medullary pyramid

Examples of medullary pyramid in the following topics:

• Hypoglossal (XII) Nerve

  • The hypoglossal nerve emerges from the medulla oblongata in the preolivary sulcus where it separates the olive (olivary body) and the pyramid (medullary pyramid).

• Organization of Motor Neuron Pathways

  • It consists of the pyramidal and extrapyramidal system.
  • The motor impulses originate in the giant pyramidal cells (Betz cells) of the motor area, i.e., the precentral gyrus of the cerebral cortex.
  • Cortical upper motor neurons originate from Brodmann areas 1, 2, 3, 4, and 6, then descend into the posterior limb of the internal capsule, through the crus cerebri, down through the pons, and to the medullary pyramids, where about 90% of the axons cross to the contralateral side at the decussation of the pyramids.
  • Included in the diagram are the following motor pathways: corticospinal tracts (pyramidal tract), and extrapyramidal tracts (tectospinal tract not delineated).
  • The pyramidal tract is visible in red, and pyramidal decussation is labeled at lower right.

• Vagus (X) Nerve

  • Upon leaving the medulla between the medullary pyramid and the inferior cerebellar peduncle, it extends through the jugular foramen, then passes into the carotid sheath between the internal carotid artery and the internal jugular vein below the head, to the neck, chest and abdomen, where it contributes to the innervation of the viscera.

• Medulla Oblongata

  • A stroke can injure the pyramidal tract, medial lemniscus, and the hypoglossal nucleus.
  • This causes a syndrome called medial medullary syndrome, a type of alternating hemiplegia characterized by recurrent episodes of paralysis on one side of the body.
  • The region between the anterior median and anterolateral sulci is occupied by an elevation on either side known as the pyramid of medulla oblongata.
  • This is known as the decussation of the pyramids.
  • Other fibers that originate from the anterior median fissure above the decussation of the pyramids and run laterally across the surface of the pons are known as the external arcuate fibers.

• Epithalamus and Pineal Gland

  • It includes the habenula and their interconnecting fibers (the habenular commissure), the stria medullaris, and the pineal gland.
  • The stria medullaris, also known as stria medullaris thalami, is a fiber bundle containing afferent fibers from the septal nuclei, lateral preoptic hypothalamic region, and anterior thalamic nuclei to the habenula.

• Medulla Injury

  • Lateral medullary syndrome, also called Wallenberg syndrome and posterior inferior cerebellar artery syndrome, is a disease that presents with a constellation of neurologic symptoms due to injury to the lateral part of the medulla in the brain, resulting in tissue ischemia and necrosis, typically from blood clot (stroke) impeding the vertebral artery and/or the posterior inferior cerebellar artery .
  • Treatment for lateral medullary syndrome involves focusing on relief of symptoms and active rehabilitation to help those suffering from the syndrome recover their activities of daily living and cope with neurologic loss that can be psychologically devastating.
  • The outlook for someone with lateral medullary syndrome depends upon the size and location of the area of the brain stem damaged by the stroke.

• Characteristics of Nervous Tissue

  • The Schwann cells are underlain by the medullary sheath.
  • The medullary sheath is interrupted at intervals by the nodes of Ranvier.

• Cerebrospinal Fluid and Its Circulation

  • This diagram indicates the (1) posterior medullary velum (2) choroid plexus (3) cisterna cerebellomedullaris of subarachnoid cavity (4) central canal (5) corpora quadrigemina (6) cerebral peduncle (7) anterior medullary velum (8) ependymal lining of ventricle (9) cisterna pontis of subarachnoid cavity

• Internal Anatomy of the Kidneys

  • The renal cortex is granular tissue due to the presence of nephrons—the functional unit of the kidney, that are located deeper within the kidney, within the renal pyramids of the medulla.
  • The medulla consists of multiple pyramidal tissue masses, called the renal pyramids, which are triangle structures that contain a dense network of nephrons.

• Sensory and Motor Tracts

  • The corticospinal tract also contains the Betz cell (the largest pyramidal cells) that are not found in any other region of the body.
  • However, connections to the somatosensory cortex suggest that the pyramidal tracts are also responsible for modulating sensory information from the body.
  • After a patient's pyramidal tracts are injured, the patient is paralyzed on the corresponding side of the body.