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BIO 150 A&P I > Unit 5: Ch 13 (Spinal Cord, Spinal Nerves, & Somatic Reflexes) > Flashcards

Unit 5: Ch 13 (Spinal Cord, Spinal Nerves, & Somatic Reflexes) Flashcards

1
Q

Cervical plexus

(do i need details for each sub-nerve?)

A
  • Located on each side of the neck
  • Receives fivers from the anterior rami of nerves C1 - C5 and gives rise to the following nerves:
    • Lesser occipital
    • Great auricular
    • Transverse cervical
    • Ansa cervicalis
    • Supraclavicular
    • Phrenic
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2
Q

*Flexor (withdrawal) reflex

A
  • The quick contraction of flexor muscles resulting in the withdrawal of a limb from an injurious stimulus
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3
Q

*Patellar tendon reflex arc

A

TBD

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4
Q

Layers of spinal meninges

A
  • Separate the tissue of the CNS from the bones of the vertebrae and skull
  • 3 layers
    1. Dura mater
    2. Arachnoid mater
    3. Pia mater
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5
Q

Afferent fibers

A
  • Carry sensory signals from receptors to the CNS
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6
Q

Ansa cervicalis n.

  • Composition
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: motor
  • Cutaneous and joint innervation (sensory): none
  • Muscular innervation (motor and proprioceptive):
    • omohyoid, sternohyoid, and sterothyroid muscles
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7
Q

Anterior corticospinal

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Anterior
  • Decussation: Spinal cord
  • Functions: Fine control of limbs
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8
Q

Anterior spinocerebellar

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Lateral
  • Decussation: Spinal cord
  • Functions: Same as posterior spinocerebellar
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9
Q

Arachnoid mater

A
  • Consists of the arachnoid membrane; 5-6 layers of squamous to cuboidal cells adhering to the inside of the dura and looser array of cells and elastic fibers spanning the gap between the arachnoid membrane and the pia mater
  • This gap, the subarachnoid space is filled with cerebrospinal fluid (CSF)
  • Notes
    • When a sample of CSF is needed for clinical purposes, it is taken from the lumbar cistern via a spinal tap
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10
Q

Ascending tracts

A
  • Carry sensory signals up the spinal cord
  • Typically travel across 3 neurons from their origin in the receptors to the destination in the brain
    • First-order neuron: detects a stimulus and transmits a signal to the spinal cord or brainstem
    • Second-order neuron: continues as far as a “gate-way” called the thalamus at the upper end of the brainstem
    • Third-order neuron: carries the signal the rest of the way to the cerebral cortex
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11
Q

Axillary n.

  • Composition
  • Cord of origin
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: mixed
  • Cord of origin: posterior
  • Cutaneous and joint innervation (sensory):
    • skin of lateral shoulder and arm
    • shoulder joint
  • Muscular innervation (motor and proprioceptive): deltoid and teres minor muscles
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12
Q

Brachial plexus

A
  • Formed predominately by the anterior rami of nerves C5 - T1
  • Subdivisions are called roots, trunks, divisions, and cords
  • 5 roots are anterior rami of C5 - Ti
    • C5 - C6: upper trunk
    • C7: middle trunk
    • C8 - T1: lower trunk
  • Each trunk divides into an anterior and posterior division
  • These nerves carry sensory signals from the skin of the shoulder and upper limb to the spinal cord
  • Major nerves
    • Musculocutaneous
    • Axillary
    • Radial
    • Median
    • Ulnar
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13
Q

List the classification of nerve fibers

A
  • Afferent fibers
  • Efferent fibers
  • Visceral fibers
  • General fibers
  • Special fibers
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14
Q

Contralateral reflex arc

A
  • The input and output are on opposite sides
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15
Q

Crossed extension reflex

A
  • The contraction of extensor muscles in the limb opposite from the one that is withdrawn
  • Extends and stiffens that limb and enables you to keep your balance
  • To produce this reflex, branches of the afferent nerve fibers cross from the stimulated side of the body to the contralateral side of the spinal cord. There, they synapse with interneurons, which excite or inhibit alpha motor neurons to the muscles of the contralateral limb
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16
Q

Cuneate fasciculus

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Posterior
  • Decussation: Medulla
  • Functions:
    • Same as gracile fasciculus; from level T6 up
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17
Q

