Term
| how many segments does the spinal cord have? |
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Definition
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Term
| what are the two enlargements of the spinal cord? |
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Definition
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Term
| what does a radiculopathy involve? |
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Definition
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Term
| around joints, movements can be thought of as having? |
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Definition
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Term
| the dura is continuous with the ______ past the ganglia. |
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Definition
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Term
| if you find several neutrophils in the CSF, the patient has? |
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Definition
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Term
| what do the enlargements of the spinal cord receive and send? |
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Definition
| receive sensory (afferent) information from the limbs and sends motor (efferent) axons to the limb muscles |
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Term
| where does the dural sac (thecal sac) typically end? |
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Definition
| S2, the level which is marked by a line through the posterior superior iliac spines (PSISs) |
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Term
| the spinal cord is attached distally to the coccyx by the _____ ______. |
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Definition
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Term
| the internal filum of the filum terminale is formed by what? |
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Definition
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Term
| the external filum of the filum terminale has a covering of what? |
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Definition
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Term
| which root of the spinal cord is associated with motor/efferent? |
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Definition
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Term
| which region of the spinal cord is associated with sensory/afferent? |
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Definition
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Term
| the spinal ganglion is derived from what structure? |
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Definition
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Term
| what does the spinal ganglion contain? |
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Definition
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Term
| True or false: many muscles contain portions of more than one myotome. |
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Definition
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Term
| what is a radiculopathy and what does it affect? |
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Definition
| an injury to a spinal nerve and affects the dermatome innervated by the segment from which that nerve arises. |
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Term
| True or false: Because a myotome contributes to more than one muscle, a radiculopathy causes muscle weakness in multiple muscles rather than paralysis of those muscles. |
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Definition
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Term
| peripheral nerve injuries affect how many dermatomes? |
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Definition
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Term
| what do peripheral nerve injuries cause? |
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Definition
| affect adjacent dermatomes and cause paralysis of the innervated muscles |
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Term
| what do sensory tracts carry? |
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Definition
| sensory information to the brain |
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Term
| what are motor tracts involved in? |
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Definition
| movement; neurons in the cortex that control movement are called upper motor neurons |
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Term
| what are upper motor neurons? |
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Definition
| neurons in the cortex that control movement |
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Term
| True or false: tracts in the spinal cord white matter are somatotopically organized. |
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Definition
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Term
| where are lower motor neurons located? |
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Definition
| reside in the anterior horn of the spinal cord |
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Term
| what do lower motor neurons innervate? |
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Definition
| their axons innervate skeletal muscle; form the motor portions of peripheral nerves and are called "the final common pathway" because they receive input from higher brain areas such as the cerebral cortex |
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Term
| where are upper motor neurons generally located? |
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Definition
| in higher centers such as the motor cortex |
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Term
| what do the axons of upper motor neurons do? |
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Definition
| they excite or inhibit lower motor neurons |
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Term
| what is the name of the region where the upper motor neuron crosses over into the lower motor neuron? |
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Definition
| caudal medulla-spinal cord junction (in the brain stem) |
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Term
| where are the lower motor neurons that innervate axial muscles generally located in the anterior horn? |
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Definition
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Term
| where are the lower motor neurons innervating the proximal limb muscles generally located in the anterior horn? |
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Definition
| lateral; lower motor neurons innervating the more distal limb muscles are most lateral |
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Term
| lower motor neurons innervating flexors are more ______ and those innervating extensors are more _____. |
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Definition
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Term
| what is the afferent component of somatic reflexes? |
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Definition
Primary afferent (sensory) neurons reside in spinal (dorsal root) ganglia.
Peripheral axon carries information from receptors in skin, muscles, tendons or joints.
Central axons, within the posterior spinal roots (dorsal roots), carry information into the spinal cord. |
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Term
| what is the efferent component of somatic reflexes? |
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Definition
Spinal efferent (motor) neurons, lower motor neurons, reside in the anterior horn.
Alpha motor neurons form neuromuscular junctions on extrafusal muscle fibers. These fibers generate force.
A single alpha motor neuron and the muscle fibers that it innervates is call a motor unit.
In large muscles (e.g. quadriceps femoris) with course movements, motor units are large.
In small muscles (e.g. extraocular eye muscles) with fine, precise movements, motor units are small.
Gamma motor neurons form junctions on intrafusal muscle fibers. These fibers regulate tension on muscle spindles.
They use acetylcholine as their transmitter |
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Term
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Definition
| a single alpha motor neuron and the muscle fibers that it innervates |
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Term
| what does the muscle spindle detect? |
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Definition
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Term
| what 2 functions do reflexes serve? |
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Definition
| postural and protective functions |
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Term
| what do absent reflexed (areflexia) or diminished reflexes (hyporeflexia)indicate? |
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Definition
| a problem with the particular spinal segment or segments involved in the reflex being tested |
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Term
| what may increased reflexes (hyperreflexia) indicate? |
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Definition
| upper motor neuron problems |
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Term
| list and describe some of the superficial reflexes |
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Definition
Stroke the skin of the abdomen, underlying muscles will contract.
Upper abdomen: T7-T9
Lower abdomen: T10-T11
Cremasteric reflex involves stroking the skin of the medial thigh. Cremasteric muscle contracts elevating testis.
Tests T12, L1 and L2
Plantar reflex involves stroking bottom of foot from heel to toe. Provokes plantar flexion of toes.
Tests L4, L5, S1 and S2
“Anal Wink” involves stimulus of perianal region. Anal sphincter contracts.
