Anatomy Nervous System 2

Myelinated nerves

Each nerve fiber in PNS is covered by cytoplasmic sheath (neurolemma/sheath of Schwann)

Nodes of Ranvier: interruptions of the sheath in PNS nerve

• Node allows action potential to travel faster

Endoneurium (sheath type)

nerve fiber

Perineurium (sheath type)

bundle of nerves

Epineurium (sheath type)

whole nerve

Ganglia

composed of sensory and autonomic neuron cell bodies

Spinal nerve formation?

dorsal & ventral rootlets that come from spinal cord and unite to form spinal nerve

• dorsal root: has sensory/afferent neuron cell bodies

• ventral root: efferent neuron cell body (motor impulses)

Gray matter

cell bodies and unmyelinated interneurons

white matter

tracts of efferent and afferent axons

Central sulcus

divides frontal lobe from parietal lobe

precentral gyrus

has cell bodies for all motor neurons that send impulses out

postcentral gyrus

neurons that receive sensory input

Association fibers

connect gytus to gyrus and lobe to lobe within the cerebral cortex

commissural fibers

connect homologous areas of the 2 cerebral hemispheres

cerebral cortex

complex cognitive functions

• memory storage and recall

• comprehension and execution of language

• musical and math skills

Lateralization

motor and sensory functions in the cortex represent OPPOSITE sides of the body *

ex: sensations on right side of body is processed in left postcentral gyrus

• higher functions (analytical thinking, language, artistic abilities, etc.) tend to be located in one hemisphere more than the other

• typically left hemisphere is dominant hemisphere for language

somatoropic organization

along pre and post central gyri, you can find the neuron control organized down the line. postcentral side is sensory and precentral side is motor

brainstem

transmit sensory impulses to cerebral cortex and motor impulses for voluntary movements originating in the cerebral cortex

• damage to brainstem results in sensory and/or motor dysfunction + cranial nerve functional deficits

reflexes

involuntary response when there is sensory (afferent neuron) input elicits a (efferent neuron) motor output