The document discusses the pyramidal tracts, which include the corticobulbar and corticospinal tracts. The corticobulbar tract conducts impulses from the brain to cranial nerves, controlling functions like swallowing and facial expression. The corticospinal tract originates in the motor cortex and travels through the brainstem and spinal cord, terminating in the spinal cord and controlling body muscle movement. Damage to these tracts can result in symptoms like hypertonia, hyperreflexia, and muscle weakness on the contralateral side of the body.

1. PYRAMIDAL TRACTS
DR MANOJ KUMAR SINGH
1ST YR PG
PHYSICAL MEDICINE AND REHABILITATION

2. PYRAMIDAL TRACTS
INCLUDES:
1.Corticospinal tract
2.Corticobulbar tract
* These are aggregations of upper motor neuron.
*nerve fibres travel from Cerebral cortex and
terminate either in brain stem(corticobulbar) or
spinal cord(corticospinal).
*Transmit moter impulses that control motor
functions of body.

4. CORTICOBULBAR TRACT
• Conduct impulses from the brain to the cranial
nerves.
• Fibres from the ventral motor cortex travel with
corticospinal tract through the internal capsule.
• The UMNs synapse directly with the LMNs
located in the motor cranial nerve nuclei:-
NAMELY- Oculomotor,
TROCHLEAR, TRIGEMINAL, ABDUCENS, FACIAL and
ACCESSORY and in the nucleus ambiguus to the
HYPOGLOSSAL, VAGUS AND ACCESSORY NERVES

5. CORTICOSPINAL TRACT
• It originate from PYRAMIDAL CELLS in layer V
of the cerebral cotex.
• PRIMARY MOTOR CORTEX
• SUPPLEMENTARY MOTOR AREA
• PREMOTOR CORTEX
• SOMATOSENSORY CORTEX
• PARIETAL LOBE
• CINGULATE GYRUS

6. • The cells have their bodies in cerebral cotex
and AXONS form the bulk of the pyramidal
tracts.
• The nerve axons travel from the cortex
through the cerebral peduncle and into the
brainstem and anterior medulla.
• Here they form two prominences called
PYRAMIDS OF THE MEDULLA.

7. • The axons that cross over move to outer part
of the medulla and form the LATERAL
CORTICOSPINAL TRACT.
• Whereas the fibres that remain form the
ANTERIOR CORTICOSPINAL TRACT.
• About 80% of axons cross over and form LCS
TRACT. 20% do not cross AND form ACS
TRACT.

8. • Termination in spinal cord: mostly laminae
3-7, few in ventral horn and laminae 1-2;
mostly innervating interneurons, although
some innervation of alpha motor neurons
• Neurotransmitter: glutamate and/or
aspartate

9. FUNCTIONS
CORTICOBULBAR TRACT-
-SWALLOWING
-PHONATION
-MOVEMENTS OF THE TONGUE
-FACIAL EXPRESSION
CORTIOSPINAL TRACT-
-INVOLVED MOVEMENT OF MUSCLES OF BODY.

10. CLINICAL SEGNIFICANCE
• Damage to the Corticospinal Tracts
• The pyramidal tracts are susceptible to damage, because they extend
almost the whole length of the central nervous system. As mentioned
previously, they particularly vulnerable as they pass through the internal
capsule – a common site of cerebrovascular accidents (CVA).
• If there is only a unilateral lesion of the left or right corticospinal tract,
symptoms will appear on the contralateral side of the body. The cardinal
signs of an upper motor neurone lesion are:
• Hypertonia – an increased muscle tone
• Hyperreflexia – increased muscle reflexes
• Clonus – involuntary, rhythmic muscle contractions
• Babinski sign – extension of the hallux in response to blunt stimulation of
the sole of the foot
• Muscle weakness

11. • Damage to the Corticobulbar Tracts
• Due to the bilateral nature of the majority of the
corticobulbar tracts, a unilateral lesion usually results in
mild muscle weakness. However, not all the cranial nerves
receive bilateral input, and so there are a few exceptions:
• Hypoglossal nerve – a lesion to the upper motor neurones
for CN XII will result in spastic paralysis of the contralateral
side of the genioglossus. This will result in the deviation of
the tongue to the contralateral side.
• Facial nerve – a lesion to the upper motor neurones for CN
VII will result in spastic paralysis of the muscles in the
contralateral lower quadrant of the face.