Related Experiment Video
Updated: Oct 5, 2025

Vascularized Composite Hand Allograft Procurement and Preparation for Distal and Proximal Forearm Allotransplantation: A Stepwise Approach
Published on: May 23, 2025
The muscular branching patterns of the ulnar nerve in fetal forearms
Anıl Tuğçe Alpaslan1,2, Piraye Kervancıoğlu3, Salih Murat Akkın4
1Department of Anatomy, School of Medicine, SANKO University, Gaziantep, Turkey. atalpaslan@sanko.edu.tr.
Objective:
We aimed to present our findings systematically by examining the muscular branching patterns of the ulnar nerve (UN) in the forearms of fetuses.
Methods:
This study was conducted on the 52 forearms of 26 formalin-fixed fetal cadavers with gestational ages varying between 19 and 37 weeks. The anatomical dissection was performed by using stereomicroscope with × 8 magnification. The numbers of muscular branches leaving UN and their order of leaving main nerve were noted down. The findings were classified according to the muscles they reached, and branching typing was done.
Results:
It was found that a total of 2-6 muscular branches left UN to reach flexor carpi ulnaris (FCU) and flexor digitorum profundus (FDP). UN was classified by separating into five main types according to the number of muscular branches, and these types were classified into 16 different branching patterns according to the order of branches leaving from the main trunk and going to FCU and FDP. The pattern where two branches left UN was classified as Type I (n = 6), three branches left was classified as Type II (n = 18), four branches left was classified as Type III (n = 24), five branches left was classified as Type IV (n = 3), and six branches left was classified as Type V (n = 1). Martin-Gruber connection occurred in 17 (32.7%) fetal forearms.
Conclusion:
We believe that the information that UN can demonstrate different branching patterns on the forearm can help the surgeons to prevent complications that may develop in potential nerve injury during the selection and transfer of relevant branch.
Related Concept Videos
Bones of the Upper Limb: Ulna
Arteries of the Upper Limbs
Spinal Nerves: Plexus I
The Cervical Plexus
The cervical plexus, formed by the anterior rami of the first four...
Muscles that Move the Forearm
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...
Bones of the Upper Limb: Radius
The radius has a nail-shaped head, and a...
Muscles 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...

