Muscular System-Arrangement of Fascicles

Question 1

What does the muscular system refer to?

Answer 1

skeletal muscles specifically

Question 2

What do skeletal muscles consist of?

Answer 2

fascicles

Question 3

What can the alignment of fascicles tell us about a muscle?

Answer 3

reveals a lot about muscles function

Question 4

How many arrangements of fascicles are there?

Answer 4

6

Question 5

Describe circular arrangment

Answer 5

-fascicles in concentric circles
-surround body openings
-close by contraction

Question 6

Examples of circular arrangment

Answer 6

orbicularis oris (mouth)
orbicularis oculi (eyes)

Question 7

Describe convergent arrangement

Answer 7

-origin of muscle is broad
-converge towards tendon of insertion
-usually triangular/fan shaped
-fibres extend from origin to insertion

Question 8

Example of convergent arrangement

Answer 8

pectoralis major

Question 9

Describe parallel arrangment

Answer 9

-long axis of fascicles run parallel to long axis of muscle
-fibres extend from origin to insertion
-two types: Fusiform and Strap-like

Question 10

fusiform definition and example

Answer 10

-expanded central belly
-biceps brachii

Question 11

strap definition and example

Answer 11

-narrow belly
-sternocleidomastoid

Question 12

Describe pennate arrangement

Answer 12

-fascicles are short and attach obliquely to the tendon that runs whole length of muscle
-feather like appearance
-multipennate, bipennate,unipennate

Question 13

multipennate definition and example

Answer 13

-many feathers side by side
-deltoid (forms roundness of the shoulder)

Question 14

bipennate definition and example

Answer 14

-fascicles insert into tendon from both sides
-rectus femoris

Question 15

unipennate definition and example

Answer 15

-fascicles insert into one side of tendon
-extensor digitorium longus muscle

Question 16

What does the arrangement of fascicles influence?

Answer 16

-amount of movement produced when contracted (range of motion)
-amount of force (power)

Question 17

How much can skeletal fibres shorten?

Answer 17

up to 1/3 their original length

Question 18

What are the effects of having more parallel fibers to a muscles’s long axis?

Answer 18

-the more the muscle can shorten (giving a larger range of movement)
*usually not that powerful

Question 19

What does power depend on?

Answer 19

total number of fibres

Question 20

What arrangements have a lot of short fibres?

Answer 20

short bipennate and multipennate

Question 21

What does more power mean for the range of movement?

Answer 21

less