The pyramidal tract originates from the sensor motor areas located in the cerebral cortex. It is one of the prominent passages of the central nervous system. It comes down via the brainstem to reach the spinal cord. It consists of extensive motor fiber groups. The pyramidal tract includes the cortico spinal tract and the corticobulbar or cortico nuclear tract.
The main parts of the brain are Cerebrum, Frontal lobe, Parietal lobe, Temporal lobe, Sensory Cortex, Motor Cortex, Wernicke's Area, Occipital Lobe, Broca's Area, Brainstem and Cerebellum. The sensory cortex covers the front portion of the parietal lobe. It plays pivotal role in receiving and transmitting information via spinal cord. The motor cortex is situated in the middle portion of the brain and control motor functions. The cerebellum is the second biggest structure inside the brain and takes care of the functions related to general motor coordination. The pyramidal tract plays an important part in this, and transmits the message to the spinal cord and the brainstem. The cerebrum is the biggest part of the brain and is associated with motor and cognitive functions such as movement, sensation and thought. The cerebral hemisphere has four lobes that assist the brain in performing different functions:
Frontal Lobe: Behavior, abstract thinking, judgement, initiative, emotions, intellect, creativity etc.
Parietal Lobe: Learning languages, reading, tactile sensation, internal stimuli visual functions.
Temporal Lobe: Hearing, speech, visual memories
Occipital Lobe: Control of vision.
Around 80% of the cells of the pyramidal tract are located on the frontal lobe’s precentral gyrus, which is also known as motor ship. Large cells (known as pyramidal cells) located in this region have their axons connected to the pyramidal tract. Nearly 20% of the pyramidal tract fibers rise from the postcentral gyrus located in the parietal lobe and Brodmann’s areas 1, 2, and 3. Irrespective of their location, pyramidal tract fibers start their downward inclination from the cortex. Since the pyramidal tract is direct, it is also monosynaptic. Due to its monosynaptic nature, the axons located on its neurons do not get involved in synapse activity with the neighboring cells until they reach the brainstem or the spinal cord. For this reason, the messages from lower motor neurons are transmitted very rapidly without interruption from the central nervous system to the peripheral nervous system. The cortico bulbar tract is formed when the fibers synapse with the cranial nerves. The ulbar region refers to the brainstem consisting of midbrain, pons and medulla.
The main function of the pyramidal tract is to transmit messages to the lower motor neuron located in the spinal cord and the brainstem necessary for voluntary movement.
Serious speech problems are caused when the upper motor neuron lesions of the pyramidal tract are bilateral. Lesions located on the brainstem and related to cranial nerves are called bulbar lesions. A paralytic condition arising due to these lesions is termed as bulbar palsy. Peripheral lesions are those that occur on the axons of cranial nerves. Whenever the upper motor neurons located in pyramidal tract get affected by bilateral nerves, a paralytic condition similar to bulbar palsy occurs and is termed as pseudobulbar palsy. Sometimes the brainstem gets a lesion due to which the cranial nerves, nucleus and upper motor neuron belonging to the pyramidal tract get damaged. Such a condition is termed as alternating hemiplegia. This condition can paralyze various parts of the body.