sciatic nerve

Examples of sciatic nerve in the following topics:

• Sciatic Nerve Injury

  • Pain caused by a compression or irritation of the sciatic nerve by a problem in the lower back is called sciatica.
  • Sciatica is a set of symptoms including pain that may be caused by general compression or irritation of one of five spinal nerve roots that give rise to each sciatic nerve, or by compression or irritation of the left or right or both sciatic nerves .
  • Sciatica is also referred to as lumbar radiculopathy, which involves compression of the sciatic nerve roots caused by a herniated (torn) or protruding disc in the lower back.
  • Sciatica is generally caused by the compression of lumbar nerves L3, L4 or L5, or sacral nerves S1, S2, or S3, or by compression of the sciatic nerve itself.
  • Left gluteal region, showing surface markings for arteries and the sciatic nerve

• Sacral and Coccygeal Plexuses

  • The largest and longest nerve of the human body, the sciatic nerve, is the main branch and gives rami to the motor innervation of the muscles of the foot, the leg, and the thigh.
  • The nerves forming the sacral plexus converge toward the lower part of the greater sciatic foramen and unite to form a flattened band from the anterior and posterior surfaces, from which several branches arise.
  • The band itself is continued as the sciatic nerve, which splits on the back of the thigh into the tibial nerve and the common fibular nerve.
  • The only nerve in this plexus is the anococcygeal nerve, which serves sensory innervation of the skin in the coccygeal region.
  • Diagram of the sacral plexus showing the various anterior and posterior nerve branches that arise from each lumbar and sacral nerve.

• Herniated (Slipped) Disc

  • They can range from little or no pain if the disc is the only tissue injured, to severe and unrelenting neck or low back pain that will radiate into the regions served by affected nerve roots that are irritated by the herniated material.
  • If the herniated disc is in the lumbar region (where the majority of herniated discs occur), the patient may also experience sciatica due to irritation of one of the nerve roots of the sciatic nerve.

• 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).

• 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.

• 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.
  • The optic nerve (II): This nerve carries visual information from the retina of the eye to the brain.
  • The abducens nerve (VI): A motor nerve that innervates the lateral rectus muscle of the eye, which controls lateral movement.
  • 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.

• Ischium

  • Two indentations run parallel to the spine—superiorly ,the greater sciatic notch and, inferiorly, the lesser sciatic notch, through which key nervous and vascular vessels pass.

• Oculomotor (III) Nerve

  • The oculomoter nerve (cranial nerve III) controls eye movement, such as constriction of the pupil and open eyelids.
  • The oculomotor nerve is the third paired cranial nerve.
  • Cranial nerves IV and VI also participate in control of eye movement.
  • Here the nerve is placed below the trochlear nerve and the frontal and lacrimal branches of the ophthalmic nerve, while the nasociliary nerve is placed between its two rami (the superior and inferior branch of oculomotor nerve).
  • Image of cranial nerves showing the position of the oculomotor nerve.

• Structure of a Nerve

  • A nerve provides a structured pathway that supports the electrochemical nerve impulses transmitted along each of the axons.
  • Neurons are sometimes referred to as nerve cells, although this term is misleading since many neurons do not occupy nerves, and nerves also include non-neuronal support cells (glial cells) that contribute to the health of enclosed neurons.
  • A nerve conveys information in the form of electrochemical impulses (known as nerve impulses or action potentials) carried by the individual neurons that make up the nerve.
  • Thus they are synonymous with afferent nerves.
  • Thus they are synonymous with efferent nerves.