The vertebral column consists of 26 bone segments called vertebrae that are arranged in five divisions from the base of the skull to the tail bone.
The first seven bones of the vertebral column from the neck bone are the cervical (C1-C7) vertebrae. These vertebrae do not articulate (joint) in the ribs.
The second set of 12 vertebrae is known as the thoracic (T1-T12) vertebrae. These vertebrae articulate with the 12 pairs of ribs.
The third set of 5 vertebral bones in the lumbar (L1-L5) vertebrae. These are the strongest and largest of the back bones.
The sacrum is a slightly curved, triangular-shaped bone. At birth, it is composed of 5 separate bones, but gradually they fuse together. The coccyx is the tailbone and this is also a fused bone, having been formed from 4 coccygeal bones.
STRUCTURE OF A VERTEBRA
A vertebra is composed of an inner, thick, disk shaped portion called the vertebral body. Between the body of one vertebra and the bodies of the vertebrae lying beneath and above are cartilaginous discs, which help to provide the flexibility and cushion against shock to the vertebral column.
The vertebral arch is the posterior part of the vertebra and it consists of a spinous process, transverse process and lamina. The neural canal is the space between the vertebral body and the vertebral arch through which the spinal cord passes.
MUSCLES IN THE VERTEBRAL COLUMN
Red muscle fibers are present at the back of human body. These muscle fibres are also known as the extensor muscles. The characteristics of red muscles are:
- They are known as the thin muscle fibers.
- They are red due to the large amount of myoglobin.
- They show slow and sustained contraction.
- Depend upon aerobic metabolism for energy.
- Mitochondria are abundant in them.
- No accumulation of lactic takes place in them.
- They perform sustained work for prolonged period of time.
Q.1. Name the muscles present at the back region of human beings:
- White muscle fibers
- Red muscle fibers.
- Extensor muscle fibers.
- both b and c
Q.2. Vertebral column cavity contains:
- Spinal cord
- both a and b
Q.3. Vertebral column consists of how many bone segments:
Q.4. Thoracic region consists of how many vertebrae:
Q.5. Which is strongest among:
- Cervical region
- Thoracic region
- Thoracic region
- Lumbar region
Q.6. Red muscle fibers are red because of: