Ascending Sensory Pathways Quiz

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Questions and Answers

Which type of tracts deliver information to the brain?

Ascending tracts (correct)

Propriospinal tracts

Descending tracts

Anterior funiculus

What is the function of the posterior funiculus?

Primarily ascending tracts (correct)

Primarily descending tracts

Deliver information to periphery

Both ascending and descending tracts

Which tract delivers information from the spinal cord to the cerebellum?

Vestibulospinal tract

Spinocerebellar tract (correct)

Propriospinal tract

Spinothalamic tract

What is the role of the lateral funiculus?

Both ascending and descending tracts Signup and view all the answers

Where are the fibers of the ascending tracts derived from?

Spinal nerves Signup and view all the answers

What is a characteristic of funiculus in the spinal cord?

Large bundles known as fasciculi Signup and view all the answers

How are tracts named in relation to the spinal cord?

"Spino" for sensory tracts and "spinal" for motor tracts Signup and view all the answers

Where is the cell body of the second-order neuron in the spinothalamic tract located?

Spinal cord Signup and view all the answers

Which sensations are carried by the lateral spinothalamic tract?

Pain and temperature Signup and view all the answers

What is the clinical manifestation of a lesion in the spinothalamic tract in the brain stem or spinal cord?

Contralateral loss of pain and temperature Signup and view all the answers

Which tracts carry discriminative touch, joint position sense, vibration, and pressure sensation?

Dorsal column-medial lemniscal pathway Signup and view all the answers

What is the function of the spinocerebellar tracts?

Carry sensory information from the spinal cord to the cerebellum for monitoring and modulating movements Signup and view all the answers

Which tract carries tactile, pressure, and proprioceptive input from muscle spindles and GTO to the cerebellum for monitoring and modulating movements?

Posterior spinocerebellar tract Signup and view all the answers

What is astereognosis associated with?

Dorsal column-medial lemniscal lesions Signup and view all the answers

Which sensory receptor is imbedded in tendons of skeletal muscles and monitors the degree of tension and force placed on the skeletal muscle?

Golgi tendon organs (GTO) Signup and view all the answers

Which pathway is responsible for reflex postural movements in response to visual stimuli?

Tectospinal Tract Signup and view all the answers

Lesions above the decussation of the corticospinal tract result in weakness seen in muscles on which side of the body?

Contralateral side Signup and view all the answers

What is the characteristic response of an upper motor neuron (UMN) lesion?

Increase in muscle tonus followed by sudden decrease in resistance to stretch Signup and view all the answers

Which descending pathway inhibits or facilitates voluntary movement and has some fibers that cross the midline at various levels?

Reticulospinal Tract Signup and view all the answers

What is the function of the Rubrospinal Tract?

Facilitates activity of extensor muscles Signup and view all the answers

Which descending pathway facilitates activity of extensor muscles and inhibits activity of flexor muscles?

Vestibulospinal Tract Signup and view all the answers

Which descending pathway originates from the red nucleus in the mid-brain and facilitates activity of flexor muscles?

Rubrospinal Tract Signup and view all the answers

Which fibers control autonomic systems and originate from the cortex, hypothalamus, amygdala, and reticular formation?

Descending Autonomic Fibers Signup and view all the answers

Which descending tract in the spinal cord carries afferent information for spinovisual reflexes?

Spinotectal tract Signup and view all the answers

Which tract in the spinal cord carries afferents influencing levels of consciousness?

Spinoreticular tract Signup and view all the answers

Which descending tract in the spinal cord carries balance and unconscious proprioceptive afferent information to the cerebellum?

Spinoolivary tract Signup and view all the answers

Which neural circuit is involved in initiating a voluntary contraction of skeletal muscle?

UMN and LMN Signup and view all the answers

Where are the cell bodies of UMN located?

Brain stem and cerebral cortex Signup and view all the answers

Which reflex is the simplest and involves only one synapse between 1 sensory and 1 motor neuron?

