Medulla oblongata

Eksternal na babaw

Naglalaman ang naunang gitnang guwang na tupi ng pia mater, at nauunat sa kahabaan ng medulla oblongata. Natatapos ito sa ibabang hangganan ng pons sa maliit na lugar na tatsulok, na tinatawag na foramen cecum. Sa kahit anong gilid ng guwang ay ang nakataas na lugar na tinatawag na medullary pyramids. Ang tagilo ay naglalaman ng pyramidal tracts–ang corticospinal at corticobulbar tract ng sistemang nerbiyos. Sa buntot na bahagi ng medulla ay ang pagtawid ng mga trakto sa ibabaw ng decussation of the pyramids na humaharang sa guwang sa puntong ito. Kilalá ang ilang himaymay na nanggagaling mula sa naunang gitnang puwang sa itaas ng decussation of the pyramids at tumatakbo sa gilid ng babaw ng pons sa tawag na anterior external arcuate fibers.
Ang rehiyon sa pagitan ng anterolateral at posterolateral sulcus sa itaas na bahagi ng medulla ay marked ng isang pares ng swellings na tinatawag na olivary bodies (also called olives). They are caused by the largest nuclei of the olivary bodies, the inferior olivary nuclei.
The posterior part of the medulla between the posterior median sulcus and the posterolateral sulcus contains tracts that enter it from the posterior funiculus of the spinal cord. These are the gracile fasciculus, lying medially next to the midline, and the cuneate fasciculus, lying laterally. These fasciculi end in rounded elevations known as the gracile and the cuneate tubercles. They are caused by masses of gray matter known as the gracile nucleus and the cuneate nucleus. The soma (cell bodies) in these nuclei are the second-order neurons of the posterior column-medial lemniscus pathway, and their axons, called the internal arcuate fibers or fasciculi, decussate from one side of the medulla to the other to form the medial lemniscus.
Just above the tubercles, the posterior aspect of the medulla is occupied by a triangular fossa, which forms the lower part of the floor of the fourth ventricle. The fossa is bounded on either side by the inferior cerebellar peduncle, which connects the medulla to the cerebellum.
The lower part of the medulla, immediately lateral to the cuneate fasciculus, is marked by another longitudinal elevation known as the tuberculum cinereum. It is caused by an underlying collection of gray matter known as the spinal trigeminal nucleus. The gray matter of this nucleus is covered by a layer of nerve fibers that form the spinal tract of the trigeminal nerve.
The base of the medulla is defined by the commissural fibers, crossing over from the ipsilateral side in the spinal cord to the contralateral side in the brain stem; below this is the spinal cord.

Halagang klinikal

A blockage (such as in a stroke) will injure the pyramidal tract, medial lemniscus, and the hypoglossal nucleus. This causes a syndrome called medial medullary syndrome.
Lateral medullary syndrome can be caused by the blockage of either the posterior inferior cerebellar artery or of the vertebral arteries.

Iba pang hayop

Kapwa ang mga lamprey at hagfish ay ma fully developed na medulla oblongata. Parehas siláng may pagkakatulad sa mga sinaunang agnathans, it has been suggested that the medulla evolved in these early fish, approximately 505 million years ago. The status of the medulla as part of the primordial reptilian brain is confirmed by its disproportionate size in modern reptiles such as the crocodile, alligator, and monitor lizard.