optic nerve

Examples of optic nerve in the following topics:

• Optic (II) Nerve

  • The optic nerve (cranial nerve II) receives visual information from photoreceptors in the retina and transmits it to the brain.
  • The optic nerve is also known as cranial nerve II.
  • Each human optic nerve contains between 770,000 and 1.7 million nerve fibers.
  • The optic nerve is the second of twelve paired cranial nerves.
  • An illustration of the brain highlighting the optic nerve and optic tract.

• Trochlear (IV) Nerve

  • The trochlear nerve (cranial nerve IV) is a motor nerve that innervates a single muscle: the superior oblique muscle of the eye.
  • The trochlear nerve (cranial nerve IV) is a motor nerve that innervates a single muscle: the superior oblique muscle of the eye.
  • The trochlear nerve is unique among the cranial nerves in several respects.
  • Other than the optic nerve (cranial nerve II), it is the only cranial nerve that decussates (crosses to the other side) before innervating its target.
  • Lesions of all other cranial nuclei affect the ipsilateral side (except of course the optic nerve, cranial nerve II, which innervates both eyes).

• Brief Overview of Cranial Nerves

  • Cranial nerves are the nerves that emerge directly from the brain (including the brainstem).
  • The terminal nerves, olfactory nerves (I) and optic nerves (II) emerge from the cerebrum or forebrain, and the remaining ten pairs arise from the brainstem, which is the lower part of the brain.
  • However, on a structural level, the olfactory, optic, and terminal nerves are more accurately considered part of the central nervous system.
  • The optic nerve (II): This nerve carries visual information from the retina of the eye to the brain.
  • The hypoglossal nerve (XII): This nerve controls the tongue movements of speech, food manipulation, and swallowing.

• Olfactory (I) Nerve

  • The olfactory nerve, or cranial nerve I, is the first of 12 cranial nerves and is responsible for the sense of smell.
  • The olfactory nerve, or cranial nerve I, is the first of the 12 cranial nerves.
  • The olfactory nerve is the shortest of the 12 cranial nerves and only one of two cranial nerves (the other being the optic nerve) that do not join with the brainstem.
  • The specialized olfactory receptor neurons of the olfactory nerve are located in the olfactory mucosa of the upper parts of the nasal cavity.
  • The olfactory nerves consist of a collection of many sensory nerve fibers that extend from the olfactory epithelium to the olfactory bulb, passing through the many openings of the cribriform plate of the ethmoid bone.

• Orbits

  • To the rear of the orbit, the optic foramen opens into the optical canal through which the optic nerve and ophthalmic artery pass.
  • Finally, the sphenoid bone forms the posterior wall of the orbit and also contributes to the formation of the optic canal.

• Development of Vision

  • Development of the optic vesicles starts in the three week embryo from a progressively deepening groove in the neural plate called the optic sulcus.
  • As this expands, the rostral neuropore (the exit of the brain cavity out of the embryo) closes and the optic sulcus and the neural plate becomes the optic vesicle.
  • The lens acts as an inducer back to the optic vesicle to transform it into the optic cup and back to the epidermis to transform it into the cornea.
  • It is critical for the induction of the retinal pigment epithelium and the optic nerve.
  • Iris is formed from the optic cup cells.

• Fourth Week of Development

  • The optical vesicle (which will eventually become the optic nerve, retina, and iris) forms at the basal plate of the prosencephalon.
  • White circle represents the area of the optice vesicle.

• Foramina

  • The human skull has numerous holes known as foramina through which cranial nerves, arteries, veins, and other structures pass.
  • The human skull has numerous foramina through which cranial nerves, arteries, veins, and other structures pass.
  • Optic foramen: Located in the sphenoid, it allows the passage of the ophthalmic artery and nerve from the optic canal into the orbit.
  • Foramina of cribriform plate: Located in the ethmoid bone, it allows the passage of the olfactory nerve.
  • Foramen rotundum: Located in the sphenoid bone, it allows passage of the maxillary nerve.

• Spinal Cord White Matter

  • White matter is composed of bundles of myelinated nerve cell processes (or axons), which connect various grey matter areas (the locations of nerve cell bodies) of the brain to each other and carry nerve impulses between neurons.
  • Myelin acts as an insulator, increasing the speed of transmission of all nerve signals.
  • The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons).
  • This myelin is found in almost all long nerve fibers and acts as an electrical insulation.
  • Raff et al. discovered that tissue samples originating from the optic nerves of rats contained two morphologically distinct types of astrocytes.

• Accessory (XI) Nerve

  • The accessory nerve (cranial nerve XI) controls the muscles of the shoulder and neck.
  • The accessory nerve (cranial nerve XI) controls the sternocleidomastoid and trapezius muscles of the shoulder and neck.
  • Unlike the other 11 cranial nerves, the accessory nerve begins outside the skull.
  • Due to its unusual course, the accessory nerve is the only nerve that enters and exits the skull.
  • However, more modern characterizations of the nerve regard the cranial component as separate and part of the vagus nerve.