Deep muscle stretch (myotatic) reflex Signup and view all the answers

Which tract is responsible for the voluntary innervation of skeletal muscle, descending through the brain stem?

Corticospinal Tract Signup and view all the answers

Which type of tracts carry discriminative touch, joint position sense, vibration, and pressure sensation?

Posterior funiculus Signup and view all the answers

Where are the cell bodies of upper motor neurons (UMNs) located?

In the cerebral cortex Signup and view all the answers

What is the function of the rubrospinal tract?

Facilitates activity of extensor muscles Signup and view all the answers

Which descending pathway originates from the red nucleus in the mid-brain and facilitates activity of flexor muscles?

Rubrospinal tract Signup and view all the answers

What is the characteristic response of an upper motor neuron (UMN) lesion?

Hypertonia and hyperreflexia Signup and view all the answers

Which descending tract in the spinal cord carries afferent information for spinovisual reflexes?

Tectospinal tract Signup and view all the answers

Which neurons are used in the grey matter and tracts of axons in the grey matter of the spinal cord?

First-order neurons Signup and view all the answers

Which descending tract in the spinal cord carries afferent information for spinovisual reflexes?

Spinotectal tract Signup and view all the answers

Where do the corticospinal fibers descend through in the brain stem?

Ventral portion of the pons Signup and view all the answers

Which tract carries balance and unconscious proprioceptive afferent information to the cerebellum?

Spinoolivary tract Signup and view all the answers

Where do the corticospinal fibers cross at the decussation of the pyramids?

80-90% Signup and view all the answers

Which descending pathway originates from the red nucleus in the midbrain and facilitates activity of flexor muscles?

Rubrospinal Tract Signup and view all the answers

What is the characteristic response of an upper motor neuron (UMN) lesion?

Clonus Signup and view all the answers

Which fibers control autonomic systems and originate from the cortex, hypothalamus, amygdala, and reticular formation?

Reticulospinal fibers Signup and view all the answers

Where is the cell body of the third-order neuron in the spinothalamic tract located?

Thalamus Signup and view all the answers

Which descending pathway is responsible for reflex postural movements in response to visual stimuli?

Tectospinal Tract Signup and view all the answers

Which tract carries information related to pain, temperature, tickle, itch, and sexual sensations?

Anterior Spinothalmic Tract Signup and view all the answers

Where are the cell bodies of gamma motor neurons located?

Anterior grey column Signup and view all the answers

Which tract is responsible for carrying discriminative touch, joint position sense (kinesthetic), vibration, and pressure sensation?

Dorsal Column - Medial Lemniscal Pathway Signup and view all the answers

What is the characteristic response of an upper motor neuron (UMN) lesion?

Increase in muscle tonus and resistance to stretch Signup and view all the answers

Which tract carries tactile, pressure, and proprioceptive input from muscle spindles and GTO to the cerebellum for monitoring and modulating movements?

Posterior Spinocerebellar Tract Signup and view all the answers

Which descending pathway originates from the red nucleus in the mid-brain and facilitates activity of flexor muscles?

Rubrospinal Tract Signup and view all the answers

What is the clinical manifestation of a lesion in the spinothalamic tract in the brain stem or spinal cord?

Contralateral loss of pain and temperature Signup and view all the answers

Which descending pathway inhibits or facilitates voluntary movement and has some fibers that cross the midline at various levels?

Reticulospinal Tract Signup and view all the answers

What is astereognosis associated with?

Loss of ability to identify an object by touching with hands Signup and view all the answers

What is the function of the Vestibulospinal Tract?

Facilitates activity of extensor muscles Signup and view all the answers

Where do the fibers of the anterior spinocerebellar tract ultimately end?

Ipsilateral side Signup and view all the answers

Where do the descending autonomic fibers controlling autonomic systems originate from?

Reticular formation Signup and view all the answers

What is the role of the 1b afferent neurons stimulated by Golgi tendon organs?

Inhibit alpha motor neurons Signup and view all the answers

Which descending pathway gives multiple branches at each level and represents about 30% of fibers going to the muscle?

