Internal structure of medulla oblongata By Essam Eldin

Internal structure of medulla oblongata By Essam Eldin Abdel. Hady Salama

Caudal medulla ØDorsally; ØTrigeminal sensory nucleus. ØExtends through the whole length of the brain stem and upper segment of spinal cord. ØSpinal tract of trigeminal, lies immediately superficial to the nucleus. ØFasciculus and nucleus gracilis on each side of middle line. ØFasciculus and nucleus cuneatus on each side lateral to gracili. ØVentrally; ØPyramidal tracts and pyramidal decussation.

Mid medulla ØDorsally; ØGracile and cuneate nuclei with their respective tracts. ØAxons of the two nuclei pass ventrally and medially as internal arcuate fibers, decussating in the middle line forming the medial lemniscus which run rostraly through rostral medulla, pons and midbrain to end in thalamus. ØVentrally; ØPyramids are prominent.

Mid medulla

Rostral medulla ØVentrally; ØPyramids remain prominent. ØMedial lemniscus lie dorsal to medial aspect of pyramids, around middle line. ØInferior olivary nucleus lies dorsolatera to pyramid and lateral to medial lemniscus. ØSpinal lemniscus and trigeminothalamic fibers are dorsal to inferior olivary nucleus and lateral to medial lemniscus.

Rostral medulla ØDorsally; ØForms part of floor of 4 th ventricle. ØHypoglossal nuclei lie lateral to middle line. ØDorsal nucleus of vagus lies lateral to hypoglossal nuclei. ØVestibular nuclei lie most laterally. ØMedial longitudinal fasciculus lie ventromadial to hypoglossal nuclei. ØRestiform body or inferior cerebellar peduncle on the dorsolateral aspect.

Rostral medulla ØDorsal and ventral choclear nuclei lie dorsal and lateral to inferior cerebellar peduncles. ØNucleus ambiguus are deep beneath the ventricular floor, and dorsal to inferior olivary nucleus.

Rostral medulla