Question

In the hospital, you see that an older patient has a positive Babinsky sign.  What does this look like?  This “positive” sign is not a good thing, what does it indicate regarding a tract? B) What information travels along this tract?  Where do neural signals originate along this tract, and what is the function of this area of the brain?  Explain the pathway for a neural signal to travel from that area of the brain to its destination, introducing relevant anatomy along the way.

Answer 1

A).In the hospital, you see that an older patient has a positive Babinsky sign.  What does this look like?This “positive” sign is not a good thing, what does it indicate regarding a tract?

Positive babinski sign happens when we scrape the sole of the foot,it causes the dorsiflexion and fanning out of the toes .This indicates an underlying of a system or brain condition that is causing the refluxes to react abnormally.

The babinsky sign is due to the upper motor neuron lesion.

B) What information travels along this tract?  Where do neural signals originate along this tract, and what is the function of this area of the brain?  Explain the pathway for a neural signal to travel from that area of the brain to its destination, introducing relevant anatomy along the way.

The motor information passes along this tract.

The signals originate in the primary motor cortex in the cerebral cortex region.Grey matter of cortex has the area from where the cell bodies of neurons arises which are associated with a specific areas of body such as feet hands and head.

The pyramidal system is the system of voluntary movements. It is controlled by the signal sent from brain to spinal cord or brain stem by the upper motor neurons. And from there to the skeletal muscles by lower motor neurons. The white matter consist of neuron axons which travel trough the brain. The axons pass through internal capsule present near to thalamus and basal ganglia. Brain stem consist of 3 parts:

• midbrain The crucial area in the midbrain is red nucleus and its crus cerebri.
• Pons
• medulla

The spinal cord tracts through which the neurons pass. The important tracts in the pyramidal system are lateral corticospinal tract and anterior corticospinal tract. The target organs of the motor neurons are the skeletal muscle cells. The majority of upper motor neurons projects from motor cortex to the spinal cord are contained in lateral corticospinal tract. The neurons that passes through the lateral corticospinal tract will crossover at the medulla. The upper motor neuron reaches at the correct spinal level and synapse with the lower motor neuron at the anterior horn of the spinal cord. Lower motor neurons are responsible for the particular movement of the body part by passing a signal to the skeletal muscle cells. There are some neurons that does not cross over at the medulla and passes through the anterior corticospinal tract in the spinal cord. Axons of the anterior corticospinal tract will crossover when they reach at he level of the spinal cord, where they synapse with the lower motor neuron. the motor neurons activated on one side of the cortex controls the activity of the opposite side of the body.The spinal tracts are under voluntary control.

Rubrospinal tracts originate in the red nucleus of midbrain and passes through the lateral  part of the spinal cord and synapse with the lower motor neuron. The rubrospinal tract along with its lower motor neurons control the flexion of the muscles and inhibit the extension of the muscle.

In summary the upper motor neuron transmits the information from the cerebral cortex to the spinal cord. and lower motor neurons transmits the information from midbrain or spinal cord to the skeletal muscles.Hence Any injury for brain such as infection or tumor can causes the lesion in the upper motor neuron. Similarly any injury to the midbrain or spinal cord; specifically the white matter of the spinal cord can cause upper motor neuron lesion.Lower motor neuron injury can occur along the tract from the spinal cord to the skeletal muscle.The lower motor injury may also be due to injury in the ventral grey matter of the spinal cord ,anterior horn of the spinal cord where the lower motor neurons starts