Term
| What are the 4 essential functions of the spinal cord? |
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Definition
| receive sensory input, motor output, spinal reflexes, descending supraspinal influence |
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Term
| Where does the sensory input come from? |
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Definition
| somatosensory (skin, skeletal muscles, tendons) and viscerosensory (thoracic, abdominal, and pelvic viscera) |
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Term
| What does the motor output innervate? |
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Definition
| • contains somatic motor neurons that innervate skeletal muscles and visceral motor neurons that, after synapsing in peripheral ganglia, influence smooth and cardiac muscle and glandular epithelium |
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Term
| What is a spinal reflex arc? |
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Definition
| sensory fiber, associated motor neuron, sometimes interneuron, and involuntary muscle contraction |
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Term
| What occurs if a somatic neuron is injured? |
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Definition
| weakness (paresis) or paralysis |
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Term
| Where do the descending supraspinal fibers orignate? |
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Definition
| • these fibers originate in the cerebral cortex and brainstem, and damage to them adversely affects the activity of spinal motor and sensory neurons |
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Term
| What are the three meningeal layers? |
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Definition
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Term
| What are the enlargements of the spinal cord? |
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Definition
| cervical (C4-T1) and lumbosacral (L1-S2) enlargements, which serve, respectively, the upper and lower extremities |
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Term
| What is the cauda equina? |
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Definition
| dorsal and ventral roots of the lumbar and sacral spinal nerves that descends from the caudal end of the cord starting at the L1/L2 level |
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Term
| What are the spinal cord segments of the neck? |
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Definition
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Term
| Segments of lateral forearm and thumb? |
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Definition
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Term
| Segments of ulnar side of hand and little fingers? |
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Definition
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Term
| Segments of xiphoid process? |
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Definition
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Term
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Definition
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Term
| Segments of pubic region? |
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Definition
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Term
| Segment of dorsal foot and big toe? |
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Definition
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Term
| Segment of lateral foot and little toe? |
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Definition
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Term
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Definition
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Term
| Where is the gray matter located? |
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Definition
| centrally placed butterfly-shaped region comprised primarily of neuron cell bodies, dendrites, and synapses (collectively called neuropil) |
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Term
| What are the three zones of gray matter? |
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Definition
| dorsal (posterior) horns, intermediated gray (-L2,3 the intermediate gray contains the intermediolateral cells column or lateral horn), ventral (anterior) horns |
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Term
| What are Rexed's laminae? |
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Definition
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Term
| What laminae numbers are within the dorsal horn? |
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Definition
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Term
| What is another name for the dorsal horn? |
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Definition
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Term
| What is substantia gelatinosa? |
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Definition
| pain and temperature fibers, |
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Term
| What is a Lissauer tract? |
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Definition
| (dorsolateral fasciculus)-small piece of white matter that is related to the substantia gelatinosa since it contains axons carrying pain and temperature one or two segments higher |
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Term
| What is the nucleus propius? |
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Definition
| consists of interneurons that receive connections from dorsal root ganglion |
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Term
| What is intermediate gray matter? |
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Definition
contains mostly interneurons
includes the lateral horn or intermediolateral cell column at spinal cord levels T1-L2,3
• neurons that give origin to preganglionic sympathetic fibers |
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Term
| What is another name of the ventral horn? |
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Definition
| motor horn because it contains ventral horn cells (motor neurons, motoneurons, alpha motor neurons |
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Term
| What is the clinical name for alpha motor neurons? |
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Definition
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Term
| What are gamma motor neurons? |
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Definition
| innervation of muscle spindles for the muscle stretch reflex |
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Term
| What are the three white matter spinal columns (funiculi)? |
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Definition
• dorsal columns = dorsal funiculus
• lateral columns = lateral funiculus
• anterior columns = anterior funiculus |
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Term
| What are the three types of white matter spinal tracts? |
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Definition
| long ascending fibers, long descending fibers, propriospinal fibers |
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Term
| Where do long ascending fiber carry their sensory info? |
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Definition
thalamus
cerebellum
brainstem nuclei |
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Term
