epaxial muscle
Quick Summary
The epaxial muscle is a deep muscle located in the back of vertebrates. In jawed fishes, the axial musculature is divided into dorsal (epaxial) and ventral (hypaxial) components. The epaxial musculature extends from the back of the skull to the tail, playing a role in swimming movements. In tetrapods, such as amphibians, reptiles, birds, and mammals, the epaxial muscles are known as the dorsalis trunci. While they retain a segmented structure, they have undergone modifications to facilitate dorsoventral bending of the spine. The erector spinae is a specific example of a deep back muscle in humans that functions to straighten and rotate the back.123
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