dorsal

Examples of dorsal in the following topics:

• Spinal Cord Grey Matter and Spinal Roots

  • The cord has grooves in the dorsal and ventral sides.
  • Axons of these sensory neurons travel into the spinal cord via the dorsal roots.
  • The dorsal root ganglia lie along the vertebral column by the spine.
  • The dorsal root ganglia develops in the embryo from neural crest cells, not the neural tube.
  • The axons of dorsal root ganglion neurons are known as afferents.

• Somatic Sensory Pathways to the Cerebellum

  • The ventral and dorsal spinocerebellar tracts convey proprioceptive information from the body to the cerebellum.
  • It is part of the somatosensory system and runs in parallel with the dorsal spinocerebellar tract.
  • The axon runs via the fila radicularia (nerve rootlets) to the dorsal horn of the gray matter.
  • Proprioceptive information is taken to the spinal cord via central processes of dorsal root ganglia (where first order neurons reside).
  • These central processes travel through the dorsal horn where they synapse with second order neurons of Clarke's nucleus.

• Branches of Spinal Nerves

  • The spinal nerves branch into the dorsal ramus, ventral ramus, the meningeal branches, and the rami communicantes.
  • The dorsal ramus: Contains nerves that serve the dorsal portions of the trunk carrying visceral motor, somatic motor, and sensory information to and from the skin and muscles of the back.

• Embryonic Development

  • At the dorsal end of the neural tube, BMPs are responsible for neuronal patterning.
  • A secondary signaling center is then established in the roof plate, the dorsal most structure of the neural tube.
  • BMP from the dorsal end of the neural tube seems to act in the same concentration-dependent manner as Shh in the ventral end.
  • Researchers observed changes in dorsal-ventral patterning; for example zebrafish deficient in certain BMPs showed a loss of dorsal sensory neurons and an expansion of interneurons.
  • Chick embryo of thirty-three hours' incubation, viewed from the dorsal aspect (30x magnification).

• Body Cavities

  • The dorsal cavity is a continuous cavity located on the dorsal side of the body.
  • The meninges is a multi-layered membrane within the dorsal cavity that envelops and protects the brain and spinal cord.
  • The cranial cavity is the anterior portion of the dorsal cavity consisting of the space inside the skull.
  • The vertebral cavity is the posterior portion of the dorsal cavity and contains the structures within the vertebral column.

• Scapula

  • Due to its flat nature the scapula presents two surfaces and three borders; the front facing costal surface and the rear facing dorsal surface, as well as the superior, lateral and medial borders.
  • The dorsal surface gives origin to the supraspinatus and infraspinatus muscles and inferiorly to the teres minor and major.

• Autonomic Ganglia

  • The dorsal root ganglia lie along the vertebral column by the spine and develop in the embryo from neural crest cells, not neural tube.
  • A dorsal root ganglion (or spinal ganglion) is a nodule on a dorsal root of the spine that contains cell bodies of nerve cells (neurons) that carry signals from sensory organs towards the appropriate integration center.
  • The axons of dorsal root ganglion neurons are known as afferents.
  • Unlike the majority of neurons found in the central nervous system, an action potential in dorsal root ganglion neuron may initiate in the distal process in the periphery, bypass the cell body, and continue to propagate along the proximal process until reaching the synaptic terminal in the dorsal horn of the spinal cord.
  • The nerve endings of dorsal root ganglion neurons have a variety of sensory receptors that are activated by mechanical, thermal, chemical, and noxious stimuli.

• Somatic Sensory Pathways

  • The somatosensory pathway is composed of three neurons located in the dorsal root ganglion, the spinal cord, and the thalamus.
  • The first always has its cell body in the dorsal root ganglion of the spinal nerve.
  • This is the target for neurons of the dorsal column medial lemniscal pathway and the ventral spinothalamic pathway.
  • Sensory nerves of a dorsal root ganglion are depicted entering the spinal cord.
  • The formation of the spinal nerve from the dorsal and ventral roots.

• Development of the Cardiovascular System

  • The human arterial system originates from the aortic arches and from the dorsal aortae starting from week 4 of embryonic life.
  • They are ventral to the dorsal aorta and arise from the aortic sac.
  • The first and second arches disappear early, but the dorsal end of the second gives origin to the stapedial artery, a vessel which atrophies in humans, but persists in some mammals.
  • The dorsal aortae are initially bilateral and then fuse to form the definitive dorsal aorta.
  • Occasionally, the entire right dorsal aorta abnormally persists and the left dorsal aorta regresses.

• Trochlear (IV) Nerve

  • *It is the only cranial nerve that exits from the dorsal aspect of the brainstem.
  • The trochlear nucleus is unique in that its axons run dorsally and cross the midline before emerging from the brainstem.
  • The unique features of the trochlear nerve, including its dorsal exit from the brainstem and its contralateral innervation, are seen in the primitive brains of sharks.