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Anatomy and Physiology I > Chapter 13 and Lab 9: Spinal Cord and Spinal Nerves > Flashcards

Chapter 13 and Lab 9: Spinal Cord and Spinal Nerves Flashcards

1
Q

What are the two divisions of the Nervous System and their main components?

A
  • Peripheral nervous system
    • Sensory Nervous system
    • Motor (somatic nervous system)
    • Motor (autonomic/visceral nervous system)
      • sympathetic division
      • parasympathetic division
  • Central nervous system
    • decision maker
    • takes input from PNS
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2
Q

What are the two principal cell types of the nervous system and their basic components?

A
  • Neurons
    • generate and transmit electrical signals
    • functional units of nervous system
    • 3 major types
      • sensory (carry info about sensations)
      • Interneurons (part of the CNS)
      • Motor neurons (carry impulses to effectors)
  • Neuroglia
    • support or protection for neurons
    • One type is Schwann cell (neurolemmocyte)
      • found in PNS
      • Neurons often wrapped in multiple Schwann cells-myelin sheath
        • gaps between Schwann cells called Nodes of Ranvier
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3
Q

What are the parts of a neuron?

A
  • Basic components: cell body, dendrites, axon
  • Cell body
    • nucleus, Nissl Bodies (rough ER), organelles
    • collections of cell bodies in CNS are nuceli, in PNS are ganglia
  • Dendrites
    • plasma membrane of a neuron
  • Axons
    • up to 3 feet long
    • collection of axons in CNS is tract, in PNS is nerve
    • usually does not touch next neuron or effector
      • synapse bridged by neurotransmitter
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4
Q

What are the 3 protective membranes of the brain and spinal cord listed in order of superficial to deep?

A
  • Dura mater
    • subdural mater
  • Arachnoid Mater
    • subarachnoid mater
  • Pia Mater
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5
Q

What nerves are in the Cervical plexus?

A

Phrenic nerve

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6
Q

What nerves are in the Brachial Plexus?

A

Axillary Nerve, Radial Nerve, Medial Nerve, and Ulnar Nerve

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7
Q

What nerves are in the lumbar plexus?

A

Femoral nerve, obturator nerve

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8
Q

What nerves are in the Sacral plexus?

A

sciatic nerve, pudendal nerve

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9
Q

What movement is associated with the Phrenic nerve?

A

Contraction causing inhalation

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10
Q

What movement is associated with the Axillary nerve?

A
  • abduction of arm
  • rotates humerus laterally
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11
Q

What movement is associated with the Radial nerve?

A
  • extesion of wrist
  • extension of fingers
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12
Q

What movement is associated with the median nerve?

A
  • flexion of wrist
  • flexion of fingers
  • pronation
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13
Q

What movement is associated with the ulnar nerve?

A
  • flexion of wrist
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14
Q

What movement is associated with the Femoral nerve?

A
  • extension of knee
  • flexion of hip
  • flexion/abduction/lateral rotation of hip
    • (innervates sartorius)
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15
Q

What movement is associated with the obturator nerve?

A
  • adduction of hip
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16
Q

What movement is associated with the sciatic nerve?

A
  • extension of hip
  • flexion of knee
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17
Q

What movement is associated with the pudendal nerve?

A
  • voluntary control of urination and defecation
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18
Q

What are the functions of the spinal cord?

A
  • conduction
    • ascending tracts: (Sensory) to brain
    • descending tracts: (motor) from brain
  • neural integration
    • gray matter
    • thinking
  • locomotion
    • groups of neurons that coordinate repetitive sequences of contraction
  • reflexes
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19
Q

What is the anatomy of the spinal cord?

A
  • flattened cylinder
    • arises from brainstem (medulla oblongata)
    • extends from foramen magnum to L1-L2
  • growth of cord stops at age 5
  • gives rise to 31 pairs of spinal nerves
    • each pair of spinal nerves is a segment
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20
Q

What is spina bifida?

A
  • congenital defect
  • one or more vertebrae fail to completely enclose spinal cord
  • lack of folic acid (form of vitamin B) increases risk
  • 1 in 1000
21
Q

How do gray matter and white matter differ?

