Organ
Medulla oblongata
Brainstem junction with the spinal cord
High-yield
Two separate crossings occur here: the pyramidal decussation for most corticospinal fibers, and the sensory decussation for the dorsal-column pathway. Their different levels help explain the organization of medullary sections.
Overview
Below the pons, the medulla narrows toward the spinal cord at the foramen magnum. Its ventral pyramids contain corticospinal fibers, and the olives mark the underlying inferior olivary nuclei. Most corticospinal fibers cross in the caudal medulla. Slightly higher, axons from the gracile and cuneate nuclei cross to form the medial lemnisci.
Reference facts
- Location
- The brainstem segment between the pons and cervical spinal cord, with the lower transition near the foramen magnum.
- Parts
- Includes pyramids, olives, dorsal-column nuclei and major tracts. Its rostral open portion borders the fourth ventricle; its caudal closed portion surrounds the central canal.
- Blood supply
- Vertebral and anterior spinal branches supply medial areas; vertebral and posterior inferior cerebellar branches contribute laterally. Territories vary.
- Relations
- The rostral dorsal surface forms part of the fourth-ventricle floor. IX and X rootlets emerge behind the olive and XII rootlets in front; traditional descriptions also assign cranial XI rootlets behind the olive.
- Function
- Carries many pathways between cord and brain and contains circuits for breathing, cardiovascular regulation, swallowing, voice and tongue movement.
Clinical correlation
Lateral medullary infarction can combine swallowing difficulty, ataxia, ipsilateral facial and contralateral body pain-temperature loss, and Horner syndrome. Limb weakness is less typical, but can occur. Medial lesions may combine contralateral weakness and impaired vibration-position sense with ipsilateral tongue weakness.
Frequently asked questions
Where is the medulla oblongata located?
The brainstem segment between the pons and cervical spinal cord, with the lower transition near the foramen magnum.
What does the medulla oblongata do?
Carries many pathways between cord and brain and contains circuits for breathing, cardiovascular regulation, swallowing, voice and tongue movement.
What are the parts of the medulla oblongata?
Includes pyramids, olives, dorsal-column nuclei and major tracts. Its rostral open portion borders the fourth ventricle; its caudal closed portion surrounds the central canal.
What is the blood supply of the medulla oblongata?
Vertebral and anterior spinal branches supply medial areas; vertebral and posterior inferior cerebellar branches contribute laterally. Territories vary.