ANATOMY OF THE SPINE

THE HUMAN SPINE

Introduction

The spine is made of 33 individual bones stacked on one another extending from the head down to the hips. Throughout the length of the spine the bones are connected to one another by ligaments and muscles which help keep the spine aligned.The spine provides most of the support your body needs for stable movements, allowing you to stand upright, bend, and twist. Protected deep inside the bones, the spinal cord connects your body to the brain, allowing movement of your arms and legs. Strong muscles and bones, flexible tendons and ligaments, and sensitive nerves contribute to a healthy spine. Keeping your spine healthy is vital if you want to live an active life without back pain.

Spinal curves

When viewing the spine from the front it seems straight but in fact when viewed from the side a noticeable natural S-shaped curve is present. The neck (cervical) and low back (lumbar) regions have a slight concave curve, while the thoracic and sacral regions have a convex curve. The curves work like a spring providing stability and allowing normal range of motion.

Cervical (neck) : Highlighted in RED 

1. The main function of the cervical spine is to support the weight of the head
2. The cervical spine has the greatest amount of flexibility and range allowing the head to flex, extend, rotate and tilt in multiple directions.

Thoracic (mid back) : Highlighted in BLUE

1. The main function of the thoracic spine is to hold the rib cage and protect the heart and lungs. 
2. The thoracic spine has the least amount of range compared to the other regions.

Lumbar (low back) : Highlighted in YELLOW

1. The main function of the lumbar spine is to bear the weight of the body. 
2. The Lumbar vertebrae are much larger in size in order to absorb the stress of lifting and carrying heavy objects.
3. Most back injuries affect the Lumbar region

Sacrum : Highlighted in GREEN 

1. The main function of the sacrum is to connect the spine to the hip bones (iliac).
2. The Sacrum together with the ilium bone form a ring called the pelvic girdle.

Coccyx region : Highlighted in PURPLE 

1. the four fused bones of the coccyx or tailbone provide attachment for ligaments and muscles of the pelvic floor.

Intervertebral discs:

Each vertebra in your spine is separated by an intervertebral disc, preventing the bones from rubbing together. Discs are designed like a radial car tire. The outer ring, called the annulus, has criss-crossing fibrous bands, much like a tire tread. These bands attach between the bodies of each vertebra. Inside the disc is a gel-filled center called the nucleus, much like a tire tube.With age, our discs increasingly lose the ability to reabsorb fluid and become brittle and flatter; this is why we get shorter as we grow older. Injury and strain can cause discs to bulge or herniate, a condition in which the nucleus is pushed out through the annulus to compress the nerve roots causing back pain as mentioned in the previous post (Herniated Disc).