Oms2 Semester 1 Spinal Cord And Neural Pathways

Front 1

Describe the four roles of the spinal cord.

Back 1

Receives primary sensory input from receptors in skin, skeletal muscles, and tendons (somatosensory fibers) and from receptors in the thoracic, abdominal, and pelvic viscera (viscerosensory fibers)

Somatic motor neurons innervate skeletal muscles and visceral motor neurons which influence smooth and cardiac muscle and glandular epithelium

Spinal reflex – involves somatosensory fibers, interneurons, motor neuron

Spinal Cord contains descending fibers that originate in the cerebral cortex and brainstem that influence the activity of motor and sensory neurons.

Front 2

Sensory and motor neurons are found in what general regions of the spinal cord respectively?

Back 2

Anterior horn - Motor

Posterior horn - Sensory

Front 3

Describe the starting and ending points of the spinal cord proper.

Back 3

Foramen magnum to L1/L2

Front 4

What are the two enlargement regions of the spinal cord?

Back 4

Cervical: C4-T1

Lumbar: L1-S2

Front 5

What is the most caudal structure of the spinal cord proper?

Back 5

Conus medullaris (L1/L2)

Front 6

Where is the cauda equina?

Back 6

"horse tail" - nerves continuing caudally within the spinal cord - extending from L1 - Co1

Front 7

What is the average level of termination of the spinal cord?

Back 7

L1/L2

Front 8

Where is a lumbar puncture performed?

Back 8

To access the CSF vestibule, L3/L4 is ideal, L4/L5 may also be used.

Front 9

What are the caudal and cranial attachments of the dura?

Back 9

Attached cranially at foramen magnum

Attached caudally at the filum terminale externum (to the coccyx)

Front 10

What are denticulate ligaments?

Back 10

Lateral attachments of the spinal cord to the dura

Front 11

At what spinal level does the dural sac end?

Back 11

S2

Front 12

What is white matter composed of? Gray matter?

Back 12

White matter - axons

Gray matter - cell bodies

Front 13

What are the three pairs of funiculi?

Back 13

Posterior (dorsal)
Anterior (ventral)
Lateral

Front 14

Where is the posterior (dorsal) median sulcus?

Back 14

Splits the spinal cord into two halves

Front 15

Where is the Posterolateral (dorsolateral) sulcus?

Back 15

It is posterior on the spinal cord, it is the entry point of sensory fibers.

Front 16

Where is the anterolateral (ventrolateral) sulcus?

Back 16

Anterolaterally on the spinal cord, an exit point for anterior fibers

Front 17

Where is the posterior (dorsal) intermediate sulcus?

Back 17

Present at spinal level T6 and higher, divides each posterior funiculus into 2 fasciculi. Marked at lower cervical.

Front 18

What is the anterior median fissure?

Back 18

Contains sulcus branches of the anterior spinal artery and divides the cord in half

Front 19

What is the anterior white commissure?

Back 19

An area just ventral to the gray area, where the axons cross from one side to another (just below the anterior median fissure)

Front 20

What two fasciculi are part of the posterior columns/medial lemniscus pathway?

Back 20

Fasciculus gracilis
Fasciculus cuneatus

Front 21

What is the lateral corticospinal tract?

Back 21

A descending spinal pathway involved in motor movement

Front 22

What is the anterolateral system?

Back 22

A bunch of axons relaying pain and temperature information from the body to the cortex.

Front 23

Which lamina(e) comprises the Posteromarginal Nucleus?

Back 23

Lamina I

Front 24

Which lamina(e) comprises the Substantia Gelatinosa?

Back 24

Lamina II

Front 25

Which lamina(e) comprises the Nucleus Proprius?

Back 25

Lamina III, IV

Front 26

Which lamina(e) comprises the Motor Neurons?

Back 26

Lamina VIII and X

Front 27

Which lamina(e) comprises the Dorsal Nucleus of Clarke and IML?

Back 27

Lamina VII

Front 28

Describe the somatotopic localization pattern of the anterior horn.

Back 28

Neurons innervating trunk - most medial
Neurons innervating hand - most lateral
Neurons innervating flexor - most posterior
Neurons innervating extensors - most anterior

Front 29

What are alpha and gamma neurons of the ventral horn?

Back 29

Lower motor neurons
Alpha - larger neurons, heavily myelinated, innervating working muscle and cause flexion or extension
Gamma - smaller neurons, moderately myelinated, innervate small, striated muscle involved in tone.

Front 30

Describe the pattern/ratio of white and gray matter in the vertebrae - any trends?

