What Is the Spinal Cord?

It is a cylinder that is slightly flat back and forth, with a total length of varying thickness. It is located in the spinal canal. The upper end is connected to the medulla at the foramen magnum. The lower end is sharpened into a cone. Silk, terminal silk down through the sacral canal and finally the back of the second coccyge, the adult spinal cord is about 42 to 45 cm in length.

It is a cylinder that is slightly flat back and forth, with a total length of varying thickness. It is located in the spinal canal. The upper end is connected to the medulla at the foramen magnum. The lower end is sharpened into a cone. Silk, terminal silk down through the sacral canal and finally the back of the second coccyge, the adult spinal cord is about 42 to 45 cm in length.

Chinese name

spinal cord

Foreign name

Spinal cord

Pronunciation

j su

category

Medicine, human body structure

Body part

Central nervous system

Location

Spinal canal

Shape

Long cylindrical

Length

41-45 cm

Spinal cord I. Overview:

The spinal cord has two enlargements. The upper one is called the cervical enlargement, which is located in the third segment of the cervical spinal cord to the second segment of the thoracic spinal cord. It is the thickest at the sixth segment of the cervical spinal cord. Conical, thickest at the 12th thoracic spine. The formation of these two swellings is related to the appearance of the limbs, due to the increase of neurons inside the spinal cord.

On the surface of the spinal cord there are six longitudinal grooves parallel to each other. The anterior (ventral) median fissure is called the anterior (ventral) medial fissure. The anterior (ventral) lateral groove is located on the anterolateral side and the anterior root exits there. The posterior (dorsal) median sulcus is called the posterolateral (dorsal) lateral sulcus, and the posterior root fibers enter the spinal cord. Between the posterior medial sulcus and the posterolateral sulcus, there is also the posterior middle sulcus. The anterior and posterior root fibers meet at the intervertebral foramen to form the spinal nerve. Before confluence, an enlargement is formed at the posterior root, called the spinal ganglia, which contains pseudomonopolar sensory neurons. The spinal cord emits 31 pairs of spinal nerves in total. The spinal cord corresponding to each pair of spinal cords is called the spinal cord segment. There are 31 segments in total, including 8 cervical segments, 12 thoracic segments, 5 lumbar segments, 5 iliac segments, and 1 Tail section.

During the development of the spinal cord and the spine, due to the imbalance in the growth rate of the two (the growth rate of the spinal cord is slower than that of the spine), the lower end of the adult spinal cord reaches only the lower edge of the first lumbar vertebra, so the spinal nerve roots around the lumbar, iliac, and tail surround the The terminal filaments are gathered into a bunch of filaments and descend vertically, forming a pony tail. Since there is no spinal cord below the first lumbar vertebra, puncture is generally performed clinically between the third to fourth lumbar vertebrae.

Spinal cord 2. Spinal cord injury:

Spinal cord injury (SCI) often causes limb paralysis, incontinence, and sexual dysfunction below the injured segment.

Due to the different stages of injury, spinal cord injury can be divided into primary spinal cord injury and secondary spinal cord injury. Primary spinal cord injury is directly caused by the violence immediately after the injury, and the magnitude of the violence is closely related to the severity of the spinal cord injury. From a pathological point of view, extensive edema can occur in the spinal cord after injury. Due to the bony limitation of the spinal canal, the restriction of the dura mater and the pia mater, nerve compression and intramedullary edema can be further aggravated, resulting in the spinal cord and spinal canal. Disorders of circulation between epidural veins and spinal arteriovenous veins cause spinal cord ischemia, edema, hemorrhage, and necrosis. In addition, spinal cord edema causes adhesions, stenosis, and even blockage in the subarachnoid space, affecting normal physiological circulation of the cerebrospinal fluid and physiological metabolism of the spinal cord. From the molecular level, a large number of catecholamine neurotransmitters such as dopamine and norepinephrine are released and accumulated in the injured area, and free radicals are accumulated, causing microvascular spasm and ischemia in the spinal cord, increasing release of inflammatory factors, and vascular permeability. Sexual increase, rupture of small veins, autophagy and apoptosis of cells, leading to secondary hemorrhage and necrosis of the spinal cord. The above-mentioned series of secondary changes in the spinal cord after the primary injury are secondary spinal cord injury. Similar to the pathological damage mechanism of osteofascial compartment syndrome, spinal cord edema and / or intramedullary hematoma can cause increased intramedullary pressure, due to the restraint of the spinal membrane, arachnoid membrane, dura mater, and Restriction, there will be a vicious cycle of ischemia-edema-ischemia. Some scholars named this series of symptoms as "spinal meningeal syndrome". Some patients may even develop ascending myelitis due to the continuous expansion of the range of edema, which eventually leads to respiratory depression, lung infections, and respiratory failure.