A Study of Extensor Pollicis longus and brevis and Abductor pollicis longus from the perspective of Evolution
Journal Title: The Journal of Medical Research - Year 2017, Vol 3, Issue 3
Abstract
Background: The Extensor pollicis longus and brevis and abductor pollicis longus muscles have evolved progressively in different primates according to the function expected from the pollux finger. Analysis of individual muscles in different primates can help our understanding of evolution. Aims and objective: The present study was undertaken to study these three muscles and to note the variations therein and to attempt to explain the existence of these variations on the probable basis of their evolutionary history. Methodology: The extensor pollicis longus, brevis and abductor pollicis longus muscles were dissected meticulously in 100 upper limbs of adult cadavers. Results: In case of extensor pollicis longus and extensor pollicis brevis, 2% incidence of duplication of muscle and 1% of duplication of tendon and 1% incidence of duplication of muscle and 2% of duplication of tendon was observed respectively. In case of abductor pollicis longus 23% incidence of variation was observed. The muscle was observed to split into multiple tendons of muscles to have widespread attachment beyond the 1st metacarpal bone. Conclusion: The extensor pollicis longus with minimum variation seems to have settled in its evolutionary trajectory. In 8% of abductor pollicis longus studied, superficial and deep heads were observed. Oudenaarde states that the superficial head is used for range of movement and the deep set of fibers are used for strength of contraction. Elliot observes that the wide attachment of the abductor pollicis longus on the muscles abductor pollicis brevis and the opponens pollicis, the 1st carpometacarpal joint capsule and trapezium bone could be for better anchorage for radial deviation at the wrist joint. The extensor pollicis brevis muscle is seen as a separate muscle only in humans, hylobatids and gorillas whereas in all other primates. The chimpanzee hand seems to have evolved one step further with two extensor pollicis brveis muscles.
Authors and Affiliations
Vaishaly Bharambe, Dinesh Patel, Purushottam Rao Manvikar, Sapna Shevade, Pallavi Gupta Bajpayee
Keywords
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- EP ID EP442636
- DOI 10.31254/jmr.2017.3311
- Views 135
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