Tests S2-S4 |
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Term
| how are deep tendon reflexes graded? |
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Definition
on a 0 to +4 scale
0 – no response – called areflexia
+2 – normal
+4 – referred to as hyperreflexia |
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Term
| what is the main spinal root involved in the ankle reflex? |
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Definition
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Term
| what is the main spinal root involved in the knee reflex? |
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Definition
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Term
| what is the main spinal root involved in the brachioradialis reflex? |
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Definition
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Term
| what is the main spinal root involved in the triceps reflex? |
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Definition
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Term
| describe the mechanism of deep tendon reflexed |
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Definition
Muscle spindles detect muscle length and stretch.
When a muscle is stretch by tapping its tendon with a reflex hammer, that information is carried to the spinal cord by a 1a afferent axon.
The 1a fiber is a proprioceptive afferent, i.e. carries information about deep somatic structures.
The 1a fibers synapse directly on alpha motor neurons that innervate the muscle (monosynaptic).
The alpha motor neurons fires and the muscle contracts.
Alpha motor neurons innervating the antagonist muscle are inhibited. |
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Term
| what is the flexor withdrawal crossed extensor reflex? |
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Definition
This is a polysynaptic reflex.
A painful or noxious stimulus to the foot causes a flexor withdrawal reflex.
To maintain balance and posture, extensor motor neurons on the opposite (contralateral) side are activated. |
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Term
| where does the lateral corticospinal tract arise from? |
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Definition
| upper motor neurons in the motor cortex |
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Term
| what does the lateral corticospinal tract innervate? |
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Definition
| lower motor neurons which innervate limb muscles |
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Term
| what percent of axons cross in the pyramidal decussation? |
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Definition
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Term
| what is the postcentral gyrus, Brodmann's areas 3,1,2? |
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Definition
| the primary sensory cortex |
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Term
| list and describe the 2 major sensory pathways in a somatosensory system. |
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Definition
Dorsal columns (lemniscal system)
discriminative touch, proprioception, and vibratory sense
Crosses in the medulla
Anterolateral (spinothalamic) system
crude touch, pain and temperature
Crosses in the spinal cord |
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Term
| which ascending sensory pathway carries crude touch, pain and temperature sense while crossing in the spinal cord? |
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Definition
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Term
| which ascending sensory pathway carries discriminative touch, vibration sense and proprioception while crossing in the medulla? |
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Definition
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Term
| what damage does upper motor neuron injury cause? |
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Definition
Injury of corticospinal system (pyramidal tract) anywhere above the pyramidal decussation causes contralateral paralysis paresis of the limbs.
Injury below the pyramidal decussation will cause ipsilateral paralysis or paresis below the lesion. |
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Term
| injury to the ____ ____ will cause loss of pain and temperature sense on the contralateral side below the lesion. |
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Definition
| spinal cord; Such an injury will cause ipsilateral loss of fine (discriminative) touch, proprioception and vibration below the lesion. |
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Term
| what does the pia mater form? |
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Definition
| denticulate ligaments and internal filum terminale |
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Term
| what is the dura mater derived from? |
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Definition
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Term
| what is the dura mater composed of? |
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Definition
| dense connective tissue with longitudinal collagen fibers with circular elastic fibers |
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Term
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Definition
Arachnoid and pia mater
Believed derived from neural crest
Arachnoid and pia contain blood vessels |
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Term
| describe the dural or thecal sac |
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Definition
The dura encloses the dural or thecal sac
The thecal sac ends at S2
Below S2 the dura continues as the external filum terminale which ends at the coccyx
The dura and extends laterally into the intervetebral foraminae to enclose the spinal ganglia |
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Term
| Can one enter the subdural space with a needle in a living patient? |
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Definition
| No, it is a potential space |
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Term
| what does the subarachnoid space function as? |
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Definition
| a cushion for the spinal cord; contains CSF |
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Term
| what is a spinal tap used for? |
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Definition
| sampling CSF or measuring intrathecal pressure |
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Term
| where is the needle inserted in a spinal tap? |
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Definition
| through the ligamentum flavum between L# and L4 or between L4 and L5; caudal to the spinal cord; the roots are not damaged, they are pushed aside within the CSF like spaghetti is a bag od water reference |
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Term
| what does an epidural allow for? |
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Definition
| allows for selective blockage of roots without affecting the cord |
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Term
| where is the anesthetic infused during an epidural? |
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Definition
| around the outside of the dural sac |
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Term
| where is the anesthetic place in spinal anesthesia? |
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Definition
| put in the subarachnoid space |
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Term
| what are the 2 components of the vertical arterial supply? |
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Definition
Single Anterior Artery
Arises intracranially from the vertebral arteries
Two Posterior Arteries
Typically arise intracranially from the vertebral arteries, but may arise from the posterior inferior cerebellar arteries |
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Term
| what are the components of the horizontal arterial supply to the spinal cord? |
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Definition
Segmental medullary arteries supplement anterior and posterior arteries
Lower 2/3 of cord dependent on a medullary segmental artery that is usually larger than the others, the arteria radicularis magna or great radicular artery of Adamkiewicz which typically (65% of people) arises on the left at T12 or L1 |
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Term
| does the epidural plexus which drains the spinal cord and meninges have any valves? |
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Definition
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Term
| what effect can increased intra-abdominal pressure have on blood? |
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Definition
| Increased intra-abdominal pressure can cause a reflux of blood into the plexus and thereby carry metastatic cells, such as prostate CA and infections, such as pelvic infections, along the spinal column to more cranial levels. |
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