The document discusses the different tracts of the spinal cord. It describes short tracts that connect parts of the same spinal cord and long tracts that connect the spinal cord to other parts of the central nervous system. The long tracts are further divided into ascending tracts that carry sensory information from the spinal cord to the brain and descending tracts that carry motor information from the brain to the spinal cord. It provides details on major ascending tracts like the posterior, spinothalamic and spinocerebellar tracts. It also describes the descending tracts including the pyramidal and corticospinal tracts, as well as extrapyramidal tracts.

1. TRACTS OF SPINAL CORD
DR. FATHIMA TASNEEM

2. • BUNDLE OR GROUPS OF NERVE FIBRES USED FOR SPINAL CORD
CONNECTIONS.
• SUB CLASSIFIED AS:
• 1. SHORT TRACTS
• 2. LONG TRACTS

3. SHORT TRACTS
• SHORT TRACTS ARE JUST WITHIN THE SPINAL CORD FOR ITS
CONNECTION WITH ITSELF.
• SUBCLASSIFIED AS:
• A. ASSOCIATIVE – CONNECTS ADJACENT PARTS OF SAME SIDE SPINAL
CORD.
• B. COMMISURAL – CONNECTS OPPOSITE HALVES OF SPINAL CORD.

4. LONG TRACTS
• LONG TRACTS CONNECTS SPINAL CORD TO OTHER PARTS OF CNS.
• SUBDIVIDED AS:
• 1. ASCENDING TRACTS – SENSORY, ASCEND FROM SPINAL CORD TO
BRAIN
• 2. DESCENDING TRACTS – MOTOR, DESCENDS FROM BRAIN TO
SPINAL CORD.

5. ASCENDING TRACTS
• 3 Major sensory tracts:
1. POSTERIOR COLUMN
2. SPINOTHALAMIC TRACT
3. SPINOCEREBELLAR TRACT

7. POSTERIOR COLUMN
• FASCICULUS GRACILIS: Proprioception, fine touch, pressure and
vibration from levels inferior to T6.
• FASCICULUS CUNEATUS: Proprioception , fine touch, pressure and
vibration from levels at or superior to T6.

9. SPINOTHALAMIC TRACT:
• LATERAL SPINOTHALAMIC TRACT: Pain and temperature sensations.
• COURSE: DRG – axons enter CNS n DR and enter posterior gray
horn. In posterior gray horn the axons enter lateral spinothalamic
tract – ventral postero lateral nucleus of thalamus.
• TERMINATION: Primary sensory cortex on side opposite stimulus.
• ANTERIOR SPINO THALAMIC TRACT: Crude touch and pressure.
• Course: In post gray horn the axons enter anterior spinothalamic
tract.

12. SPINOCEREBELLAR TRACTS
• POSTERIOR SPINOCEREBELLAR TRACTS: Proprioception.
• Course: Dorsal root ganglia – axons enter CNS in dorsal roots. In
posterior gray horn axons enter post spinocerebellar tract on same
side.
• Termination: Cerebellar cortex on side of stimulus.

13. • ANTERIOR SPINOCEREBELLAR TRACTS: Proprioception.
• Course: DRG- axons enter CNS n DR. In same spinal segments axons
enter anterior spinocerebellar tract on same or opp side, cross
before entering the tract and then cross again within cerebellum.
• Termination: Cerebellar cortex primarily on side of stimulus.

14. DESCENDING TRACTS
• DESCEND FROM SPINAL CORD AND CARRY MOTOR INFORMATION.
• THEY ARE FURTHER DIVIDED AS :
• 1. PYRAMIDAL TRACTS.
• 2. EXTRAPYRAMIDAL TRACTS.

15. PYRAMIDAL TRACTS
• CORTICOSPINAL TRACTS ORIGINATE FROM MOTOR AREA OF THE
CEREBRAL CORTEX AND TERMINATE IN SPINAL CORD.
• CORTICOBULBAR TRACTS MOTOR CORTEX TO BRAIN STEM.

16. • DIAMETER OF EACH NERVE FIBER IS 4 – 22 MICRONS.
• THEY ARE PRESENT SINCE BIRTH, BUT LATER IN OLD AGE THEY MAY
DISSAPPEAR.
• ORIGIN: THESE ORIGINATE FROM MOTOR AREA OF CEREBRAL CORTEX
FROM FOLLOWING CELLS.
• BETZ CELLS – AREA 4 (30%)
• PREMOTOR AREA – 6 (30%)
• SOMATOSENSORY AREA OF PARIETAL LOBE (39%)
• OTHER PARTS OF FRONTAL LOBE (1%)

17. CORTICOSPINAL TRACT
• IT ORIGINATES FROM PYRAMIDAL CELLS IN LAYER 5 OF THE
CEREBRAL CORTEX CALLED BETZ CELLS.
• THE NERVE AXON TRAVEL FROM CORTEX THROUGH THE POSTERIOR
LIMB OF INTERNAL CAPSULE.
• THE NEURONS PASS THROUGH CRUS CEREBRI OF THE MID BRAIN ,
PONS AND INTO THE MEDULLA.
• THE AXONS FORM 2 PROMINENCES CALLED THE PYRAMIDS OF THE
MEDULLA.
• IN THE MOST INFERIOR PART OF MEDULLA THE TRACT DIVIDES INTO
2:

18. • THE FIBERS WITHIN THE LATERAL CORTICOSPINAL TRACT
DECUSSATE (CROSS OVER TO THE OTHER SIDE ), RESULTING IN
MUSCLE BEING CONTROLLED BY THE OPPOSITE SIDE OF THE BRAIN.
THEY THEN DESCEND INTO SPINAL CORD TERMINATING IN THE
VENTRAL HORN.
• THE ANTERIOR CORTICO SPINAL TRACT REMAINS IPSILATERAL
DESCENDING INTO THE SPINAL CORD.
• ABOUT 80% OF AXONS CROSS OVER & FORM LCS TRACT.
• 20% DO NOT CROSS AND FORM ACS TRACT

19. • FUNCTIONS:
• 1.VOLUNTARY MOVEMENTS
• 2. FINE AND SKILLED MOVEMENTS OF THE BODY.

