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Thorax - PowerPoint PPT Presentation

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Thorax. Thorax. Thorax is the superier part of the trunk between the neck and adomen . It extends below the neck to the diaphragm. It contains the primary organs of respiratory and cardiovascular system. Thoracic Skeleton.

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  • Thorax is the superier part of the trunk between the neck and adomen.

  • It extends below the neck to the diaphragm.

  • It contains the primary organs of respiratory and cardiovascular system

Thoracic Skeleton

  • The thoracic skeleton forms the osteocartilaginous thoracic cage, which protects the thoracic viscera and some abdominal organs.

Thoracic Skeleton

  • The thoracic skeleton includes the thoracic cage formed by the horizontal bars formed by ribs and costal cartilages supported by the vertical sternum,anterierly and thoracic vertebrae,posterierly

  • A typical human rib cage consists of 24 ribs, the sternum, costal cartilages, and the 12 thoracic vertebrae.

  • All ribs are attached in the back to the thoracic vertebrae.

Thoracic ribs

  • The upper seven are true ribs, are attached in the front to the sternum by means of costal cartilage. Due to their elasticity they allow movement when inhaling and exhaling.

  • The 8th, 9th, and 10th ribs are called false ribs, and join with the costal cartilages of the ribs above.

  • The 11th and 12th ribs are known as floating ribs, as they do not have any anterior connection to the sternum.

  • The spaces between the ribs are known as intercostal spaces; they contain the intercostal muscles, nerves, and arteries.


  • The sternum is the flat,elongated bone that forms the middle of the anterior part of thoracic cage.

  • The sternum consists of

  • Manubrium,

  • Body,

  • Xiphoid process


  • The thoracic cavity is divided into three major spaces.

  • The central/median compartment called mediastinum houses the conducting structures(esophagus,trachea,major blood vessels and most importantly heart).

  • The two lateral compartments contains the lungs

Nasal cavity check this

  • The lateral wall of the nasal cavity is mainly made up by the maxilla, and the conchae on the wall

  • The floor of the nasal cavity, which forms the roof of the mouth, is made up by the bones of the hard palate.

  • The nasal cavity is divided in two by nasal septum,formed by

Nasal Cavity

The air passing through the nasal cavity is

  • warmed or cooled to within 1 degree of body temperature.

  • humidified, and dust and other particulate matter is removed by vibrissae, short, thick hairs, present in the vestibule.

    The cilia of the respiratory epithelium move the particulate matter towards the pharynx where it passes into the esophagus and is digested in the stomach.


  • The pharynx (plural: pharynges) is the part of the neck and throat situated immediately posterior to (behind) the mouth and nasal cavity


  • The pharynx is part of the digestive system and respiratory system

  • food and air pass through the pharynx, a flap of connective tissue called the epiglottis closes over the trachea when food is swallowed to prevent choking or aspiration.


  • The human pharynx is conventionally divided into three sections:

  • Nasopharynx

  • Oropharynx

  • Laryngopharynx


  • The nasopharynx region extends between the internal nares and the soft palate and lies superior to the oral cavity.

  • The Eustachian tubes, or auditory tubes(equalizing the air pressure in the middle ear to that of the atmosphere. This is needed for proper conduction of sound), which connect the middle ear to the pharynx, open into the nasopharynx.


  • The oropharynx lies behind the oral cavity.

  • the lateral wall is made up of the tonsil, the superior wall consists of the inferior surface of the soft palate and the uvula.


  • It lies inferior to the upright epiglottis and it is continuous with the respiratory tract anterierly and digestive pathways,posterierly.

  • During swallowing, food has the "right of way", and air passage temporarily stops.

  • epiglottis closes over the trachea when food is swallowed


  • The larynx ("voice box“), is involved in protection of the trachea and sound production.

  • The laryngeal skeleton consists of nine cartilages: three single (thyroid, cricoid, and epiglottic) and three paired (arytenoid, corniculate, and cuneiform).

Nerve supply of Larynx

  • Superier and inferior laryngeal brances of vaus nerve(CN X).

  • Superier laryngeal nerve divides into int(supplies sensory and autonomic) and ext(motor) laryngeal nerve

  • Inferier laryngeal nerve is the primary motor nerve


  • The trachea (windpipe), is a fibrocartilagenous tube that connects to the pharynx/larynx, to the lungs.

  • It has mucosal goblet cells which produce mucus. This mucus lines the cells of the trachea to trap inhaled foreign particles which the cilia then waft upwards towards their larynx and then the pharynx where it can either be swallowed into the stomach or expelled as phlegm.


  • Trachea is supported by incomplete cartilaginous rings(keeping the trachea patent), that occupies a median position in the neck.

  • The posterior gap in tracheal rings is spanned by involuntary trachealismuscle,smooth muscle connecting the ends of the cartilages.

  • The esophagus is right behind the trachea, so the smooth muscle of trachea can accommodate according to the esophagus.

