A 55 year old man presents to the emergency department with a numb left leg. On examination, he has clear deficits in both discriminatory touch and vibration sense in his left leg. The neurological examination reveals no other abnormalities. A medical student who sees this case tries to understand the underlying sensory pathway from the leg to the brain.

Within which part of the medulla do neurons carrying discriminatory touch information from the legs enter?

Options:
explanation: This question is testing your knowledge of the dorsal column. This is the pathway through which sensory information travels to the brain, including fine touch and vibration sense. Sensory information from T7 or below (like that from the leg) enters the spinal cord via first-order neurons, forming the gracile fasciculus within the spinal cord. The first-order neuron ascends ipsilaterally within the gracile fasciculus before entering the brainstem at the gracile nucleus within the medulla. If the information was coming from above T7, then it would enter the spinal cord and form the cuneate fasciculus before entering the medulla at the cuneate nucleus.
name: Cuneate fasciculus
label: e
answer: no
explanation: This is the pathway through which sensory information travels to the brain, including fine touch and vibration sense. Sensory information from T7 or below (like that from the leg) enters the spinal cord via first-order neurons, forming the gracile fasciculus within the spinal cord. The first-order neuron ascends ipsilaterally within the gracile fasciculus before entering the brainstem at the gracile nucleus within the medulla.
name: Gracile fasciculus
label: c
answer: no
explanation: This question is testing your knowledge of the dorsal column. This is the pathway through which sensory information travels to the brain, including fine touch and vibration sense. Sensory information from T7 or below (like that from the leg) enters the spinal cord via first-order neurons, forming the gracile fasciculus within the spinal cord. The first-order neuron ascends ipsilaterally within the gracile fasciculus before entering the brainstem at the gracile nucleus within the medulla. If the information was coming from above T7, then it would enter the spinal cord and form the cuneate fasciculus before entering the medulla at the cuneate nucleus.
name: Cuneate nucleus
label: b
answer: no
explanation: This question is testing your knowledge of the dorsal column. This is the pathway through which sensory information travels to the brain, including fine touch and vibration. Sensory information from T7 or below (like that of the leg) enters the spinal cord via first-order neurons, forming the gracile fasciculus within the spinal cord. The first-order neuron ascends ipsilaterally within the gracile fasciculus before entering the brainstem at the gracile nucleus within the medulla.
name: Gracile nucleus
label: a
answer: yes
explanation: This question is testing your knowledge of the dorsal column. This is the pathway through which sensory information travels to the brain, including fine touch and vibration sense. Sensory information from T7 or below (like that from the leg) enters the spinal cord via first-order neurons, forming the gracile fasciculus within the spinal cord. The first-order neuron ascends ipsilaterally within the gracile fasciculus before entering the brainstem at the gracile nucleus within the medulla. The ventral posterolateral nucleus is the location of the synapse between the 2nd and 3rd order neurones in this pathway, located in the thalamus.
name: Ventral posterolateral nucleus
label: d
answer: no

Correct answer: a