Back 30

From cervical to sacral vertebrae, the ratio of gray:white matter slowly increases until when it reaches the sacrum there is more gray matter than white matter.

Front 31

Describe the spinal cord (cross section) at the cervical level.

Back 31

Oval shape, large, lots of white matter, contains both gracile and cuneate fasciculi, large anterior and posterior horns at C4-C8

Front 32

Describe the spinal cord (cross section) at the thoracic level.

Back 32

Round shape, posterior and anterior horns are small, contain both gracile and cuneate fasciculi in upper thoracic, only gracile in lower thoracic. Contains Dorsal Nucleus of Clarke, and lateral horns (intermediolateral nucleus)

Front 33

Describe the spinal cord (cross section) at the lumbar level.

Back 33

Round, large posterior and anterior horns, Nucleus of Clarke at L1/L2

Front 34

Describe the spinal cord (cross section) at the sacral level.

Back 34

Round and small, primarily gray matter, S2, S3, S4 contain the sacral parasympathetic nucleus.

Front 35

Describe the Posterolateral Fasciculus of Lissauer (PLF)

Back 35

Ascending and descending collaterals of primary sensory axons (a tract)

Front 36

Describe the Substantia Gelatinosa.

Back 36

Receives sensory input, mostly nociception, and are projection neurons

Front 37

What is the Nucleus Propius?

Back 37

Sensory input, mostly touch, and are projection neurons.

Front 38

What is the Medial Motor Nucleus?

Back 38

Skeletal muscles of the ipsilateral neck and trunk.

Front 39

What is the Lateral Motor Nucleus?

Back 39

Skeletal muscle of the upper of lower ipsilateral extremity (C4-T1) and (L1-S2)

Front 40

What is the Dorsal Nucleus of Clarke?

Back 40

Reflex proprioception, dorsal spinocerebellar tract T1-L2

Front 41

What is the Intermediolateral Nucleus?

Back 41

Sympathetic preganglionic neurons, lateral horn T1-L2

Front 42

What is the Sacral Parasympathetic Nucleus?

Back 42

Parasympathetic preganglionic neurons for pelvic viscera S2-S4

Front 43

What is the Phrenic Motor Nucleus?

Back 43

Skeletal muscle of the ipsilateral half of the diaphragm, mostly C3-C5

Front 44

What is the Spinal Accessory Nucleus?

Back 44

Innervates the skeletal muscles of the ipsilateral sternocleidomastoid and trapezius muscles.

Front 45

Describe Peripheral and Central overlap of sensory branches.

Back 45

Peripheral overlap - branches from different nerves share dermatomes

Central overlap - a collection of peripheral nerves (or a nerve) branch as it returns to the spinal cord and returns to multiple vertebral levels (C4, C5, C6)

Front 46

How many nerves must be affected to create anesthesia in one dermatome?

Back 46

At least three adjacent nerves

Front 47

What may result from two adjacent nerves being cut?

Back 47

Sensory change, hypoesthetic

Front 48

What results from destroying 1-2 ventral roots of spinal nerves?

Back 48

You would expect to see some motor deficiencies such as weakness, not necessarily paralysis, since many muscles are supplied by multiple nerves.

Front 49

What is a spinal tract?

Back 49

A group of neurons (and their axons) in a pathway

Tract-pathway name = describes whether the tract is ascending or descending, locate the cell body, place where the axons terminate.

Front 50

What is a spinal reflex?

Back 50

An involuntary, coordinated pattern of muscle contraction and relaxation that is elicited by a peripheral stimulus.

Front 51

Describe how a spinal reflex works.

Back 51

Golgi tendon bodies/muscle sends a signal --> sensory input synapses on another nerve --> the other nerve synapses on a motor nerve that innervates muscle for a response

Front 52

Trace the path of the Pain and Temperature Pathway (Anterolateral System) (Lateral Spinothalamic Tract).

Back 52

PRG (neuron 1) --> Substantia Gelatinosa (neuron 2) Anterolateral system (lateral spinothalamic tract) --> Thalamus [Ventral posterolateral nucleus] --> Cortex [postcentral gyrus - area 3,1,2]

Front 53

Trace the path of General Tactile - Crude and Light Touch = Anterolateral System (Venous Spinothalamic Tract).

