Tracts Of The Nervous System Flashcards
List all the Ascending tracts.
- Fasciculus cuneatus (posterior or dorsal column)
- Fasciculus gracilis (posterior or dorsal column)
- Spinocerebellar tract (dorsal)
- Spinocerebellar tract (ventral)
- Spino-olivary tract
- Spinoreticular tract
- Spinotectal tract
- Spinothalamic tract (anterior)
- Spinothalamic tract (posterior)
List all the descending tracts.
- Cortiocspinal tract (anterior)
- Corticospinal Tract (Lateral)
- Reticulospinal tract
- Rubrospinal tract
- Tectospinal tract
- Vestibulospinal tract
What is the purpose of the ascending tracts?
Relay SENSORY feedback to the cerebrum and cerebellum.
What do sensory tracts ascending in the WHITE matter of the spinal cord arise from?
Either from cells of spinal ganglia or form intrinsic neurons within the gray matter that receive primary sensory input
Fasciculus cuneatus (posterior or dorsal)
- Sensory tract for trunk, neck, and UE proprioception
- Vibration
- Two-point discrimination
- Graphesthesia
Fasciculus gracilis (posterior or dorsal)
- Sensory tract for trunk and LE proprioception
- Two-point discrimination
- Vibration
- Graphesthia
Spinocerebellar Tract (dorsal)
- Sensory tract that ascends to the cerebellum for IPSILATERAL subconscious proprioception
- Tension in muscles
- Joint sense
- Posture of the trunk and LE
Spinocerebellar tract (ventral)
- Sensor tract that ascends to the cerebellum, some fibers crossing w/ subsequent recrossing at the level of the pons for IPSILATERAL subconscious proprioception
- Tension in the muscles
- Joint sense
- Posture of the trunk, UE, LE
Spino-olivary tract
Ascends to cerebellum and relays information from cutaneous and proprioceptive organs
Spinoreticular tract
Afferent pathway for the reticular formation that influences levels of consciousness
Spinotectal tract
Sensory tract providing afferent information form spinovisual reflexes and assists with movement of eyes and head towards a stimulus
Spinothalamic tract (anterior)
Sensory tract for light touch and pressure
Spinothalamic tract (lateral)
Sensory tract for pain and temperature sensation
Corticospinal tract (anterior)
Pyramidal motor tract responsible for ipsilateral voluntary, discrete, skilled movements
What are tracts descending to the spinal cord involved in?
Voluntary motor function
Muscle tone
Reflexes and equilibrium
Visceral innervation
Modulation of ascending sensory signals
Where does the largest descending tract (corticospinal tract) originate? Where do the other descending tracts originate from?
Cerebral cortex
Others originate in the midbrain, pons and medulla Oblongata
Corticospinal tract (lateral)
Pyramidal motor tract responsible for CONTRALTERAL voluntary fine movement
What may damage to the corticospinal (pyramidal) tracts resut in?
(+) babinski sign—toes in flexion
Absent superficial abdominal reflexes and cremasteric reflex
Loss of fine motor or skilled voluntary movements
Reticulospinal tract
Extrapyramidal motor tract responsible or facilitation nor inhibition of voluntary and reflex activity through the influence of alpha and gamma motor neurons
Rubrospinal tract
Extrapyramdial motor tract responsible for motor input of gross postural tone, facilitating activity of flexion muscles and inhibiting the activity of extensor muscles
Tectospinal tract
Extrapyramdial motor tract responsible for CONTRALATERAL postural muscle tone associated with auditory/visual stimuli
Vestibulospinal tract
Extrapyramidal motor tract responsible for IPSILATERAL gross postural adjustments subsequent to head movements, facilitating activity of the extensor muscles and inhibiting activity of the flexor muscles
What does damage to the extrapyramdial tracts result in?
- Significant paralysis
- Hypertonicity
- Exaggerated DTR
- Clasp-knife reaction
What is brown-sequard’s Syndrome typically caused by?
Incomplete lesion typically caused by a stab wound which produces hemisection of the spinal cord
What are the consequences of brown-sequard’s Syndrome ?
Paralysis and loss of vibratory sense and position sense on IPSILATERAL side as the lesion due to the damage to the CORTICOSPINAL tracts and dorsal column
Loss of PAIN and TEMPERATURE on the CONTRALATERAL side of the lesion from damage to the lateral spinothalmaic tract
