THORAX OS powerpoint

Is an irregularly shaped cylinder with a narrow opening superiorly and relatively large opening inferiorly

Boundaries: o root of the neck

superiorly and diaphragm inferiorly, thoracic wall laterally

Has flexible musculoskeletal wall consists of vertebrae, ribs, muscles and the sternum

Left and right pleural cavity each surrounding a lung• Separated

from each other by the mediastinum

Mediastinum A thick soft

tissue partition oriented longitudinally in a median sagittal position

Contains the heart, esophagus, trachea, major nerves and systemic blood vessels

1. Breathing

2. Protection of vital organs

3. Conduit

A. Thoracic Wall Consists of skeletal elements and muscles

Boundaries:Posteriorly T1-12 vertebrae and IV discsLaterally 12 ribs on each sideAnteriorly sternum

B. Superior thoracic aperture

Boundaries: Posteriorly body of T1 vertebraLaterally medial margin of rib 1Anteriorly manubrium

IV disc between T2-T3 – same horizontal plane with the superior margin of the manubrium

C. Inferior thoracic aperture

- large and expandable

Boundaries:Posteriorly body of T12 vertebraPosterolaterally 12th rib and distal end of

11th ribAnterolaterally distal cartilaginous ends

of 7th -10th ribsAnteriorlyC. xiphoid process

IV disc between T9-T10 – same horizontal plane with the joint between the coastal margin and sternum

D. Diaphragm

- Closes the inferior thoracic aperture - Is not flat but has a dome shape: right dome ( reach up to 5th rib ) is higher than the left -During its contraction, there is a decrease on the height of the dome and an increase on the volume of the thorax

E. Mediastinum - A thick midline partitionBoundaries:AnteriorlySternumPosteriorly thoracic vertebraSuperiorly superior thoracic apertureInferiorlyinferior thoracic aperture

Divisions: horizontal plane passing from sternal angle to IV disc of T4-T5

A. Superior mediastinumB. Inferior mediastinum• subdivided by the pericardium:I. anterior mediastinum – lies between the sternum and the pericardiumII. middle mediastinum – consists of the pericardium and heartIII. posterior mediastinum – lies between the pericardium and the thoracic vertebra

F. Pleural Cavities - Situated on either side of the mediastinum - Lined by a mesothelial membrane called the pleura

A. Parietal pleura – lining the walls of the thoracic cavityB. Visceral pleura – lines those that reflected from the mediastinum and onto the surfaces of the lungs

Costodiaphragmatic recess – the largest and clinically most important; it lies inferiorly between thoracic wall and diaphragm

IV disc between T4-T5: one of the most significant structure at its horizontal plane• Passes through the sternal angle anteriorly, marking the position of the anterior articulation of the coastal cartilage of the 2nd rib with the sternum• Separates the superior and inferior mediastinum, marks the position of the superior limit of pericardium• Marks where the arch of the aorta begins and ends• Passes through the site where the superior vena cava penetrates the pericardium to enter the heart• Is the level at which the trachea bifurcates into right and left main bronchi• Marks the superior limit of the pulmonary trunk

A. ArteriesThoracic aorta, internal thoracic arteries,

interior and posterior intercostal arteries

B. NervesIntercostal nerves – innervates the wall,

related parietal pleura and associated skin

C. Dermatomes - T2-T12

CHEST

• External to the thoracic wall and anchors the upper limb to the trunk

•Consists of:

A superficial compartment containing skin, superficial fascia and breastsA deep compartment containing muscles and associated structures

Arterial supply

axillary artery branchesInternal thoracic artery branches2nd -4th intercxostal arteries

Lymphatic drainage

axillary nodes

Venous Drainage

axillary, internal thoracic and intercostal veins

Innervation

Breasts -2nd -6th intercostal nervesNipple – 4th intercostal nerve

MUSCLES:

pectoralis majorPectoralis minorSubclavius

originates from the ant. Thoracic wall and inserts into bones of the upper limb

CLINICAL CONDITION:

Breast Cancer F > M one of the most common malignancies in womenDevelops in the cells of the acini, lactiferous ducts

and lobules of the breastMastectomy

surgical removal of the breast might damage the long thoracic nerve that

innervates the SA causing paralysis Winged scapula

HEART

Is a broad central partition that separates the two laterally placed pleural cavities

It contains: thymus glandPericardial sacHeartTracheaMajor Arteries and Veins

DIVISIONS:1. Superior Mediastinum2. Inferior Mediastinum a. Anterior b. Middle c. Posterior

MIDDLE MEDIASTINUM- Contains the pericardium, heart,

origins of the great vessels, various nerves and smaller vessels

PERICARDIUM- Is a fibroserous sac surrounding

the heart and the roots of the great vessels

Consists of:1. Fibrous pericardium2. Serous pericardium

I. FIBROUS PERICARDIUM - Is a tough connective tissue outer layer that defines the boundaries of the middle mediastinum - Is a cone-shaped bag with its base on the diaphragm and its apex continuous with the adventitia of the great vessels

Attachments:Base – attached to the central tendon of the diaphragm and to a muscular area of the diaphragm on the left sideAnteriorly – attached to the posterior surface of the sternum by sternopericardial ligaments

phrenic nerves and pericardiacophrenic vessels

II. SEROUS PERICARDIUM - Is thin and consists of:A. Parietal layer • Lines the inner surface of the fibrous pericardiumB. Visceral layer • Adheres to the heart and forms its outer covering

Pericardial Cavity – a narrow space that contains a small amount of fluid between the two layers of serous pericardium allows the uninhibited movement of the heart

CARDIAC ORIENTATION • apex of this pyramid projects forward, downward and to the left • base is opposite the apex and faces in a posterior direction

• Is quadrilateral and directed posteriorly• It consists of:

The left atriumA small portion of the

right atriumThe proximal parts of

the great veins (sup. And inf. Vena cava, pulmonary veins)

•Is fixed posteriorly to the pericardial wall , opposite to the bodies of T5-T8 or when standing T6-T9

• Is formed by the inferolateral part of the left ventricle• Positioned deep to the left 5th intercostal space

Anterior Surface

• Faces anteriorly and consists mostly of the right ventricle with some of the right atrium on the right and some of the left ventricle on the left

Diaphragmatic Surface • Faces inferiorly, rests on the diaphragm• Separated from the base of the heart by the coronary sinus and extends from the base to the apex of the heart• Consists of the left ventricle and the small portion of the right ventricle separated by the posterior interventricular groove

Left pulmonary surface • Faces the left lung • Is broad and convex and consists of the left ventricle and a portion of the left atriumRight pulmonary surface • Faces the right lung • Is broad and convex, consists of the right atrium

Right and Left margins • Same as the right and left pulmonary surfaces of the heart Inferior margin • The sharp edge between the anterior and diaphragmatic surfaces of the heart • Formed by the right ventricle and small portion of the left ventricle near the apexObtuse margin • Separates the anterior and left pulmonary surfaces • It is round and extends from the left auricle to the cardiac apex • Formed by the left ventricle and superiorly by a small portion of the left auricle

• Are external grooves

I Coronary sulcus Circles the heart, separating the atria from the ventricles It contains the right coronary artery, the small cardiac vein, the coronary sinus, and circumflex branch of the left coronary artery

II. Anterior and Posterior Interventricular Sulci Separates the 2 ventricles

A. Anterior interventricular sulcus Located on the anterior surface of the heart Contains the anterior interventricular artery and the great cardiac veinB. Posterior Interventricular sulcus Located on the diaphragmatic surface of the heart Contains the posterior interventricular artery and the middle cardiac vein

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