Reticulospinal Tract Signup and view all the answers

Where is the cell body of the third-order neuron in the spinothalamic tract located?

In the thalamus Signup and view all the answers

Where do the corticospinal fibers descend through in the brain stem?

Pons Signup and view all the answers

What is astereognosis associated with?

Inability to identify an object by touching with hands Signup and view all the answers

Which descending pathway originates from the red nucleus in the midbrain and facilitates activity of flexor muscles?

Rubrospinal Tract Signup and view all the answers

Which neural circuit is involved in initiating a voluntary contraction of skeletal muscle?

Reticulospinal Tract Signup and view all the answers

Where are the cell bodies of gamma motor neurons located?

Spinal Cord Signup and view all the answers

What is the function of the spinocerebellar tracts?

Monitor and modulate movements using sensory input from muscle spindles and GTO Signup and view all the answers

Which type of tracts primarily carry information to the brain?

Ascending tracts Signup and view all the answers

What is the specific function of the rubrospinal tract?

Inhibiting or facilitating voluntary movement Signup and view all the answers

Where are the cell bodies of upper motor neurons (UMNs) located?

In the motor cortex of the brain Signup and view all the answers

Which sensory receptor is embedded in tendons of skeletal muscles and monitors the degree of tension and force placed on the skeletal muscle?

Golgi tendon organ (GTO) Signup and view all the answers

What is the clinical manifestation of a lesion in the spinothalamic tract in the brain stem or spinal cord?

Impaired pain and temperature sensation Signup and view all the answers

Where do the corticospinal fibers cross at the decussation of the pyramids?

Cervical level of the spinal cord Signup and view all the answers

Which descending pathway originates from the red nucleus in the mid-brain and facilitates activity of flexor muscles?

Rubrospinal tract Signup and view all the answers

Which tract carries afferent information for spinovisual reflexes and terminates by synapsing on neurons in the superior colliculus?

Spinotectal tract Signup and view all the answers

Which descending pathway inhibits or facilitates voluntary movement and has some fibers that cross the midline at various levels?

Rubrospinal Tract Signup and view all the answers

Where are the fibers of the ascending tracts derived from?

Spinal Cord Signup and view all the answers

What is the role of the lateral funiculus?

Facilitating activity of flexor muscles Signup and view all the answers

Which sensory receptor is embedded in tendons of skeletal muscles and monitors the degree of tension and force placed on the skeletal muscle?

Golgi Tendon Organs (GTO) Signup and view all the answers

What is astereognosis associated with?

Lesion in the Spinocerebellar tracts Signup and view all the answers

Which neural circuit is involved in initiating a voluntary contraction of skeletal muscle?

UMN and LMN circuit Signup and view all the answers

Which descending pathway originates from the red nucleus in the midbrain and facilitates activity of flexor muscles?

Rubrospinal Tract Signup and view all the answers

What is the characteristic response of an upper motor neuron (UMN) lesion?

Increased muscle tonus and sudden decrease in resistance to stretch Signup and view all the answers

Where are the cell bodies of gamma motor neurons located?

Anterior grey column Signup and view all the answers

Which descending pathway is responsible for reflex postural movements in response to visual stimuli?

Tectospinal Tract Signup and view all the answers

What is the role of the 1b afferent neurons stimulated by Golgi tendon organs?

Inhibit alpha motor neurons Signup and view all the answers

Which descending pathway facilitates activity of extensor muscles and inhibits activity of flexor muscles?

Vestibulospinal Tract Signup and view all the answers

Where do the corticospinal fibers cross at the decussation of the pyramids?

Medulla oblongata Signup and view all the answers

Which tract carries tactile, pressure, and proprioceptive input from muscle spindles and GTO to the cerebellum for monitoring and modulating movements?

Spinocerebellar Tracts Signup and view all the answers

What is the function of the Rubrospinal Tract?

Facilitates activity of extensor muscles Signup and view all the answers

Which type of tracts primarily carry information to the brain?

