THORAX
Thoracic Wall
Thorax


The thorax is an irregularly shaped cylinder with a
narrow opening (superior thoracic aperture)
superiorly and a relatively large opening (inferior
thoracic aperture) Inferiorly.
The superior thoracic aperture is open, allowing
continuity with the neck; the inferior thoracic
aperture is closed by the diaphragm.
Superior thoracic aperture

Completely surrounded
by skeletal elements, the
superior thoracic
aperture consists of the
body of vertebra TI
posteriorly, the medial
margin of rib I on each
side, and the manubrium
anteriorly.
Inferior thoracic aperture

The inferior thoracic aperture is closed by the
diaphragm, and structures passing between the
abdomen and thorax pierce or pass posteriorly to
the diaphragm.
Thorax

Thoracic cavity
 Surrounded
by thoracic wall
 Contains heart, lungs, thymus,
distal part of trachea, and
most of esophagus

Thoracic wall
 Consists
of skin, fascia,
nerves, vessels, muscles, and
bones
Thoracic wall
The thoracic wall consists of skeletal elements and
muscles
1.
Posteriorly, it is made up of twelve thoracic
vertebrae and their intervening intervertebral
discs
2.
Laterally, the wall is formed by ribs (twelve on
each side) and three layers of flat muscles.
3.
Anteriorly, the sternum, which consists of the
manubrium of sternum, body of sternum, and
xiphoid process.
Ribs

Two types of classification
 True
ribs (1-7)
 False ribs (8-10)
 Floating ribs (11-12)
 Typical
ribs (3-9)
 Atypical ribs
(1,2,10,11,12)

R1-7 (True Ribs)
 Vertebrocostal
 Attach

to sternum via a costal cartilage
R8-10 (False Ribs)
 Vertebrochondral
 Their
cartilages are joined to the cartilage of rib above and
via that connection to sternum

R11-12 (Free or floating ribs)
 Do
not connect even indirectly with sternum but have a
costal cartilage on their tips. Tips embedded in muscles
Components of ribs Typical Rib (3-9)
Atypical Ribs
First Rib



No Angle
Shortest & flattest
Has grooves for
subclavian vein and
artery
2nd rib

Its main atypical
feature is a rough
area on its upper
surface, the tuberosity
for serratus anterior,
from which part of
that muscle originates.
th
10

to12th ribs
like the 1st rib, have
only one facet on their
heads and articulate
with a single vertebra.

The 11th and 12th ribs
are short and have no
neck or tubercle.
Thoracic Vertebrae
12 vertebrae
 Components
Body:



Articulates head of rib
Heart shaped
Spinous process:

Inclined downward
Transverse process:

Facet for each rib at
costovertebral j.
Pedicle:

Connect transverse process to
body
Lamina:

Connect transverse process to
spinous process
Sternum
 Midline of anterior chest wall
 flat bone
 3 parts
Manubrium sterni
 Opposite T3 &T4
 Jugular notch
Body of sternum
 Opposite T5-T9
 Articulates with 2nd–7th C.C
 Xiphosternal joint
Xiphoid process
 Flat, cartilagenous process
 Unites with body of sternum after middle age
 Attached to linea alba caudally
Sternal Angle (Angle of Louis)
Sternal Angle (Angle of Louis)

Junction between Manubrium and Body of
sternum - at this level --



The second ribs articulate with the sternum.
The aortic arch begins and ends.
The trachea bifurcates into the right and left bronchi at the carina.
A transverse plane can pass through the intervertebral disk
between T4 and T5.