21. CORTICOBULBAR TRACT
• CONDUCTS IMPULSE FROM BRAIN TO CRANIAL NERVES.
• THE CORTICOBULBAR TRACTS ARISE FROM THE LATERAL ASPECT OF
THE PRIMARY MOTOR CORTEX. THEY RECEIVE SAME INPUT AS
COTICOSPINAL. THE FIBERS CONVERGE AND PASS THROUGH
INTERNAL CAPSULE TO THE BRAINSTEM.
• THE NEURONS TERMINATE IN THE MOTOR NUCLEI OF THE CRANIAL
NERVES. HERE THEY SYNAPSE WITH THE LMNs , WHICH CARRY THE
MOTOR SIGNALS TO THE MUSCLES OF FACE & NECK.
• INVOLVED IN CONTROL OF FACIAL AND JAW MUSCULATURE,
SWALLOWING AND TONGUE MOVEMENTS.

22. EXTRA PYRAMIDAL TRACTS:
• MEDIAL LONGITUDINAL FASCICULIS: Descends through posterior part of
anterior white column.
• Origin:
• 1. vestibular nuclei- present in medulla.
• 2. reticular formation: region of pons involved in sleep wake cycle.
• 3. superior colliculus: area below thalamus- surrounds pineal gland.
• 4. internal cells of cajal: pace maker cells of GIT that produce Basal
electrical rhythm.

23. • Course: Directly enters the spinal cord from brain
stem and are well defined at cervical region only.
• Termination: They terminate on anterior motor
neurons either directly or indirectly via
internuncial neurons.
• Functions: helps in reflex occular movements and
movements of the neck.

24. ANTERIOR VESTIBULOSPINAL TRACTS
• SITUATED IN ANTERIOR WHITE COLUMN ALONG ITS PERIPHERY.
• ORIGIN: ARISE FROM MEDIAL VESTIBULAR NUCLEI AND EXTEND
UPTO THORACIC REGION.
• TERMINATION: ANTERIOR MOTOR NEURONS DIRECTLY OR
INDIRECTLY.
• FUNCTION: CONCERNED WITH ADJUSTMENT OF POSITION OF HEAD
AND BODY DURING ANGULAR AND LINEAR MOTION.

25. LATERAL VESTIBULOSPINAL TRACTS
• SITUATED IN ANTERIOR PART OF LATERAL WHITE MATTER.
• ORIGIN: LATERAL VESTIBULAR NUCLEI OF MEDULLA –
DIETERS NUCLEUS.
• EXTENT: PRESENT THROUGHOUT THE SPINAL CORD.
• COURSE: DESCENDS FROM DIETERS NUCLEUS DIRECTLY IN
THE SPINAL CORD TO ITS LATERAL WHITE COLUMN WITH
FEW BEING CROSSED BEFORE REACHING SPINAL CORD.
• TERMINATION: ANTERIOR MOTOR NEURONS DIRECTLY OR
INDIRECTLY.

26. 4 RETICULOSPINAL TRACTS
• Situated in anterior white column, posterior to anterior
vestibulospinal tracts.
• Origin: Reticular formation of pons and medulla.
• Course: pontine are uncrossed and descend in medial part of
anterior column.
• From medulla are crossed and uncrossed and descends to anterior
parts of anterior and lateral column.

27. • EXTENSION: Upto the thoracic segments.
• TERMINATION: Gamma motor neurons of anterior gray horn.
• FUNCTIONS: Controls diameter of blood vessel, breathing,
movement maintanance.

28. TECTOSPINAL TRACT
• Situated in anterior white column of spinal tract.
• Origin: superior colliculus of brain.
• Extension: Lower cervical segments.
• Course: After origin it crosses the mid line and at
decussation level and then descends directly in to spinal
cord.
• Termination : Anterior motor neurons directly / indirectly.
• Function: Movement of head in response to audio and
video stimuli.

29. RUBROSPINAL TRACT
• Present in lateral white column of spinal cord.
• ORIGIN: Red nucleus of mid brain.
• EXTENT: Upto thoracic level of spinal cord.
• COURSE: After origin , it cross the midline and at
decussation level and then descends directly in to spinal
cord through reticular formation of mid brain.
• TERMINATION: Terminates at anterior motor neurons
directly.
• FUNCTIONS: Facilitates the function of flexor joints.

30. OLIVOSPINAL TRACT
• Situated in lateral white column of spinal cord.
• ORIGIN: Medulla oblongata – inferior olivary nucleus.
• COURSE: Descends directly to spinal cord from medulla.
• TERMINATION: Anterior motor neurons.
• FUNCTIONS: Reflex movements of joints.

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