11.3: Macroscopic Anatomy of Skeletal Muscles
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Macroscopic Anatomy of Skeletal Muscles
Arrangement of the fascicles in skeletal muscles have certain patterns and arrangements including:
- circular muscle: fascicles arranged in a circle (also called sphincters)
- convergent muscle: broad muscle with fascicles converging in a single point of attachment
- parallel fusiform muscle: muscle with rounded middle with the fascicles parallel to each other
- parallel non-fusiform muscle: flat muscle with the fascicles parallel to each other
- unipennate muscle: fascicles branch off a central tendon like one side of a feather
- bipennate muscle: fascicles branch off a central tendon on two sides like a feather
- multipennate muscle: fascicles branch off a central tendon on more than two sides in a feather-like pattern
Above: Shape and arrangement patterns of fascicles in different skeletal muscles.
Names of skeletal muscles are diverse and may be based on the shape of the muscle, its origin and insertion, its action, its location, its size, or its direction. Here are some terms you will see when learning the skeletal muscles and their meanings:
- adductor: causes adduction
- brevis: short muscle
- extensor: causes extension
- flexor: causes flexion
- longus: long muscle
- major: larger muscle than another (the minor)
- maximus: the largest
- minimus: the smallest
- minor: smaller muscle than another (the major)
- oblique: fascicles travel at an oblique angle (large angle)
- pronator: causes pronation
- rectus: "rectus" means "straight" and therefore refers to a straight shape where fascicles are parallel
- transverse: fascicles travel at a right angle (90°)
- vastus: "great" or larger muscle
Attributions
- "Anatomy and Physiology" by J. Gordon Betts et al., OpenStax is licensed under CC BY 4.0