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Anatomy & Physiology > Week 8 - Peripheral Nervous System (PNS) > Flashcards

Week 8 - Peripheral Nervous System (PNS) Flashcards

1
Q

What is the Peripheral Nervous System?

A
  • PNS consists of nerves and ganglia outside the CNS
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2
Q

What is the structure of a nerve?

A
  • bundles of neurons found outside the CNS
  • endoneurium is a connective tissue sheath that surrounds each fiber
  • perineurium wraps groups of fibers bound into a fasicle
  • epineurium binds groups of fascicles
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3
Q

What are mixed nerves?

A
  • contain both sensory and motor fibers
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4
Q

What are sensory (afferent) nerves?

A
  • carry impulses toward the CNS
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5
Q

What are motor (efferent) nerves?

A
  • carry impulses away from the CNS
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6
Q

What are Cranial nerves?

A
  • 12 PAIRS*** of nerves serve mostly the head and neck
  • only the pair of vagus nerves extends to thoracic and abdominal cavities
  • most are mixed nerves, but three are sensory only
    1. optic
    2. olfactory
    3. vestibulocochlear
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7
Q

Function of Olfactory nerves (I)

A
  • purely sensory

- carries impulses for the sense of smell

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8
Q

Function of Optic nerves (II)

A
  • purely sensory

- carries impulses for vision

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9
Q

Function of Oculomotor nerves (III)

A
  • supplies motor fibers to four of the six muscles (superior, inferior, and medial rectus, and inferior oblique)
  • that direct the eyeball
  • to the eyelid
  • and to the internal eye muscles controlling lens shape and pupil size
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10
Q

Function of Trochlear nerves (IV)

A
  • supplies motor fibers for one external eye muscle (superior oblique)
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11
Q

Function of Trigeminal nerves (V)

A
  • conducts sensory impulses from the skin of the face and mucosa of the nose and mouth
  • contains motor fibers that activate the chewing muscles
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12
Q

Function of Abducens nerves (VI)

A
  • supplies motor fibers to the lateral rectus muscle, which rolls the eye laterally
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13
Q

Function of Facial nerves (VII)

A
  • activates the muscles of facial expression and the lacrimal and salivary glands
  • carries sensory impulses from the taste buds of anterior tongue
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14
Q

Function of Vestibulocochlear nerves (VIII)

A
  • purely sensory
  • vestibular branch transmits impulses for the sense of balance
  • cochlear branch transmits impulses for the sense of hearing
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15
Q

Function of Glossopharyngeal nerves (IX)

A
  • supplies motor fibers to the pharynx (throat) that promote swallowing and saliva production
  • carries sensory impulses from taste buds of the posterior tongue and from pressure receptors of the carotid artery
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16
Q

Function of Vagus nerves (X)

A
  • fibers carry sensory impulses from and motor impulses to the pharynx, larynx, and the abdominal and thoracic viscera
  • most motor fibers are parasympathetic fibers that promote digestive activity and help regulate heart activity
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17
Q

Function of Accessory nerves (XI)

A
  • mostly motor fibers that activate the sternocleidomastoid and trapezius muscles
18
Q

Function of Hypoglossal (XII)

A
  • motor fibers control tongue movements

- sensory fibers carry impulses from the tongue

19
Q

What are spinal nerves?

A
  • 31 pairs
  • formed by the combination of the ventral and dorsal roots of the spinal cord
  • named for the region of the spinal cord from which they arise
20
Q

What are spinal nerves plexus?

A
  • plexus = networks of nerves serving motor and sensory needs of the limbs
  • form from ventral rami of spinal nerves in the cervical, lumbar, and sacral regions
21
Q

How many plexuses are there and what are they?

A
  • 4
  1. cervical
  2. brachial
  3. lumbar
  4. sacral
22
Q

What is the origin of the cervical plexus?

23
Q

What is the origin of the Brachial plexus?

A

C5 - C8 and T1

24
Q

What are the important nerves of the cervical plexus?

