Tracts & Nuclei (from Caitlin)

Question 1

MLF (med. long. fasc.)

Function and Pathway?

Answer 1

Function:
coordinates eye movements, vestibular inputs,
and head and neck movements.

Pathway:
Descends only as far as the cervical and upper thoracic regions; terminates bilaterally

Question 2

TECTOSPINAL (descends in MLF)

Function and Pathway?

Answer 2

Function:
Reflex head & arm movement to stimuli (esp. visual and auditory)

Pathway:
superior colliculus→ dorsal tegmental decussation→ spinal cord

Question 3

CORTICOPONTINE-PONTOCEREBELLAR

Pathway?

Answer 3

cortex→ synapse in ipsilateral pontine nuclei - decussate→ contralateral middle cerebellar peduncle to neo-cerebellum (mossy fibers)

Question 4

RUBROSPINAL (“old motor”)

Pathway?

Answer 4

red nucleus→ ventral tegmental decussation→ spinal cord (mostly proximal limb flexors)

Question 5

VESTIBULOSPINAL

Pathway?

Answer 5

vestibular nuclei→ entire cord (postural extensor muscle reactions to vestibular stimuli)

Question 6

OLIVOCEREBELLAR

Pathway?

Answer 6

(only inferior olivary output): inferior olive→ decussate→ inferior cerebellar peduncle→ cerebellum (only source of climbing fibers)

Question 7

LATERAL LEMNISCUS

Pathway?

Answer 7

superior olive→ inferior colliculus

Question 8

SUPERIOR CEREBELLAR PEDUNCLE

Pathway?

Answer 8

dentato-rubro-thalamic tract from dentate nucleus decussate in caudal midbrain→ travels through red nucleus to thalamus (VA and VL)→ cerebral cortex

Question 9

SUPERIOR COLLICULUS

Pathway?

Answer 9

brachium→ lateral geniculate (visual reflexes)

Question 10

INFERIOR COLLICULUS

Pathway?

Answer 10

brachium→ medial geniculate (auditory pathway)

Question 11

DORSAL MOTOR NUCLEUS OF X

Function?

Answer 11

GVE (parasympathetic) to visceral smooth muscle

Question 12

NUCLEUS SALIVATORIUS

Function?

Answer 12

GVE to parotid and glands of oropharynx (CN VII & IX)

Question 13

TRACTUS AND NUCLEUS SOLITARIUS

Function?

Answer 13

GVA sensory fibers from CN IX & X.

The rostral portion = “gustatory” nucleus for taste (CN VII, IX & X)

Question 14

NUCLEUS AMBIGUUS

Answer 14

SVE branchial motor of CN IX & X (to pharynx and larynx)

Question 15

DORSAL COLUMN – MEDIAL LEMNISCUS

Function and Pathway?

Answer 15

Function:
fine, well-localized touch, joint position, vibration
[light crude touch present]

Pathway:
sensory afferents synapse in gracilis and cuneate nuclei in medulla→ internal arcuate fibers – decussate→ medial lemniscus→ VPL of thalamus→ postcentral gyrus

Question 16

ANTEROLATERAL SYSTEM

Function and Pathway?

Answer 16

Function:
pain and temperature
[light crude touch present ]

Pathway:
sensory afferents (tract of Lissauer) synapse in substantia gelatinosa – decussate in ventral white commissure → spinothalamic tract→ VPL of thalamus→ postcentral gyrus

Question 17

DORSAL SPINOCEREBELLAR and CUNEOCEREBELLAR

Function and Pathway?

Answer 17

Function:
NCONSCIOUS PROPRIOCEPTION  (to ipsilateral cerebellum)

Pathway:
sensory afferents synapse in nucleus dorsalis (Clark’s column), spinal cord levels L3 to C8; above C8 synapse in lateral (accessory) cuneate nucleus→ dorsal spinocerebellar or cuneocerebellar tract→ inferior cerebellar peduncle→ cortex of spinocerebellum (mossy fibers)

Question 18

Describe the pathway for FINE, WELL LOCALIZED TOUCH, JOINT POSITION, and VIBRATION in the head.

Answer 18

sensory afferents in trigeminal nerve synapse in chief (principle) sensory nucleus of V – decussate→ ventral trigeminothalmic tract→ VPM of thalamus→ postcentral gyrus

Question 19

Describe the pathway for PAIN and TEMPERATURE in the head.

Answer 19

ensory afferents in trigeminal nerve descend in the spinal tract of V and synapse in spinal nucleus of V at multiple levels – decussate→ ventral trigeminothalmic tract → VPM of thalamus→ postcentral gyrus