The spine, also called the backbone, extends from the skull to the pelvis. It accounts for two-fifths of total body weight and is made up of connective tissue and a series of bones called vertebrae, which overlap in the shape of a spine, hence the term spine. The vertebral column consists of 24 vertebrae + sacrum + coccyx and together with the head, sternum and ribs, the axial skeleton.


Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.


Superiorly, it articulates with the occipital bone (skull); inferiorly, it articulates with the hip bone (iliac).

The spine is divided into four regions: Cervical, Thoracic, Low back and Sacrococcygeal.

Are 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and about 4 coccygeal vertebrae.


Spinal Column Regions
Source: ADAM.


Spinal Bends

In a lateral view, the spine presents several curvatures considered physiological.

Are they:

 Cervical (ventrally convex & #8211; LORDOSE),

 Thoracic (ventrally concave & #8211; KYPHOSIS),

 Low back (convex ventrally & #8211; LORDOSE)

 Pelvic (ventrally concave & #8211; KYPHOSIS).

When one of these curvatures is increased, we call it HYPERCYPHOSIS (Dorsal and pelvic region) or HYPERLORDOSIS (Cervical and lumbar region).

In an anterior or posterior view, the spine shows no curvature. When any curvature occurs in this plane we call it SCOLIOSIS.


Spinal Bends
Source: ADAM.


Spinal Functions

 Protects the spinal cord and spinal nerves;

 Supports body weight;

 Provides a partially rigid and flexible shaft for the body and a pivot for the head;

 It plays an important role in posture and locomotion;

 It serves as a fixation point for the ribs, pelvic girdle and back muscles;

 It provides flexibility for the body, being able to bend forward, backward and sideways and still rotate about its major axis.

Vertebral canal

Vertebral canalThe spinal canal follows the different curves of the spine. It is large and triangular in regions where the spine is more mobile (cervical and lumbar) and is small and round in the region that does not have much mobility (thoracic).
In the adjacent image (upper view of the spine), we can see the vertebral canal. It is formed by the junction of the vertebrae and serves to protect the spinal cord. In addition to the vertebral canal, the medulla is also protected by meninges, cerebrospinal fluid, and the blood-brain barrier.

Vertebrae can be studied on three aspects: general, regional and individual characteristics.


General features Regional Features Individual Features


In the spine we also find the sacrum (about four or five fused & #8211; nonmobile vertebrae) and inferiorly to the same is the coccyx (fusion of 4 & #8211; nonmobile).


Sacrum Coccyx



Intervertebral Disc

Between the bodies of two adjacent vertebrae from the second cervical to the sacrum, there are intervertebral discs.

Consisting of a peripheral fibrous disc composed of fibrocartilaginous tissue, called FIBER RING; and a soft elastic inner substance called Pulpous Core. The discs form strong joints, allow various movements of the spine and absorb impacts.



Intervertebral Disc




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