Sternal angle
The sternal angle (also known as the angle of Lewis, angle of Louis, angle of Ludovic, or manubriosternal junction) is the projecting angle formed between the manubrium and body of a sternum at their junction at the manubriosternal joint. The sternal angle is a palpable and visible landmark in surface anatomy, presenting as either a slight body ridge or depression upon the upper chest wall which corresponds to the underlying manubriosternal joint. The sternal angle is palpable and often visible in young people. The sternal angle corresponds to the level of the 2nd costal cartilage on either side, and the level between the fourth and fifth thoracic vertebra. The sternal angle is used to define the transverse thoracic plane which represents the imaginary boundary between the superior and inferior mediastinum. It is also used to identify the second rib during physical examination and then the rest of the ribs by counting.
| Sternal angle | |
|---|---|
 Lateral border of sternum | |
 Anterior surface of sternum and costal cartilages. (Sternal angle not labeled, but visible at second costal cartilage.) | |
| Details | |
| Identifiers | |
| Latin | angulus sterni, angulus sternalis, angulus Ludovici |
| TA98 | A02.3.03.005 |
| TA2 | 1133 |
| FMA | 7547 |
| Anatomical terminology | |
The sternal angle (also known as the angle of Lewis,[1] angle of Louis,[2]: 297 angle of Ludovic, or manubriosternal junction[citation needed]) is the projecting[2]: 297 angle formed between the manubrium and body of a sternum at their junction at the manubriosternal joint.[2]: 297 [3]
The sternal angle is a palpable and visible landmark in surface anatomy, presenting as either a slight body ridge or depression upon the upper chest wall which corresponds to the underlying manubriosternal joint.[4] The sternal angle is palpable and often visible in young people.[2]: 319
The sternal angle corresponds to the level of the 2nd costal cartilage on either side, and the level between the fourth and fifth thoracic vertebra. The sternal angle is used to define the transverse thoracic plane which represents the imaginary boundary between the superior and inferior mediastinum. It is also used to identify the second rib during physical examination and then the rest of the ribs by counting.
Anatomy
[edit]The sternal angle forms an angle of about 162° in males.[5]
Relations
[edit]It marks the approximate[6] level of the 2nd pair of costal cartilages,[6][2]: 319 (sources differ) the level of the intervertebral disc between thoracic vertebra T4-T5[6][2]: 319 or the lower border of the thoracic vertebra T4,[7]: 218 and the space between the spinous processes of thoracic vertebrae T3-T4.[2]: 319 The horizontal plane that passes through the sternal angle and the articular disc between the 4th and 5th thoracic vertebrae (the so-called plane of Louis) represents the imaginary boundary between the superior mediastinum and inferior mediastinum.[citation needed]
It is located approximately 7 cm inferior to the superior margin of the manubrium.[citation needed]
The sternal angle is used in the definition of the thoracic plane.[citation needed]
The angle also marks the level of a number of features:
- Boundary between the superior and inferior portion of the mediastinum[citation needed]
- Passage of the thoracic duct from right to left behind esophagus[citation needed]
- Tracheal bifurcation.[2]: 387, 1039, 1060 The carina of the trachea is thus, present here. It is deep to the sternal angle.
- The bifurcation of the pulmonary trunk[2]: 336
- The superior limit of the fibrous pericardium surrounding the ascending aorta[2]: 350
- Termination of the azygos vein into the superior vena cava[7]: 193
- Ligamentum arteriosum[citation needed]
- Loop of left recurrent laryngeal nerve around aortic arch[citation needed]
- The beginning and end of the aortic arch[2]: 383 [7]: 190
Clinical significance
[edit]The sternal angle is the most frequent site of sternal fracture among elderly people.[2]: 303
Surface anatomy and physical examination
[edit]The sternal angle marks the point at which the costal cartilage of either second rib articulates with the sternum. During physical examinations, the readily palpated sternal angle is thus used as a landmark to identify the 2nd rib, and by extension, by counting, also the remaining ribs. Meanwhile, the first rib cannot be used for this purpose because it cannot be palpated.[2]: 321 Counting ribs is essential attempting to make a thoracic incision; an incision at the first or second rib interspace can result in damage to large, important blood vessels and the brachial plexus. Identification of the second rib and thus the second intercostal space inferiorly is useful when auscultating heart sounds. The optimal location for auscultation of the aortic valve is generally the right second intercostal space, whereas the optimal location for auscultation of the pulmonic valve is generally the left second intercostal space.[citation needed]
The sternal angle is used as the starting point in physical examinations of the heart since the sternal angle is located 5 cm superior to the right atrium.[citation needed]
History
[edit]The sternal angle is also called the angle of Louis, but the reason for that name was lost. Once thought to be after Antoine Louis or Wilhelm Friedrich von Ludwig, it is now believed to be after Pierre Charles Alexandre Louis.[8]
See also
[edit]References
[edit]- ^ Clinical Anatomy of the Spine, Spinal Cord, and Ans. Elsevier. 2014. p. 226. doi:10.1016/c2009-0-42801-0. ISBN 978-0-323-07954-9.
- ^ a b c d e f g h i j k l m Moore, Keith L.; Dalley, Arthur F.; Agur, Anne M. R. (2017). Essential Clinical Anatomy (6th ed.). Lippincott Williams & Wilkins. ISBN 978-1496347213.
- ^ Cramer, Gregory D.; Darby, Susan A. (2014). Clinical Anatomy of the Spine, Spinal Cord, and Ans (3rd ed.). Elsevier. p. 226. doi:10.1016/c2009-0-42801-0. ISBN 978-0-323-07954-9.
- ^ Srebnik, Herbert H. (2012). Concepts in Anatomy. doi:10.1007/978-1-4615-0857-1. ISBN 978-1-4615-0857-1.
- ^ Susan Standring; Neil R. Borley; et al., eds. (2008). "Chapter 54: Chest wall and breast". Gray's anatomy : the anatomical basis of clinical practice (40th ed.). London: Churchill Livingstone. p. 922. ISBN 978-0-8089-2371-8.
- ^ a b c Wilson, Herbert H. Srebnik ; illustrations by Genevieve M. (2002). Concepts in anatomy. Boston: Kluwer Academic Publishers. p. 70. ISBN 0792375394.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ a b c Sinnatamby, Chummy S. (2011). Last's Anatomy (12th ed.). ISBN 978-0-7295-3752-0.
- ^ Coscione, Alberto; Dixon, L.; Ellis, H. (2013). "The "Angle of Louis"" (PDF). Eur. J. Anat. 17 (3): 190–192.
External links
[edit]- Anatomy photo:18:st-0212 at the SUNY Downstate Medical Center - "Thoracic Wall: Bones"