  • The brachiocephalic trunk is related to the right side of the trachea in the root of the neck.

  • So any deviation of the trachea from midline,apparent superficially or radiographically, is the sign of any pathological process.

  • Trachea bifrucates at the level of sternal angle into primary bronchus, one to each lung to enter the lung at the hila

  • The right main bronchus is wider,shorter and runs more vertically than left

  • Within the lungs the bronchi branch in a constant fashion.

  • Each main bronchus divides into lobar bronchi(secondary bronchi) 2 on left and 3 on right.

  • Lobar bronchus several segmental bronchi

  • segmental bronchi after 30-35 generation of branches end in terminal bronchioles.

  • Terminal bronchioles respiratory bronchiole alveolar ducts alveolar sacs , which are lined by alveoli


  • Their principal function is to transport oxygen from the atmosphere into the bloodstream, and to release carbon dioxide from the bloodstream into the atmosphere.

  • This exchange of gases is accomplished in the mosaic of specialized cells that form millions of tiny, exceptionally thin-walled air sacs called alveoli,that are sorrounded by the pulmonary capillaries


  • The pleura is a serous membrane which form a two-layered, membrane structure.

  • The outer parietal pleura is attached to the chest wall.

  • The inner visceral pleura covers the lungs

  • The thin space between the two pleural layers is known as the pleural cavity; it normally contains a small amount of pleural fluid

  • The parietal pleura is highly sensitive to pain while the visceral pleura is not, due to its lack of sensory innervation.

Bronchopulmonary Segments

  • Right lung is divided into superier,middle and inferior lobes

  • Left lung is divided into superior and inferior lobe

  • These lobes are inturn divided into 10 bronchopulmonary segments, each of which are seperated anatomically from each other by a connective tissue layer.

  • each segment is indepently supplied by a segmental bronchi and a tertiary branch of pulmonary artery.


  • Pulmonary alveolus is the basic structural unit of gas exchange in the lung.

  • In both lungs by 8 yrs of age we have 300 million alveoli

Blood supply

  • The lungs have a double blood supply, the pulmonary circulation for gas exchange with the alveoli and the bronchial circulation to supply the parenchyma (tissue) of the lung itself.


  • The thoracic cavity is divided into three major spaces.

  • The central/median compartment called mediastinum houses the conducting structures(including pericardium,heart and roots of its great vessels


There are two layers to the pericardial sac:

  • the fibrous pericardium and

  • the serous pericardium.

  • The serous pericardium, in turn, is divided into two layers, the parietal pericardium and visceral pericardium

  • In between the parietal and visceral pericardial layers there is a potential space called the pericardial cavity.

  • It normally contains thin film of fluid,pericardial fluid that enables the heart to move and beat in a frictionless environment

  • The inferior wall of the fibrous pericardium is firmly attached and partically blended with central tendon of diaphragam. The heart is well tethered in place inside the fibrous sac


The wall of each heart chamber consists of

  • Endocardium:thin internal layer of endothelium

  • Myocardium: thick, middle layer composed of cardiac muscle

  • Epicardium:thin external layer fromed by the visceral layer of serous pericardium

  • The heart has four chambers:

  • Right and left atria

  • Right and left Ventricles

  • three borders of the heart:

  • right border made up of the right atrium

  • inferior border made up of right atrium, right ventricle and left ventricle

  • left border made up of the left ventricle

Surfaces of the heart

  • Anterior sterno-costal surface, formed mainly by R. ventricle

  • Diaphragmatic or inferior surface is formed mainly by L. ventricle and partly by R. ventricle.

  • Right pulmonary surface is formed by R. atrium

  • Left pumonary surface is formed by L. ventricle which forms the cardiac impression of the left lung

Apex of the heart

  • Is the infero-lateral part of left ventricle

  • Lies beneath the 5thintercostal space in adults, approxiamately 9 cam from median plane

  • Is where the sounds of mitral valve closure(apex beat) are maximal


  • The superior vena cava opens at the level of R. 3rd costal carilage and inferior vena cava at 5th costal cartilage.

  • The right atrium opens into the R. ventricle thru Tri cuspid valve

  • The pairs of right and left pulmonary veins enter the posterior aspect of atrium.

  • The left atrium opens into L. ventricle thru Bicuspid or mitral valve.

Right Atrium

Left Atrium


  • The auricles are think ear-like conical muscular pouch which projects from the atria, increasing the capacity of atria

  • Each atria has an auricle on the superior surface


  • Receives the deoxygenated blood from the atium

  • And thru R. and L. pulmonary arteries pumps blood to the lungs

  • Receives the oxygenated blood from the atium

  • And thru Aorta pumps blood to the systemic circulation

Right ventricle

Left ventricle

Papillary muscles

  • Papillary muscles are nothing but the conical muscular projections from the myocardium of the heart

  • They support, strenghthen and responsible for the opening and closure of the cuspid valves.

  • They ara attached to the cuspid valves thru tendinous cords called chordaetendinae


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