National Physical Therapy Examination (NPTE) Practice Exam

In which region of the nervous system is a lesion likely located if a patient is unable to sit independently?

1. Cerebrum

2. Brainstem

3. Spinal cord

4. Peripheral nerve

The correct answer is: Cerebrum

The inability to sit independently is most often associated with impairments in the control of posture and balance, which are primarily regulated by the cerebellum and its interaction with higher brain centers. However, since the cerebrum is responsible for voluntary motor control, coordination, and sensory perception, a lesion in this area can significantly affect a patient's ability to maintain the necessary muscle tone and coordination required to sit upright without support. The cerebrum is particularly critical because it integrates sensory information and orchestrates appropriate motor responses necessary for complex tasks like sitting. When a lesion occurs in the cerebrum, it can disrupt this integration, leading to difficulties in performing functional tasks such as maintaining an independent sitting position. While lesions in the brainstem, spinal cord, or peripheral nerves can also contribute to functional impairments, they typically lead to different symptoms. For instance, spinal cord injuries can affect lower body function and stability, while peripheral nerve lesions usually present as weakness or loss of sensation in the affected limb, but tend to preserve the broad ability to maintain posture if the neural pathways to the spinal cord are intact.