A
  • gray matter
    • neuron cell bodies, unmyelinated axosn, dendrites
    • site of information processing, synaptic integration
  • white matter
    • myelinated axons in 3 columns
    • carry signals from one part of the CNS to another
22
Q

What is the anatomy of gray matter?

A
  • pair of posterior (dorsal) horns
  • pair of anterior (ventral) horns
  • Gray commissure connects right and left sides
    • has central canal lined with ependymal cells and filled with CSF
  • Lateral horns: visible from T2 through L1
    • contains neurons of sympathetic nervous system
23
Q

What is the anatomy of white matter?

A
  • Bundles of axons that course up and down the cord providing communication between different levels of the CNS
  • Columns or funiculi (3 pairs)
    • posterior (dorsal), lateral, and anterior (ventral) columns
  • Tracts or fasciculi (subdivisions of each column)
24
Q

What are the components of spinal tracts?

A
  • Fibers in a given tract have similar origin, destination, and function
  • Ascending v. descending
  • Decussation
    • they cross over
  • Contralateral v. ipsilateral
25
Q

What are the functions of the ascending spinal tracts?

A
  • Carry sensory signals up to spinal cord
  • Uses 3 neurons from origin (receptors) to destintation (sensory area in brain)
    • First order: detect stimulus and transmit signal to spinal cord or brain stem
    • Second order: continues to the thalamus at the upper end of the brainstem
    • Third order: carries the signal the rest of the way to the sensory region of the cerebral cortex
26
Q

What are the functions of the descending spinal tracts?

A
  • Carry motor signals down brainstem and spinal cord
  • Involve 2 motor neurons
    • Upper motor neuron
      • originates in cerebral cortex or brainstem and terminates on a lower motor neuron
    • Lower motor neuron
      • soma is in brainstem or spinal cord
      • axon leads to muscle or other target organ
27
Q

Define a nerve and a mixed nerve.

A
  • Spinal cord communicates with the rest of the body by way of nerves
  • Nerve: cordlike organ composed of numerous nerve fibers (axons) bound together by connective tissue
    • Mixed nerves contain both afferent (sensory) and efferent (motor) fibers
28
Q

What is the general anatomy of a nerve?

A
  • Nerve fibers of the PNS surrounded by Schwann cells forming neurilemma/myelin sheath around axon
  • Endoneurium: wrapping external to neurilemma
  • PErineurium: surrounds each fasicle
  • Epineurium: covering of entire nerve
    • Blood vessels penetrate connective tissue coverings
29
Q

What are Poliomyelitis and ALS (Lou Gehrig’s Disease)?

A
  • Poliomyelitis
    • caused by poliovirus (fecal contamination of water)
    • destroys motor neurons in brainstem and anterior horn of spinal cord
    • paralysis, muscular dystrophy, and respiratory arrest
  • ALS (Amyotrophic lateral sclerosis or Lou Gehrig’s disease)
    • destruction of motor neurons and muscular atrophy
    • sclerosis (scarring) of lateral regions of spinal cord
    • early signs: muscular weakness, difficulty speaking, swallowing, and using hands
    • sensory/intellectual functions remain unaffected
30
Q

What is a ganglia? List 2 examples.

A
  • Ganglion: cluster of neurosomas outside the CNS
    • enveloped in endoneurium
  • Posterior root ganglion
  • Sympathetic trunk ganglion
31
Q

What are the numbers for the 31 pairs of spinal nerves?

A
  • 8 cervical (C1-C8)
    • first cervical nerve exits between skull and atlas (only 7 vertebrae)
    • others exit at intervertebral foramina
  • 12 thoracic (T1-T12)
  • 5 Lumbar (L1-L5)
  • 5 Sacral (S1-S5)
  • 1 Coccygeal (Co1)
32
Q

What are the roots of the spinal nerves?

A
  • Each spinal nerve is formed from two roots
    • posterior (dorsal) root-sensory
      • posterior (dorsal) root ganglion
        • contains the somas of sensory neurons
      • enters posterior horn of cord
  • Anterior (ventral) root: motor
  • Cauda equina
    • formed from roots arising from L2 to Co1
    • dorsal and ventral roots of lowest spinal nerves
33
Q

What are the rami of the spinal nerves?

