External configuration | Brain-inter-atlas

Anterior surface

Anterior median fissure
- Prolongation of the anterior median fissure of the spinal cord
- Triangular enlargement before reaching the pons: foramen caecum
- Blurring in its bottom quarter with the decussation of pyramids
Pyramid
- protrusion on each side of the anterior median fissure
- Apparent prolongation (unreal) of the anterior funiculus of the spinal cord
- Lateral boundary: anterolateral sulcus
  → emergence of the hypoglossal nerve (XII)

Posterior surface

Lower half
Akin to the cervical spinal cord
- Posterior funiculus
  - Bounded by the posterior median and the posterolateral sulci
  - Divided into gracile and cuneate fasciculi
Upper half
- Gap between the two posterior funiculi:obex
  → the lower half of the floor of the fourth ventricle is visible
- Gracile tubercle
- Cuneiform tubercle

Lateral surfaces

Anterolateral sulcus
emergence of the hypoglossal nerve (IX)
Posterolateral sulcus
site of exit of three cranial nerves:
- Glossopharyngeal nerve (IX)
- Vagus nerve (X)
- Accessory nerve (XI))

Upper end

Limit between the medulla oblongata and the pons
Foramen caecum
Emergence of
- Abducens nerve (VI)
- Facial nerve (VII)
- Vestibulocochlear nerve (VIII)

Lower end

Truncated cone
Limit between the medulla oblongata and the spinal cord
Coincides with the lower end of the decussation of pyramids