3. •Vertebral column consists of a number of separate
irregular bones called VERTEBRAE
•Forms the central axis of the body.
•Functions:
Protects spinal cord.
Supports and transmits body weight.
Provides attachment to axial muscles.
Provides movement of the trunk.
4. • Vertebrae are named according to region in which they lie.
• There are 33 vertebrae but only 31 spinal nerves.
Vertebrae Number Spinal Nerve Number
Cervical 7 Cervical 8
Thoracic 12 Thoracic 12
Lumbar 5 Lumbar 5
Sacral 5 Sacral 5
Coccygeal 4 Coccygeal 1
• In adults, 5 sacral vertebrae fuse together to form ‘sacrum’ 4 coccygeal
vertebrae fuse together to form ‘coccyx’.
5. Characteristics of a vertebrae:
• A typical vertebrae has two parts:
1. Body- anterior or ventral part.
2. Arch-posterior or dorsal part (also called neural arch).
• Vertebral foramen: lies between the body and arch.
• Vertebrae are placed one above the other with intervertebral discs between
them and forms a vertebral canal(spinal canal) which lodges the spinal cord
with its meninges and blood vessels.
6. 1. Body of vertebrae:
• It is nearly cylindrical in shape, the size and shape varying in vertebrae of different regions.
• It possesses 6 surfaces: Upper, Lower, Anterior, Posterior and two Lateral.
i. Upper and Lower surfaces – Rough and provide attachment to intervertebral discs.
ii. Anterior surface – convex fom side to side; concave from above downwards; it also bears
few small openings for passage of veins.
iii. Posterior surface – flat from above downwards; slightly concave side to side; it also bears
one or more large openings of exit of basi-vertebral vein and a no of small foramina for
nutrient arteries.
iv. Lateral surface – continuous with anterior surface and has the same features.
• Bodies of vertebrae lie one above another separated by intervertebral disc and form the
central axis.
7. 2. Vertebral (neural) arch:
• The vertebral arch consists of:
I. A pair of pedicles.
II. A pair of lamina.
III. Seven processes:
o Spinous ---- one
o Articular ---- four
o Transverse --- two
The arch is connected to the body by pedicles.
Pedicles:
• Short, thick processes pass backward from the junction of lateral and posterior surfaces of
the body.
• Possess 2 surfaces and 4 borders.
8. Surfaces:
Medial---forms lateral boundary of vertebral column.
Lateral---free and rough.
Borders:
Anterior—united with the body.
Posterior—united with the lamina.
Superior---concave which forms superior vertebral notch.
Inferior---concave which forms inferior vertebral notch.
Intervertebral foramen: When two vertebrae articulate with each other the inferior vertebral
notch of the vertebrae above together with the superior vertebral notch of the vertebrae
below form the intervertebral foramen.
Transmits: Spinal nerves and vessels.
9. Lamina:
• Broad plates of bone lying behind and medial to pedicles.
• They fuse behind in the median plane into the spinous process.
• They form posterior boundary of vertebral foramen.
Processes:
A. Spinous process----
Passes backwards and downwards from the junction of the two laminae.
Shape and size varies in vertebrae of different regions.
Gives attachment to muscles and ligaments.
10. B. Articular process:
4 in number, 2 superior and 2 inferior.
Arise from the junction of pedicles and laminae.
Superior articular process:
i. Project upwards from the junction of laminae and pedicles.
ii. Articular surface faces more or less backwards.
iii. Articulate with inferior articular processes of the vertebrae.
Inferior articular process:
i. Project downwards.
ii. Articular surface faces more or less forwards.
iii. Articulate with superior articular processes of the vertebrae below.
11. C. Transverse processes:
• 2 in number.
• Project laterally from the junction of pedicle and lamina.
• In thoracic region they articulate with ribs.
The most important distinguishing feature of vertebrae of different regions
is-----
Cervical: Presence of a foramen in the transverse process, called Foramen
Transversarium.
Thoracic: Presence of costal facets on the body
Lumbar: No foramen transversariumand no costal facets on the body.
