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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?

A

C1 - C5

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?

A
  • phrenic
25
Q

what are the important nerves of the brachial plexus?

A
  • axillary
  • radial
  • median
  • musculocutaneous
  • ulnar
26
Q

What body areas does the cervical plexus serve?

A
  • diaphragm

- skin and muscles of shoulder and neck

27
Q

What body areas does the brachial plexus serve?

A
  • 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
Q

What is the origin of the lumbar plexus?

A

L1 - L4

29
Q

What are the important nerves of the lumbar plexus?

A
  • femoral (including lateral and anterior cutaneous branches)
  • obturator
30
Q

What body areas does the lumbar plexus serve?

A
  • 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
Q

What is the origin(s) of the sacral plexus?

A

L4 - L5 and S1 - S4

32
Q

What are the important nerves of the sacral plexus?

A
  • 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
Q

What body areas does the sacral plexus serve?

A
  • 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
Q

What is the Autonomic Nervous System?

A
  • 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
Q

Somatic Nervous System VS. Autonomic Nervous System

A

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
Q

What is the anatomy of the Parasympathetic division?

A
  • 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
Q

What is the anatomy of the Sympathetic division?

A
  • 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
Q

What is Autonomic functioning?

A
  • 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
Q

What is the autonomic functioning of the Sympathetic division of SYMPATHETIC?

A
  • 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
Q

What are the Spinal Nerves in the PNS?

A
  • 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
Q

What is the Autonomic Functioning of PARASYMPATHETIC?

A

“housekeeping” activities

  • rest-and-digest system
  • conserves energy
  • maintains daily necessary body functions
  • remember as the “D” division
  • – digestion
  • – defecation
  • – diuresis
42
Q

What are the Developmental aspects of the Nervous System?

A
  • 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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