Human Anatomy Vol 1

THORAX

Region

1. Thoracic vertebrae


2. Cervical veftebrae


3. Lumbar vertebrae


4. Sacrum

Spinal nerve T3

Transverse costal facet

Articular processes

lntervertebral

foramen

Shaft of

sth rib

Fig. 13.20: lntervertebral foramina and articulation of head of a
typical rib

Thorocic Veilebroe

I nlificalion

The thoracic vertebrae are identified by the presence
of costal facets on the sides of the vertebral bodies.
The costal facets may be two or only one on each side
(Fig. 13.18).

There are (^12) thoracic vertebrae, out of which the
second to eighth are typical, and the remaining five
(first, ninth, tenth, eleventh and twelfth) are atypical.
1 The body is heart-shaped with roughly the same
measurements from side to side and antero-
posteriorly. On each side, it bears two costal demi-
facets. The superior costal demifucet islarger and placed
on the upper border of the body near the pedicle. It
articulates with the head of the numerically
corresponding rib. The inferior costal demifacet is
smaller and placed on the lower border in front of
the inferior vertebral notch. It articulates with the
next lower rib (Figs 13.18 and 13.20).
Costal element
Forms the rib

. Anterior wall of foramen transversarium,
. Anterior tubercle,
. Costotransverse bar,
. Posterior tubercle, and
. Lateral part of the posterior wall of the foramen

Forms the real (descriptive) transverse process

Forms the anterior part of the lateral mass

2 The aertebral foramen is comparatively small and

circular.

3 The aertebral arch shows:

a. The pedicles are directed straight backwards. The

superior vertebral notch is shallow, while the

inferior vertebral notch is deep and conspicuous.

b. The laminae overlap each other from above.

c. The superior articular ptocesses project upwards

from the junction of the pedicles and laminae. The

articular facets are flat and are directed

backwards. This direction permits rotatory

movements of the spine.

d. The inferior qrticular processes are fused to the

laminae. Their articular facets are directed

forwards.

e. The transuerseprocesses are large, and are directed

laterally and backwards from the junction of the

pedicles and laminae. The anterior surface of each

process bears a facet near its tip, for articulation

with the tubercle of the corresponding rib. In the

upper six vertebrae, the costal facets on the

transverse processes are concave, and face

forwards and laterally. In lower six, the facets are

flat and face upwards, laterally and slightly

forwards (see costotransverse joints below).

f. The spine is long, and is directed downwards and

backwards. The fifth to ninth spines are the longest,

more vertical and overlap each other. The upper

and lower spines are less oblique in direction.

A ehrnenfs

1 The upper and lower borders of the body give

attachment, in front and behind respectively to the

anterior and posterior longitudinal ligaments (Fig. 13.5).

2 The upper borders and lower parts of the anterior

surfaces of the laminae provide attachment to the

ligamenta flazta.

3 The transverse process gives attachment to:

a. The lateral costotranszserse ligament at the tip.

Table 13.1 : The transverse and costal elements of the vertebrae

Transverse element

Forms the descriptive transverse process

It fuses with the costal element and forms

the medial part of the posterior wall of the

foramen transversarium

Forms the accessory process

It fuses with the costal element to form

the posterior part of the lateral mass

Head of Sth rib

lntervertebral

disc

Spinal nerve

T5