Human Anatomy Vol 1

ln Coronal Flane (L*teral

There is slight lateral curve in the thoracic region with
its concavity towards the left. It is possible due to the
greater use of the right upper limb and the pressure of
the aorta.
The curvatures add to the elasticity of the spine, and
the number of curves gives it a higher resistance to
weight than would be afforded by a single curve.

Pods of o lypicolVeilebto

A typical vertebra is made up of the following parts:
1 The body lies anteriorly. It is shaped like a short
cylinder, being rounded from side to side and having
flat upper and lower surfaces that are attached to
those of adjoining vertebrae by intervertebral discs
(Fig. 13.17).
2 The pedicles, right and left are short rounded bars
that project backwards, and somewhat laterally, from
the posterior aspect of the body.
3 Each pedicle is continuous, posteromedially, with a
vertical plate of bone called the laminn. The laminae
of the two sides passbackwards and mediallyto meet
in the midline. The pedicles and laminae together
constitute tJaie uertebral or neural arch.
4 Bounded anteriorly by the posterior aspect of the
body, on the sides by the pedicles, and behind by
the lamina, there is a large aertebral foramen.
Each vertebral foramen forms a short segment of the
vertebral canal that runs through the whole length
of the vertebral column and lodges the spinal cord.
5 Passing backwards and usually downwards from the
junction of the two laminae there is the spine or
spinous process (Fig. 13.18).
6 Passing laterally and usually somewhat downwards
from the junction of each pedicle and the
corresponding lamina, there is a transtserse process.
The spinous and transverse processes serve as levers
for muscles acting on the vertebral column.

Body

Vertebral foramen

Superior costal facet

Pedicle

Transverse process

Facet for tubercle

of rib

Superior articular

process

Lamina

BONES AND JOINTS OF THORAX

From a morphological point of view, the transverse

processes are madeup of two elements, the transverse

element and the costal element. In the thoracic regiory

the two elements remain separate, and the costal

elements form the ribs. In the rest of the vertebral

column, the derivatives of costal elementare different

from those derived from transverse element. This is

shown in Table 13.1.

Projecting upwards from the junction of the pedicle

and the lamina there is on either side, a superior

articular process;and projecting downwards there is

an inferior articular process (Fig. 13.19). Each process

bears a smooth articular facet: The superior facet of

one vertebra articulates with the inferior facet of the

vertebra above it.

The pedicle is much narrower in vertical diameter

than the body and is atthched nearer its upper border.

As a result there is a large inferior ztertebral notchbelow

the pedicle. Above the pedicle there is a much

shallower superior aertebral notch. The superior and

inferior notches of adjoining vertebrae join to form

the interaertebral foramina which give passage to the

dorsal andventral rami of the spinalnerves emerging

from the spinal cord (Fig. 13.20).

Superior costal demifacet

Superior vertebral notch

Superior

articular process

Costal facet on the

transverse process

for tubercle of

corresponding rib

lnferior articular process

lnferior verterbal notch

Spine

Fig. 13.18: Typical thoracic veftebra, lateral view

Superior articular

process

Lamina

Transverse process

lnferior articular

process

Spine

Flg. 13,17: Typical thoracic vertebra, superior aspect Fig. 13.19: Typical thoracic vertebra, posterior aspect