Ascending tracts Signup and view all the answers

What is the role of the lateral funiculus?

Facilitates intersegmental coordination Signup and view all the answers

Where are the cell bodies of gamma motor neurons located?

Grey matter of the spinal cord Signup and view all the answers

Which descending pathway inhibits or facilitates voluntary movement and has some fibers that cross the midline at various levels?

Rubrospinal tract Signup and view all the answers

What is the characteristic response of an upper motor neuron (UMN) lesion?

Increased muscle tone and hyperreflexia Signup and view all the answers

Where is the cell body of the third-order neuron in the spinothalamic tract located?

Thalamus Signup and view all the answers

What is the function of the Vestibulospinal Tract?

Facilitates activity of extensor muscles and inhibits activity of flexor muscles Signup and view all the answers

Where is the cell body of the third-order neuron in the spinothalamic tract located?

In the thalamus Signup and view all the answers

Which tract carries pain, temperature, tickle, itch, and sexual sensations?

Lateral Spinothalamic Tract Signup and view all the answers

Where do the axons of the second neuron in the dorsal column-medial lemniscal pathway cross midline and ascend as the medial tract in the brain stem?

Medulla Signup and view all the answers

Which spinocerebellar tract is responsible for conveying tactile, pressure, and proprioceptive information from muscle spindles and GTO to the cerebellum?

Posterior Spinocerebellar Tract Signup and view all the answers

What is the characteristic clinical manifestation of a lesion in the spinothalamic tract in the brain stem or spinal cord?

Ipsilateral loss of pain and temperature sensation Signup and view all the answers

What is the clinical correlate of lesions in the dorsal column-medial lemniscal pathway?

Loss of discriminative touch and joint position sense Signup and view all the answers

Where do the second-order neurons in the spinothalamic tract have their cell bodies located?

In the spinal cord Signup and view all the answers

Which tract carries balance and unconscious proprioceptive afferent information to the cerebellum?

Spinoolivary tract Signup and view all the answers

Where do the corticospinal fibers cross at the decussation of the pyramids?

80-90% of fibers cross at the decussation of the pyramids Signup and view all the answers

What is the primary motor cortex responsible for?

Initiating voluntary contraction of skeletal muscle Signup and view all the answers

Which neurons initiate involuntary motor responses to a sensory stimulus?

Sensory neurons Signup and view all the answers

What is the characteristic response of an upper motor neuron (UMN) lesion?

Hyperreflexia and muscle atrophy Signup and view all the answers

Which descending pathway originates from the red nucleus in the midbrain and facilitates activity of flexor muscles?

Rubrospinal tract Signup and view all the answers

Which neural circuit is involved in initiating a voluntary contraction of skeletal muscle?

UMN and LMN circuit Signup and view all the answers

Which descending pathway originates from the red nucleus in the mid-brain and facilitates activity of flexor muscles?

Rubrospinal Tract Signup and view all the answers

What is the characteristic response of an upper motor neuron (UMN) lesion?

Increased resistance to muscle stretch followed by sudden decrease Signup and view all the answers

Where are the cell bodies of gamma motor neurons located?

Anterior grey column Signup and view all the answers

What is astereognosis associated with?

Inability to recognize objects by touch Signup and view all the answers

Where do the descending autonomic fibers controlling autonomic systems originate from?

Reticular formation Signup and view all the answers

Which descending pathway inhibits or facilitates voluntary movement and has some fibers that cross the midline at various levels?

Reticulospinal Tract Signup and view all the answers

What is the function of the spinocerebellar tracts?

Deliver information from the spinal cord to the cerebellum for monitoring and modulating movements Signup and view all the answers

Which type of tracts carry discriminative touch, joint position sense, vibration, and pressure sensation?

Posterior column-medial lemniscus pathway Signup and view all the answers

Where are the cell bodies of upper motor neurons (UMNs) located?