Dermatome

A
  • A specific region innervated by a spinal nerve
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18
Q

Dermatome map

A
  • A diagram of the cutaneous regions innervated by each spinal nerve
  • Dermatomes overlap at their edges up to 50%, therefore severance of one sensory nerve root does not fully deaden sensation from a dermatome
  • It is necessary to sever or anesthetize 3 sequential spinal nerves to produce a total loss of sensation from one dermatome
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19
Q

Distal branches

A
  • Immediately after emerging from the intervertebral foramen, the nerve divides into the following branches
    • anterior ramus
    • posterior ramus
    • meningeal branch
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20
Q

Dura mater

A
  • Forms a loose-fitting sleeve called the dural sheath around the spinal cord
  • Tough membrane; composed of multiple layers of dense irregular connective tissue
  • The space between the sheath and the vertebral bones is the epidural space, which is occupied by
    • blood vessels
    • adipose tissue
    • loose connective tissue
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21
Q

Efferent fibers

A
  • Carry motor signals from the CNS to effectors
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22
Q

Femoral n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory):
    • skin of anterior, and lateral thigh and knee
    • skin of medial leg and foot
    • hip and knee joints
  • Muscular innervation (motor & proprioceptive):
    • iliacus
    • pectineus
    • quadriceps femoris
    • sartorius muscles
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23
Q

Fibular n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory):
    • skin of anterior distal 3rd of leg
    • dorsum of foot
    • toes I-II
    • knee joint
  • Muscular innervation (motor & proprioceptive):
    • biceps femoris muscle
    • anterior and lateral muscles of leg
    • extensor digitorum brevis muscle of foot
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24
Q

Ganglion

A
  • A cluster of neurosomas outside the CNS
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25
Q

General fibers

A
  • Innervate widespread organs such as muscles, skin, glands, viscera, and blood vessels
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26
Q

Genitofemoral n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory):
    • skin of middle anterior thigh
    • male scrotum
    • female labia majora
  • Muscular innervation (motor & proprioceptive): male cremaster muscle
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27
Q

Gracile fasciculus

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Posterior
  • Decussation: In medulla
  • Functions:
    • Sensations of limb and trunk position and movement, deep touch, visceral pain, and vibration, below level T6
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28
Q

Gray matter

A
  • Core consists mainly of two posterior (dorsal) horns, which extend toward the posterolateral surfaces of the cord and two thicker anterior (ventral) horns, which extend toward the anterolateral surfaces
  • Right and left sides connected by the gray commissure
  • In the middle of the commissure is the central canal
  • Lateral horn is visible on each side of the gray matter from segments T2 through L1. Contains neurons of the sympathetic NS
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29
Q

Great auricular n.

  • Composition
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: somatosensory
  • Cutaneous and joint innervation (sensory):
    • most of the external ear, mastoid region, region from parotid salivary gland
  • Muscular innervation (motor and proprioceptive): none
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30
Q

Iliohypogastric n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation: skin of lower anterior abdominal and posterolateral gluteal regions
  • Muscular innervation (motor & proprioceptive):
    • internal and external oblique
    • transverse abdominal muscles
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31
Q

Ilioinguinal n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory):
    • skin of upper medial thigh
    • male scrotum and root of penis
    • female labia majora
  • Muscular innervation (motor & proprioceptive): internal oblique
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32
Q

Inferior gluteal n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory): none
  • Muscular innervation (motor & proprioceptive): gluteus maximus
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33
Q

Intersegmental reflex arc

A
  • When the input and output occur at different levels (segments) of the spinal cord
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34
Q

Ipsilateral reflex arc

A
  • When the sensory input and motor output are on the same side of the spinal cord
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35
Q

Lateral corticospinal

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Lateral
  • Decussation: Medulla
  • Functions: Fine control of limbs
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36
Q

Lateral femoral cutaneous n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: somatosensory
  • Cutaneous & joint innervation (sensory): skin of anterior and upper lateral thigh
  • Muscular innervation (motor & proprioceptive): none
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37
Q

Lateral reticulospinal

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Lateral
  • Decussation: None
  • Functions:
    • Balance and posture
    • Regulation of awareness of pain
38
Q

Lateral vestibulospinal

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Anterior
  • Decussation: None
  • Functions: Balance and posture
39
Q

Lesser occipital n.

