Muscle Shape Classification

Question 1

circular muscles

Answer 1

muscle of mouth (orbicularis oris) and eye (orbicularis oculi), sphincters of bowels and bladder

Question 2

convergent

Answer 2

origin is wider than point of insertion to allow for maximum force production. example includes pec.

Question 3

parallel

Answer 3

sometimes called strap muscles. long muscles, large movements. lower strength, higher endurance. example includes sartortius.

Question 4

fusiform

Answer 4

can be included in parallel muscle group. spindle shaped. muscle belly wider than both origin and insertion such as biceps brachii.

Question 5

pennate

Answer 5

large number of fibers for high strength

Question 6

unipennate

Answer 6

fibers arranged to insert in diagonal direction onto the tendon such as in lumbricals and extensor digitorum longus

Question 7

bipennate

Answer 7

two rows of muscle fibers, facing in opposite diagonal directions. has central tendon, like feather. greater power, less range of motion such as rectus femoris of quads

Question 8

multipennate

Answer 8

multiple rows of diagonal fibers with central tendon that branches such as deltoid

Question 9

hypaxial

Answer 9

vental rami. extrinsic back muscles such as SPS and SPI

Question 10

epaxial

Answer 10

dorsal rami, intrinsic back muscles such as erector spinae group and transverospinalis group