2. Study aims:

To know: spine structure, reflectory function, role in motor and vegetative functions regulation, activity principles, pyramidal and extrapyramidal ways; muscular tone spinal regulation mechanisms; spinal reflexes study role for spine disorders topic diagnostics; spinal shock and its developmental mechanisms.

To be able to: assess tendineal reflexes existence and muscular tone in the investigated person.

3. Pre-auditory self-work materials.

3.1.Basic knowledge, skills, experiences, necessary for study the topic:

Subject	To know	To be able to
Histology	Spine histological structure	Recognize spinal cord preparation
Anatomy	Spine anatomical structure and conductive ways	Draw spine ascending and descending conductive ways
Biochemistry	Nervous tissue metabolism peculiarities
Neurology	Spine external and internal structure, superficial and deep reflexes; disorders of motor activity delt with spine.	Draw spine ascending and descending conductive ways; reproduce spine reflexes on the patient.

3.2. Topic content.

Spinal cord lies loosely in the vertebral canal. It extends from foramen magnum where it is continuous with medulla oblongata, above and up to the lower border of first lumbar vertebra below. The coverings of the spinal cord are membranous in nature and are called the meninges. The meninges are dura mater, pia mater and arachnoid mater. These meninges are responsible for protection and nourishment of the nervous tissues. The length of the spinal cord is about 45 cm in males and about 43 cm in females.

Spinal cord is cylindrical in shape with two spindle shaped swellings—the cervical and lumbar enlargements. These two portions of spinal cord innervate upper and lower extremities respectively. Below the lumbar enlargement, the spinal cord rapidly narrows to a cone shaped termination called conus medullaris. A slender non-nervous filament called filum terminale extends from conus medullaris downward to the fundus of the dural sac at the level of second sacral vertebra. Spinal cord is made up of 31 segments.

Cervical segments = 8

Thoracic segments = 12

Lumbar segments = 5

Sacral segments = 5

Coccygeal segment = 1

In fact, the spinal cord is a continuous structure. The appearance of the segment is given by the 31 pairs of nerves arising from the spinal cord. Thus, the segments of spinal cord correspond to the 31 pairs of spinal nerves in a symmetrical manner.

Cervical nerves= 8

Thoracic nerves= 12

Lumbar nerves= 5

Sacral nerves= 5

Coccygeal nerve= 1

Each spinal nerve is formed by an anterior (ventral) root and a posterior (dorsal) root. Both the roots on either side leave the spinal cord and pass through the corresponding intervertebral foramina. The first cervical spinal nerves pass through the foramen between occipital bone and the first vertebra called atlas. The cervical and thoracic roots are shorter whereas, the lumbar and sacral roots are longer. The long nerves descend in dural sac to reach their respective intervertebral foramina. This bundle of descending roots surrounding the filum terminale resembles the tail of horse. Hence, it is called cauda equina.

On the anterior surface of spinal cord, there is a deep furrow known as anterior median fissure. The depth of this is about 3 mm. Lateral to the anterior median fissure on either side, there is a slight depression called the anterolateral sulcus. This denotes the exit of anterior nerve root. On the posterior aspect, there is a depression called posterior median sulcus. The posterior median sulcus is continuous with a thin glial partition called the posterior median septum. It extends inside the spinal cord for about 5 mm and reaches the gray matter. On either side, lateral to the posterior median sulcus, there is posterior intermediate sulcus. It is continuous with posterior intermediate septum, which extends for about 3 mm into the spinal cord. Lateral to the posterior intermediate sulcus, is the posterolateral sulcus. This denotes the entry of posterior nerve root.