Lecture 16: Peripheral Nervous System Flashcards
what is PNS?
everything outside of CNS, cranial nerves, spinal nerves, ganglia
how is the PNS divided?
PNS is divided into sensory (afferent) and motor (efferent) divisions
explain the in/outputs of the PNS?
afferent nerves carry information from sensory receptors to CNS
- somatic (skin, muscles, joint) causes a reflex action
- visceral organs
efferent nerves carry information away from CNS to the effector organs
- somatic motor nerves innervate skeletal muscle
- autonomic nerves innervate smooth muscle, cardiac muscle and glands.
is somatic voluntary or involuntary movements?
somatic is voluntary and autonomic is involuntary.
what is the autonomic system split into?
sympathetic (fight or flight) and parasympathetic nervous system (rest and digest)
what are the three key anatomical differences ANS divisions?
- site of origin: para - fibres originate in the craniosacral region
sym - fibres originate in the thoracolumbar region - lengths of fibres: para - preganglionic fibres are long, and postganglionic fibres are short
sym - preganglionic fibres are short, and postganglionic fibres are long. - location of ganglia: para-ganglia is near or within visceral effector organs
sym - ganglia is close to the spinal cord
what are the 2 types of nerves in the PNS?
spinal nerves - arise from spinal cord
cranial nerves - arise from brain
what are the three connective tissues surrounding nerves?
epineurium (outer, surrounds the peripheral nerve)
perineurium (middle, surrounds fascicles)
endoneurium (inner, surrounds individual nerve axons)
how many spinal cords are attached to the spinal cord? name them and state how many.
31 altogether. 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal.
dorsal rami vs ventral rami?
dorsal rami provide sensory and motor innervation to the skin and back muscles. ventral rami provide sensory and motor innervation to the rest of trunk and limbs
what are the four main plexuses?
cervical, brachial, lumbar, sacral
where the plexuses located?
cervical - under sternocleidomastoid (neck)
brachial - located in neck and shoulder
lumbar - innervates abdominal wall, anterior and medial thigh
sacral - located posterior to lumbar, buttocks, lower limb and pelvis
what makes up the brachial plexus?
5 roots (ventral rami), 3 trunks, 3 cords, 5 peripheral nerves
names of the 3 cords in brachial plexus?
lateral, posterior, medial
names of the peripheral nerves in brachial plexus?
axillary, musculocutaneous, median, ulnar, radial