Medulla Flashcards
Where is the medulla located in relation to the midbrain and pons?
Most inferior aspect of the brainstem and is continuous with the spinal cord
On the anterior surface of the medulla, what is the name of the fissure which lies in the midline of the medulla?
Anterior median fissure - this is continuous along the length of the spinal cord
What temporarily interrupts the anterior median fissure?
Decussation of the pyramids
Name the two sulci visible on the anterior surface of the medulla
ventrolateral sulcus
posterolateral sulcus
What are the pyramids located on the anterior surface of the medulla?
Pyramids are paired swellings found between the anterior median fissure and the ventrolateral sulcus
What are the medullary pyramids?
Swelling marking the position of underlying fibres passing from the cerebral hemispheres to the cord - the corticospinal (pyramidal) tracts
What is the decussation of the pyramids?
Diagonally oriented bundles of fibres crossing the fissure via which about 80% of the corticospinal fibres cross the midline to enter the opposite lateral white column of the spinal cord
Where are the olives located on the anterior surface of the medulla?
Olives are another pair of swellings located laterally to the pyramids between the ventrolateral and posterolateral sulci
What are the olives?
Swelling is caused by the presence of the underlying inferior olivary nucleus and is concerned with the control of movement
Which cranial nerve arises from the junction between the pons and the medulla?
Abducens nerve CN VI
Which cranial nerves extend out of the ventrolateral sulcus?
Hypoglossal nerve CN XII
Which cranial nerves extend out of the posterolateral sulcus?
CN IX
CN X
CN XI
Unlike the anterior surface, the posterior surface is largely obstructed from view and is relatively devoid of features. In order to appreciate the posterior surface, the cerebellum must be removed. Similar to the anterior surface, the posterior surface has a midline structure - what is this called?
Posterior median sulcus - continuous below as the posterior median sulcus of the spinal cord
As we move lateral from the midline on the posterior surface of the medulla, what can be seen?
Fasciculus gracilis - carries fine touch, vibration, two-point discrimination and proprioception from the lower limb
Fasciculus cuneatus - carries fine touch, vibration, two-point discrimination and proprioception from the upper limb
What overlies the fasciculus gracilis and fasciculus cuneatus?
gracile tubercle and cuneate tubercle - round swellings either side of the midline
