ALL motor pathways 

in the spinal cord are located in

the Lateral and Anterior

Funiculi.

Tectospinal & Bulbar Tracts

Part of SUPRASPINAL  REFLEX  PATHWAYS

Tectospinal & Bulbar Tracts are crossed   pathways  for movement of head and eyes in response  to auditory and visual stimuli

VESTIBULOSPINAL TRACTS

Part of Supraspinal Reflex Pathway

Lateral Vestibulospinal Tract is an uncrossed

descending pathway from the lateral vestibular

nucleus for control of posture, equilibrium,

balance, and muscular tone. Strong excitatory

input to lower motor neurons innervating

antigravity (axial & extensor) muscles.

Medial Vestibulospinal & Bulbar Tracts

control postural and equilibrium movements

of head and coordinate head and eye movements

Vestibular Lesions

Vestibular Lesions  :

LIMBIC  PATHWAYS

-CERULEOSPINAL &  BULBAR  TRACTS

-RAPHESPINAL  &  BULBAR  TRACTS

These descending pathways  have

a diffuse effect on lower motor

neurons and are controlled by

higher limbic regions modulating

muscular strength and

responsiveness in accordance with

varying emotional states

Upper Motor Neurons

Upper Motor Neurons are projection neurons

In layer V of the cerebral cortex which

execute voluntary movement via Pyramidal

and Extrapyramidal pathways. 

Most upper motor neurons are located in the

Motor cortex (M1  area or Brodmann’s area 4)

and the Premotor cortex (M2  area or

Brodmann’s area 6)

Upper Motor Neurons Control  Lower Motor Neurons

Via interneurons in the Intermediate Zone

Betz Cells

:  Some large  Pyramidal Upper Motor  Neurons in the Motor Cortex (Betz Cells) have direct connections  with Lower Motor Neurons which control the intrinsic muscles of hand.

PYRAMIDAL  TRACT

CORTICOBULBAR  TRACT

&

CORTICOSPINAL  TRACT

The Major motor pathway

in humans. Exclusive  involvement

in individual, fractionated, precise,

skilled movements.

Pyramidal Tract Decussation 90%

Blood Supply of Pyramidal Tract

Middle Cerebral Artery- Part of Face, Hand and Trunk of Motor Homunculus

Anterior Cerebral Artery-  Lower Body and Leg part of Motor Homunculus

Lateral Striate, Anterior Choroidal

Arteries for Internal Capsule

CORTICOSPINAL  TRACTS

Lateral Corticospinal Tract is the major pathway

for voluntary movement. This crossed pathway has

a large percentage of its axons controlling distal

musculature involved in fine, skilled movements. This

tract has exclusive control over intrinsic muscles

of hand  which  is characterized by a two neuron

hookup (UMN-LMN) with no interneuron. Fifty percent

 of axons of this tract control intrinsic muscles of hand.

Anterior Corticospinal Tract is a small crossed

and uncrossed pathway that controls proximal

musculature on ipsilateral and contralateral sides, chiefly

in the upper body region.

CORTICOBULBAR TRACT

 Corticobulbar Tract is a crossed and

 uncrossed pathway which has voluntary

 control over lower motor neurons mediated

 via cranial nerves on both the ipsilateral and

 contralateral sides. The contralateral side,

 however, receives a greater percentage of

 axons.* Corticobulbar fibers cross at the

 level of the cranial nerve nucleus being

 innervated.

* EXCEPTION:     Lower half of the face receives  ONLY crossed fibers.

Majority of Corticobulbar axons control.... 

Majority of Corticobulbar axons control lower motor neurons in cranial nerves VII (facial expression) and X and XII (speech).

EXTRAPYRAMIDAL  PATHWAYS

-RUBROSPINAL  TRACT

-RETICULOSPINAL TRACTS

(MEDIAL & LATERAL)

RUBROSPINAL  TRACT

Rubrospinal Tract is a crossed pathway which has a strong excitatory effect on proximal flexors of upper extremity

RETICULOSPINAL  TRACT

Medial Reticulospinal Tract is functionally  crossed

and uncrossed and is the MAJOR ALTERNATE

PATHWAY for control of axial and proximal

 musculature. This pathway has a strong excitatory

effect on antigravity musculature (axial and

extensor musculature). 

Lateral Reticulospinal Tract is crossed &

uncrossed and gives rise to a variety of

excitatory and inhibitory actions on axial and proximal limb muscles.