Spinal cord tracts

Question 1

What type of neuron is the nociceptor in the spinothalamic pathway?

Answer 1

Pseudounipolar neuron with cell body in the dorsal root ganglion

Question 2

Lateral corticospinal tract

Answer 2

Decussates at the pyramids and descends into the spinal cord and terminates in the ventral horn to synapse with lower motor neurons. It supplies the contralateral appendicular muscles.

Question 3

Corticobulbar

Answer 3

Tract which synapses with cranial nerves

Question 4

Extrapyramidal tracts which provide contralateral innnervation

Answer 4

Rubrospinal and tectospinal tract

Question 5

Extrapyramidal tracts which provide ipsilateral innervation

Answer 5

Vestibulospinal and rubrospinal tract

Question 6

Substantia gelatinosa

Answer 6

Area in dorsal horn tip where first order neurons synapse with second order neurons after following Lissauer’s tract

Question 7

Level of decassation of second order neurons in the dorsal column pathway?

Answer 7

Medulla- after synapse in the nucleus gracilis/cuneatus, it decussates and travels up to the thalamus via the medial leminiscus tract

Question 8

Anterior corticospinal tract

Answer 8

Remains ipsilateral when descending. Terminates in the ventral horn of the cervical and upper thoracic level.

Question 9

Fine control of hand movement

Answer 9

Function of rubrospinal tract- along with ongoing muscle flexors

Question 10

Which neurons are the first to decussate in the spinothalamic tract?

Answer 10

Second order neurons following synapse with first order neurons. They decussate in the anterior white commissure.

Question 11

Corticobulbar tract

Answer 11

Pyramidal tract which arises from the primary motor cortex. It innervates the cranial nerves of the head and face. It passes through the internal capsule -> brainstem and terminates in the CONTRALATERAL cranial nerve nuclei of trgeminal, facial and hypoglossal nerve

Question 12

Lateral reticulospinal tract

Answer 12

Arises from medulla and inhibits voluntary movements and reduces muscle tone. Increases flexion muscles in the trunk and proximal limbs.

Question 13

Pyramidal tracts

Answer 13

Pass through the pyramids in medulla and provide voluntary control of body and face musculature. Includes the corticospinal and corticobulbar and corticopontine tracts.

Question 14

Below T6 in the spinal cord

Answer 14

Fasciulus gracilis

Question 15

Above T6 in spinal cord

Answer 15

Fasiculus cuneatus

Question 16

Medial reticulospinal tract

Answer 16

Arises from pons and increases muscle tone and facillitates voluntary movement. It controls the axial and trunk muscle extensors.

Question 17

Lateral reticulospinal tract

Answer 17

Arises from medulla, inhibits voluntary movement and reduces muscle tone

Question 18

Third order neurons in spinothalamic tract

Answer 18

From the thalamus to ipsilateral cortex of brain

Question 19

Conscious ascending tract

Answer 19

Spinothalamic and dorsal column

Question 20

Function of Extraypyramidal tract-

Answer 20

Descending spinal tract for involuntary control of musculature- reticulospinal, vestibulospinal, tectospinal, rubrospinal

Question 21

Corticospinal tract

Answer 21

Arises from motor cortex, descends through internal capsule and divides into lateral and anterior at pyramids. Provides Motor supply to muscles of body

Question 22

Medial division of the dorsal horn in spinal cord composed of fibres where first order neurons synapse with second order neurons

Answer 22

Fasiculus gracilis from lower body

Question 23

Lateral division of the dorsal horn in spinal cord composed of fibres where first order neurons synapse with second order neurons

Answer 23

Fasiculus cuneatus from upper body.

Question 24

When does the anterior and lateral divisions of the spinothalamic tract form?

Answer 24

Formerly singular spinothalamic tract- when second order neurons form, it decussates at the anterior white commissure and ascends as either the lateral or ventral/anterior

Question 25

Where do first and second order neurons synpase in the spinothalamic tract?

Answer 25

First order neurons form at level of entry in dorsal horn of spinal cord. It ascends one-two spinal segments via Lissauer’s tract to enter grey matter. It then reaches the substantia gelatinosa and synapses with second order neurons.

Question 26

Where do third order neurons of the spinothalamic tract arise?

Answer 26

Ventroposterolateral nucleus of the thalamus to pass through the posterior limb of internal capsule to ipsilateral cortex

Question 27

Where does the spinothalamic tract terminate?

Answer 27

Post central gyrus

Question 28

Difference between fasiculus and funiculus?

