ANATOMY OF THE THORAX Dr. Heba Al-Hussaini Assistant professor Department of Anatomy Faculty of Medicine 11/12/2012

OBJECTIVES Describe the thoracic wall. Describe the thoracic apertures. Describe the organization of the thoracic cavity – pleural cavities and mediastinum. Describe the organization of the thoracic viscera.

THE THORAX Function of thoracic cage: 1- Protect thoracic organs. 2- Support the pectoral girdle. 3- Provide attachments for muscles 4- Take part in breathing. 5- Conduit for structures that pass to and out of thorax

THE THORACIC WALL The skeletal elements of the thoracic wall consist of 12 thoracic vertebrae posteriorly, 12 pairs of ribs laterally and the sternum anteriorly.

SUPERIOR THORACIC APERTURE

THORACIC OUTLET SYNDROME The axillary inlet to the upper limb lies on each side of the superior thoracic aperture. Cervical rib syndrome results from compression of the inferior trunk of brachial plexus. The costoclavicular syndrome results from compression of the subclavian artery between the clavicle and 1 st rib.

INFERIOR THORACIC APERTURE Generally muscle fibers of the diaphragm arise radially from the margins of the inferior thoracic aperture, and converge into a large central tendon. Attachment of the diaphragm: xiphoid process, d istal cartilaginous ends of ribs VII to X, ribs XI and XII, vertebrae of lumber region. 6 5

DIAPHRAGM SUPERIOR VIEW VIEW MAJOR STRUCTURES THAT PASS THROUGH THE DIAPHRAGM The esophagus pass through the muscular part of the diaphragm and the inferior vena pass through the central tendon of the diaphragm whereas the aorta passes posterior to the diaphragm.

THE THORACIC CAVITY The thoracic cavity is subdivided into three major compartments. The pleural cavities are completely separated from each other by the mediastinum.

MEDIASTINUM The sternal angle is used to find the position of the rib II as reference for counting ribs. Anterior mediastinum contains a portion of thymus and fat. Middle mediastinum contains the pericardium and heart.

CONTENT OF THE MEDIASTINUM Superior mediastinum contains the thymus, Superior vena cava, brachiocephalic veins, arch of aorta and roots of its major branches. Posterior mediastinum contains the esophagus, descending aorta, azygos vein, thoracic duct, sympathetic trunk and thoracic splanchnic nerves.

PERICARDIUM The pericardium is a fibroserous sac surrounding the heart and the roots of the great vessels. Consists of two components: 1- fibrous pericardium is a tough connective tissue outer layer that defines the boundaries of the middle mediastinum, 2- the serous pericardium is thin and consist of the parietal layer lines the inner surface of the fibrous and visceral layer adheres to the heart and forms its outer covering.

BORDERS OF THE HEART Right border formed by right atrium and extend between the SVC & IVC. Inferior border formed by the right ventricle and slightly by the left ventricles. Left border formed mainly by the left ventricle and slightly by left auricle. Superior border formed by the right and left atria and auricles.

Posterior viewAnterior view Anterior formed (sternocostal) mainly by Rt. Ventricle. Inferior formed (diaphragmatic) mainly by the Lt. ventricles and partly by Rt. Ventricle. Posterior (base) formed by the Lt. atrium. Lt. Atrium THREE SURFACES OF THE HEART THREE SURFACES OF THE HEART

PLEURAL CAVITY Each pleural cavity is lined by the pleura which is divided in to two types: 1- Parietal pleura associated with the walls of the pleural cavity. 2- visceral pleura which reflects from the medial wall and onto the surface of the lung to cover the lung.

ARTERIES OF THE THORACIC WALL Vessels that supply the thoracic wall consist of posterior intercostal which originate from the aorta and anterior intercostal arteries which originate from the internal thoracic (branch of subclavian).

VEINS OF THE THORACIC WALL Most intercostal veins ends in the azygos venous system of veins which ultimately drains into the SVC. The 1 st -3 rd superior intercostal veins drain into brachiocephalic vein.

LYMPHATIC DRAINAGE THORACIC WALL Lymphatic vessels of the thoracic wall drain mainly in to parasternal, intercostal and diaphragmatic lymph nodes. Parasternal nodes drains into bronchomediastinal and intercostal nodes into thoracic duct.

TRANSVERSE SECTION THROUGH THE SUPERIOR MEDIASTINUM AT THE LEVEL VERTEBRA TIII

TRANSVERSE SECTION THROUGH THE SUPERIOR MEDIASTINUM AT THE LEVEL VERTEBRA TV

CLINICAL APPLICATION

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