Back 53

PRG (neuron 1) --> Nucleus Proprius (neuron 2) Anterolateral system (ventral spinothalamic tract) --> Thalamus [Ventral Posterolateral nucleus] (neuron 3) Thalamocortical fibers --> Cortex (postcentral gyrus, area 3, 1, 2)

Front 54

Trace the path of Conscious Proprioception and fine or discriminatory touch (2 point discrimination) = Fasciculus Gracilis and Cuneatus

Back 54

PRG (neuron 1) --> Fasciculus Gracilis or Cuneatus (neuron 2), Medial Lemniscus --> Thalamus [Ventral Posterolateral nucleus] (neuron 3) Thalamocortical fibers --> Cortex (postcentral gyrus area 3,1,2)

Front 55

Trace the path of Reflex Proprioception (Posterior-lateral and anterior spinocerebellar tracts).

Back 55

PRG (neuron 1) --> Posterior and Anterior Spinocerebellar tracts and Cuneocerebellar tracts --> Dorsal nucleus of Clarke (C8-L3) or nucleus proprius or lateral (accessory) cuneate nucleus (neuron 2) Inferior or Superior cerebellar peduncle --> Cerebellum

Front 56

What is the role of the Posterior Columns/Medial Lemniscus?

Back 56

Brings sensory information to the cortex

Front 57

How do the three neurons in the PC/ML pathway connect?

Back 57

Receptor neuron (pseudounipolar)
Lower center to Thalamus
Thalamus to Cortex

Front 58

What are the three tracts of the PC/ML pathway?

Back 58

Dorsal column tract
Medial lemniscus tract
Thalamocortical tract

Front 59

What is the role of the corticospinal tract/motor pathway?

Back 59

Relays motor information from the cortex to the muscle.

Front 60

What are the two neurons in the corticospinal tract?

Back 60

Upper motor neurons - sends info from the cortex to the spinal cord

Lower motor neurons - sends info from the spinal cord to the muscles

Front 61

What are the two tracts in the corticospinal tract/motor pathway?

Back 61

Cortical spinal neurons
Peripheral nerve

Front 62

What is the role of the anterolateral system?

Back 62

Relays somatic pain, sharp, well localized, easy to describe precisely; temperature (hot, cold)

Front 63

Describe the somatotopic organization of the anterolateral system.

Back 63

From lateral to medial: Sacral cords, Lumbar cords, Thoracic cords, Cervical cords

Front 64

What are the three neurons in the anterolateral system?

Back 64

Axons of the lateral spinothalamic tract
Peripheral nerve tract
Thalamocortical tract

Front 65

What S/S may there be if a peripheral nerve of the anterolateral system had a lesion?

Back 65

Loss of pain and temperature fibers - at the level of that dermatome

Front 66

What S/S may there be if a lesion develops in the spinothalamic tract of the anterolateral system?

Back 66

Loss of pain and temperature on the contralateral side of the body below the level of the lesion

Front 67

What is the role of the PC/ML pathway?

Back 67

This pathway carries fine or discriminatory touch, 2 point discrimination, position and vibratory sense from the body

Front 68

What are the three main tracts of the Reflex Proprioception Pathway?

Back 68

Anterior Spinocerebellar Tract - Lower Extremities
Posterior Spinocerebellar Tract - Lower Extremities
Cuneocerebellar Tract - Upper Extremities and Neck

Front 69

What is the role of the Voluntary Motor Pathway?

Back 69

Initiates skilled movements carried out by somatic skeletal muscles especially hand and finger movements.

Front 70

Where are the lower and upper extremities represented in the spinal cord?

Back 70

Lower extremities - lateral

Upper extremities - medial

Front 71

What are the two neurons in the Voluntary Motor Pathway?

Back 71

Upper motor neuron (corticospinal/lateralcorticospinal tracts)
Lower motor neuron (anterior horn of spinal cord, peripheral axons)

Front 72

Where does crossover occur in the Voluntary Motor Pathway?

Back 72

Lowest level of the brainstem

Front 73

Where would effects be seen relative to a lesion in the brainstem affecting the Voluntary Motor Pathway vs a lesion in the spinal cord?

Back 73

Lesion in the brainstem = Contralateral side

Lesion in the spinal cord = Ipsilateral side

Front 74

What are some additional tracts that affect the Voluntary Motor Pathway?

Back 74

Reticulospinal Tract (movement, tone)
Vestibulospinal Tract (tone)
Rubrospinal Tract (movement)
Tectospinal Tract
Tegmentospinal Tract
Lateral Corticospinal Tract

Front 75

What is Syrigomyelia?

Back 75

Cavitation of the central canal of the spinal cord, usually beginning in the cervical region and destroys the anterior white commissure fibers of the spinothalamic tract (ALS). Pain sensation is lost bilaterally but tactile sensation is intact because there is no damage to the posterior columns (PC/ML).

Front 76

What is Brown-Sequard Syndrome?

