Where the Fibres Cross
Asystole

Two coloured threads, a paper spine,
We follow each across the line.

Vibration, fine touch, joint position,
Dorsal columns carry them high.
First they climb on the same side,
To the medulla, then cross the line.
Gracile brings the lower body,
Cuneate adds the upper part.
Medial lemniscus takes the message
Toward the thalamus and on.

Find where the fibres cross,
Then you can place the loss.
Touch and position cross up high,
Pain and temperature cross nearby.
Most motor cross in the medulla,
Then descend on the other side.
Name the tract and find its crossing,
Let the pattern be your guide.

Pain and temperature reach the dorsal horn,
Their next cells cross within the cord.
Through the anterior white commissure,
Spinothalamic fibres climb aboard.
Lateral corticospinal commands
Come down from the brain to the hand.
Most crossed at the pyramids already,
In the cord, same-side strength can fall.

Find where the fibres cross,
Then you can place the loss.
Touch and position cross up high,
Pain and temperature cross nearby.
Most motor cross in the medulla,
Then descend on the other side.
Name the tract and find its crossing,
Let the pattern be your guide.

Right half of the thoracic cord:
Right-side power falls below.
Right vibration and position fade;
Left pain and temperature go.
That pain loss starts a little lower,
Often one or two segments down.
Brown-Séquard, a crossing pattern,
Draw the sides before the sound.
Spinal shock can quiet reflexes;
Later, brisk responses may be found.
A front-cord lesion can spare vibration,
While power, pain and temperature fall.

Find where the fibres cross,
Then you can place the loss.
Touch and position cross up high,
Pain and temperature cross nearby.
Most motor cross in the medulla,
Then descend on the other side.
Name the tract and find its crossing,
Let the pattern be your guide.

Two coloured threads, the page is clear,
I trace the crossing; you stay here.