The sternal angle (also known as the angle of Louis, angle of Ludovic or manubriosternal junction) is the
synarthrotic joint formed by the articulation of the
manubrium and the body of the
sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sha ...
.
The sternal angle is a palpable clinical landmark in
surface anatomy
Surface anatomy (also called superficial anatomy and visual anatomy) is the study of the external features of the body of an animal.Seeley (2003) chap.1 p.2 In birds this is termed ''topography''. Surface anatomy deals with anatomical features th ...
.
Anatomy
The sternal angle, which varies around 162 degrees in males, marks the approximate level of the 2nd pair of
costal cartilage
The costal cartilages are bars of hyaline cartilage that serve to prolong the ribs forward and contribute to the elasticity of the walls of the thorax. Costal cartilage is only found at the anterior ends of the ribs, providing medial extension.
...
s, which attach to the second ribs, and the level of the
intervertebral disc between
T4 and T5.
In clinical applications, the sternal angle can be palpated at the T4 vertebral level.
The sternal angle is used in the definition of the
thoracic plane
The mediastinum (from ) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is an undelineated region that contains a group of structures within the thorax, namely the heart and its vessels, the esophagu ...
. This marks the level of a number of other anatomical structures:
The angle also marks a number of other features:
:* Carina of the trachea is deep to the sternal angle
:*
:*Passage of the thoracic duct from right to left behind esophagus
:*
:* Ligamentum arteriosum
:*
:* Loop of left recurrent laryngeal nerve around aortic arch
The angle is in the form of a secondary cartilaginous joint (
symphysis
A symphysis (, pl. symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint.
# A symphysis is an amphiarthrosis, a slightly movable joint.
# A growing togethe ...
).
This is where the 2nd rib joins with the sternum. A clinically useful feature of the (manubriosternal) joint is that it can be palpated easily. This is because the manubrium normally angles posteriorly on the body of the sternum, forming a raised feature referred to as the sternal angle.
History
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
Antoine Louis (; 13 February 1723, Metz – 20 May 1792) was an 18th-century French surgeon and physiologist.
He was originally trained in medicine by his father, a sergeant major at a local military hospital. As a young man he moved to Paris, w ...
or
Wilhelm Friedrich von Ludwig
Wilhelm Frederick von Ludwig (16 September 1790 – 14 December 1865) was a German physician known for his 1836 publication on the condition now known as Ludwig's angina.
Early life
Ludwig was born in Uhlbach (near Stuttgart) in the state of Wür ...
, it is now believed to be after
Pierre Charles Alexandre Louis
Pierre-Charles-Alexandre Louis (14 April 178722 August 1872) was a French physician, clinician and pathologist known for his studies on tuberculosis, typhoid fever, and pneumonia, but Louis's greatest contribution to medicine was the development o ...
.
See also
*
Thoracic plane
The mediastinum (from ) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is an undelineated region that contains a group of structures within the thorax, namely the heart and its vessels, the esophagu ...
*
List of medical mnemonics
This is a list of mnemonics used in medicine and medical science, categorized and alphabetized. A mnemonic is any technique that assists the human memory with information retention or retrieval by making abstract or impersonal information more acc ...
References
External links
* - "Thoracic Wall: Bones"
{{DEFAULTSORT:Sternal Angle
Bones of the thorax