Answer 28

Funiculus is a large group of axons in a given area enclosed by perineum which can form a fasicle. Anterior funiculus vs posterior funiculus. Fasiculus is a small bundle of axons

Question 29

What does the dorsal root of the spinal cord carry?

Answer 29

Sensory neurons to CNS

Question 30

What does the ventral root of the spinal cord carry?

Answer 30

Motor neurons from the CNS

Question 31

Where do sensory neurons project to in the brain?

Answer 31

Post central gyrus

Question 32

What type of neurons are mechanoreceptors?

Answer 32

Pseudounipolar which enter spinal cord via dorsal root ganglion

Question 33

Where do first and second order neurons in the dorsal column pathway synapse?

Answer 33

Fasiculus cuneatus/gracilis in the spinal cord

Question 34

When do second order neurons synapse in the dorsal column pathway?

Answer 34

Nucleus cuneatus/gracilis in the medulla

Question 35

Where do second and third order neurons synapse in the dorsal column pathway?

Answer 35

Ventral posterioro lateral nucleus of the thalamus.

Question 36

Where do second and third order neurons synapse in the spinothalamic tract?

Answer 36

Ventroposterolateral nucleus in the thalamus

Question 37

Anterior spinothalamic tract?

Answer 37

Pressure and Crude touch

Question 38

What muscles do corticobulbar tracts innervate?

Answer 38

Bilateral

Question 39

Pain and temperature pathway for the face

Answer 39

Spinal trigeminal tract- Arises from nociceptor free nerve endings in the face. First order neurons travels along branches like the inferior alveolar nerve/mandibular nerve to reach the trigeminal nerve and synapse with first order neurons. It enters in pons and descends to the spinal trigeminal nuclei in the medulla and synapses with second order neurons. Second order decussates and ascends up through the trigeminothalamic tract to the thalamus. It enters the thalamus via the trigeminal leminiscus formed of fibres from other spinothalamic tracts. Second order synapses with third order neurons in the ventral posterolateral nucleus of the thalamus. Third order neurons project to the somatosensory cortex

Question 40

Function of corticopontine tract?

Answer 40

Co-ordinate planned motor movements via providing communication with opposite cerebellum.

Question 41

Corticopontine tract

Answer 41

Upper motor neurons arise from the primary motor and sensory cortex. It descends to the pons and enters the pontine nuclei. Lower motor neurons carry these signals to the muscles of the face, head and neck.

Question 42

Location of vestibular nuclei

Answer 42

In the medulla and pons

Question 43

Vestibulospinal tract

Answer 43

Vestibular nucleus located in the medulla receives input about propioception from the fastigial nucleus of the cerebellum. It provides ipsilateral innervation to control extensor muscles for balance and posture in the head, neck, axial and appendicular skeleton. It has a medial and lateral tract.

Question 44

Role of the medial vestibulospinal tract

Answer 44

Terminates in the cervical spinal segments and controls muscle extensors of the head and neck

Question 44

Role of the lateral vestibulospinal tract

Answer 44

Terminates in the thoracic spinal segments and controls extensor muscles of the axial and appendicular skeleton

Question 45

What regulates the vestibulospinal tract innervation of extensor muscles?

Answer 45

Rubrospinal tract- it inhibits the vestibulospinal tract to prevent extensor hypertonia

Question 46

Where is the reticular nuclei located?

Answer 46

Reticular formation is found from the midbrain to medulla/throughout brainstem. It receives input from ascending tracts such as dorsal column, spinoreticular and spinothalamic.

Question 47

Role of alpha motor neuron

Answer 47

Innervates extrafusal muscle fibres to contract

Question 48

Role of gamma motor neuron

Answer 48

Innervates intrafusal muscle fibres to control length of muscle spindle

Question 49

What is the role of the pontine reticulospinal tract?

Answer 49

Also known as medial reticulospinal tract, it Controls extensor muscles. Works alongside the vestibulospinal tract. Receives input from the reticular formation of the pons which projects down to the cervical and thoracic spinal levels to control head, neck and axial extensor muscles for locomotion, reaching and posture.

Question 50

Location of red nuclei

Answer 50

Midbrain

Question 51

Role of the rubrospinal tract

Answer 51

Control flexors and fine motor control. It receives input from the emboliform and globose deep cerebellar nuclei of spinocerebellar tract and cortical fibres. Rubrospinal tract immediately decussates in midbrain and provides contralateral supply to muscle flexors.

Question 52

Role of the medullary reticulospinal tract

Answer 52

Also known as lateral reticulospinal tract- it arises from reticular formation in medulla and provides innervation to the muscle flexors in the head and neck and axial and appendicular skeleton.