A-THE THORACIC WALL

Posteriorly by the thoracic part of the vertebral column

Boundaries

Anteriorly by the sternum and costal cartilages

Laterally by the ribs and intercostal spaces

Superiorly by the suprapleural membrane

Inferiorly by the diaphragm, which separates the thoracic cavity from the abdominal cavity

A-THE THORACIC WALL

Posteriorly by the thoracic part of the vertebral column

Boundaries

Anteriorly by the sternum and costal cartilages

Laterally by the ribs and intercostal spaces

Superiorly by the suprapleural membrane

Inferiorly by the diaphragm, which separates the thoracic cavity from the abdominal cavity

1- STERNUM

It is a flat bone Divides into three

parts:

2-Body of the sternum

1-Manubrium sterni

3- Xiphoid process

The sternal angle (angle of Louis)

formed by the articulation of the manubrium with the body of the

sternum

second costal cartilage

The point from which all costal cartilages and ribs are counted

Lies at the level of

2-RibsThere are 12 pairs of ribs, all of which are attached posteriorly to the thoracic vertebrae.

The ribs are divided into three categories according to their relation to the sternum:

False ribs: The 8th, 9th, and 10th pairs of ribs are attached anteriorly to each other and to the 7th rib by means of their costal cartilages.

True ribs: The upper seven pairs are attached anteriorly to the sternum by their costal

cartilages

Floating ribs: The 11th and 12th pairs have no anterior attachment

Typical Rib

A typical rib is a long, twisted, flat bone having a rounded, smooth superior

border and

a sharp, thin inferior border

A rib has a head, neck, tubercle, shaft, and angle

The inferior border forms THE COSTAL GROOVE

which accommodates the intercostal vessels and nerve.

intercostal vein intercostal artery intercostal nerve

VANim

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3-The Vertebral Column

7 cervical

is composed of 33 vertebrae

12 thoracic

5 lumbar

5 sacral (fused to form the sacrum)

4 coccygeal (the lower 3 are commonly fused)

The vertebral arch gives rise to seven processes:

a-One spinousb-Two transversec- Four articular(2 superior 2 inferior)

A typical thoracic vertebra consists of:

1-a rounded body anteriorly (body bearing)

2-a vertebral arch posteriorly.

(protect the spinal cord)They enclose a space called

The vertebral foramen through which run the spinal

cord and its coverings

Characteristics of a Typical Thoracic Vertebra

The body is heart shaped

The vertebral foramen is small and circular

The spines are long and inclined downward

Costal facets are present on the sides of

the bodies for articulation with the

heads of the ribs

Costal facets are present on the

transverse processes for articulation with the tubercles of the ribs

The body and the vertebral arch are connected by means of pedicles

The pedicles are notched on their

upper and lower bordersForming

the superior and inferior vertebral notches.

These foramina, in an articulated skeleton, serve to

transmit the spinal nerves and blood vessels .

On each sidethe superior notch of one vertebra and the inferior

notch of an adjacent vertebra together form an

intervertebral foramen .

The diaphragm is a thin muscular and tendinous septum

that separates the chest cavity above

from the abdominal cavity below

The diaphragm is the most important muscle of

respiration. It is dome shaped and

consists of a peripheral muscular part

and a centrally placed tendon

4-The diaphragm

The inferior vena cava passes through the central tendon at

approximately vertebral level T8

The esophagus passes through the muscular part of the diaphragm, approximately at vertebral

level T10

The aorta passes behind the posterior attachment of the

diaphragm at vertebral level T12

Main Openings in the diaphragm

Nerve supply of the diaphragm

The phrenic nerves

1-SKIN2-SUPERFISCIAL FASCIA3- THREE MUSCLES OF RESPIRATION: THE EXTERNAL INTERCOSTALTHE INTERNAL INTERCOSTAL THE INNERMOST INTERCOSTAL MUSCLE4-THE ENDOTHORACIC FASCIA 5-THE PARIETAL PLEURA.

The intercostal nerves and blood vessels run between the intermediate (internal intercostal) and deepest

layers (innermost intercostal) of muscles They are arranged in the following order from above

downward:

INTERCOSTAL VEIN INTERCOSTAL ARTERY INTERCOSTAL NERVE

(VAN)

5-Intercostal Spaces

The external intercostal muscle

the most superficial layer. Its fibers are directed

downward and forward

The Internal Intercostal Muscle

forms the intermediate layer. Its fibers are directed

downward and backward

The innermost intercostal muscle

Forms the deepest layer

It is an incomplete muscle layer and crosses more than one intercostal space within

the ribs.

B-CHEST CAVITY

The chest cavity is bounded by the chest wall and below by the

diaphragm

The chest cavity can be divided

into

LATERALLY PLACED

PLEURAE AND LUNGS

MEDIAN PARTITION

CALLED THE

MEDIASTINUM

2-PleuraeThe pleurae and lungs lie

on either side of the mediastinum within the

chest cavity

the lung is covered with visceral pleura and the thoracic

wall is lined with parietal pleura

FORMATION OF THE LUNGS

Each lung bud invaginates the wall of the cavity and

then grows to fill a greater part of the cavity

The original cavity is reduced to a slitlike space called the pleural cavity as a result of the growth

of the lung.

Each pleura has two parts:

2 -Visceral layer :completely covers the outer surfaces of

The lungs

1 -Parietal layer, which lines A-The thoracic wall

The parietal and visceral layers of pleura

are separated from one another by a slit like space

The Pleural Cavity

Trachea

The trachea is a mobile cartilaginous and membranous

tube It begins in the neck as a continuation of the larynx at

the lower border of the cricoid cartilage at the level of the

sixth cervical vertebra

ends at the carina by dividing into right and left principal (main)

bronchi at the level of the sternal angle (opposite the disc

between the fourth and fifth thoracic vertebrae).

Principal BronchiThe right principal (main) bronchus

1-wider2-shorter

3 -more vertical than the left 4-is about 1 in. (2.5 cm) long

The left principal (main) bronchus is 1-narrower2-longer3-more horizontal than the right4- is about 2 in. (5 cm) long.

Inhalation of foreign bodies into the lower respiratory tract is common, especially in childrenBecause the right bronchus is the wider and more direct continuation of the trachea foreign bodies

tend to enter the right instead of the left bronchus

INHALED FOREIGN BODIES

Lungs

In the child, they are pink, but with age, they become dark because of the inhalation of dust particles that become trapped in the phagocytes of the lung.

The lungs are situated so that one lies on each side of the mediastinum.

Each lung is conical, covered with visceral pleura

Each lung has a blunt apex, which projects upward into the neck for about 1 in. (2.5 cm) above the clavicle

a concave base that sits on the diaphragm

a convex costal surface, which corresponds to the concave chest wall

a concave mediastinal surface, which is molded to the pericardium and other mediastinal structures

At about the middle of mediastinal

surface is the hiluma depression in which the bronchi,

vessels, and nerves that form the root enter and leave the lung.

The anterior border is thin and overlaps the heartThe posterior border is thick and lies beside the vertebral column

Right LungThe right lung is

slightly larger than the left is divided by

the oblique and horizontal fissures into three lobes:

THE UPPERMIDDLE

LOWER LOBES

Left LungThe left lung is

divided by a similar oblique fissure into

two lobes :the upper and lower

lobes There is no horizontal fissure in

the left lung

For the Practical

sessions you do need to recognize

the following

)1 ,2 & 3 (according to

their anatomical positions

1-Pulmonary artery

Superior in position

2-Pulmonary veinsInferior

in position

3-Main bronchus Posterior

in position

anteriorposterior

superior

inferior