Tracts and Nuclei

Question 1

Marginal zone

Answer 1

Contains spinothalamic tract neurons that relay to ventral posterior thalamic nucleus.
All levels of spinal cord.

Question 2

Substantia gelatinosa

Answer 2

Contains interneurons modulating pain and temperature inputs.
All levels of spinal cord.

Question 3

Nucleus proprius

Answer 3

Where somatosensory inputs are processed and relayed to ventral horn (for reflexes) and brain.
All levels of spinal cord.

Question 4

Dorsolateral fasciculus

Answer 4

Dorsal root entry zone for pain and temperature fibres.
All levels of spinal cord.

Question 5

Nucleus dorsalis

Answer 5

Clarke’s column.
Contains tract neurons relaying proprioceptive input from LOWER limbs to cerebellum.
T1-L2 (all thoracic, some lumbar)

Question 6

Intermediolateral nucleus

Answer 6

Contains preganglionic sympathetic neurons.
In lateral horn, only T1-L3.

Question 7

Sacral autonomic nucleus

Answer 7

Contains preganglionic PARAsympathetic neurons (autonomic neurons to pelvic viscera).
Only S2-S4.

Question 8

Medial motor nucleus

Answer 8

Contains motor neurons of axial musculature.
All spinal levels.

Question 9

Lateral motor nucleus

Answer 9

Contains motor neurons of distal musculature.
Only at spinal enlargements.

Question 10

Spinal cord sensory/motor organisation?

Answer 10

Sensory: above sulcus limitans.
Motor: below sulcus limitans.

Question 11

Spinal cord somatic/visceral organisation?

Answer 11

Somatic: closer to sulcus limitans
Visceral: further from sulcus limitans

Question 12

Gracile fasciculus

Answer 12

Function: discriminative touch, vibration, proprioception for LOWER LIMBS.
Start: dorsal root ganglion from below T6.
End: gracile nucleus.
Cross: uncrossed.

Question 13

Cuneate fasciculus

Answer 13

Function: discriminative touch, vibration and proprioception for UPPER LIMBS.
Start: dorsal root ganglion above T6.
End: cuneate nucleus.
Cross: uncrossed.

Question 14

Spinothalamic tract

Answer 14

Function: pain (sharp), temperature, some light touch.
Start: marginal zone, nucleus proprius (and sometimes modulated in substantia gelatinosa)
End: thalamus
Cross: at level of spinal cord.

Question 15

Dorsal spinocerebellar tract

Answer 15

Function: proprioception and some touch of LOWER limbs.
Start: nucleus dorsalis.
End: cerebellum.
Cross: uncrossed.

Question 16

Ventral spinocerebellar tract

Answer 16

Function: proprioceptive info (incl. reflexes) of LOWER limbs.
Start: nucleus proprius and intermediate zone of lumbosacral cord.
End: cerebellum.
Cross: crosses ventral white commisure, crosses back to ipsilateral as it enters cerebellum.

Question 17

Cuneocerebellar tract

Answer 17

Function: proprioception and some touch for UPPER limbs.
Start: lateral cuneate nucleus in caudal medulla.
End: cerebellum (v. short tract).
Cross: uncrossed.

Question 18

Lateral corticospinal tract

Answer 18

Function: motor, skilled voluntary movements of distal muscles.
Start: M1 and premotor areas of cortex.
End: spinal enlargements.
Cross: at pyramidal decussation in caudal medulla.

Question 19

Ventral corticospinal tract

Answer 19

Function: motor, skilled voluntary movements of trunk and proximal limbs.
Start: M1 and premotor areas of cortex.
End: throughout spinal cord.
Cross: uncrossed.

Question 20

Rubrospinal tract

Answer 20

Function: autonomic motor, muscle tone in distal muscles of upper limbs.
Start: red nucleus.
End: lateral motor column (spinal enlargements).
Cross: early in midbrain.

