Anatomy PNS vocab

nerve

a bundle of neuron fibers found outside the CNS

endoneurium

delicate connective tissue sheath that surrounds each neuron fiber

perineurium

coarse connective tissue that wraps groups of neuron fibers

fascicles

fiber bundles

epineurium

tough fibrous sheath that binds multiple fascicles together

mixed nerves

nerves carrying both sensory and motor fibers

sensory nerves

nerves that only carry impulses towards the CNS

motor nerves

nerves that only carry impulses away from the CNS

cranial nerves

the 12 pairs of nerves that arise from the brain

dorsal rami

branch of a spinal nerve that arises from the posterior side of the vertebral column; contains both sensory and motor fibers

ventral rami

branch of a spinal nerve that arises from the anterior side of the spinal column; contains both motor and sensory fibers

plexus

complex network of nerves that serve the motor and sensory needs of the limbs

autonomic nervous system

major subdivision of the PNS that controls body activities automatically; regulates cardiac, smooth muscles, and glands

involuntary nervous system

another term for the autonomic nervous system (ANS)

preganglionic axon

axon that arises from the first motor neuron in an ANS motor pathway; its cell body is in the CNS

postganglionic axon

axon that arises from the second motor neuron in an ANS motor pathway; its cell body is in the PNS

sympathetic division

division of the ANS that mobilizes the body during extreme situations such as fear, rage, or exercise

parasympathetic division

division of the ANS that reverses the affects of the sympathetic division to relax the body and conserve energy

terminal ganglion

cluster of nerve cell bodies in the parasympathetic nervous system that receives impulses from the preganglionic; the cell body of the postganglionic ason

splanchnic nerves

nerves that arise from the second neuron in a sympathetic nerve pathway and travel towards the internal organs (viscera)

cerebral palsy

a condition that is possibly caused by a temporary lack of oxygen to the brain during birth; results in a neuromuscular disability in which the voluntary muscles are poorly controlled

anencephaly

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

spina bafida

a condition in which the vertebrae do not form completely before birth; worst cases result in nerves and parts of the spinal cord protruding from the spine, which paralyzes the lower limbs and makes the child unable to control their bladder/bowels

arteriosclerosis

degenerative changes in the arteries, leading to decreased elasticity in the arteries and decreased supply of oxygen to the brain neurons; can result in nervous system deterioration

senility

forgetfulness, irritability, and decreased concentration that stems from a gradual lack of oxygen due to the aging process