Medulla Oblongata (lab)

Olive

Only present in cranial half

Vital centers (cardio and resp) immediately dorsal → Damage leads to death

Anterior median fissure

Space between pyramids

Anterior lateral sulcus

Space between pyramid and olive

Where CNXII leaves brainstem

Posterolateral sulcus

Space between olive and lateral funiculus

Where CNs IX, X, XI leave the brainstem

Structures present on ventral view medial to lateral

Pyramid → Olive → Lateral funiculus

Lateral funiculus

Directly continuous with funiculi of spinal cord

4th ventricle in the medulla

Cranial: Open, medulla floor and cerebellum roof

Caudal: Closed and smaller from medulla wrapping → Continuous with spinal canal

Inferior olivary nucleus

Receives input from spinal cord and sends fibers into contralateral cerebellar hemisphere through inferior cerebellar peduncles

Synapse on Purkinje cells for error detection in motor movements

Superior cerebellar peduncles

Connects cerebellum and mesencephalon

Predominantly output, mostly fibers to red nucleus

Decussate in level of inferior colliculus of mesencephalon

Damage → Contralateral cerebellar ataxia

Middle cerebellar peduncle

Connects cerebellum to pons

Only input into cerebellum (efferent copies)

Decussate in transverse fibers within the base of the pons

Damage → Ipsilateral cerebellar ataxia

Inferior cerebellar peduncles

Connect cerebellum to medulla

Main input to cerebellum

Damage → Ipsilateral cerebellar ataxia (?)

The way the cerebellum communicates back to cortex is through…

Red nucleus and superior cerebellar peduncle

Damage to inferior olivary nucleus results in…

Contralateral cerebellar ataxia

Muscles spindles to the cerebellum

Unconscious proprioception stays ipsilateral

Conscious does decussate

Caudal medulla

Pyramids and 4th ventricle (closed) still present

No inferior olivary nucleus

Nucleus Gracilus

Sensory for lower limbs

Synapse in VPL of thalamus

Nucleus Cuneatus

Sensory for upper limbs

Synapse in VPL of thalamus

Cuneocerebellar tract

HyUnconscious proprioception

CNXII pathway

Hypoglossal

Nucleus in medulla, travels ventral and laterally to exit anterolateral sulcus

Pass near inferior olivary nucleus, damage to it may present as a CN palsy

Corticospinal tract

BA 4 → Posterior limb of internal capsule → Crus cerebri in mesencephalon → Longitudinal fibers of the pons → Medullary pyramids → Decussate at caudal aspect of medulla

Lateral decussates in medulla, anterior decussates at spinal level