Question 21

Vestibulospinal tract

Answer 21

Function: autonomic motor, controls postural muscles for balance and posture.
Start: lateral vestibular nucleus in medulla.
End: interneurons in ventral horn at all levels.
Cross: uncrossed.

Question 22

Anterolateral system

Answer 22

Spinothalamic tract + spinoreticulothalamic tract.
Light touch, pain and temperature.
Runs between inferior olivary nucleus and spinal trigeminal nucleus in medulla, then dorsolaterally to medial meniscus in pons and midbrain.

Question 23

Reticulospinal tract

Answer 23

Function: autonomic motor, stereotyped movements in axial and distal muscles, muscle tone, visceral smooth muscle.
Start: reticular formation of pons and medulla.
End: interneurons in ventral horn at all spinal levels, as well as lateral horn and sacral autonomic nucleus.
Cross: uncrossed.

Question 24

Upper motor neuron lesion

Answer 24

Spastic paralysis:
- loss of voluntary control to muscles
- hypertonia
- hyperreflexia
- Babinski sign (extensor plantar response)

Question 25

Lower motor neuron lesion

Answer 25

Flaccid paralysis: - loss of neural input to muscle - hypotonia - hyporeflexia - muscle wasting

Question 26

Brown-Sequard Syndrome

Answer 26

- hemisection of spinal cord - spastic paralysis on contralateral side - loss of sensation on ipsilateral side - loss of pain and temp. sensation on contralateral side

Question 27

Lumbar cistern

Answer 27

A reservoir of CSF between L1-2 to S1-2. It is where spinal cord ends.

Question 28

Cerebral peduncles

Answer 28

- aka. crus cerebri - attach cerebrum to brainstem - contain corticopontine, corticobulbar and corticospinal tracts - arises from ventral pons

Question 29

Middle cerebellar peduncle

Answer 29

- largest - contains pontocerebellar fibres - originates in basis pontis

Question 30

Superior cerebellar peduncle

Answer 30

- smallest - originates in cerebellum - decussates in midbrain - terminates in thalamus - contains cerebellothalamic, cerebellorubral and ventral spinocerebellar tracts

Question 31

Inferior cerebellar peduncle

Answer 31

- originates in medulla - terminates in cerebellum - contains spinocerebellar fibres (cuneocerebellar, olivocerebellar and dorsal spinocerebellar)

Question 32

Inferior olivary nucleus

Answer 32

Coordinates signals from spinal cord to cerebellum. Regulates motor coordination and learning.

Question 33

Superior colliculi

Answer 33

Involved in incorporating environmental stimuli and coordinating gaze shifts with head movements.

Question 34

Inferior colliculi

Answer 34

Involved in sound localisation, frequency determination and integration of auditory and non-auditory inputs.

Question 35

Medial lemniscus

Answer 35

Function: discriminative touch, vibration and proprioception. Start: gracile and cuneate nuclei in medulla. End: ventral posterior nucleus in thalamus. Cross: sensory decussation of medulla.

Question 36

Medial longitudinal fasciculus

Answer 36

Function: coordinating eye movements with head position (connects the abducens, trochlear, occulomotor and vestibular nuclei). Cross: crossed and uncrossed.

Question 37

Lateral lemniscus

Answer 37

Function: carries auditory information, part of auditory pathway. Start: superior olivary nucleus and cochlear nuclei. End: inferior colliculi. Cross: posterior tegmental commissure.

Question 38

Central tegmental tract

Answer 38

- between red nucleus (midbrain) and inferior olivary nucleus (medulla) - contains fibres of RF

Question 39

Corticopontine fibres

Answer 39

- synapse with pontine nuclei in basis pontis - form pontocerebellar fibres post-synapse - then ascend to cerebellum via MCP - don't enter pons or medulla

Question 40

Corticobulbar tract

Answer 40

- target motor nuclei of cranial nerves (trigeminal, facial, hypoglossal) and nucleus ambiguus in pons and medulla - enters pons but not medulla or spinal cord