Anatomy of vertebral column – Anatomy Lectures – MBBS Lectures

Learning objectives

• General features of vertebral column
• No. of vertebrae in different regions
• Curvatures of vertebral column
• Movements of vertebral column
• Abnormal curves of vertebral column

Vertebral column

• The vertebral column, also called the spine, spinal column or backbone.
•  Composed of a series of bones called vertebrae (singular is vertebra).
•  About 71 cm (28in): adult male.
• About 61 cm (24in): adult female.
•  Total number of vertebrae during early development is 33.
•  As a child grows, several vertebrae in the sacral and coccygeal regions fuse.
•  Adults have 26 vertebrae. *Sacrum and coccyx bones become fused.

Regions of vertebral column

• 7 cervical vertebrae (C1 – C7 )
• 12 thoracic vertebrae (T1 –T12)
• 5 lumbar vertebrae (L1 – L5)
• 1 sacrum ( 5 fused )
• 1 coccyx ( 4 fused )
• *The sacrum and coccyx do not have number.

Regions of vertebral column

• The cervical, thoracic and lumbar vertebrae…movable
•  Sacrum and coccyx … immovable
•  Between adjacent vertebrae from the second cervical vertebra to the sacrum are intervertebral disc (inter = between).

General structure of vertebrae

1. Cervical vertebrae (C1-C7)

 • Formed framework of neck region

• Support skull

• Small in size

• Presence foramen in each transverse process

 2. Thoracic vertebrae (T1-T12)

 • Formed posterior part of thoracic cage

 • Articulates with associated ribs

3. Lumbar Vertebrae (L1-L5)

• Formed skeletal support for posterior abdominal wall

• Characterized by large in size

4. Sacrum Vertebrae

 • Fusion of 5 sacral bones

 • Immovable (synostosis)

 • Articulates with L5 at lumbosacral joint

 • Articulates laterally with pelvic bone at sacroiliac joint.

 • Formed posterior wall of lower abdominal and pelvic cavity

5. Coccyx

• Fusion of 4 coccyx bones

• Immovable (synostosis)

 • Formed part of pelvic cavity

Functions of vertebral column

1. Supports the head.
2. Help maintain balance in the upright position.
3. Enclose and protect the spinal cord.
4. Permits movement (move forward, backward, sideways, and rotate).
5. Absorbs shocks during walking.
6. Serve as a point of attachment for the ribs, pelvic girdle and muscles of the back and upper limbs

Development of the vertebral curves

• In the fetus, there is a single concave curve.
•  At 3 months after birth when infant lifts head as it begins to crawl the cervical curve develops.
•  When child sits up, stands and walks the lumbar curve develops

• In adult, it shows four slight bends called normal curve:
• Cervical and lumbar curve are convex (bulging out)
•  Thoracic and sacral curve are concave (cupping in)

Curves of vertebral column

• The thoracic and sacral curves are called primary curves because they form first during fetal development.
•  The cervical and lumbar curves are called secondary curves because they form later, several months after birth.
•  All curve fully developed by age 10.
• However, secondary curves may be progressively lost in old age. 

• Newborn Spinal Curvature :
  •   C-shaped curve
  •  Known as Primary Curve
  •  Single curve
• Adult Spinal Curvature:
  •  S-shaped vertebral column
  •  Four curve (cervical, thoracic, lumbar amd sacral curve)

 Secondary curvatures develop after birth

• Consist of four slight bends (cervical, thoracic, lumbar, sacral)
•  Cervical and lumbar curve are convex (bulging out).
•  The thoracic and sacral curves are concave (cupping in).

Functions of normal curve

• Increases its strength
•  Help maintain balance in the upright position
•  Absorb shocks during walking
• Help protect the vertebrae from fracture 

Abnormal spinal curvature

• Scoliosis:
  •  lateral bending of the vertebral column, usually in the thoracic region.
• Kyphosis:
  •  Increase in the thoracic curve of the vertebral column.
• Lordosis (Hollow back)
  • Increase in the lumbar and cervical curve of the vertebral column.

Parts of vertebra

• Typical vertebrae consists of:
•  A body
•  A vertebral arch (pedicles and lamina) ◦
• Seven processes: two transverse processes, one spinous process, four articular processes

Movements of vertebral column

• Flexion (to bend)
•  Extension (to stretch out)
• Hyperextension
• Lateral flexion
•  Rotation – right and left rotate 

Cervical motion

• Flexion: C1 (atlas):
• allows for forward and backward motion of the head.
• Extension: Straightening the joint, moving the spine back
•  Lateral Flexion (Abduction): moving the spine to the side (left or right); the neck moves toward the shoulder.
•  Rotation: C2 (axis) for rotation making a “no” motion. Turning the spine to the side (right or left); the neck turns toward the shoulder.

Thoracic and lumber motion

• Flexion:
•  moving the spine forward, the thorax moves toward the pelvis.
•  Extension / Hyperextension: Straightening the joint by moving the spine back, the thorax moves away from the pelvis.
•  Lateral Flexion (Abduction): moving the spine to the side (left or right), the thorax moves to the side toward the pelvis.
•  Rotation: turning the spine to the side (right or left); the thorax rotates to one side.

Hyperextension

• Hyperextension is a straightening movement that goes beyond the normal, healthy boundaries of the joint

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