Surface Anatomy of the Chest
Sunday 17/2/2019 Dr: Hassna B. Jawad
• At the end of this lecture you should know: • 1.The surface marking of chest • 2.Bones forming the thoracic cage • 3.Parts of sternum • 4.False and true ribs • 5.Typical and atypical ribs • 6.Feature of thoracic vertebrae • 7.Clinical notes
*The surface marking of the chest: The most important land marks in the chest are the following: 1. Suprasternal notch : Located in the superior border of manubrium of sternum , opposite to the lower border of 2nd thoracic vertebrae . Its significant : to localize the position of the trachea which must be centrally located normally . Deviation of trachea indicates pathology which pushes or pulls the trachea .
2. Angle of Louis( manubriuosternal angle ) : *Prominence in the upper part of the chest *is formed by articulation of manubrium and body of sternum * It lies opposite to lower border of T5 .
Its significant:
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Sunday 17/2/2019 Dr: Hassna B. Jawad
It lies at the level of 2nd costal cartilage of the second rib by this we can calculate our ribs and intercostal spaces begins with the second rib .
3. Nipples and areola : *In male usually situated in the 4th intercostal space . *In female its situation different according to the size of the breast . Its significant: to localize the location of the apex of the heart .
Male Female
4. The apex beat :
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Sunday 17/2/2019 Dr: Hassna B. Jawad
*The pulsation of the heart can be felt below the left areola this pulsation is corresponded to the ( apex of the left ventricle ) . . *Normally It lies in the 5th intercostal space along mid clavicular line neither right nor left but if it is at right this mean the heart is pulled and if it is at left means the heart is pushed or the heart larger than usual . Its significant : to determine the apex of the heart( left ventricle) .
Surface lines: All surface lines are imaginary but used in clinical practice to help locate specific sites and commonly used as reference points including:
Mid clavicular line : an imaginary line that passes perpendicularly from the midpoint of the clavicle downward between jugular notch and sternoclavicular joint. Anterior axillary line : an imaginary line that passes perpendicularly from anterior axillary fold downward between the middle of the clavicle and the lateral end of the clavicle.. Posterior axillary line : an imaginary line that passes perpendicularly from posterior axillary fold downward .Runs parallel with the anterior axillary line . Mid axillary line : an imaginary line that passes perpendicularly from the midpoint in between the anterior and posterior axillary lines .
Scapular line 0n the posterior surface of the thorax runs vertically through the inferior angle of the scapula.
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Sunday 17/2/2019 Dr: Hassna B. Jawad
Midsternal line in the front of the thorax ,it is the most important vertical lines . approximately two-thirds of the heart lies to the left of the midsternal line.
Surgical Scars
Midline sternotomy scar - Indicates previous coronary artery bypass grafting (CABG), aortic valve replacement or transplantation.
Left submammary scar - Indicates previous mitral valvotomy.
Infraclavicular scar - Indicates previous pacemaker insertion.
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Sunday 17/2/2019 Dr: Hassna B. Jawad
*The chest wall: The chest wall is comprised of skin, fat, muscles, and the thoracic skeleton. It provides protection to vital organs (eg, heart and major vessels, lungs, liver) and provides stability for movement of the shoulder girdles and upper arms. Although the thoracic skeleton consists of rigid bones and cartilage, its interconnection with the muscular components forms for a dynamic structure that is able to expand during inspiration, thereby increasing intrathoracic volume and allowing for maximal breaths to take place. The frame work of the chest wall is flat anteroposteriorly and rounded laterally .It consists of sternum anteriorly ,12 pairs of ribs and their costal cartilages laterally , and 12 thoracic vertebra posteriorly.
1.The sternum Dagger like flat bone. Has three parts: 1. Manubrium lies superiorly. 2. Body of sternum is the middle largest portion. 3. xiphoid process is the inferior smallest portion . *The manubrium -small square bone -has 4 articulations: with the sternum at manubriuo-sternal joint to form the Louis angle , with the second costal cartilage , with the clavicle , and with the first rib . -the manubrium is the site of aspiration of bone marrow for examination from the midpoint of the manubrium exactly between the suprasternal notch and Louis angle . * The body of sternum Long and consists of multiple facets on both sides and they are sites for articulation with the 3rd, 4th, 5th, 6th, 7th costal cartilage. *Xiphoid process Cartilaginous structure , but calcified in advancing age and can be felt as small movable prominence in the epigastric region .