  • Composition
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: somatosensory
  • Cutaneous and joint innervation (sensory):
    • upper third of medial surface of external ear
    • skin posterior to ear
    • posterolateral neck
  • Muscular innervation (motor and proprioceptive): none
40
Q

Lumbar plexus

A
  • Formed from the anterior rami of nerves L1-L4 and some fibers from T12
  • Sensory fibers carry signals from the hip and knee joints and from skin of the genitalia, lower abdominal and gluteal regions, and the thigh, leg, and foot
  • The motor fibers control muscles of the hip, thigh, and scrotum
  • Gives rise to 6 major nerves
    1. Iliohypogastric
    2. Ilioinguinal
    3. Genitofemoral
    4. Lateral femoral cutaneous
    5. Femoral
    6. Obturator
41
Q

Major ascending tracts

A
  • Posterior funiculus
  • Spinothalamic tract
  • Spinoreticular tract
  • Posterior and anterior spinocerebellar tracts
42
Q

Major descending tracts

A
  • Lateral and anterior corticospinal tracts
  • Tectospinal tract
  • Lateral and medial reticulospinal tracts
  • Lateral and medial vestibulospinal tracts
43
Q

Medial reticulospinal

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Anterior
  • Decussation: None
  • Functions: Same as lateral reticulospinal
44
Q

Medial vestibulospinal

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Anterior
  • Decussation: Medulla (some fibers)
  • Functions: Control of head position
45
Q

Median n.

  • Composition
  • Cord of origin
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: mixed
  • Cord of origin: lateral and medial
  • Cutaneous and joint innervation (sensory):
    • skin of lateral 2/3 of hand
    • tips of digits I-IV
    • joints of hand
  • Muscular innervation (motor and proprioceptive):
    • mainly forearm flexors
    • thenar group and lumbricals I-II of hand
46
Q

Mixed nerves

A
  • Consist of both efferent and afferent fibers, and therefore conduct signals in two directions
  • However, any one fiber in the nerve conducts signals in only one direction
47
Q

Monosynaptic reflex arcs

A
  • Where there is one synapse between the afferent and efferent neuron, so there is little synaptic delay and a very prompt response
48
Q

Muscle spindles

A
  • Function is to inform the brain of muscle length and body movement
  • Enables the brain to send motor commands back to the muscles that control muscle tone, posture, coordinated movement, and corrective reflexes
49
Q

Musculocutaneous n.

  • Composition
  • Cord of origin
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: mixed
  • Cord of origin: lateral
  • Cutaneous and joint innervation (sensory):
    • skin of anterolateral forearm
    • elbow joint
  • Muscular innervation (motor and proprioceptive):
    • brachialis, biceps brachii, coracobrachialis muscles
50
Q

Nerve

A
  • A cordlike organ composed of numerous nerve fibers (axons) bound together by connective tissue
  • Smaller branches are called peripheral nerves
51
Q

Nerve plexuses

A
  • Except in the thoracic region, the anterior rami branch and anastomose (merge) repeatedly to form 5 webs called nerve plexuses
    • cervical plexus
    • brachial plexus
    • lumbar plexus
    • sacral plexus
    • coccygeal plexus
52
Q

Nervous tissue of the spinal cord

A
  • Gray matter
    • Site of synaptic contact between neurons; thus it is the site of all neural integration in the spinal cord
    • Contains little myeline
    • Contains somas, dendrites, and proximal parts of the axons of neurons
  • White matter
    • Bright, pearly white appearance due to an abundance of myelin
    • Composed of bundles of axons (tracts) that carry signals from one level of the CNS to another
53
Q

Obturator n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory):
    • skin of medial thigh
    • hip and knee joints
  • Muscular innervation (motor & proprioceptive):
    • obturator externus
    • medial (adductor) thigh muscles
54
Q

Peripheral nerve fibers

A
  • 2 kinds
    • Sensory (afferent): fibers carrying signals from sensory receptors to the CNS
    • Motor (efferent): fibers carrying signals from the CNS to muscles and glands
  • Depending on the nerves they innervate, either can be classified as somatic or visceral and as general or special
55
Q

Phrenic n.

  • Composition
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: mixed
  • Cutaneous and joint innervation (sensory):
    • diaphragm
    • pleura
    • pericardium
  • Muscular innervation (motor and proprioceptive): diaphragm
56
Q

Pia mater

A
  • Delicate, transparent membrane composed of 1-2 layers of squamous to cuboidal cells and collagenous and elastic fibers
  • Follows the contours of the spinal cord
  • Continues beyond the medullary cone as a fibrous strand, the terminal filum, within the lumbar cistern
57
Q

Plexus

A

A network of blood vessels, lymphatic vessels, or nerves

58
Q

Polysnaptic reflex arc

A
  • A pathway in which signals travel over many synapses on their way back to the muscle
59
Q

Posterior cutaneous n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: somatosensory
  • Cutaneous & joint innervation (sensory):
    • skin of gluteal region
    • perineum
    • posterior and medial thigh
    • popliteal fossa
    • upper posterior leg
  • Muscular innervation (motor & proprioceptive):
    • hamstring muscles
    • posterior muscles of leg
    • most intrinsic foot muscles
60
Q

Posterior spinocerebellar

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Lateral
  • Decussation: None
  • Functions: Feedback from muscles (proprioception)
61
Q

Proprioceptors

A
  • Sense organs specialized to monitor the position and movement of body parts
62
Q

Proximal branches

A
  • Anterior (ventral) root
  • Posterior (dorsal) root
  • Posterior (dorsal) root ganglion
63
Q

Pudendal n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory):
    • skin of penis and scrotum of male
    • clitoris
    • labia majora and minora
    • lower vagina of female
  • Muscular innervation (motor & proprioceptive):
    • muscles of perineum
64
Q

Radial n.

  • Composition
  • Cord of origin
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: mixed
  • Cord of origin: posterior
  • Cutaneous and joint innervation (sensory):
    • skin of posterior arm
    • posterior and lateral forearm and wrist
    • joints of elbow, wrist and hand
  • Muscular innervation (motor and proprioceptive): mainly extensor muscles of posterior arm and forearm
65
Q

Reciprocal inhibition

A
  • A reflect that prevents muscles from working against each other by inhibiting antagonists
66
Q

Reflex arc

A
  • Signals that travel along the following pathway
    • somatic receptors in the skin, muscles, and tendons
    • afferent nerve fibers
    • an integrating center
    • efferent nerve fibers
    • effectors
  • The more interneurons there are, the more complex the information processing can be, but with more synapses, there is a delay between input and output
67
Q

Reflexes

A
  • Quick, involuntary, stereotyped reactions of glands or muscles to stimulate
  • Include glandular secretion and contractions of all 3 types of muscle
  • 4 important properties
    • Require stimulation
    • Quick
    • Involuntary
    • Stereotyped
68
Q

Sacral & Coccygeal Plexuses

A
  • Sensory fibers of these nerves carry signals from joints of the hip, knee, and foot; from the gluteal and perineal regions and the genitals; and from skin from the gluteal region to the foot
  • Sacral plexus
    • Formed from the anterior rami of nerves L4, L5, and S1-S4
    • 6 roots and anterior and posterior divisions
  • Coccygeal plexus
    • tiny plexus formed from the anterior rami of S4, S5, and Co1
    • tibial and common fibular nerves travel together, called the sciatic nerve
  • Major nerves
    • superior gluteal
    • inferior gluteal
    • posterior cutaneous
    • tibial
    • fibular
    • pudendal
69
Q

Somatic fibers

A
  • Innervate skin, skeletal muscles, bones, and joints
70
Q

Somatic reflexes

A
  • Reflexes of the skeletal muscle
  • Involve the somatic nervous system
71
Q

Special fibers

A
  • Innervate more localized organs in the head, including the eyes, ears, olfactory and taste receptors, and muscles of chewing, swallowing, and facial expression
72
Q

Spinal cord principal functions

A
  1. Conduction: conduct information up and down the cord
  2. Neural integration: receive input, integrate information, & execute output
  3. Locomotion: initiates walking and determines speed
  4. Reflexes: posture, motor coordination, and protective responses to pain or injury (involuntary)
73
Q

Spinal cord regions

A
  • Cervical
  • Thoracic
  • Lumbar
  • Sacral
74
Q

Spinal nerves

A
  • 31 pairs of spinal nerves
    • 8 cervical (C1 - C8)
    • 12 thoracic (T1 - T12)
    • 5 lumbar (L1 - L5)
    • 5 sacral (S1 - S5)
    • 1 coccygeal (Co1)
75
Q

