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Fiber arrangements
Fiber arrangements and muscle shapes
Question | Answer |
---|---|
Fiber arrangement affects | 1. Muscle's ability to exert F 2. ROM |
Greater cross section diameter= | Greater F exertion |
Longer muscle= | Greater ROM |
2 major types of fiber arrangements | 1. Parallel 2. Pennate |
Parallel Muscles | Fibers arranged parallel to length of the muscle Produce >ROM |
Types of Parallel Muscles | Flat Fusiform Strap Radiate Sphincter (Circular) |
Flat | Ex- Rectus Abdominus, External Oblique Thin and broad, originating from sheet like aponeuroses Forces are spread over a broad muscle |
Fusiform | Ex- Brachialis, Biceps Brachii Spindle-shaped w/ central belly that taper into tendons on each end F is focused onto small, bony targets |
Strap | Ex-Sartorius Uniform in diameter F is focused onto small bony targets |
Radiate | Ex-Pectoralis Major, Trapezius Triangular or Fan-Shaped or Convergent Flat+Fusiform |
Sphincter (Circular) | Ex- Orbicularis Oris Endless Strap Muscles Surrounds openings and functions to close them upon contraction |
Pennate Muscles | shorter fibers arranged obliquely to their tendons > Cross sectional diameter...> Power |
Types of Pennate Muscles | Unipennate Bipennate Multipennate |
Unipennate | Ex- Biceps Femoris, Extensor Digitorum Longus, Tibialis Posterior Fibers run obliquely from tendon on one side ONLY |
Bipennate | Ex- rectus femoris, flexor hallicus longus Fibers run obliquely on both sides of a central tendon |
Multipennate | Ex-Deltoid Several tendons with fibers running diagonally btwn them |
Strongest Contraction produced by | Bipennate and Multipennate |