Primary motor cortex Signup and view all the answers

Study Notes

Friedreich's Ataxia: three descending tracts in the spinal cord: Spinotectal, Spinoreticular, and Spinoolivary
Spinotectal tract: carries afferent information for spinovisual reflexes, terminates by synapsing on neurons in the superior colliculus
Spinoreticular tract: carries afferents influencing levels of consciousness, terminates on neurons in the reticular formation
Spinoolivary tract: carries balance and unconscious proprioceptive afferent information to the cerebellum, 3rd order neurons in the inferior olivary nuclei in the medulla, axons cross and enter the cerebellum
Sensory tracts: organization based on the site of origin, arranged in a somatotopic manner, medial-lateral rule: neurons that enter a lower level of the spinal cord are more medial, neurons that enter at a higher level are more lateral
Motor system: voluntary innervation of skeletal muscle, basic neural circuit: upper motor neuron (UMN) and lower motor neuron (LMN), initiating a voluntary contraction: an LMN must be innervated by a UMN, UMN: LMN: cell bodies in brain stem and cerebral cortex, cell bodies in the ventral horn of the spinal cord and cranial nerve nuclei in the brain stem, LMN (in spinal cord) axons exit the spinal cord in a ventral root, join and course with a spinal nerve, reach and synapse on a neuromuscular junction in skeletal muscle
Motor neuron groups in the spinal cord: Anterior Grey Column, Alpha Efferents: large, multipolar LMN of brainstem and spinal cord, innervate extrafusal muscle fibers of skeletal muscle, present in most segments, innervate skeletal muscles of neck, trunk, intercostals, abdominals, present in some cervical and lumbosacral segments, innervate the diaphragm, accessory nucleus, lumbosacral nucleus, Corticospinal Tract: voluntary innervation of skeletal muscle, primary motor cortex: precentral gyrus of the frontal lobe, corticospinal fibers descend through the brain stem in the ventral portion of the mid brain, pons, and medulla, corticospinal tract in the lower medulla: 80-90% of fibers cross at the decussation of the pyramids, continue in the contralateral part of the spinal cord as the lateral corticospinal tract, descend full length of the cord in the lateral part of the white matter, as it descends axons leave and enter the gray matter of the ventral horn to synapse on a LMN, corticospinal tract in the lower medulla: 80-90% of fibers cross at the decussation of the pyramids, corticospinal tract reflex innervation of skeletal muscle: involuntary motor responses to a sensory stimulus, requires a minimum of 2 neurons: a sensory neuron that initiates a motor response and lower motor neurons, reflexes range from simple 2-neuron circuits to more complex reflexes, deep muscle stretch (myotatic) reflex: simplest of the reflexes, involves only one synapse between 1 sensory and 1 motor neuron, tests the integrity of the reflex in the limbs provides important clinical information when assessing different types of motor weaknesses and dysfunction, present in most skeletal muscles, provides the important physiological mechanism of regulating and maintaining proper muscle tone throughout the skeletal muscular system.
Friedreich's Ataxia: three descending tracts in the spinal cord: Spinotectal, Spinoreticular, and Spinoolivary
Spinotectal tract: carries afferent information for spinovisual reflexes, terminates by synapsing on neurons in the superior colliculus
Spinoreticular tract: carries afferents influencing levels of consciousness, terminates on neurons in the reticular formation
Spinoolivary tract: carries balance and unconscious proprioceptive afferent information to the cerebellum, 3rd order neurons in the inferior olivary nuclei in the medulla, axons cross and enter the cerebellum
Sensory tracts: organization based on the site of origin, arranged in a somatotopic manner, medial-lateral rule: neurons that enter a lower level of the spinal cord are more medial, neurons that enter at a higher level are more lateral
Motor system: voluntary innervation of skeletal muscle, basic neural circuit: upper motor neuron (UMN) and lower motor neuron (LMN), initiating a voluntary contraction: an LMN must be innervated by a UMN, UMN: LMN: cell bodies in brain stem and cerebral cortex, cell bodies in the ventral horn of the spinal cord and cranial nerve nuclei in the brain stem, LMN (in spinal cord) axons exit the spinal cord in a ventral root, join and course with a spinal nerve, reach and synapse on a neuromuscular junction in skeletal muscle