| Where do long descending fibers carry their motor information from? |
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Definition
cerebral cortex
brainstem nuclei |
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Term
| What is the function of propriospinal fibers? |
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Definition
interconnect various spinal cord levels
function in coordination of reflex activity |
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Term
| What does the dorsal primary rami do? |
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Definition
| small and supply the back muscles and skin of the back |
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Term
| What does the ventral primary rami do? |
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Definition
| large and supply the rest of the body, including the upper and lower limbs |
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Term
| What do psuedounipolar sensory neurons do? Where are they? |
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Definition
a single process that immediately divides into two processes
peripheral process extends to sensory receptors or ends as free nerve endings in the periphery
• functions as a dendrite by carrying nerve impulses (sensory information) toward the cell body
central process enters the spinal cord to synapse with cells within the dorsal horn of the spinal gray matter
• functions as an axon since it conveys information from the cell towards a synaptic ending in the spinal cord |
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Term
| What are types of exteroceptive info? |
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Definition
pain (free nerve endings)
touch (Merkel’s disks and Meissner’s corpuscles)
• light or crude touch
• discriminative touch
temperature (Krause end-bulbs)
vibration (Pacinian corpuscles)
Pressure (Merkel’s disks)
hair follicle receptors |
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Term
| What is the proprioceptive info? |
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Definition
joint receptors for awareness of movement and position of body parts
muscle stretch receptors (muscle spindles)
Golgi tendon organs for detecting muscle tension |
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Term
| What type of information do large diameter, heavily myelinated dorsal root ganglion neurons carry? |
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Definition
discriminative touch and proprioception into the spinal cord
o these cells have an axon collateral that ascends in the dorsal white column to convey their information to higher levels |
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Term
| What type of info do small, thinly-myelinated or non-myelinated, dorsal root ganglion cells carry? |
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Definition
carry pain and temperature information into the spinal cord
o these cells typically synapse with interneurons in the dorsal horn, and it is in the interneuron whose axon ascends in the white matter to convey information to higher levels |
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Term
| What are the two types motor neurons? |
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Definition
| alpha (directly innervate muscle cells), gamma (innervate muscle spindles) |
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Term
| What do the cells of the intermediolateral column (T1-L3) eventually activate? |
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Definition
| smooth muscle, cardia muscle, or glandular epithelium (preganglionic sympathetic axons) |
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Term
| What are the 3 components of a reflex? |
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Definition
| receptor, afferent, and efferent |
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Term
| What are the 3 major types of spinal reflexes? |
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Definition
| muscle stretch, flexor-withdrawal and Golgi-tendon organ reflexes |
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Term
| What is the role of the interneuron in reflexes? |
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Definition
| spinal cord interneurons frequently “connect” sensory and motor neurons forming reflex arcs |
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Term
| What is the pathway of the gamma loop? |
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Definition
| supraspinal activationgamma motor neuronintrafusal fiber contractionincrease sensory fiber activityactivation of alpha motor neurons = muscle tone via descending pathway control |
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Term
| What does the Golgi tendon organ do? |
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Definition
the afferent fiber of the Golgi tendon organ innervates inhibitory interneurons that project to motor neurons supplying the same muscle from which the afferent originates
• activation of the afferent results in inhibition of the motor neurons supplying the muscle that experiences the stretch, leading to relaxation of the muscle |
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Term
| What is the crossed extension reflex of the flexor withdrawal? |
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Definition
musculature of the opposite side of the body may also be activated by what is called the crossed extension reflex
• by way of interneurons, there is excitation of contralateral extensor muscles and inhibition of flexor muscles |
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Term
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Definition
| gain clinical information about the integrity of both the peripheral nerve and the spinal cord segments involved and the descending input |
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Term
| What happens to the DTR with a peripheral nerve injury? |
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Definition
| frequently diminished (hyporeflexia) or absent (areflexia |
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Term
| What happens to a DTR when the descending pathway is disrupted? |
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Definition
| hyperreflexia (descending pathways inhibit) |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| Ankle-jerk (achilles) reflex? |
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Definition
| gstrocnemius, soleus; S1, S2; tibial |
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Term
| Spasticity (hypertonia) is indicative of what type of abnormal activity? |
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Definition
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Term
| What signs/symptoms of UMN lesion? |
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Definition
| • often a patient with a spinal cord injury or stroke will have a combination of paralysis, hyperactive reflexes and increased muscle tone; they will be described as having spastic paralysis with hyperreflexia |
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Term
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Definition
| hyperactivity of the stretch reflex also results in an abnormal response to rapid stretch – a prolonged oscillation of contraction and relaxation of the limb |
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