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Sunday 17/2/2019 Dr: Hassna B. Jawad
2.The ribs Thoracic cage consist of 12 pair of ribs and their costal cartilages. *True ribs : from 1st to 7th , which have direct articulation by its own costal cartilages with the sternum anteriorly . *False ribs : 8th , 9th , 10th which have indirect articulation with the sternum ,the costal cartilage of these ribs articulate with the costal cartilage of the 7th rib and then to the sternum . Floating ribs : 11th , 12th which have no articulation with the sternum Why ? To give more elasticity, flexibility and free movement to the chest during the processes of inspiration and expiration .
The typical rib
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Sunday 17/2/2019 Dr: Hassna B. Jawad
Curved bone , with 2 surfaces : anterior and posterior. The anterior end has cartilaginous connection with the sternum The posterior end articulates with its corresponding thoracic vertebrae Has upper rounded and smooth thin sharp inferior border . The sharp ( inferior ) border has a groove ( intercostal groove ) which accommodate the intercostal vessels ( artery and vein ) and intercostal nerve . ( V A N : from superior to inferior ) . Each typical rib has head , neck , shaft and the shaft there is a prominence called tubercle articulates with transvers process of its corresponding vertebra. The head of rib processes two facet for articulation : 1. Superior facet articulates with the body of superior vertebrae . 2. Inferior facet articulates with the body of the corresponding vertebrae . The tubercle has a facet which is a sit of articulation with the transverse process of the corresponding vertebrae.
Atypical ribs : The first rib
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Sunday 17/2/2019 Dr: Hassna B. Jawad
The neck is narrow and rounded. The tubercle, thick and prominent, is placed on the outer border. It bears a small facet for articulation with the transverse process of T1 has 2 surfaces : superior and inferior and two borders ant. & post. borders cannot be felt because it is situated behind the clavicle .
scalene anterior muscle lies in between the subclavian vein and artery so the artery is protected by the subclavian vein and the muscle. ……………………………………………. The upper surface of the body is marked by two shallow grooves, separated from each other by a slight ridge prolonged internally into a tubercle, the scalene tubercle, for the attachment of anterior scalene; the anterior groove transmits the subclavian vein, the posterior the subclavian artery and the lowest trunk of the brachial plexus.
The second rib: Is much longer than the first rib. has a very similar curvature. Head has 2 articular surface for above and corresponding vertebra.
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Sunday 17/2/2019 Dr: Hassna B. Jawad
The non-articular portion of the tubercle is occasionally only feebly marked. The angle is slight, and situated close to the tubercle. The body is not twisted with superior and inferior surfaces. Near the middle of superior surface is a rough eminence for the origin of the lower part of the first and the whole of the second digitation of the serratus anterior.
Eleventh & twelfth ribs: Have a single articular facet on the head, which is of rather large size. They have no necks or tubercles, and are pointed at their anterior ends. The eleventh has a slight
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Sunday 17/2/2019 Dr: Hassna B. Jawad angle and a shallow costal groove, whereas the twelfth does not. The twelfth rib is much shorter than the eleventh rib, and its head is inclined slightly downward.
Clinical note : *During bone marrow aspiration care should be taken to avoid injury to descending aorta *To obtain a sample of pleural fluid or drain pus or blood from the pleural cavity, the needle or drain is passed through the intercostal space just above the upper border of the rib to avoid the subcostal groove and the neurovascular bundle.
3.Thoracic vertebrae:
In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical and lumbar vertebrae; they increase in size going towards the lumbar vertebrae, with the lower ones being a lot larger than the upper.
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Sunday 17/2/2019 Dr: Hassna B. Jawad
Each typical thoracic vertebra has:
1.The body in the middle of the thoracic region are heart-shaped. They are slightly thicker behind than in front, flat above and below, convex from side to side in front, deeply concave behind, and slightly constricted laterally and in front. They present, on either side, two costal demi-facets, one above, near the root of the pedicle, the other below, in front of the inferior vertebral notch.
2.Vertebral arch : has
*The pedicles are directed backward and slightly upward,. *The laminae are broad, thick, and imbricated and connected with the pedicles to surround and protect the spinal cord.
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Sunday 17/2/2019 Dr: Hassna B. Jawad
3.The intervertebral foramen is small, and circular, with two at each intervertebral level, one for the right and one for the left exiting nerve roots. 4. The vertebral foramen is the large opening posterior to the vertebral body also known as the spinal canal. It contains and protects the spinal cord at the thoracic level. 5.The spinous process is long, directed obliquely downward, arising from the lamina .These processes overlap from the fifth to the eighth. 6. The superior articular processes are thin plates of bone projecting upward from the junctions of the pedicles and laminae; 7.The inferior articular processes are fused to a considerable extent with the laminae 8.The transverse processes arise from the arch behind the superior articular processes and pedicles for articulation with the tubercle of a rib.
The function of each part of the vertebra is shown in the diagram below:
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