The Medulla

Question 1

What important structures does the medulla house?

What is the shape of the medulla and its size?

Answer 1

1) Ascending and descending nerve tracts
2) Brainstem nuclei

Conical - 3x2cm

Question 2

What is the location of the medulla?

Answer 2

Superior margin is marked by the pontomedullary junction.

The inferior margin is marked by the origin of the 1st pair of cervical spinal nerves. This occurs just as the medulla exits the skull through the foramen magnum.

Question 3

What are the main features of anterior surface of the medulla?

Answer 3

1) The anterior median fissure that is located in the midline of the medulla. This is interrupted by the decussation of pyramids before continuing down the spinal cord.
2) The pyramid - a pair of swellings located just lateral to the anterior median fissure.
3) Ventrolateral and posterior lateral sulci - located just lateral to the pyramids.
4) Olives - Located between the sulci.
5) Hypoglossal nerve (CN XII) extending out of the venterolateral sulcus.
6) CN IX, X, XI join the medulla in the posterolateral sulcus.

Question 4

What are the main features of the posterior surface of the medulla?

Answer 4

Largely obstructed from view and devoid of features.

When removing the cerebellum, a number of features can be observed:

1) Posterior median sulcus - in the midline.
2) Fasciculus gracilis and cuneatus separated by the posterior intermediate sulcus.