Muscles 1

Question 1

Function of axial muscles in birds & mammals

Answer 1

Epaxial stabilize vertebral column
Hypaxials for protective body wall (esp. in lumbar region - no ribs), 3 layers hold in viscera & move trunk - all tetrapods
Hypaxials expand/compress ribcage for ventilation - all amniotes

Question 2

Describe the appendicular muscles of anurans

Answer 2

(frogs, toads) large, for jumping

Question 3

Function of muscles

Answer 3

Provide force for movement - skeletal or internal

Question 4

Where does the muscle in the walls of blood vessels come from?

Answer 4

Either mesenchyme or splanchnic hypomere mesoderm

Question 5

Function of hypobranchial muscles in jawed fish?

Answer 5

• open jaw
• move tongue
• expand buccal & branchial cavities

Question 6

Which muscles does splanchnic hypomere mesoderm give rise to?

Answer 6

Cardiac

Smooth around some blood vessels & in digestive tract lining

Question 7

From where do hypobranchial muscles arise?

Answer 7

anterior/ventral growth of somites

Question 8

Describe the appendicular muscles of caecilians

Answer 8

None - 2° loss (use lateral undulation)

Question 9

How are axial muscles divided?

Answer 9

Into myomeres along length of body

Epaxial above horizontal septum, hypaxial below

Question 10

Function of branchiomeric muscles in tetrapods

Answer 10

open/close mouth
in middle ear
facial muscles
muscles for branchial arches III-VII reduced, in larynx/pharynx/pectoral girdle & forelimbs

Question 11

Where does the smooth muscle around the digestive tract come from?

Answer 11

Some from splanchnic hypomere mesoderm, some (around visceral organs) from mesenchyme

Question 12

Axial muscle function in tetrapods with sprawled limb posture

Answer 12

Provide force for lateral undulation (locomotion not taken over by limbs)

Question 13

Which muscles does myotome epimere mesoderm (somites) give rise to?

Answer 13

Most skeletal muscle (axial & appendicular), hypobranchial (from anterioventral growth)

Question 14

Describe the appendicular muscles of tetrapods, in general

Answer 14

more prominent than in fish & divided into several groups for complex motion; even helped by some axial (& branchial, in forelimbs) muscles

Question 15

General function of branchiomeric muscles

Answer 15

Form muscular pharyngeal pump by attaching to splanchnocranium branchial arches

Question 16

Function of branchiomeric muscles in chondrichthyes & osteichthyes

Answer 16

Pump water over gills & move jaws

Question 17

Where are hypobranchial muscles found in tetrapods?

Answer 17

Larynx, tongue, throat, hyoid apparatus

Question 18

Where does cardiac muscle come from?

Answer 18

splanchnic hypomere mesoderm

Question 19

Describe the appendicular muscles of fish

Answer 19

Small, on top & bottom of fins connecting girdle to pterygiophores

Question 20

Axial muscle function in amniotes

Answer 20

Hypaxials for protective body wall (esp. in lumbar region w/o ribs), in 3 layers to hold in viscera & move trunk - all tetrapods
Also expand/compress ribcage for ventilation

Question 21

Describe the appendicular muscles of salamanders

Answer 21

Diversified (as in all tetrapods), but small because still primarily use lateral undulation for locomotion

Question 22

List the 5 types of antagonistic muscle pairs

Answer 22

• Abduction/adduction
• Flexion/extension
• Protraction/retraction
• Levation/depression
• Constriction/dilation

Question 23

Which types of muscles does mesenchyme give rise to?

Answer 23

Smooth in walls of some blood vessels & visceral organs

Question 24

What gives rise to branchiomeric muscles & extrinsic eye muscles?

Answer 24

Somitomeres in head

Question 25

Where does most skeletal muscle come from?

Answer 25

Myotome epimere mesoderm in somites

Question 26

Describe the appendicular muscles of birds & cursorial tetrapods

Answer 26

Mass concentrated proximally to reduce distal mass and improve efficiency (also makes birds more stable in flight)
Connected to distal sites by tendons

Question 27

Function of axial muscles in tetrapods

Answer 27

Hypaxials for protective body wall (esp. in lumbar region w/o ribs), in 3 layers to hold in viscera & move trunk

Question 28

Function of branchiomeric muscles in agnathans

Answer 28

pump water over gills