Structure of the Thoracic Wall

human anatomy 2016 lecture eleven Dr meethak ali ahmed neurosurgeon

opening of the thorax

The thoracic cavity communicates with the root of the neck through an opening called the thoracic inlet ; is bounded post. by first thoracic vertebra, laterally by the medial border of the first ribs & their costal cartilage , & ant. by the superior border of the manubrium sterni. the opening is obliquely placed facing upward & forward . Through this small opening pass the esophagus &trachea and many vessels & nerve . because of the obliquely of the opening ,the apices of the lung and pleurae project upward into the neck.

The thoracic cavity communicates with abdomen through a large opening called the thoracic outlet . The opening is bounded post. by the twelfth thoracic vertebrae , laterally by the curving costal margin ,& ant. by xiphisternal joint . Through this large opening , which is closed by the diaphragm ,pass the esophagus & many large vessels & nerve ,all which pierce the diaphragm. structure of the thoracic wall

The thoracic wall is coverd on the outside by skin & by muscles attaching the shoulder girdle to the trunk. lined with parietal pleura . thoracic part of the vertebral column is concave forward & is made up of twelve vertebrae , together with their intervertebral disc. sternum the sternum is flat bone that may be divided into three parts

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manubrium; is the upper part of the sternum ,& it articulates with the clavical & the first & upper part of the second costal cartilages on each side . it opposite the third and fourth thoracic vertebrae. body of the sternum articulates above with manubrium by fibrocartilaginus joint , below it articulate with the xiphoid process. on each side are noches for articulation with lower part of the second costal cartilage & third to seventh costal cartilage articulate with the sternum at synovial joint. xiphoid process is the lowest & smallest part of the sternum it is thin plate of hyaline cartilage that becomes ossified at its proximal end in adult life . sterna angle (angle of Louis) ,formed by the articulation of the manubrium with the body of the sternum , can be recognized by the presence of transverse ridge on the anterior aspect of the sternum , the sternum angle lies opposite the intervertebral disc between the fourth and fifth thoracic vertebrae. xiphisternal joint lies opposite the body of the ninth thoracic vertebrae. costal cartilage are barsof hyaline cartilage connecting the upper seven ribs to the lateral edge of the sternum , & eighth , ninth & tenth ribs to the cartilage immediately above . the cartilage of the eleventh & twelfth ribs end in the abdominal musculature. ribs there are twelve pairs of the ribs , all of which are attached posteriorly to the thoracic vertebrae .the upper seventh pairs are attached anteriorly to the sternum by their costal cartilage . the eighth , ninth & tenth pairs of the ribs are attached anteriorly to each other & to the seventh synovial

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joints . the eleventh & twelfth pairs have no anterior attachment & are referred to as floating ribs. typical ribs is a long ,twisted ,flat bone having thin inferior border overhangs & forms the costal groove , which accommodates the intercostal vessels & nerve .

A rib has a head , neck tubercle, shaft , angle . the head has two facets for articulation with the numerically corresponding vertebral body & that of the vertebra immediately above . the neck is a constricted portion situated between the head & the tubercle. the tubercle is a prominence on the outer surface of the rib at the junction of the neck with the shaft . it has a facet for articulation with the transverse process of the numerically corresponding vertebra . the shaft or body is thin and flattened and twisted on its long axis . its inferior border has the costal groove . the angle is where the shaft of the rib bends sharply forward . the anterior end of each rib is attach to the corresponding costal cartilage. The first rib is atypical . its important because of its close relation ship to the nerve of the brachial plexus and main vessels to the arm ,namely the subclavian vessels .this rib is flattened from above down ward . it has tubercle on the inner border , known as the scalene tubercle , for the insertion of the scalenus anterior muscle . anterior to the tubercle the subclavian vein crosses the rib , posterior to the tubercle is subclavian groove , where the subclavian artery & the lower trunk of the brachial plexus cross the rib & lie in contact with the bone. intercostals spaces the space between the rib are called intercostals space , each space contains three muscles of respiration :the external intercostals , the internal intercostals & transverses thoracic muscle . the transverses thoracis muscle is lined internally by the endothoracic fascia & parietal pleura . the intercostals nerve & blood vessel run between the intermediate & deepest layer of the muscle , they are arrange in the

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following order from above downward : intercostals vein ,intercostals artery , intercostals nerve. intercostals muscle the external intercostals muscle form superfaicial layer its fiber are directed downward & forward from the inferior border of the rib above to the superior border of the rib below . the extend forward from the rib tubercle behind to the costochondral junction in front where the muscle replaced by an aponeurosis the anterior ( external) intercostals membrane. the internal intercostals muscle froms the intermediate layer . its fiber directed downward backward from the subcostal groove of the rib above to the upper border of the rib below the muscle extends back ward from the sternum in front to the angle of the rib behind where the muscle is replaced by the an aponeurosis , the posterior (internal ) intercstal membrane . the transversus thorcis muscle ,from the deepest layer and corresponds to the transversus abdominis muscle in the anterior abdominal wall . divided into three portions which are more or less separated from one another (1) the subcastalis (2) intercostalis intimus (3) sternocostalis.

reference, snell clinical anatomy human anatomy 2016 lecture eleven Dr meethak ali ahmed neurosurgeon

blood and nerve supply from intercostals nerve and vessels

reference, snell clinical anatomy human anatomy 2016 lecture eleven Dr meethak ali ahmed neurosurgeon

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