SUPERFICIAL GROUP OF MUSCLES OF POSTERIOR COMPARTMENT OF THE FOREARM – AN ANATOMICAL STUDY Dr. Harsimarjit Kaur Associate Professor, Department of Anatomy, Government Medical College, Patiala, Punjab. Original Research Paper Anatomy 1. INTRODUCTION Hand is the most versatile organ for manipulating the physical environment. The ne movements of the hand are the result of the balance between the exor and extensor muscle groups at the wrist and ngers[1]. The muscles of the posterior compartment of the forearm have undergone a number of variations while adapting to the bipedal walking compared to lower animals[2]. They ensure both gross and ne control of various activities, consequently any injury to these tendons can lead to loss of function affecting the quality of life. A number of variations in the tendons, as well as their arrangements have been reported by various authors in clinical and anatomical studies[3]. When transplantation of extensor tendon is undertaken, confusion can result unless the surgeon is completely familiar with the possible arrangements of the tendons as well as the relative frequency of the variations[4]. A comprehensive knowledge of the anatomy of these tendons is essential to ensure adequate repair and restoration of the normal functions[5]. 2. MATERIALS AND METHODS A total of 50 upper limbs from 25 phenol embalmed adult human cadavers were included in the studied; of these, 28 were male and 22 were female specimens. Cadavers with visible abnormality of the upper limb, history of trauma to the limb in the past, any lesions in the upper limb were excluded. Dissection Protocol: The skin was reected from the back of arm (lower two-third), forearm, the dorsum of hand and the digits by giving skin incisions. The supercial fascia was removed. Then the deep fascia was reected carefully after isolating the extensor retinaculum and securing its attachments. This exposed the muscles and tendons of the posterior group of the forearm. The pattern of arrangement of the tendons of these muscles as they pass beneath the extensor retinaculum was studied. Then the extensor retinaculum was divided longitudinally over each of its compartment for the full exposure of the tendons. Brachioradialis and extensor carpi radialis longus muscles were identied on the lateral aspect of lower third of upper arm. Anconeus was identied and cleaned between the posterior aspect of the lateral epicondyle of humerus and the lateral border of the olecranon process of ulna. Other supercial extensor muscles of the forearm were also identied and separated from one another by splitting the fascial septa through which they were united in their proximal parts. The origin of these muscles was cleaned from the posterolateral aspect of the humerus and their tendons were followed as they passed beneath the extensor retinaculum and on the dorsum of the hand as far as their insertions. The radial nerve was identied between the brachioradialis and the brachialis muscles. Its branches to the brachioradialis & extensor carpi radialis longus were traced and then its deep branch i.e. posterior interosseous nerve was identied and followed through the substance of the supinator muscle. The branches of this nerve from proximal to distal were then traced up to the neurovascular hilum of the remaining forearm extensors, which it supplies. Any variation regarding the mode of origin, insertion and nerve supply of the individual muscles was noted along with the presence of any accessory or anomalous muscle and the variations were photographed. The observations were recorded on the proforma and master chart was made of the muscle and tendon lengths. The data was compiled, analyzed and compared to the standard textbook and the variant patterns of the posterior group of forearm muscles. 3. RESULTS: In the present study there were variations observed in origin, number of tendons of various muscles of the posterior compartment. Brachioradialis: In 86% of the specimens, brachioradialis was found to have origin from the proximal two thirds of the lateral supracondylar ridge of the humerus and inserted by a single tendon on to the lateral aspect of the distal end of the radius just proximal to its styloid process. In the remaining 14% of the specimens, variations were observed. In 6% (3/50) of the specimen the origin extended proximally up to the insertion of deltoid. There were two slips of the tendon inserting on the lateral aspect of radius in 8% (4/50) of the specimens (Figure 1). Objective: To understand the normal anatomical variations in the muscles of the posterior compartment. Material and Methods: A total of 50 upper limbs from 25 phenol embalmed adult human cadavers were studied. The supercial and deep fascia were dissected carefully and reected along skin incision. The origin, insertion, and other variations in the muscle bellies and tendons of the supercial extensor muscles were studied after careful dissection. Results: Brachioradialis had origin extending up to the insertion of deltoid in 3 specimens and had insertion on the radius as two-slips in 4 limbs. The muscle bellies of ECRL and ECRB were fused in 2 limbs. The ECRL also had double and triple tendinous insertions. An accessory muscle, Extensor Carpi Radialis Intermedius, was noted in 2 limbs. The EDC tendon to little nger tendon was bifurcated in 20 limbs, had an intertendinous connection in 12 limbs. An accessory tendinous extension from lower part of ECU tendon was present in 5 limbs. Conclusion: Extensor muscles of the forearm have undergone a dramatic change during the period of evolution; however, these are not uniform and there are number of anatomical variations which are of signicance during the repair of extensor tendon injury or during tendon transfer surgeries. ABSTRACT INDIAN JOURNAL OF APPLIED RESEARCH 1 Volume - 11 | Issue - 04 | April - 2021 | . PRINT ISSN No 2249 - 555X | DOI : 10.36106/ijar KEYWORDS : Extensor muscles, Forearm, Posterior Compartment, Human Cadaver Dr. Divya Mahajan Reader and Head of Department, Department of Anatomy, Dr HSJ Dental College, Chandigarh. Dr. Abha Bajaj* Reader, Department of Anatomy, Dr. HSJ Dental College, Chandigarh. *Corresponding Author Dr. Apurba Patra Assistant Professor of Anatomy, AIIMS, Bhatinda, Punjab. Dr. Manjeet Singh Professor and Head of Department, Maharishi Markandeshwar Institute of Medical Sciences and Research, Mullana, Ambala, Haryana.