The spinal cord (Latin: Medulla spinalis) is a thin, tubular neural structure located inside and protected by the spine in the spinal canal; it is an extension of the central nervous system derived from the brain. Cells in the central nervous system rely on complex connections to process and transmit information. The main function of the spinal cord is to transmit neural information between the brain and the periphery.
Structure of the spinal cord
The spinal cord is extended from the brain from the medulla oblongata to the cone of the spinal cord. The position of the vertebral cone is close to the lumbar L1-2, and is terminated by a fibrous extension, the terminal filament.
The spine is about 45 cm long in men, while it is about 42 cm long in women. The shape is ovate.
The spine expands around the neck and waist. On the periphery of the spine is the white matter tract of the nerve, which contains sensory and motor neurons. The middle part is grass-shaped and surrounds the central tube (an extension of the fourth ventricle) which contains nerve cell bodies.
The spine is covered by three layers of meninges, the outermost layer is the dura mater, the middle is the arachnoid membrane, and the innermost layer is called the soft membrane.
They are three layers of meningeal membranes that continue the brainstem and cerebral hemispheres, and the membrane contains cerebrospinal fluid found in the subarachnoid cavity, which protects the spinal cord by absorbing concussions.
The dentate ligaments that are connected to the spine in the pia, extend laterally to the dorsal and ventral roots and then to the dura mater, allowing the spine to settle in the dura mater. The dural capsule ends at the spinal layer of S2.
Spinal ganglion The human spinal cord can be divided into 31 distinct parts, in which the motor nerve roots leave the abdomen and the sensory nerve roots enter the back. Later, the ventral and dorsal roots combine and form pairs of spinal nerves. One spinal nerve on each side. In the human spinal cord, there are 31 spinal ganglia. These include: 8 cervical ganglia nerves will leave the spine above C1 to C7, and the eighth pair of cervical nerves will leave the spine at the lower margin of C712 thoracic ganglia nerves will leave the spine below T1 to T125 lumbar ganglion nerves will leave the spine below L1 to L5 5 sacral ganglion nerves will leave the spine below S1 to S51 to S5 1 caudal ganglion nerve will leave the spine at the coccyx
Because the length of the spine is longer than the length of the spinal cord, the spinal cord segment is longer than the corresponding vertebrae, and the tail of the adult spinal cord is even greater.
In the fetus, the level of the spine originally corresponds to the spinal cord segment.
In adults , the spinal cord cone , the end of the spinal cord , is located approximately in the spinal cord layer L1 or L2 , and the entire spinal cord segment is higher than this.
For example, cervical and recommendr segments can be found in T9 to L2 in the spinal cord layers. S4 spinal cord nerve roots originate from the upper lumbar or lower thoracic segments of the spinal cord, both parts of the spine and descend in the spinal canal. After passing through the tail of the spinal cord, they become part of the horse's tail. Eventually the roots of S4 will leave the spine in the bone.
The spinal cord enlarges the neck in the following two parts
Roughly equivalent to the brachial plexus, which innervates the upper limbs. This includes the spinal cord nodes of C4 to T1, while the enlarged spinal cord layer is roughly the same.
The enlargement of the waist is equivalent to the lumbosacral plexus, which dominates the lower limbs. This includes the spinal cord segments of L2 to S3 and can be found in the spinal cord layers T9 to T12.
Source: Rehabilitation Center of the First Affiliated Hospital of Henan University of Traditional Chinese Medicine