Dr Gawad Physiology Course Online Exams –descending Tracts, Spinal Cord Transection, Rf, EEG, Sleep

The contralateral reticular formation descending tract is responsible for inhibiting muscle contraction. This tract sends signals from the brainstem to the spinal cord to suppress muscle activity. This inhibition helps to regulate and control muscle movements, preventing excessive or unwanted contractions.

The correct answer is "fibers are mainly crossing the midline." The pyramidal tracts are responsible for controlling voluntary muscle movements. They consist of nerve fibers that originate in the motor cortex of the brain and travel down the spinal cord. These fibers primarily cross the midline of the body, meaning that the motor signals from the brain control muscles on the opposite side of the body. This allows for coordinated movement and control of both sides of the body.

During REM (Rapid Eye Movement) sleep, dreams can be consolidated. This is because REM sleep is characterized by intense brain activity and vivid dreaming. During this stage, the brain consolidates and processes emotional experiences and memories, which can result in the formation of dreams. The other statements are not true for REM sleep. Heart rate and respiratory rate may vary during REM sleep, and muscle tone is actually decreased, causing temporary paralysis to prevent acting out dreams.

The dorsal column leminiscus pathway will never be affected in syringomyelia because syringomyelia is a condition characterized by the formation of a fluid-filled cavity within the spinal cord, which typically affects the central gray matter. The dorsal column leminiscus pathway, which is responsible for transmitting touch, vibration, and proprioception sensations, is located in the posterior part of the spinal cord, away from the central gray matter. Therefore, it is not directly affected by the fluid-filled cavity and remains intact.

During the spinal shock phase, the body experiences a temporary loss of reflexes and functions below the level of the spinal cord injury. Sensations and motor function below the lesion are typically lost during this phase. However, autonomic bowel and bladder function is not intact during spinal shock. This means that the individual may experience loss of control over their bowel and bladder movements.

The statement "patient with spinal transection at T1 has higher blood pressure than a patient with transection at T12" is not true. In fact, a patient with spinal transection at T1 would have lower blood pressure compared to a patient with transection at T12. This is because the sympathetic nervous system, which controls blood pressure, is affected by spinal cord injuries. The higher up the injury is, the more severe the impact on blood pressure regulation.

The basal ganglia are involved in the central control of extrapyramidal tracts. These tracts are responsible for involuntary movements and are separate from the pyramidal tracts that control voluntary movements. The basal ganglia help regulate and modulate the activity of the extrapyramidal tracts, ensuring smooth and coordinated movement. Therefore, the statement that basal ganglia are included in the central control of these tracts is correct.

The statement "None of the above" is the correct answer because all of the statements provided are true regarding Brown Sequard syndrome. In this condition, there is a hemisection or damage to one side of the spinal cord. This results in the loss of dorsal column sensations from the ipsilateral part of the body below the lesion, while the spinothalamic tract sensations from the ipsilateral part of the body below the lesion remain intact. Additionally, there is an upper motor neuron lesion (UMNL) of the ipsilateral muscles below the lesion. Therefore, none of the statements are false.