Spinal tracts

A
  • All nerve fibers in a given tract have a similar origin, destination, and function
  • Ascending tracts
    • carry sensory information up the cord
  • Descending tracts
    • conduct motor impulses down
76
Q

Spinoreticular

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Lateral & anterior
  • Decussation: Spinal cord
  • Functions:
    • Sensations of light touch, tickle, itch, temperature, pain, and pressure
77
Q

Spinoreticular

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Lateral & Anterior
  • Decussation: Spinal cord (some fibers)
  • Functions: Sensation of pain from tissue injury
78
Q

Stretch reflex

A
  • Mediated primarily by the brain
  • Is not a spinal reflex, but a weak component of it is spinal and occurs even if the spinal cord is severed from the brain
79
Q

Superior gluteal n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory): hip joint
  • Muscular innervation (motor & proprioceptive):
    • gluteus minimus
    • gluteus medius
    • tensor fasciae latae muscles
80
Q

Supraclavicular nn.

  • Composition
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: somatosensory
  • Cutaneous and joint innervation (sensory):
    • lower anterior and lateral neck, shoulder, anterior chest
  • Muscular innervation (motor and proprioceptive): none
81
Q

Tectospinal

  • Funiculus
  • Decussation
  • Functions
A
  • Funiculus: Anterior
  • Decussation: Midbrain
  • Functions: Reflexive head-turning in response to visual and auditory stimuli
82
Q

Tendon organs

A
  • Proprioceptors located in a tendon near its junction with a muscle
  • When muscle contraction pulls on a tendon, the collagen fibers come together like the two sides of a stretched rubber band and squeeze the nerve endings between them
83
Q

Tendon reflex

A
  • A response to excessive tension on the tendon
  • Inhibits alpha motor neurons to the muscle so the muscle doesn’t contract as strongly
  • Also functions when parts of a muscle contract more than others. It inhibits the muscle fibers connected with overstimulated tendon organs so their contraction is more comparable to the contraction of the rest of the muscle. This spreads the workload more evenly over the entire muscle
84
Q

Tibial n.

  • Composition
  • Cutaneous & joint innervation (sensory)
  • Muscular innervation (motor & proprioceptive)
A
  • Composition: mixed
  • Cutaneous & joint innervation (sensory):
    • skin of posterior leg
    • plantar skin
    • knee and foot joints
  • Muscular innervation (motor & proprioceptive):
    • hamstring muscles
    • posterior muscles of leg
    • most intrinsic foot muscles
85
Q

Tract pathway terminology

A
  • Decussation: When tracts cross over from the left side of the body to the right, or vice versa
  • Contralateral: when the origin and destination of a tract are on opposite sides of the body
  • Ipsilateral: when its origin and destination are on the same side of the body
86
Q

Transverse cervical n.

  • Composition
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: somatosensory
  • Cutaneous and joint innervation (sensory):
    • anterior and lateral nexk
    • underside of chin
  • Muscular innervation (motor and proprioceptive): none
87
Q

Unar n.

  • Composition
  • Cord of origin
  • Cutaneous and joint innervation (sensory)
  • Muscular innervation (motor and proprioceptive)
A
  • Composition: mixed
  • Cord of origin: medial
  • Cutaneous and joint innervation (sensory):
    • skin of palmar and medial hand
    • digits III-V
    • joints of elbow and hand
  • Muscular innervation (motor and proprioceptive):
    • some forearm flexors
    • adductor pollicis
    • hypothenar group
    • interosseous muscles
    • lumbricals III-IV
88
Q

Visceral (autonomic) reflexes

A
  • Smooth and cardiac muscle
89
Q

Visceral fibers

A
  • Innervate blood vessels, glands, and viscera
90
Q

White matter

A
  • Surrounds gray matter
  • Consists of bundles of axons that course up and down the cord and provides avenues of communication between different levels of the CNS
  • Bundles are arranged in 3 pairs called funiculi
    • Posterior (dorsal)
    • Lateral
    • Anterior (ventral) funiculus
  • Each column consists of subdivisions called tracts or fasciculi

BIO 150 A&P I (25 decks)

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