The thorax is the body cavity, surrounded by the bony rib cage that contains the heart and lungs, the great vessels, the oesophagus and trachea, the thoracic duct and the autonomic innervations of these structures

1. ANATOMY OF THORAX
Dr. Pinki Maheshwari
PG Department of Rachna Sharir
Email. Id- drpinky.maheshwari@hotmail.com

2. INTRODUCTION
The thorax is the body cavity, surrounded by the bony rib cage that contains the heart and lungs, the
great vessels, the oesophagus and trachea, the thoracic duct and the autonomic innervations of these
structures. The inferior boundary of the thoracic cavity is the respiratory diaphragm, which separates
the thoracic and abdominal cavities. Superiorly, the thorax communicates with the root of the neck
and upper extremity. The wall of the thorax contains the muscle involved with respiration and those
connecting the upper extremity to the axial skeleton. The wall of the thorax is responsible for
protecting the contents of the thoracic cavity and for generating the negative pressure required for the
respiration. The thorax is covered by skin and superficial fascia, which contains the mammary tissue.

3. SURFACE LANDMARKS OF THORAX
 Juglar notch corresponds with
• The 2nd thoracic vertebra in male, the 3rd thoracic
vertebra in female
Sternal angle (angle of Louis) corresponds with
• Connects 2nd costal cartilage laterally
• The lower border of 4th thoracic vertebra
• The bifurcation of the trachea in the adult
• The beginning of the aortic arch which ends posteriorly at
the same level
• The oesophagus is crossed by the left main bronchus
 Xiphisternal joint
• The costal margin on each side is formed by the 7th -10th
costal cartilages.
• It lies at the level of the upper border of the 9th thoracic
vertebra.

4. LANDMARKS…..

5. THORACIC WALL
 Superficial structures
• Skin
• Superficial fascia
1. Superficial artery
2. Superficial vein
- Thoracoepigastric vein
- Lateral thoracic vein
3. Superficial nerve
- Supraclavicular nerve
- Anterior and lateral cutaneous branches
of intercostal nerve
 Deep structures
• Deep fascia
1. Superficial layer
2. Deep layer – clavipectoral fascia
• Muscle of thorax
1. Subclavius
2. Pectoralis major
3. Serratus anterior
4. External intercostal
5. Internal intercostal
6. Transversus thoracis
• Endothoracic fascia

6. RIBS AND STERNUM
The skeleton of thorax is also knows as the
thoracic cage.
 Formation
 Anteriorly by the sternum
 Posteriorly by the 12 thoracic vertebrae and the
intervening intervertebral discs
 Each rib articulates posteriorly with the vertebral
column. Anteriorly, only the upper 7 ribs articulate
with the sternum through their cartilages and called
as true or vertebrosternal ribs.
 The costal cartilages of 8th, 9th,10th end by joining
the next higher costal cartilage and knows as
vertebrochondral ribs.
 The anterior ends of 11th and 12th ribs are free and
called as floating or vertebral ribs.

7. Sternum
The sternum can be divided into three parts; the manubrium,
body and xiphoid process.
1. Manubrium:
• The manubrium is the most superior portion of the sternum.
It is trapezoid in shape.
• The superior aspect of the manubrium is concave, producing
a depression known as the jugular notch.
• Inferiorly, the manubrium articulates with the body of the
sternum, forming the sternal angle.
2. Body
• The body is flat and elongated – the largest part of the
sternum. It articulates with the manubrium superiorly
(manubriosternal joint) and the xiphoid process inferiorly
(xiphisternal joint).
3. Xiphoid Process
• It is the most inferior and smallest part of sternum. It is
variable in shape and size with its tips located at the level of
T10 vertebra.

14. MUSCLES ASSOCIATE WITH THE RIBS
 The thoracic cage forms the skeletal framework
of the wall of the thorax. The gaps between the
ribs are called intercostal spaces. They are filled
by the intercostal muscles and contain the
intercostal nerves, vessels and lymphatics.
• Intercostal Muscles: These are:
1. The external intercostal muscle
2. The internal intercostal muscle
3. Transverse thoracis
a. Subcostalis
b. Intercostalis intimi / Innermost intercostal
c. Sternocostalis
4. Levator costrum

16. 4. Transeversus thoracis
• Four or five muscular slips that arise from the xiphoid
and body of sternum
• They expand superiorly and laterally to the 2nd – 6th
costal cartilages
• Origin – Posterio- inferior sternum
• Insertion – Internal surface of costal cartilage 2-6
• Action – Depress the ribs (assist)
• Innervation- Intercostal nerves (T2-T6)
5. Subcostales
• Thin muscular slips that extend from the angle of a rib
on the internal surface to external surface of rib
below.
• They cross two intercostal spaces
• They run in the same direction as the internal
intercostals
• Origin – Inferior surface of the lower ribs near
rib angle
• Insertion – Inner surface of 2 – 3 ribs below
• Action – Depress ribs (assist)
• Innervation – Intercostal nerves

18. INTERCOSTAL NERVES
• The intercostal nerves are the anterior primary rami
of T1 – T11 spinal nerves after the dorsal primary
ramus has been given off.
• The anterior primary ramus of the 12th thoracic
nerve forms the subcostal nerve.
• In addition to supplying the intercostal spaces, the
upper two also supply the upper limb.
• T7 - T11 also supply abdominal wall so knows as
thoracoabdominal nerves.
• T3-T6 supply only the thoracic wall thus called as
typical intercostal nerves.
• Course: Intercostal nerve runs in the costal groove
and ends near the sternum.
• Relations: The relationship of structures in the
costal groove from above downwards is posterior
intercostal vein, posterior intercostal artery and
intercostal nerve (VAN).

19. INTERCOSAL VESSELS
• The intercostal muscles and the skin of the thorax receive
their blood supply from both the intercostal arteries and the
internal thoracic artery.
• Intercostal arteries 3-11 (and the subcostal artery) are
branches directly from the thoracic descending aorta.
• The first two intercostal arteries are branches of the supreme
intercostal artery, which is a branch of the costocervical trunk
from the subclavian artery.
• The posterior intercostals run with the intercostal nerve and
pass with the nerve between the innermost and internal
intercostal muscles.
• The intercostals then anastomose with anterior intercostal
branches arising from the internal thoracic artery descending
immediately lateral to the sternum.
• The internal thoracic arteries are anterior branches from the
subclavian arteries bilaterally.
• The intercostal arteries are accompanied by intercostal veins.
These veins drain to the azygos system of veins in the
posterior mediastinum.

20. DIAPHRAGM AT THE OUTLET OF THORAX
 The outlet is closed by a large musculotendinous
partition called the diaphragm.
 Structures passing through the Diaphragm: There are
3 large and several small openings in the diaphragm are
as follows-
• Large openings:
1. Vena caval opening in the central tendon
2. Oesophageal opening in the right crus of diaphragm
3. Aortic opening behind the median arcuate ligament
• Small openings:
1. Superior epigastric artery passes in the space of Larrey
2. Musculophrenic artery perforates diaphragm at the level
of 9th costal cartilage
3. Lower five intercostal vessels and nerves pass between
costal origin of diaphragm and transverses abdominis
4. Subcostal vessels and nerves etc.