Kinesiology : fascicle arrangements

Parallel arrangements

Longitudinal, quadrilateral, fusiform, triangular/fan-shaped

Longitudinal arrangement

• long, strap-like muscle with fibers parallel to its long axis

• allows for high rom, less power/force

Longitudinal examples

Sartorius and sternocleidomastoid

Sartorius

Longest muscle cells in the body

Sternocleidomastoid

Turning head from side to side

Quadrilateral

• Four sided and usually flat

• Very bulky/meaty, short

• Parallel muscle fibers that allow high power, low rom

Quadrilateral examples

Rhomboids and masseter

Rhomboid

One of the prime movers when moving scapula; rowing

Masseter

Chewing muscle

Fusiform

• Rounded muscle that tapers at either end

• Bulky in middle, tapers outside

• Allows for both power and rom

Fusiform examples

Biceps brachii and brachioradialis

Triangular or fan shaped

• origin of muscle is broad

• Fascicles converge toward tendon of insertion

• Occurs if a large, powerful muscle has to be focused at a restricted point of leverage

Triangular or fan shaped example

Pectoralis major

Pectoralis major

Often torn because it’s such a big muscle with a small insertion ; big muscle to one tendon

• fasicles converge toward tendon of insertion

• On chest

Pennate arrangements

• Feathery in appearance

• offer strength without bulk; big muscles are flat or found operating in confined spaces

Unipennate, bipennate, multipennate

Unipennate

• looks like half a feather

• Series of short, parallel, feather-like fibers that extend diagonally for side of a long tendon

Unipennate examples

Tibialis posterior and flexor pollicus longus

Tibialis posterior

• Primary cause of shin splints

• Tendon failure here is a big reason for flat

Flexor pollicis longus

Long thumb flexor

Bipennate

• Feather

• has a long central tendon with fibers extending diagonally in pairs from either side of the tendon

Bipennate example

Rectus femoris

Rectus femoris

Quad

Multipennate arrangements

• bouquet of feathers

• Several tendons are present with fibers running diagonally between them

Multipennate example

middle deltoid

Middle deltoid

Shoulder - fibers run diagonal between tendons

Pennate

A lot of force through short rom

Parallel

• Exert force over a longer distance

• Larger rom