Your spine, also called your backbone or vertebral column, is composed of 33 bones, called vertebrae, which provide your body with support and protect your spinal cord from injury. The vertebrae can be divided into five groups: cervical, thoracic, lumbar, sacrum, and the coccyx, each of which has unique features suited to their functions. There are 7 cervical vertebrae, numbered C1-C7, 12 thoracic vertebrae, numbered T1-T12, 5 lumber vertebrae, numbered L1-L5, 5 sacral vertebrae, numbered S1-S5, and the coccyx. The upper 24 vertebrae are articulating, separated by intervertebral disc s. The sacral vertebrae and the bones of the coccyx are fused.
The cervical vertebrae – which are the vertebrae of your neck – support your head, which weighs around 10-13 pounds. C1 and C2 are specialized vertebrae that allow for the greatest range of motion of all the vertebrae. C1 is called atlas, after the man from Greek mythology who held up the earth. It is ring-shaped and attaches directly to your skull. This vertebra allows you to nod your head. C2, called “axis”, serves as an axis about which C1 pivots, allowing you to shake your head when saying “no”. C1 is able to pivot on this vertebra thanks to a specialized process called the dens, or odontoid process.
The thoracic vertebrae – which are the vertebrae of your mid to upper back – hold the rib cage and protect your heart and lungs. They have a limited range of motion. The lumbar vertebrae – which are the vertebrae of your lower back, bear the weight of your upper body and are larger in order to support the stress, especially when you lift something heavy. The sacral vertebrae connect your spine to your hip bones. These vertebrae are fused together. Together with your hip bones, they form the pelvic girdle. The coccyx, or tailbone, is made up of four fused bones, which provide attachment points for ligaments and muscles of the pelvic floor.
Now let’s cover the parts of a vertebra. A vertebra has 3 parts – the body, vertebral arch, and the processes. The body bears weight, the vertebral arch houses the spinal cord, and the processes allow for muscle attachment. The vertebral arch is made of two supporting pedicles and two laminae. The space inside, which houses the spinal cord, is called the vertebral foramen. Under each pedicle, spinal nerves exit and pass through the intervertebral foramen.
7 bony processes arise from each vertebral arch to form facet joints and processes for muscle attachment. Facet joints allow for back motion. Each vertebra has two pairs of facet joints – 1 pair connects to the vertebra above (superior facets), and 1 pair that connects to the vertebra below. There is also a pair of transverse process and a spinous process.
Between the vertebrae are the intervertebral discs, which provide cushioning and prevent the bones from rubbing together. Note that there is no intervertebral disc between C1 and C2. Discs are composed of am annulus, which is made up of several layers, or laminae, of fibrocartilage – crisscrossing fibrous bands that attach between the bodies of the vertebrae above and below, and a gel-filled center called the nucleus. The nucleus distributes the pressure evenly within each disc during compression.
The nucleus is full of proteoglycans – large molecules with sugar subunits that are very hydrophilic. This structure swells with water, unless it experiences constraints from the surrounding tissues. Hence, the nucleus absorbs fluid at night or when you’re lying down and then this fluid is pushed out during the day when you are upright and pressure is applied to the intervertebral discs. We shorten as we age because the discs lose the ability to reabsorb fluid during rest, flatten, and get more brittle.
3D models from:
https://www.turbosquid.com/3d-models/human-torso-muscles-max/647193
https://www.cgtrader.com/3d-models/character/anatomy/human-body-anatomy
Video Rating: / 5
Spine or Vertebral column | Spine bones joints | Human Spine Anatomy 3D animation | Elearnin
This video illustrates one of the main parts of human body, the spinal cord or the vertebral column. Understand the intricacies of the movements of vertebral column by getting familiar with the joints and bones, and the set of complex muscles which make up the spinal cord.
The vertebral column in the mammals is known as the back bone or the spine. The vertebral column protects the spinal cord and even supports the head. The spinal cord serves as a joint for the ribs and musculature of the back. The spine is a cord like bony structure in the human body and other vertebrates.
Human vertebral column is formed by serially arranged units called the vertebrae and are inward placed. This vertebral column extends from the base of the skull and constitutes the main framework of the trunk. These vertebras have a central hollow potion which is called the neural canal. The spinal cord passes through this neural canal. The first vertebra is called the atlas and this atlas articulates the occipital condyle, which is a kidney-shaped convex surface found in the lower back part of the skull. The entire vertebral column is differentiated into cervical, thoracic, lumbar, sacral and coccygeal region starting from the skull.
The human body consists of about 24 articulating (or the joint) vertebrae that comprise these three sections. However, in reality, it consists of 33 vertebrae where the other five are fused to form the sacrum.
Broadly, the three main sections of the spine include: cervical spine, thoracic spine and the lumbar spine.
The cervical spine begins at the base of the skull. Seven vertebrae make up the cervical spine, which are small and delicate, with eight pair of cervical nerves. It is these vertebrae that help in the movement of the head and the neck.
The thoracic spine is located in the chest area and it contains 12 vertebrae. These are connected to the ribs which limits the flexibility of these vertebrae. The ribs aid in the protection of many vital organs in the human body. There is another float bone on the ventral midline of the thorax which is called the sternum.
The vertebrae in the lumbar spine in most people are five in number. They are larger than the thoracic or the cervical spine. They carry most of the body’s weight and support easy flexibility and extension.
Each of the vertebrae is supported by fibrous discs, known as the intervertebral discs that act like cushions between the bones. The body of the vertebrae provide a resting place for these fibrous discs. The vertebra increase in size from the neck, downwards, that is from the second cervical to the first thoracic. There is a slight decrease in the next three vertebrae and then again there is a gradual increase in size till the sacrum vertebrae.
Each fibrous disc is made up of two parts. The annulus is the hard outer layer of the vertebra. It surrounds a sponge-like centre called the nucleus. There are four facet joints in each vertebra, one pair faces upwards.
Stability to the spine is provided by interlocking with the adjacent vertebrae. A bone called the sacrum lies just below the lumbar spine. The sacrum is uniquely shaped. The lamina covers the spinal canal. It is a large hole in the centre of the vertebra. The spinal nerves pass through them.
Part of the spine bones seem to be projecting outside the spine, and these can be felt while running hands down the backbone. This part of the bone that projects outside is known as the spinous process. The spinous process is paired with two transverse processes, which are oriented 90 degrees to the spinous process, one on each side. They provide attachment to the back muscles.
Hope this gives you a fair understanding of spine. By the way, if you haven’t yet, pls go ahead and Subscribe to our channel, elearnin, for latest update on high-end 3D Anatomy videos here.
Video Rating: / 5
