anatomy of vertebral column

VERTEBRAL COLUMNBy Sharmin SusiwalaFY BPT

•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.

•Vertebrae are named according to region in which they lie.

•There are 33 vertebrae but only 31 spinal nerves.

Vertebrae Number Spinal Nerve NumberCervical 7 Cervical 8Thoracic 12 Thoracic 12Lumbar 5 Lumbar 5Sacral 5 Sacral 5Coccygeal 4 Coccygeal 1

• In adults, 5 sacral vertebrae fuse together to form ‘sacrum’ 4 coccygeal vertebrae fuse together to form ‘coccyx’.

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.

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.

2.Vertebral (neural) arch:• The vertebral arch consists of:I. A pair of pedicles.II. A pair of lamina.III. Seven processes:o Spinous ---- oneo Articular ---- fouro 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.

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.

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.

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:iv. Project downwards.v. Articular surface faces more or less forwards.vi. Articulate with superior articular processes of

the vertebrae below.

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 bodyLumbar: No foramen transversarium and no

costal facets on the body.