A
  • Outside vertebra, nerve divides into rami (distal branches)
  • Anterior ramus
    • in thoracic region gives rise to intercostal nerve
    • In other regions forms plexuses
  • Posterior ramus
    • innervates the muscles and joints in that region of the spine and the skin of the back
  • Rami communicantes
    • only in thoracic region
    • autonomic nerve fibers (sympathetic)
  • Meningeal branch
    • reenters the vertebral canals
      • to where the meninges are
34
Q

Why doesn’t the thoracic region have a plexus?

A
  • It goes into the intercostals and helps with breathing
35
Q

What are the 2 functions of nerve plexuses?

A
  • Somatosensory
    • carry sensory signals from bones, joints, muscles, and skin
    • proprioception: information about body position and movements from muscles, tendons, and joints
  • Motor
    • primarily to stimulate muscle contraction
36
Q

What is Shingles?

A
  • “Herpes Zoster”
  • painful trail of skin discoloration and fluid-filled vesicles along path of nerve
  • Chickenpox/caused by the varicella-zoster virus
  • Virus remains for life in the posterior root ganglia
    • kept in check by immune system
    • can pop out in elderly
  • Immune system is compromised: virus travels down sensory nerve
37
Q

What happens if you break your neck above C3?

A

You can’t breathe on your own (can with break below C3)

38
Q

What does irritation of the phrenic nerve do?

A

Causes hiccups

39
Q

What are the radial and sciatic nerve injuries?

A
  • Radial
    • passes through axilla
    • crutch paralysis: crutches too high, pressure on nerve, lose function
    • wrist drop: cast/wrap too tight
  • Sciatic
    • Sciatica: sharp pain that travels from gluteal region along the posterior side of the thigh and leg to ankle
    • usually caused by herniated intervertebral disc or osteoperosis of lower spine
40
Q

What is a dermatome?

A
  • A specific area of skin that conveys sensory input to a spinal nerve
  • Dermatome map: a diagram of the cutaneous regions innervated by each spinal nerve
  • Dermatomes overlap their edges as much as 50%
41
Q

What are the traits of reflexes?

A
  • Require stimulation
  • Quick
  • Involuntary
  • Stereotyped
    • the same for everyone
  • Inclue glandular secretion and contraction for all 3 types of muscle
  • Somatic reflexes inolve the somatic nervous system innervating skeletal muscle
42
Q

What is the pathway of a somatic reflex?

A
  • Somatic receptors: in skin, muscles, or tendons
  • Afferent (sensory) nerve fibers
  • Integrating center
  • Efferent (motor) nerve fibers
  • Effectors: skeletal muscle
  • Example: patellar reflex
43
Q

What is the muscle spindle?

A
  • Stretch receptors embedded in skeletal muscles
  • Muscle spindles inform the brain of muscle length and body movement
  • Enables brain to send motor commands back to the muscles that control coordinated movement, corrective reflexes, muscle tone, and posture
    • e.g. helps you stand upright while on a boat
44
Q

What is the stretch reflex?

A
  • Stretch (myotactic) reflex: when a muscle is stretched, it “fights back” and contracts
  • Helps maintain equilibrium and posture
  • Mediated primarily by brain, sometimes spine is involved
  • Stabilizes joints by balancing tension between flexion/extension, etc.
  • Testing these helps diagnosis many diseases
45
Q
A
46
Q

What is reciprocal inhibition?

A
  • reflex phenomenon that prevents muscles from working against each other by inhibiting antagonist when agonist is excietd
47
Q

What are some examples of stretch reflexes?

A
  • patellar tendon
  • flexor (withdrawal)
    • e.g. man stepping on a nail
    • ipsilateral
  • crossed extension reflex
    • e.g. man that stepped on nail maintains balance on other leg
    • contralateral
48
Q

What is spinal cord trauma and its types of paralysis?

A
  • 10,000 to 12,000 people paralyzed each year by spinal cord trauma
    • USually vertebral fractures
    • Usually males 16 to 30
    • 55% in automobile or motorcycle accidents
  • Complete transection: complete severence of cord
    • immediate loss of motor control below level of injury
    • Above C4 threat of respiratory failure
  • Paralysis
    • paraplegia (lower limbs)
    • quadraplegic (all 4 limbs)
    • Hemiplegia (one side of body, strokes)
    • Paresis (partial paralysis or weakness of limbs)

Anatomy and Physiology I (19 decks)

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