Muscle Architecture and Shape Guide

A series of vocabulary flashcards summarizing key concepts related to muscle architecture and shape, including definitions and examples.

Muscle Architecture

Refers to the orientation and arrangement of muscle fibers (or fascicles).

Parallel Muscle

Muscle fibers or fascicles are aligned parallel to each other, such as in the quadratus lumborum.

parallel muscle example

quadratus lumborum, sartorius, external oblique, biceps brachii (long head)

Strap-like Muscle

A muscle that is flat, long, and narrow, typical of the sartorius.

Fusiform Muscle

A muscle characterized by a spindle shape, offers large excursion but is relatively weak.

Pennate Muscle

Muscle fibers or fascicles are angled to the main tendon, increasing strength but reducing excursion.

Examples of pennate

Flexor polliciis longus (unipennate), rectus femoris (bipennate), deltoid (multipenate)

Bipennate Muscle

A type of pennate muscle with fibers inserting on both sides of the tendon.

Multipennate Muscle

A complex pennate muscle with multiple rows of diagonal fibers, such as the deltoid.

Convergent Muscle

Muscle fibers converge at one attachment site and spread out at another, allowing for versatile movement.

Examples of convergent muscle

pectoralis major

Circular Muscle

Muscle fibers arranged in a circular pattern, acting as a sphincter to close openings.

Examples of circular muscle

obicularis oculi and obicularis oris

Dilators

Muscles that open an orifice, often found in opposition to circular muscles.

Digastric Muscle

A muscle with two bellies in series, such as the digastric and omohyoid.

Bicipital Muscle

A muscle with two heads, exemplified by the biceps brachii.

Tricipital Muscle

A muscle with three heads, such as the triceps brachii.