Structures of the Medulla

Question 1

Medullary Pyramids

Answer 1

Location: Rostral/Caudal Medulla

Function = Contain descending motor fibers of corticospinal and corticobulbar tracts - known together as the pyramidal tracts

Question 2

Inferior Cerebellar Peduncle

Answer 2

Location: Rostral Medulla

Function = Afferent and efferent fibers between cerebellum and medulla

Question 3

Open Medulla

Answer 3

Location: Rostral Medulla

Function = Ventral wall of 4th ventricle

Question 4

Inferior Olivary Nuclei

Answer 4

Location: Rostral/Caudal Medulla

Function = Accepts motor and sensory input from a multitude of sources and projects information about muscle and limb movement

Question 5

Nuclei Gracilis

Answer 5

Location: Caudal Medulla

Function = Gives rise to dorsal column medial lemniscus pathway - Major ascending somatosensory pathway carrying discriminative touch, light touch, vibration, proprioception of muscles innervated by T6 spinal nerve roots and below. (Lower body)

Question 6

Nuclei Cuneatus

Answer 6

Location: Caudal Medulla

Function = Gives rise to dorsal column medial lemniscus pathway - Major ascending somatosensory pathway carrying discriminative touch, light touch, vibration, proprioceptions of muscles innervated by T6 spinal nerve roots and above. (Upper body)

Question 7

Medial Lemniscus Decussation

Answer 7

Location: Caudal Medulla

Function = Crossing of the medial lemniscal dorsal pathway, caring afferent somatosensory information from the body.

Question 8

Pyramidal Decussation

Answer 8

Location: Cervicomedullary Junction

Function = Crossing of the pyramidal tracts, descending to provide motor drive to the body

Question 9

What is the reticular formation?

Answer 9

An intricate system composed of loosely clustered neurons.

Extends through central core of the medulla, pons, and midbrain.

Question 10

Where does the reticular formation project to?

Answer 10

Thalamus, cerebellum, spinal cord, and optic

Question 11

What are the 4 functions of the reticular formation?

Answer 11

1. General arousal and awareness.
2. Reticular Activating System (RAS)
   - Synapses with all major ascending tracts
   - Functions in arousal from sleep
3. Motor awareness
   - Medial and Lateral reticulospinal tracts
4. Autonomic regulation

Question 12

Nuclei Ambiguous

Answer 12

Location: Rostral and caudal medulla

Function = group of cell bodies of motor divisions of cranial nerves IX and X that go on to innervate ipsilateral muscles of the jaw and mouth and throat that are ultimately responsible for swallowing and speaking.

Question 13

Nuclei Solitarius

Answer 13

Location: Rostral and caudal medulla

Function = Relay station for general visceral and taste afferents carried by cranial nerves VII, IX, and X
Has critical role in initiation and integration of a wide variety of reflexes controlling cardiovascular function, respiration, and GI motility.

Question 14

Vestibular Nuclei

Answer 14

Location: Rostral medulla

Function:
Inferior = gives rise to medial vestibulospinal tract, descends to c-spine for neck control.
Medial = give rise to medial longitudinal fasciculus; gives rise to medial vestibulospinal tract.

Question 15

Spinal Trigeminal

Answer 15

Location: Rostral medulla

Function = afferent crude touch, pain, temperature of face (CN V, VII, IX, X)