3 LONGITUDINAL LAMINAE OF THE BRAINSTEM:

Question 1

3 LONGITUDINAL LAMINAE OF THE BRAINSTEM:

Answer 1

tectum, tegmentum, base

Question 2

tectum

Answer 2

Midbrain
- 2 superior colliculi
- 2 inferior colliculi (the 4 colliculi are often called the quadrigeminal plate)
There is no tectum in the pons and medulla.

Question 3

TEGMENTUM

The middle lamina, the tegmentum contains:

Answer 3

• cranial nerve nuclei
• the supplementary motor nuclei (the inferior olivary nuclei in the medulla, and the red nucleus as well as the substantia nigra in the midbrain)
• the remainder of the tegmentum is filled with reticular formation
• sensory (ascending) tracts travelling to the thalamus
• descending extrapyramidal tracts.

Question 4

TEGMENTUM - reticular formation

Answer 4

The reticular formation is located in the tegmentum throughout the entire length of the brainstem. The neurons that make up the reticular formation are arranged in a net‐like structure (rete = net) and form a continuous network of efferent and afferent pathways through the brainstem. It receives and sends impulses to and from the entire CNS.

Question 5

base - The base is the ventral lamina and contains:

Answer 5

descending pyramidal tracts / pathways (corticobulbar and corticospinal tracts) as its main components. The corticospinal tracts pass through the pontine base into the medullary base, where they become visible on the surface of the medulla (pyramids) and then decussate.

Question 6

base - largest size

Answer 6

*is largest in the pons because of the presence of numerous nuclei. These nuclei receive corticopontine fibers, which in turn project to the cerebellum in the pontocerebellar pathway.

Question 7

base - smallest size

Answer 7

• The base is smallest in the medulla, because many of the fibre tracts have already terminated.

Question 8

midbrain (mesencephalon)

Answer 8

The midbrain lies between the diencephalon (rostral) and the pons (caudal). An imaginary line passing through the cerebral aqueduct divides the midbrain into a larger ventral part (= tegmentum + base) and a smaller dorsal part (= tectum = roof).