Common flexor origin of the elbow

Last revised by Joachim Feger on 19 Dec 2021

Citation, DOI, disclosures and article data

Citation:

Feger J, Sharma R, Common flexor origin of the elbow. Reference article, Radiopaedia.org (Accessed on 24 Apr 2024) https://doi.org/10.53347/rID-89384

DOI:

https://doi.org/10.53347/rID-89384

Permalink:

https://radiopaedia.org/articles/89384

rID:

89384

Article created:

7 May 2021, Joachim Feger ◉

Disclosures:

At the time the article was created Joachim Feger had no recorded disclosures.

View Joachim Feger's current disclosures

Last revised:

19 Dec 2021, Joachim Feger ◉

Disclosures:

At the time the article was last revised Joachim Feger had no recorded disclosures.

View Joachim Feger's current disclosures

Revisions:

5 times, by 2 contributors - see full revision history and disclosures

Systems:

Musculoskeletal

Sections:

Anatomy

Tags:

elbow, cases3, figures

Synonyms:

Common flexor origin (elbow)
Flexor-pronator muscles
Flexor-pronator mass
Common flexor-pronator tendon
Common flexor-pronator mass
Common flexor tendon of the elbow

The common flexor origin of the elbow refers to a common attachment of the following flexor-pronator muscles at the medial epicondyle of the distal humerus ^1-3:

The flexor carpi radialis (FCR) and palmaris longus (PL) muscles, which also originate from the medial epicondyle and are overlying the flexor digitorum superficialis are also counted to the flexor-pronator mass and variably to the common flexor origin ^1-4.

The common flexor origin is a thick tendinous structure originating from the medial epicondyle ^1-3 splitting in anterosuperior and posteroinferior common tendinous portions. Those are formed by the pronator teres and the flexor digitorum superficialis muscle and again the latter and the flexor carpi ulnaris muscle and have a close relationship to the anterior bundle of the medial collateral ligament of the elbow ^1-5.

Function

The common flexor origin functions as a dynamic stabilizer of the elbow joint and as a secondary restraint to valgus force supporting the medial collateral ligament of the elbow ¹.

Attachments

The common flexor tendon originates from the medial epicondyle and the anterior joint capsule just proximal to the humeral insertion of the anterior bundle of the medial collateral ligament.

All three muscles but especially the flexor digitorum superficialis blend with the medial collateral ligament at several locations also on the ulnar side, the flexor digitorum superficially, the pronator teres superoanteriorly and the flexor carpi ulnaris inferoposteriorly ^1-3.

Relations

The common flexor origin and especially the tendinous part of the flexor digitorum superficialis muscle is located deep to the origin of the flexor carpi radialis and the palmaris longus muscles ².

The median nerve pierces the tendinous septum between the pronator teres and flexor digitorum superficialis muscle and the ulnar nerve courses posterior to the tendinous septum between the flexor digitorum superficialis and flexor ulnaris muscle ³.

Radiographic features

Ultrasound

The common flexor origin is best assessed on ultrasound with the elbow extended or mildly flexed and the forearm in forceful supination with the transducer placed medially generating longitudinal coronal images ⁴.

The common flexor tendon can be visualized as a beak-like parallel and homogeneous fibrillar structure that appears larger but shorter than the common extensor tendon ⁶. The distinct tendinous portions of the individual flexor muscles cannot be separated on ultrasound.

MRI

The common flexor origin and the common flexor tendon can be identified as a low signal intensity band originating from the medial humeral epicondyle immediately above and superficial to the anterior bundle of the ulnar collateral ligament ^7,8.