Motor neuron groups in the spinal cord: Anterior Grey Column, Alpha Efferents: large, multipolar LMN of brainstem and spinal cord, innervate extrafusal muscle fibers of skeletal muscle, present in most segments, innervate skeletal muscles of neck, trunk, intercostals, abdominals, present in some cervical and lumbosacral segments, innervate the diaphragm, accessory nucleus, lumbosacral nucleus, Corticospinal Tract: voluntary innervation of skeletal muscle, primary motor cortex: precentral gyrus of the frontal lobe, corticospinal fibers descend through the brain stem in the ventral portion of the mid brain, pons, and medulla, corticospinal tract in the lower medulla: 80-90% of fibers cross at the decussation of the pyramids, continue in the contralateral part of the spinal cord as the lateral corticospinal tract, descend full length of the cord in the lateral part of the white matter, as it descends axons leave and enter the gray matter of the ventral horn to synapse on a LMN, corticospinal tract in the lower medulla: 80-90% of fibers cross at the decussation of the pyramids, corticospinal tract reflex innervation of skeletal muscle: involuntary motor responses to a sensory stimulus, requires a minimum of 2 neurons: a sensory neuron that initiates a motor response and lower motor neurons, reflexes range from simple 2-neuron circuits to more complex reflexes, deep muscle stretch (myotatic) reflex: simplest of the reflexes, involves only one synapse between 1 sensory and 1 motor neuron, tests the integrity of the reflex in the limbs provides important clinical information when assessing different types of motor weaknesses and dysfunction, present in most skeletal muscles, provides the important physiological mechanism of regulating and maintaining proper muscle tone throughout the skeletal muscular system.
Friedreich's Ataxia: three descending tracts in the spinal cord: Spinotectal, Spinoreticular, and Spinoolivary
Spinotectal tract: carries afferent information for spinovisual reflexes, terminates by synapsing on neurons in the superior colliculus
Spinoreticular tract: carries afferents influencing levels of consciousness, terminates on neurons in the reticular formation
Spinoolivary tract: carries balance and unconscious proprioceptive afferent information to the cerebellum, 3rd order neurons in the inferior olivary nuclei in the medulla, axons cross and enter the cerebellum
Sensory tracts: organization based on the site of origin, arranged in a somatotopic manner, medial-lateral rule: neurons that enter a lower level of the spinal cord are more medial, neurons that enter at a higher level are more lateral
Motor system: voluntary innervation of skeletal muscle, basic neural circuit: upper motor neuron (UMN) and lower motor neuron (LMN), initiating a voluntary contraction: an LMN must be innervated by a UMN, UMN: LMN: cell bodies in brain stem and cerebral cortex, cell bodies in the ventral horn of the spinal cord and cranial nerve nuclei in the brain stem, LMN (in spinal cord) axons exit the spinal cord in a ventral root, join and course with a spinal nerve, reach and synapse on a neuromuscular junction in skeletal muscle
Motor neuron groups in the spinal cord: Anterior Grey Column, Alpha Efferents: large, multipolar LMN of brainstem and spinal cord, innervate extrafusal muscle fibers of skeletal muscle, present in most segments, innervate skeletal muscles of neck, trunk, intercostals, abdominals, present in some cervical and lumbosacral segments, innervate the diaphragm, accessory nucleus, lumbosacral nucleus, Corticospinal Tract: voluntary innervation of skeletal muscle, primary motor cortex: precentral gyrus of the frontal lobe, corticospinal fibers descend through the brain stem in the ventral portion of the mid brain, pons, and medulla, corticospinal tract in the lower medulla: 80-90% of fibers cross at the decussation of the pyramids, continue in the contralateral part of the spinal cord as the lateral corticospinal tract, descend full length of the cord in the lateral part of the white matter, as it descends axons leave and enter the gray matter of the ventral horn to