalon

thalamus- collection of nuclei that relays info to the cortex; process emotions and some memory; sensory integration, regulate consciousness/arousal/attention

hypothalamus- inferior to thalamus; maintains homeostasis; regulates growth and reproductive organs

epithalamus (pineal gland)- postero-superior to thalamus; influences other endocrine glands (pituitary and adrenal)

subthalamus- inferolateral to thalamus; movement control; closely related to the basal ganglia

cerebellum

connects the brain stem to the cortex- motor coordination, postural control, and emotional/cognitive function

2 large cerebellar hemispheres

• vermis connects the 2 hemispheres

• 3 cerebellar peduncles (axon tracts) connect cerebellum to brainstem

Brainstem

midbrain- most superior; motor and sensory processing, oculomotor control, vision and auditory processing, arousal and consciousness, pain perception

pons- middle; motor coordination/control, facial movements and swallowing, sensory processing from face and head, auditory processing

medulla- inferior; sensory processing (body/face), motor output, vestibular function, taste, cardiovascular and respiratory control, vital reflexes (cough, sneeze, vomit, swallow)

longitudinal divisions:

• basilar (anterior)

• tegmentum (posterior)

• tectum (posterior to tegmentum in midbrain)

Pons

Medulla

Spinal Cord

contained within the vertebral column and runs from the foramen magnum to the 1st lumbar vertebra

• nerve fibers continue below L1—> cauda equina

• gray matter (interneurons, cell bodies) in the middle and white matter (axons and myelin) surrounding

• sends info between peripheral structures and the brain

31 Pairs of Spinal Nerves

dorsal nerve root- carries afferent fibers, cell bodies in dorsal root ganglia

ventral root- carries efferent fibers, cell bodies in spinal gray matter