Related Experiment Video

Updated: Nov 9, 2025

Vascularized Composite Hand Allograft Procurement and Preparation for Distal and Proximal Forearm Allotransplantation: A Stepwise Approach

Vascularized Composite Hand Allograft Procurement and Preparation for Distal and Proximal Forearm Allotransplantation: A Stepwise Approach

Published on: May 23, 2025

Anatomical Study of Stabilizing Structures of the Extensor Carpi Ulnaris Tendon Around the Wrist

Shohei Omokawa¹, Treerat Gumpangseth², Pornhatai Komutrattananont²

¹Department of Hand Surgery, Nara Medical University, Kashihara Nara, Japan.

The Journal of Hand Surgery

|April 13, 2021

Abstract

Purpose:

The sixth dorsal extensor compartment is a relatively common site of stenosing tenosynovitis in the upper extremity, but the exact location of stenosis is not fully understood. The objective of this study was to investigate the detailed anatomy of structures surrounding the extensor carpi ulnaris (ECU) tendon around the wrist.

Methods:

Fifty fresh human cadaveric wrists were used for gross observation and morphology measurements of the sixth dorsal compartment and the ECU subsheath. An additional 13 wrists were used for histological examination. We evaluated the morphology of supporting structures in 3 regions: the ulnar groove (zone I), the ulnar styloid process (zone II), and the triquetrum (zone III).

Results:

The fibro-osseous tunnel comprising the ulnar groove and the overlying subsheath (zone I) stabilized the ECU tendon, and the subsheath had thin membranous collagen fibers attached to the periosteum. We consistently found the distal extension of ECU subsheath (zone II), which connected the ulnar styloid process and the dorsal radioulnar ligament. Variations in the length of the distal extension increased with the forearm in pronation. Collagen fiber thickness around the ECU tendon in zone II was greater than that of zone I. In zone III, the overlying extensor retinaculum and septa, which were composed of thick circumferential collagen structures, supported the ECU tendon by attaching to the triquetrum on both sides of the ECU tendon. We found the presence of an ulnar septum of the sixth compartment attached to the triquetrum in 84% of dissected wrists.

Conclusions:

The ECU tendon was supported by the ECU subsheath, which had thin and elastic collagen fibers over the ulnar groove. Distal extension of the subsheath and surrounding radial and ulnar extensor retinaculum septa attached to the triquetrum provided thicker supporting structures.

Clinical Relevance:

Stenosing ECU tenosynovitis may occur not only in the ulnar groove but also in the more distal ulnar styloid process and triquetrum areas.

Keywords:

Extensor carpi ulnaris extensor retinaculum histology septum subsheath

More Related Videos

Novel Triple-Loop Technique for Suturing TFCC Injuries without Transosseous Tunnel

Novel Triple-Loop Technique for Suturing TFCC Injuries without Transosseous Tunnel

Published on: May 23, 2025

Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies

Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies

Published on: January 11, 2019

Related Concept Videos

Bones of the Upper Limb: Ulna

Bones of the Upper Limb: Ulna

The ulna and radius are parallel bones of the antebrachium or the forearm. The ulna lies medially and consists of a bony tip called the olecranon process at its proximal end. This hook-like projection articulates with the olecranon fossa of the humerus and forms the "hinged" ulnohumeral part of the elbow joint. This joint facilitates forearm extension and flexion while preventing its hyperextension. Similarly, the coronoid process, another bony projection on the proximal/anterior side...

Muscles of the Forearm that Move the Hand and Fingers

Muscles of the Forearm that Move the Hand and Fingers

The muscles of the forearm that move the wrist, hand, and digits are numerous and diverse. They can be classified into two groups based on their location and function — the anterior and posterior compartment muscles.
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...

Bones of the Upper Limb: Radius

Bones of the Upper Limb: Radius

The radius is longer of the two bones that make up the human antebrachium or forearm. At the proximal end, the radius articulates with the capitulum of the humerus and the radial notch of the ulna to form the elbow joint. At the distal end, the radius articulates with the ulna via the ulnar notch, forming the distal radioulnar joint. Distally, the radius also attaches to the carpal wrist bones (scaphoid and lunate) to form the radiocarpal joint.
The radius has a nail-shaped head, and a...

Muscles that Move the Forearm

Muscles that Move the Forearm

The muscles that move the forearms can be divided into four groups: forearm flexors, forearm extensors, forearm pronators, and forearm supinators. The flexors and extensors act on the elbow joint, while the pronators and supinators act on the radioulnar joints.
Forearm Flexors
The biceps brachii, brachialis, and brachioradialis are forearm flexors. The biceps brachii is made up of two heads. Its long head originates at the supraglenoid tubercle of the scapula, whereas that of the short head is...

Spinal Nerves: Plexus I

Spinal Nerves: Plexus I

Nerve plexuses are networks of interlacing nerves that serve as communication hubs to distribute and organize nerve action across various body regions. The nerve plexuses are organized into the cervical plexus located in the neck region, brachial plexus in the shoulder area, lumbar plexus found in the lower back, sacral plexus situated in the pelvis, and coccygeal plexus located in the coccygeal region.
The Cervical Plexus
The cervical plexus, formed by the anterior rami of the first four...

Bones of the Upper Limb: Humerus

Bones of the Upper Limb: Humerus

The upper limb consists of the arm, forearm, wrist, and hand bones. The humerus is the single bone of the upper arm region. Proximally, it has a large, spherical, smooth head that articulates with the glenoid cavity of the scapula to form the glenohumeral or shoulder joint. The margin of the head is the anatomical neck, a residual epiphyseal plate. Laterally it extends to form bony projections called the greater tubercle and the lesser tubercle. Next to the tubercles is the surgical neck, a...

Articles linked to this work by shared authors, journal, and citation graph.

Risk of radial nerve injury during deltoid intramuscular injection in shoulder internal rotation and abduction position-cadaveric anatomical study.

Human vaccines & immunotherapeutics·2026

Unlocking forensic potential: machine learning-driven estimation of sex, age, and stature from proximal femur using dual-energy X-ray absorptiometry.

International journal of legal medicine·2026

Depth of the Dorsalis Pedis Artery Distal to the First and Second Tarsometatarsal Joints: A Cadaveric Anatomical Study.

Foot & ankle orthopaedics·2026

AI-driven differentiation of 2D proximal femur morphometry and hounsfield units for integrated forensic estimation of sex, stature, and age in a modern Thai dry bone sample.

Anatomical science international·2026

Application of machine learning for sex estimation using the first and second ribs in the Northern Thai population.

Anatomy & cell biology·2026

Biomechanical Effects of Lunate Excision Alone and Proximal Row Carpectomy on Dart-Throwing Motion, Circumduction, and Carpal Stability: A Cadaveric Study.

Journal of hand surgery global online·2026

See all related articles