synapse on a LMN, corticospinal tract in the lower medulla: 80-90% of fibers cross at the decussation of the pyramids, corticospinal tract reflex innervation of skeletal muscle: involuntary motor responses to a sensory stimulus, requires a minimum of 2 neurons: a sensory neuron that initiates a motor response and lower motor neurons, reflexes range from simple 2-neuron circuits to more complex reflexes, deep muscle stretch (myotatic) reflex: simplest of the reflexes, involves only one synapse between 1 sensory and 1 motor neuron, tests the integrity of the reflex in the limbs provides important clinical information when assessing different types of motor weaknesses and dysfunction, present in most skeletal muscles, provides the important physiological mechanism of regulating and maintaining proper muscle tone throughout the skeletal muscular system.
Friedreich's Ataxia: three descending tracts in the spinal cord: Spinotectal, Spinoreticular, and Spinoolivary
Spinotectal tract: carries afferent information for spinovisual reflexes, terminates by synapsing on neurons in the superior colliculus
Spinoreticular tract: carries afferents influencing levels of consciousness, terminates on neurons in the reticular formation
Spinoolivary tract: carries balance and unconscious proprioceptive afferent information to the cerebellum, 3rd order neurons in the inferior olivary nuclei in the medulla, axons cross and enter the cerebellum
Sensory tracts: organization based on the site of origin, arranged in a somatotopic manner, medial-lateral rule: neurons that enter a lower level of the spinal cord are more medial, neurons that enter at a higher level are more lateral
Motor system: voluntary innervation of skeletal muscle, basic neural circuit: upper motor neuron (UMN) and lower motor neuron (LMN), initiating a voluntary contraction: an LMN must be innervated by a UMN, UMN: LMN: cell bodies in brain stem and cerebral cortex, cell bodies in the ventral horn of the spinal cord and cranial nerve nuclei in the brain stem, LMN (in spinal cord) axons exit the spinal cord in a ventral root, join and course with a spinal nerve, reach and synapse on a neuromuscular junction in skeletal muscle
Motor neuron groups in the spinal cord: Anterior Grey Column, Alpha Efferents: large, multipolar LMN of brainstem and spinal cord, innervate extrafusal muscle fibers of skeletal muscle, present in most segments, innervate skeletal muscles of neck, trunk, intercostals, abdominals, present in some cervical and lumbosacral segments, innervate the diaphragm, accessory nucleus, lumbosacral nucleus, Corticospinal Tract: voluntary innervation of skeletal muscle, primary motor cortex: precentral gyrus of the frontal lobe, corticospinal fibers descend through the brain stem in the ventral portion of the mid brain, pons, and medulla, corticospinal tract in the lower medulla: 80-90% of fibers cross at the decussation of the pyramids, continue in the contralateral part of the spinal cord as the lateral corticospinal tract, descend full length of the cord in the lateral part of the white matter, as it descends axons leave and enter the gray matter of the ventral horn to synapse on a LMN, corticospinal tract in the lower medulla: 80-90% of fibers cross at the decussation of the pyramids, corticospinal tract reflex innervation of skeletal muscle: involuntary motor responses to a sensory stimulus, requires a minimum of 2 neurons: a sensory neuron that initiates a motor response and lower motor neurons, reflexes range from simple 2-neuron circuits to more complex reflexes, deep muscle stretch (myotatic) reflex: simplest of the reflexes, involves only one synapse between 1 sensory and 1 motor neuron, tests the integrity of the reflex in the limbs provides important clinical information when assessing different types of motor weaknesses and dysfunction, present in most skeletal muscles, provides the important physiological mechanism of regulating and maintaining proper muscle tone throughout the skeletal muscular system.

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Description

Test your knowledge of ascending sensory pathways in the nervous system with this quiz. Explore the spinotectal tract, spinoreticular tract, and spinoolivary tract, and understand their roles in transmitting afferent information for various reflexes and functions.