Medical Terminology Daily - Est. 2012

Medical Terminology Daily (MTD) is a blog sponsored by Clinical Anatomy Associates, Inc. as a service to the medical community. We post anatomical, medical or surgical terms, their meaning and usage, as well as biographical notes on anatomists, surgeons, and researchers through the ages. Be warned that some of the images used depict human anatomical specimens.

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A Moment in History

Jean George Bachman

Jean George Bachmann
(1877 – 1959)

French physician–physiologist whose experimental work in the early twentieth century provided the first clear functional description of a preferential interatrial conduction pathway. This structure, eponymically named “Bachmann’s bundle”, plays a central role in normal atrial activation and in the pathophysiology of interatrial block and atrial arrhythmias.

As a young man, Bachmann served as a merchant sailor, crossing the Atlantic multiple times. He emigrated to the United States in 1902 and earned his medical degree at the top of his class from Jefferson Medical College in Philadelphia in 1907. He stayed at this Medical College as a demonstrator and physiologist. In 1910, he joined Emory University in Atlanta. Between 1917 -1918 he served as a medical officer in the US Army. He retired from Emory in 1947 and continued his private medical practice until his death in 1959.

On the personal side, Bachmann was a man of many talents: a polyglot, he was fluent in German, French, Spanish and English. He was a chef in his own right and occasionally worked as a chef in international hotels. In fact, he paid his tuition at Jefferson Medical College, working both as a chef and as a language tutor.

The intrinsic cardiac conduction system was a major focus of cardiovascular research in the late nineteenth and early twentieth centuries. The atrioventricular (AV) node was discovered and described by Sunao Tawara and Karl Albert Aschoff in 1906, and the sinoatrial node by Arthur Keith and Martin Flack in 1907.

While the connections that distribute the electrical impulse from the AV node to the ventricles were known through the works of Wilhelm His Jr, in 1893 and Jan Evangelista Purkinje in 1839, the mechanism by which electrical impulses spread between the atria remained uncertain.

In 1916 Bachmann published a paper titled “The Inter-Auricular Time Interval” in the American Journal of Physiology. Bachmann measured activation times between the right and left atria and demonstrated that interruption of a distinct anterior interatrial muscular band resulted in delayed left atrial activation. He concluded that this band constituted the principal route for rapid interatrial conduction.

Subsequent anatomical and electrophysiological studies confirmed the importance of the structure described by Bachmann, which came to bear his name. Bachmann’s bundle is now recognized as a key determinant of atrial activation patterns, and its dysfunction is associated with interatrial block, atrial fibrillation, and abnormal P-wave morphology. His work remains foundational in both basic cardiac anatomy and clinical electrophysiology.

Sources and references
1. Bachmann G. “The inter-auricular time interval”. Am J Physiol. 1916;41:309–320.
2. Hurst JW. “Profiles in Cardiology: Jean George Bachmann (1877–1959)”. Clin Cardiol. 1987;10:185–187.
3. Lemery R, Guiraudon G, Veinot JP. “Anatomic description of Bachmann’s bundle and its relation to the atrial septum”. Am J Cardiol. 2003;91:148–152.
4. "Remembering the canonical discoverers of the core components of the mammalian cardiac conduction system: Keith and Flack, Aschoff and Tawara, His, and Purkinje" Icilio Cavero and Henry Holzgrefe Advances in Physiology Education 2022 46:4, 549-579.
5. Knol WG, de Vos CB, Crijns HJGM, et al. “The Bachmann bundle and interatrial conduction” Heart Rhythm. 2019;16:127–133.
6. “Iatrogenic biatrial flutter. The role of the Bachmann’s bundle” Constán E.; García F., Linde, A.. Complejo Hospitalario de Jaén, Jaén. Spain
7. Keith A, Flack M. The form and nature of the muscular connections between the primary divisions of the vertebrate heart. J Anat Physiol 41: 172–189, 1907.


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Biceps brachii muscle - Image modified from the original, Wikimedia Commons. Public domain
Biceps brachii muscle.
Click on the image for a larger depiction

The musculus biceps brachii is a long muscle found in the anterior, aspect of the arm and is one of the three muscles contained in the anterior compartment (flexor compartment) of the arm, the other two being the brachialis and coracobrachialis muscles.  It is composed by two muscular heads, one long (lateral) , and one short (medial) that originate superiorly from separate tendons that attach to the scapula. These two heads join to  form a single long, oval-shaped belly with a single tendon that crosses the elbow joint and attaches to the radius. 

The short tendon of the biceps brachii passes anteromedial to the shoulder joint and attaches to the coracoid process of the scapula by way of a tendon that mixes with the tendon of the coracobrachialis muscle.

The long cylindrical tendon of the biceps brachii is found in the intertubercular (bicipital) groove (Lat: sulcus intertubercularis) of the humerus, and passes between the greater and lesser tubercles of the humerus, entering the articular cavity of shoulder joint, and continues superiorly to insert in the supraglenoid tubercle of the scapula.

The distal, common tendon of the biceps brachii courses inferiorly and attaches to the radial (bicipital) tuberosity of the radius. There is a well-defined bursa between the radial tuberosity and the biceps brachii tendon that allows for movement of the tendon.

Also, a flat, fascial extension of the tendon, known as the bicipital aponeurosis extends inferomedially to blend with the antebrachial aponeurosis that covers the epitrochlear muscles of the forearm (pronator teres, flexor carpi radialis muscles). The brachial artery passes between the tendon of the biceps brachii and the bicipital aponeurosis in the anterior aspect of the elbow joint.

The biceps brachii crosses both the shoulder and the elbow join. As such, its functions will depend on which joint is fixed and which one is not. This muscle flexes the elbow, supinates the forearm, and flexes the shoulder.

It is innervated by the musculocutaneous nerve (C5,D6) which is a branch of the brachial plexus. It receives arterial supply by way of muscular branches that arise from the brachial artery.

The name of the muscle literally means "two heads" as the prefix "bi" means "two" and the Latin term "-ceps" means "head".

Note: Because the long and the short head of the biceps brachii attach to different locations of the scapula, some authors and Internet websites say that there are 18 muscles that attach to the scapula. I do not agree, as the biceps brachii is a single muscle that happens to have to separate attachments to the scapula. It would be different if this article was titled "Name the 18 separate muscular attachment points of the scapula". Dr. Miranda

The image is modified from the original via Wikimedia. Public domain. Animated image below by Wikimedia Commons - Anatomography [CC BY-SA 2.1 following Creative Commons attributes.

Niwadare, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia CommonsSources:
1. “Gray’s Anatomy” Henry Gray, 1918
2. "Tratado de Anatomia Humana" Testut et Latarjet 8th Ed. 1931 Salvat Editores, Spain
3. "Gray's Anatomy" 42nd British Ed. Churchill Livingstone 2021
4. “An Illustrated Atlas of the Skeletal Muscles” Bowden, B. 4th Ed. Morton Publishing. 2015
5. "Trail Guide to The Body" 4th. Ed. Biel, A. Books of Discovery. 2010