Anatomic Variations of the Hand Extensor Muscle Tendons

  • Yadigar Kastamoni Yaşar
  • Afitap Anıl
  • Feza Anıl
  • Menekşe Kastamoni
  • Tuncay Peker
Keywords: Anatomic variations, accessory head, extensor carpi radialis brevis, extensor digitorum, tendon variations


Variations of muscles on the dorsal aspect of the forearm are seen very common. These variations can be symptomatic but generally they are diagnosed incidentally. On the posterior compartment of forearm, extensor carpi radialis brevis related to abduction of the wrist and extensor digitorum related to extension of the wrist and fingers. This case report showed rare variations of extensor carpi radialis brevis and extensor digitorum muscles. During routine dissections of the extensor compartment of the forearm for anatomy education, it was observed that extensor carpi radialis brevis muscle had an accessory head which attached to dorsum and proximal phalanx of the index finger. Besides, it was found that extensor digitorum muscle divided into three tendons distally. When we followed these tendons, it was observed that tendon of index finger was absent and other three tendons went to middle, ring and little fingers. Accessory muscles located on the extensor compartment of the forearm are seen common. They can be reason of the symptoms of the nerve entrapment. Besides, these unusual muscles may confuse radiologists, surgeons and anatomists. In order to prevent diagnostic errors and avoid surgical complications, these anatomical variations should be well-known.


Vessal S, Rai SB. Accessory extensor carpi radialis brevis muscle, a pseudomass of the distal forearm: ultrasound and MR appearances –case report and literature review. Clin Radiol 2006; 61: 442-5.

Standring S. Gray’s Anatomy. 39th ed. London: Elsevier Churchill Livingstone; 2005.

Yammine K. The prevalence of the extensor digitorum communis tendon and its insertion variants: A systematic review and meta-analysis. Clin Anat 2014; 27: 1284-90.

Agarwal P, Tirthani G. Cadaveric study of the long extensor tendons of the finger over the dorsum of the hand. Eur J Anat 2011; 15: 129-35.

Abdel-Hamid GA, El-Beshbishy RA, Abdel Aal IH. Anatomical variations of the hand extensors. Folia Morphol (Warsz) 2013; 72: 249-57.

Celik S, Bilge O, Pinar Y, et al. The anatomical variations of the extensor tendons to the dorsum of the hand. Clin Anat 2008; 21: 652-9.

Arora J, Dave V, Kumar A, et al. Unusual architecture of extensor digitorum muscle of hand in conjunction with accessory belly of extensor carpi radialis brevis: a clinico-anatomical insight. Clin Ter 2013; 164: 31-3.

Melling M, Steindl M, Wilde J, et al. An anatomical variant of the extensor carpi radialis brevis muscle. Wien Klin Wochenschr 2001; 113: 960-3.

Gumusalan Y, Kalaycioglu A, Yazar F, et al. Accessory extensor carpi radialis muscle and interconnecting muscular bundle. Acta Anat (Basel) 1997; 159: 57-60.

Tuncali D, Yavuz N, Terzioglu A, et al. The rate of upper-extremity deep-structure injuries through small penetrating lacerations. Ann Plast Surg 2005; 55: 146-8.