Back 76

Following spinal hemisection (damage to half the spinal cord) – pain and temperature are lost contralateral to the lesion, paralysis and posterior columns information (tactile discriminatory, vibratory, position sense), lost ipsilaterally. All losses are caudal to the lesion site.

Front 77

What are the S/S of an upper motor neuron lesion?

Back 77

Spastic paresis, hyperreflexia, Babinski sign (abnormal after age 2, stroking plantar portion of foot caused big toe to go up)

Front 78

What are the S/S of a lower motor neuron lesion?

Back 78

S/S – Flaccid paralysis, Hyporeflexia, Muscle atrophy/fasciculations

Front 79

Define "Nerve"

Back 79

Nerve - a Conglomerate of axons bounded together by connective tissue layers and located in the PNS. Nerves transmit information from the CNS to the PNS and vice versa.

Front 80

Define "Nerve Fiber"

Back 80

– It refers to an axon inside a peripheral nerve. We say that a peripheral nerve contains many functionally different nerve fibers. We talk about nerve fibers referring to PNS fibers.

Front 81

Define "Fiber Tract"

Back 81

Conglomerate of axons in the CNS.

Front 82

What are the two major motor systems?

Back 82

Somatic/skeletal (Controlled by the cerebral cortex, innervates skeletal muscles of the body); Autonomic/visceral (Controlled by the hypothalamus, innervates smooth muscle of the viscera)

Front 83

What are the three divisions of the Autonomic Nervous System?

Back 83

Sympathetic
Parasympathetic
Enteric

Front 84

Where is the Sympathetic ANS?

Back 84

Located in the thoraco-lumbar spinal cord in the lateral horn (IML cell column) - the sympathetic nucleus contains the preganglionic sympathetic neurons.

Front 85

Where is the Parasympathetic ANS?

Back 85

Brainstem, Sacral spinal cord - known as the cranio-sacral system because of the location of nuclei.

Front 86

Where is the Enteric ANS?

Back 86

Plexuses very near/inside the viscera

Front 87

Where are nuclei and ganglions respectively?

Back 87

Nuclei - CNS
Ganglions - PNS

Front 88

What four cranial nerves have parasympathetic fibers?

Back 88

CN III
CN VII
CN IX
CN X

Front 89

Trace the parasympathetic fibers of the Oculomotor nerve (CN III)

Back 89

Oculomotor nerve --> Ciliary ganglion --> Pupillary constrictor muscle, ciliary muscle

Front 90

Trace the parasympathetic fibers of the Facial nerve (CN VII)

Back 90

Facial nerve --> Pterygopalatine ganglion (--> Lacrimal glands, glands of nasal mucosa) and Submandibular ganglion (--> Submandibular gland, sublingual gland)

Front 91

Trace the parasympathetic fibers of the Glossopharyngeal nerve (CN IX)

Back 91

Glossopharyngeal nerve --> Otic ganglion --> Parotid gland

Front 92

What are the three salivary glands?

Back 92

Submandibular
Sublingual
Parotid

Front 93

Trace the parasympathetic fibers of the Vagus nerve (CN X)

Back 93

Vagus nerve --> Intramural ganglion --> Smooth m., Cardiac m., Secretory Glands in the Heart, Lung, Viscera, GI tract to descending colon

Front 94

Where are preganglionic neurons of the parasympathetic nervous system located?

Back 94

CNS

Front 95

Where are postganglionic neurons of the parasympathetic nervous system located?

Back 95

PNS

Front 96

Where are preganglionic neurons of the sympathetic nervous system?

Back 96

Thoraco-lumbar system

Front 97

Trace the path of the sympathetic neurons from the spinal cord.

Back 97

Spinal Cord --> Anterolateral Sulcus --> Gray Ramus (medial) and White Ramus (lateral) --> Sympathetic Chain Ganglion --> Preganglionic Sympathetic Neurons (between ganglia of sympathetic chain), and Splanchnic Nerve --> Collateral Sympathetic Ganglion --> Neuroeffector junctions on smooth muscle, cardiac muscle, secretory glands, metabolic cells, immune cells.

Front 98

What are the targets of the sympathetic nervous system fibers?

Back 98

All visceral organs – smooth muscle
Smooth muscles of arteries and veins
Exclusive innervation to sweat glands and piloerector muscles of the skin.
Exclusive innervation to tarsal eye lid muscle and dilator pupillary muscle

Front 99

What are the targets of parasympathetic nervous system fibers?

Back 99

Exclusive innervation of constrictor pupillary and ciliary muscles
Salivary and lachrymal glands
Smooth muscle of all viscera and associated glands