PNS Chapter 7

Nerve

is a bundle of neuron fibers found outside the CNS

Endoneurium

each fiber is surrounded by a delicate connective tissue sheath

Perineurium

groups of fibers are bound by a coarser connective tissue wrapping

fascicles

form fiber bundles

Epineurium

all fascicles are bound together by a tough fibrous sheath to form a cordlike nerve

Mixed nerves

Nerves carrying both sensory and motor fibers all spinal nerves are _______.

sensory/ afferent nerves

nerves that carry impulses toward the CNS only

Motor / efferent nerves

nerves that carry only motor fibers

Cranial nerves

primarily serve the head and neck 12 pairs

Dorsal rami

spinal nerve serve the skin and muscles of the posterior trunk

ventral rami

of spinal nerve T1 -T12 form intercostal nerves which supply the muscles in between the ribs and the skin and muscles of the anterior and lateral trunk

plexuses

the ventral rami of all other spinal nerves form complex networks of nerves

Autonomic nervous system

the motor subdivision of the PNS that controls body activities automatically

Involuntary nervous system

the motor subdivision of the PNS that controls body activities with conscious control

Preganglionic axon

the first motor neuron of each pair is in the brain or spinal cord. ITs axon, the ______________ leaves the CNS to synapse with the second motor neuron in a ganglion outside the CNS

Postganglionic axon

the axon of this neuron the _____________ then extends to the organ it serves

Sympathetic division

mobilizes the body during extreme situations

parasympathetic division

allows us to unwind and conserve energy

Terminal ganglion

a cluster of nerve cells, or ganglion located near or within the organ it innervates

Splanchnic nerves

Paired preganglionic autonomic nerves running along either side of the vertebral column

Cerebral palsy

a neuromuscular disability in which the voluntary are poorly controlled and spastic because of brain damage

Anencephaly

a failure of the cerebrum to develop resulting in a child who cannot hear, see, or process sensory inputs

Spina bifida

results when the vertebrae form incompletely

Arteriosclerosis

decreasing supply of oxygen to the brain

Senility

forgetfulness irritability difficulty in concentrating and thinking clearly and confusion from lack of oxygen to the brain