Muscles

Question 1

muscles: function

Answer 1

• provide force for movement

Question 2

skeleton: function (3)

Answer 2

• support the body
• protect delicate body tissues
• provide levers for muscles to act on to produce movement

Question 3

what happens when a muscle contracts

Answer 3

• it shortens and applies force by PULLING

Question 4

skeletal muscles attachment sites

Answer 4

• origin

- insertion

Question 5

skeletal muscles attachment sites: origin

Answer 5

• relatively fixed structure

Question 6

skeletal muscles attachment sites: insertion

Answer 6

• relatively mobile site

Question 7

antagonistic pairs

Answer 7

• pairs of muscles that pull the same body part in opposite directions

Question 8

flexion (2)

Answer 8

• to bend one part relative to another about a joint

- decreases the angle between these two parts

Question 9

extension

Answer 9

• to straighten one part relative to another about a joint

- increases the angle between these two parts

Question 10

levators

Answer 10

• elevate (raise) a body part

Question 11

depressors

Answer 11

• depress (lower) a body part

Question 12

adduction (2)

Answer 12

• to move a body part towards the midline of the body

- to elevate the lower jaw, closing the mouth

Question 13

abduction (2)

Answer 13

• to move a body part away from the midline of the body

- to depress the lower jaw, opening the mouth

Question 14

protractors (2)

Answer 14

• projection of a part away from its base

- movement of an appendage in the anterior direction

Question 15

retractors (2)

Answer 15

• withdrawal of a body part: pulling it back closer to its base
• movement of an appendage in the posterior direction

Question 16

classification of skeletal muscles (4)

Answer 16

• branchiomeric
• hypobranchial
• axial
• appendicular

Question 17

trunk somites

Answer 17

• myotome of trunk somites develop into axial and appendicular muscles

Question 18

anterior somites (2)

Answer 18

• grow ventrally and anteriorly to form hypobranchial muscles
• ventral to pharyngeal slits

Question 19

somitomeres

Answer 19

• epimere mesoderm forms connected clusters in the head

- develop into branchiomeric muscles

Question 20

terrestrial locomotion: propulsive stroke (2)

Answer 20

• foot contacts the ground

- limb moves from anterior to posterior (retraction) propelling body forward

Question 21

terrestrial locomotion: recovery stroke (2)

Answer 21

• foot is lifted (no contact with ground)

- limb moves from posterior to anterior (protraction), back into position for another propulsive stroke

Question 22

sprawled limb posture (2)

Answer 22

• amphibia, testidunata, lepidosauria, and crocodilia

- limbs positioned laterally

Question 23

erect limb posture (2)

Answer 23

• mammalia, aves

- limbs are positioned directly under the body

Question 24

terrestrial locomotion: sprawled limb posture (3)

Answer 24

• walk or run with lateral undulations of the body, using feet as pivot points
• recovery stroke requires an overarm swing for each limb
• limb movement is both anterior/posterior and dorsal/ventral

Question 25

terrestrial locomotion: erect limb posture (2)

Answer 25

• recovery stroke achieved with a pendulum-like swing

- limb movement is generally restricted to anterior/posterior direction

Question 26

what posture is more efficient for terrestrial locomotion

Answer 26

• erect posture: higher proportion of energy used for limb movement will contribute to propelling the body forward than to moving the limbs back into position

Question 27

what determines the amount of force generated by skeletal muscles (2)

Answer 27

• cross-sectional area of the muscle is directly related to force
• does not depend on length

Question 28

axial muscles

Answer 28

• muscles of the body wall organized into myomeres separated by mysepta
• epaxial (T) and hypoaxial (B) separated by horizonatal septum
• chond, actin: attach to vetebral column (sarc: noto) to produce lateral udulations of body = powerful thrust to propel body forward in H2O
• tetrapod (sprawled): both appen and axia contributw to locomoton
• tetrapod (erect): epaxial (pull neural spines to stabilize column to bridge weight of internal organs to legs)
• tetrapods (hypaxial): form large portion of body wall and help protect internal organs
• amniotes: aspiration pump to expand/compress flexible ribcage

Question 29

appendicular

Answer 29

• chond + actin = extend from gridles to fins; each find has forsal ad ventral muscle; smaller cross-sectional area as they are used for stability and steering more than axial muscles
• tetrapods: limbs provide main source of propulsive force, so relatively large; pectoral and pelvic adductor and abductor masses divded into many distinct muscles allowing for highly maneuverable limbs
• aves: muscle bunched proximally, connected to distal ends by long tendons; keep muscle mass close to centre of gravity for flight stability; muscles of pectoral girdle and forelimb relatively large (pectoralis attaches to sternum, adducts wings);