25
what are the important nerves of the brachial plexus?
- axillary - radial - median - musculocutaneous - ulnar
26
What body areas does the cervical plexus serve?
- diaphragm | - skin and muscles of shoulder and neck
27
What body areas does the brachial plexus serve?
- deltoid muscle and skin of shoulder - muscles and skin of superior thorax - triceps and extensor muscles of the forearm - skin of posterior upper limb - flexor muscles and skin of forearm and some muscles of hand - flexor muscles of arm - skin of lateral forearm - some flexor muscles of forearm - wrist and many hand muscles - skin of hand
28
What is the origin of the lumbar plexus?
L1 - L4
29
What are the important nerves of the lumbar plexus?
- femoral (including lateral and anterior cutaneous branches) - obturator
30
What body areas does the lumbar plexus serve?
- lower abdomen - anterior and medial thigh muscles (hip flexors and knee extensors) - skin of anteromedial leg and thigh - adductor muscles - skin of medial thigh and hip joint
31
What is the origin(s) of the sacral plexus?
L4 - L5 and S1 - S4
32
What are the important nerves of the sacral plexus?
- sciatic (largest nerve in the body; splits to common fibular and tibial nerves just above knee) - -- common fibular (superficial and deep branches) - -- tibial (including sural and plantar branches) - superior and inferior gluteal
33
What body areas does the sacral plexus serve?
- lower trunk and posterior surface of thigh (hip extensors and knee flexors) - lateral aspect of leg and foot - posterior aspect of leg and foot - gluteus muscles of hip
34
What is the Autonomic Nervous System?
- motor subdivision of the PNS - consists only of motor nerves controls the body automatically (aka "involuntary nervous system") - regulates cardiac and smooth muscles and glands
35
Somatic Nervous System VS. Autonomic Nervous System
Somatic Nervous System - motor neuron cell bodies originate inside the CNS - axons extends to skeletal muscles that are serves Autonomic Nervous System - Chain of TWO (2) motor neurons - ---- preganglionic neuron is in the brain or spinal cord - ---- postganglionic neuron extends to the organ - Has TWO arms - ---- sympathetic division - ---- parasympathetic division
36
What is the anatomy of the Parasympathetic division?
- aka "Craniosacral division" - preganglionic neurons originate in: - -- cranial nerves III, IX and X - -- S2 through S4 regions of the spinal cord - preganglionic neurons synapse with terminal ganglia - -- from there, postganglionic axons extend to organs that are served
37
What is the anatomy of the Sympathetic division?
- aka "thoracolumbar division" - preganglionic neurons originate from T1 - L2 - ---- axons pass through a ramus comminicans to enter a sympathetic trunk ganglion - ---- sympathetic trunk, or chain, lies near the spinal cord - after synapsing at the ganglion, the axon may synapse with a second neuron at the same or different level - or, the preganglionic neuron may pass through the ganglion without synapsing and form a part of the splanchnic nerves - ---- splanchnic nerves travel to the collateral ganglion - ---- collateral ganglia serve the abdominal and pelvic organs
38
What is Autonomic functioning?
- body organs served by the autonomic nervous system receive fibers from both divisions - -- exceptions: blood vessels, structures of the skin, some glands, and the adrenal medulla - -- these exceptions receive ONLY sympathetic fibers - when body divisions serve the same organ, they cause antagonistic effects due to different neurotransmitters - -- parasympathetic (cholinergic) fibers release acetylcholine - -- sympathetic postganglioinic (adrenergic) fibers release norepinephrine - -- preganglionic axons of BOTH divisions release acetylcholine
39
What is the autonomic functioning of the Sympathetic division of SYMPATHETIC?
- sympathetic "fight or flight" division - response to unusual stimulus when emotionally or physically stressed or threatened - takes over to increase activities - remember as the "E" division - -- exercise - -- excitement - -- emergency - -- emergency - -- embarrassment
40
What are the Spinal Nerves in the PNS?
- dorsal root => brings sensory impulses from periphery to spinal cord - dorsal root ganglion => cell bodies of sensory neurons - ventral root => sends motor impulses out to skeletal muscles via motor neuron axons * **dorsal root and ventral root fuse to form the spinal nerve
41
What is the Autonomic Functioning of PARASYMPATHETIC?
"housekeeping" activities - rest-and-digest system - conserves energy - maintains daily necessary body functions - remember as the "D" division - -- digestion - -- defecation - -- diuresis
42
What are the Developmental aspects of the Nervous System?
- Brain growth ends in young adulthood. Neurons die throughout life and are not replaced; thus, brain mass declines with age - Orthostatic hypotension is low blood pressure due to changes in body position - healthy aged people maintain nearly optimal intellectual function - disease --- particularly cardiovascular disease --- is the major cause of declining mental function with age - ---- arteriosclerosis is decreased elasticity of blood vessels

Anatomy & Physiology (9 decks)

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