AN58.1-4 | Medulla Oblongata — Glossary

Rounded ridge on the anterior surface of the medulla containing corticospinal fibres; site of the pyramidal decussation at its caudal end

Crossing of 85% of corticospinal fibres at the caudal medulla; explains contralateral motor control by the brain

Oval eminence on the anterior surface of the medulla overlying the inferior olivary nucleus; a relay for the cerebellum

Large crenated (wrinkled) nucleus in the medulla that relays error signals to the cerebellum via climbing fibres; forms the olive on the surface

Motor nucleus (SVE) deep in the medullary reticular formation supplying pharyngeal and laryngeal muscles via CN IX, X, and cranial XI

NTS — sensory nucleus receiving taste (SVA) from CN VII, IX, X and visceral afferents (GVA) from the carotid body and thoracoabdominal viscera

GSE motor nucleus near the midline in the floor of the 4th ventricle (hypoglossal triangle); supplies all tongue muscles except palatoglossus

GVE parasympathetic nucleus in the vagal triangle; sends preganglionic parasympathetic fibres to the thoracoabdominal viscera via CN X

Lateral medullary syndrome from PICA occlusion; ipsilateral Horner's, facial pain/temp loss, dysphagia, ataxia; contralateral body pain/temp loss

Medial medullary syndrome from anterior spinal artery occlusion; contralateral hemiplegia, fine touch loss; ipsilateral tongue deviation

2nd order sensory axons from nucleus gracilis and cuneatus that cross the midline (sensory decussation) to form the medial lemniscus

Ascending sensory tract formed after the sensory decussation in the medulla; carries fine touch, vibration, and proprioception to the VPL thalamus

Branch of CN X supplying all intrinsic laryngeal muscles except cricothyroid; left loops under aortic arch, right under subclavian artery

LMN lesion of CN IX, X, XII nuclei or nerves causing nasal speech, dysphagia, wasted fasciculating tongue, and absent jaw jerk

Bilateral UMN lesion of corticobulbar tracts causing spastic tongue, brisk jaw jerk, emotional lability, and Donald Duck speech

Posterior inferior cerebellar artery — branch of the vertebral artery; occlusion causes Wallenberg (lateral medullary) syndrome

Opening in the skull base transmitting CN IX, X, XI, the internal jugular vein, and the inferior petrosal sinus

Small projection at the lower end of the 4th ventricle floor marking where the central canal opens into the ventricle

Nucleus in the posterior medulla where 1st order neurons from the fasciculus gracilis (lower body) synapse; source of internal arcuate fibres

Nucleus in the posterior medulla where 1st order neurons from the fasciculus cuneatus (upper body) synapse; source of internal arcuate fibres

Hallmark of brainstem lesions: ipsilateral cranial nerve deficit with contralateral body motor/sensory deficit, because cranial nerves exit before tracts cross