Related Experiment Video
Updated: Jul 29, 2025
Bilateral Assessment of the Corticospinal Pathways of the Ankle Muscles Using Navigated Transcranial Magnetic Stimulation
Published on: February 19, 2019
MRI evaluation of interconnections between flexor hallucis longus and flexor digitorum longus around the Master knot
Seung-Hwan Park1, Bo Mi Chung2, Sujin Kim3
1Department of Orthopedic Surgery, Chung-Ang University Hospital, Chung-Ang University College of Medicine, 102, Heukseok-ro, Dongjak-Gu, Seoul, 156-755, Republic of Korea.
Objectives:
To demonstrate the magnetic resonance imaging (MRI) findings of interconnections between flexor hallucis longus (FHL) and flexor digitorum longus (FDL) around the Master knot of Henry (MKH).
Methods:
Fifty-two MRI scans of adult patients were retrospectively analyzed. The types and subtypes of interconnections between the FHL and FDL were evaluated using the classification suggested by Beger et al based on the direction and number of the tendon slips and contributions to the lesser toes. The layering organization formed by the FDL, quadratus plantae, and tendon slip from the FHL was evaluated. The distance between bony landmarks and the branching site of tendon slips and the cross-sectional area (CSA) of the tendon slips were measured. Descriptive statistics were reported.
Results:
MRI scans revealed that type 1 interconnection was the most common (81%), followed by type 5 (10%) and types 2 and 4 (4% each). All tendon slips from the FHL contributed to the second toe, and 51% of the tendon slips contributed to the second and third toes. For the layering organization, the two-layered type was the most common (59%), followed by the three-layered (35%) and single-layered (6%) types. The mean distance between the branching site and bony landmarks was longer in the FDL to FHL cases than that in the FHL to FDL cases. The mean CSA of the tendon slips from the FHL to FDL was larger than that of the FDL to FHL.
Conclusions:
MRI could provide detailed information about the anatomical variations around the MKH.
Clinical Relevance Statement:
In lower extremity reconstruction surgery, the flexor hallucis longus and flexor digitorum longus tendons serve as donor tendons. A preoperative MRI scan could provide information on anatomical variations around the Master knot of Henry, which can help predict postoperative functional outcomes.
Key Points:
• Normal anatomical variations around the Master knot of Henry were not extensively studied in the radiology literature before. • MRI identified the various types, sizes, and locations of interconnections between the flexor digitorum longus tendon and the flexor hallucis longus tendon. • MRI is a useful noninvasive tool for evaluating the interconnections between the flexor digitorum longus tendon and the flexor hallucis longus tendon.
Related Concept Videos
01:17Muscles of the Forearm that Move the Hand and Fingers
Anterior Compartment
The anterior compartment muscles originate from the humerus. They primarily function as flexors and are also known as flexor muscles. They typically insert on the carpals, metacarpals, and phalanges. The superficial layer includes the flexor carpi...
01:28Muscles of the Leg that Move the Foot and Toes
Anterior Compartment
The anterior compartment includes muscles that contribute to the dorsiflexion of the foot. This compartment houses the tibialis anterior, extensor hallucis longus, and extensor digitorum longus muscles....