Neuroanatomy: Pyramidal Tract Functions

The upper motor neuron (UMN) is responsible for the voluntary movement of muscles.

The lower motor neuron (LMN) carries signals from the UMN to the muscles, causing them to contract.

The cerebellum, proprioception, and vestibular system are essential for coordinating smooth and accurate movements.

The extrapyramidal system regulates the quantity and speed of movement.

The praxis system plans and coordinates the sequence of movements required to achieve a goal.

A neuromuscular junction is the point of contact between a motor neuron and a muscle fiber, where signals are transmitted to cause muscle contraction.

Damage to the upper motor neuron can lead to weakness, spasticity, and hyperreflexia.

Damage to the lower motor neuron can cause muscle weakness, atrophy, fasciculations, and hyporeflexia.

Essential structures are necessary for the movement to occur. Auxiliary structures contribute to the quality of movement but aren't strictly required for it.

Striated muscle is the type of muscle responsible for voluntary movements such as walking and talking.

A motor pathway that carries signals from the cerebral cortex to the spinal cord. It is responsible for voluntary limb and trunk movements.

A neuron in the brain that initiates voluntary movement. It sends signals to lower motor neurons in the spinal cord.

A neuron in the spinal cord that directly controls muscle contraction. UMNs send signals to them.

The region in the brain where the cell bodies of upper motor neurons are located. It is responsible for planning and initiating voluntary movement.

A white matter structure in the brain that connects different areas of the brain. Upper motor neurons pass through it.

The region in the spinal cord where lower motor neurons are located. It receives signals from upper motor neurons.

The connection between a nerve and a muscle fiber where a signal is transmitted to initiate muscle contraction.

The type of muscle that is responsible for voluntary movement. It is controlled by lower motor neurons.

An increase in muscle resistance to passive movement, especially noticeable when a muscle is stretched quickly.

A neurological sign characterized by an abrupt increase in muscle tone, followed by a decrease with continued movement.

A gait pattern caused by a combination of muscle weakness and spasticity, often affecting one side of the body.

Abnormal briskness of the stretch reflex, elicited by tapping a tendon.

A neurological sign that indicates damage to the corticospinal tract. It is characterized by the extension of the big toe and splaying of the other toes when the sole of the foot is stimulated.

A series of rhythmic, involuntary muscle contractions that occur in response to a sudden stretch.

A cluster of symptoms resulting from damage to lower motor neurons, affecting the spinal cord or peripheral nerves.

Wasteing away of muscle tissue, often due to disuse or nerve damage.

The corticospinal tract is a major descending motor pathway responsible for initiating voluntary movements of the limbs and trunk. It originates in the motor cortex of the brain and travels down through the spinal cord, where it synapses with lower motor neurons that directly control muscle contraction.

The UMNs (Upper Motor Neurons) in the motor cortex initiate voluntary movement by sending signals through the corticospinal tract down to the spinal cord. These signals can influence the speed and intensity of the movement.

The LMNs receive signals from the UMNs in the spinal cord and relay these signals to skeletal muscles, causing them to contract and produce movement.

The decussation is the point where the corticospinal tract fibers cross over from one side of the brain to the opposite side of the spinal cord. This is why damage to one side of the brain often affects the opposite side of the body.

The Corticonuclear or Corticobulbar tract is similar to the corticospinal tract, but it controls voluntary movements of the face, head and neck, instead of the limbs and trunk. It also starts in the motor cortex and synapses with LMNs in the brainstem.

The Corticonuclear/Corticobulbar tract decussates at the brainstem, not the medulla. This is important because damage to the brainstem can affect facial and head movements on the same side of the body.

The anterior horn of the spinal cord is the location where the cell bodies of the LMNs reside. These neurons receive signals from the UMNs in the corticospinal tract and send them to the skeletal muscles, initiating movement.

The primary motor cortex is the region in the brain responsible for planning and initiating voluntary movements, sending signals through the corticospinal tract to the spinal cord.

A reflex that is triggered by stroking the sole of the foot. It is characterized by flexion of the big toe and the adduction and flexion of the other toes. It is normal in children over 2 years of age.

An abnormal reflex that indicates a possible upper motor neuron lesion. It is characterized by extension of the big toe and abduction of the other toes when the sole of the foot is stroked. It is normal in children under 2 years of age.

A neurological condition characterized by weakness or paralysis, increased muscle tone, reflex abnormalities, and muscle atrophy. It arises from damage to the upper motor neurons within the brain.

A condition affecting the motor cortex of the brain. The corticospinal tract is affected resulting in either monoplegia (affecting one limb) or hemiplegia (affecting one side of the body). The symptoms are contralateral to the lesion.

A condition affecting the internal capsule in the brain, where upper motor neuron axons converge. Results in hemiplegia - paralysis affecting one side of the body. Symptoms are contralateral to the lesion.

A condition affecting the brainstem, specifically the midbrain. Results in contralateral hemiplegia and central facial palsy - weakness of the facial muscles on the opposite side of the body. The corticospinal tract is affected.

A condition affecting the brainstem, specifically the pons. Results in contralateral hemiplegia and peripheral facial palsy. The corticospinal tract is affected.

A condition affecting the brainstem, specifically the medulla oblongata. Results in hemiplegia - paralysis affecting one side of the body, and dysphagia and dysarthria - difficulty swallowing and speaking. The corticospinal tract, as well as cranial nerves IX, X, XI, and XII are affected.

A condition affecting the spinal cord. Depending on the level of the lesion, it can cause hemiplegia, monoplegia, tetraplegia, or paraplegia. The symptoms are ipsilateral (affecting the same side) to the lesion.

A condition affecting the motor cortex, the area responsible for initiating movement. It can cause either monoplegia - paralysis of a single limb, or hemiplegia - paralysis of one side of the body. The symptoms are contralateral (affecting the opposite side) to the lesion.

A decrease in muscle tone (resistance to passive stretch) caused by damage to the lower motor neuron (LMN). The LMN is responsible for carrying signals from the brain to the muscles.

An abnormal increase in muscle tone, usually caused by damage to the upper motor neuron (UMN). This can lead to spasticity, clasp-knife response, and other abnormal movements.

Muscle weakness or paralysis (complete loss of strength) affecting a specific group of muscles supplied by a single nerve root or plexus.