Nerve Tracts/Pathways Flashcards
Thalamus
-interprets sensation information and perceives it
Name of Pathways
-origin and site of termination for 2nd order neruon
Types of Somatosensory Pathways to Brain
Conscious Relay:
-info about location and stimulus type to conscious awareness
-discriminative sensations
Divergent:
-info to many locations in brainstem and cerebrum
-conscious and non-conscious
Non-Conscious Relay:
-proprioceptive and other movement to cerebellum
Conscious Relay Pathways
-info about location and stimulus type to conscious awareness
-discriminative sensations
Crude Awareness: thalamus
Detailed Awareness: somatosensory cortex
Dorsal Column
Anterolateral Column
Divergent Relay Pathways
-info to many locations in brainstem and cerebrum
-conscious and non-conscious
-medial/slow nociception
-subconscious temperatue
Spinomesencephalic, spinoreticular and spino-emotional tracts
Non-Conscious Relay Pathways
-proprioceptive and other movement to cerebellum
Spinocerebellar Tracts
Grey Matter Fibers: Brain
-Motor
-cortex filled with cell bodies, folded in 6 layers
-Pyramidal cell: primary output
White Matter Fibers: Brain
Projection fibers, commissural fibers, Association fibers
Descending Motor Fibers
Pyramidal Tracts: cerebral cortex
Extrapyramidal Tracts: Brainstem
Flexor-Extensor Rule
-MNs that innervate flexors are located posteriorly to MNs that innervate extensors
Proximal-Distal Rule
-MNs that innervate distal muscles are located laterally to MNs that innervate proximal muscles
Lateral Corticospinal Tracts
-crossed at pyramidal decussation of medulla
-fractionated movements
-primary motor cortex
-most CST fibers
-descends in lat funiculus
Medial Corticospinal Tracts
-uncrossed
-postural movements
-originates from premotor cortex
-descends in venttral funiculus
Nonspecific Motor tracts
-facilitate activity of interneurons and MNs
-activate during intense emotions
Ceruleospinal and Raphespinal Tracts
Corticobrainstem Tracts
-voluntary control of many MM of head and neck
-originate in cortex motor areas and reach CN nuclei in brainstem
Secondary Somatosensory Gyrus
-post to primary
-processes info from primary and thalamus for stereognosis and sensory memory
Dorsal Column Medial Leminiscus
-Ascending tract
-Light touch, proprioception, sterognosis
1st: Dorsal horn ganglion to FG or FC
2nd: Nucleus Gracilis or Cuneatus in Medulla
CROSS with Internal Arcuate Fibers
3rd: Thalamus to PSSC
Anterolateral System
-ascending tract
-crude touch
Anterior: crude touch
Lateral: Fast nociception and temp
1st: Dorsal root ganglion to DH
CROSS at Anterior Commissure
2nd: Anterior commisure and travels up LST to thalamus
3rd: Thalamus to PSSC
Medial Nociception
-dull/slow pain
-ascending, divergent pathway
1st: C fibers with free ending in DH
CROSS
2nd:
Spinomesencephalic: Sup. colliculi and periaqueductal grey
Spinoreticular: Reticular Formation
Spinoemotional: Cortex
-reaches consciousness
Dorsal Spinocerebellar
-ascending, LE, uncrossed
-Nonconsious postural movements
-coordination and proprioception
1st: DRG to via FG Clark’s Nucleus
2nd: Up DPT through Inferior Cerebellar Peduncle to Cerebellum
Ventral Spinocerebellar
-ascending, LE, crossed, bilateral
-Nonconsious postural movements
-coordination and proprioception
1st: Anterior Hron
CROSS
2nd: Up VPT through Superior Cerebellar Peduncle
CROSS to Cerebellum
Cuneocerebellar
-ascending, UE, uncrossed
-Nonconsious postural movements
-coordination and proprioception
1st: DRG to Nucleus Cuneatus
2nd: Up NC through Inferior Cerebellar Peduncle to Cerebellum
Rostrospinocerebellar
-ascending, UE, uncrossed
-Nonconsious postural movements
-coordination and proprioception
1st: DRG to Superior Cerebellar Peduncles to cerebellum
Medial/Ventral Corticospinal Tract
-automatic trunk movements, uncrossed
-pyramidal
Premotor cortex > internal capsule > Cerebral Peduncle (midbrain)> FG> medial/anterior horn
Lateral Corticospinal Tract
-voluntary limb mmts
-pyramidal
Primary Motor Cortex> internal capsule> Cerebral peduncles (midbrain)>crosses at decussation of medulla>FC>lateral horn
Corticobulbar Tract
-facial movements
-Pyramidal
Primary motor cortex> cerebral peduncles> crosses a lot at CNs> exits cervical ventral horn
Reticulospinal Tract
-extrapyramidal
-postural and gross movements (walking), extensors
Reticular formation in Pons>FG>ventral horn
Vestibulospinal Tract
-extrapyramidal
-postural and vestibular movements
Medial: head and neck motions to maintain position
Lateral: limb and trunk reactions to gravity
Vestibular Nuclei in Pons and medulla>lateral column>ventral horn
Rubrospinal Tract
-extrapyramidal
Red nucleus (midbrain)>cross> down RST of lat column>ventral horn
