Lab 9

Question 1

What happened to the muscles pectoralis and trapezius in mammals?

Answer 1

a single muscle split into two discrete muscles that insert at different points

Question 2

What are the most dramatic differences that distinguish muscles of mammals from other chordates? What does the complexity of these mammalian muscles allow?

Answer 2

cranial and appendicular musculature

allows them to be used in nursing, mastication, and communication (facial expression)

Question 3

Compare muscles of mammals to amphibians.

Answer 3

• facial muscles of mammals are homologous to two muscles only in amphibians
• five mammalian branchiomeric muscles (masseter and temporalis) are homologous to the adductor mandibulae of amphibians
• mylohyoid and digastric of mammals are homologous to the intermandibularis of amphibians
• sternohyoid, omohyoid, thyrohyoideus are homologous to just one muscle in amphibians
• caudofemoralis, semitendinosus, biceps femoris, semimembranosus and gracilis are homologous to only two muscles of salamanders

Question 4

What is different about the pectoral girdle of mammals compared to amphibians?

Answer 4

• pectoral girdle of mammals is not attached to the vertebral column
• it is suspended by a sling of muscles between the two scapulae which have spines for muscle attachment

Question 5

Why is the pectoral girdle of mammals not attached to the vertebral column?

Answer 5

to absorb shock of the front limbs hitting the ground, reducing the jarring of the viscera and brain

Question 6

What is the function of the cutaneous trunci? Where does it originate and insert?

Answer 6

moves the skin, originates from some of the shoulder muscles and inserts on the underside of the skin

Question 7

What is the role of the cremasteric pouch?

Answer 7

contains the testes, blood vessels and sperm ducts

penis embedded within it

Question 8

Since minks are part of the skunk family, what structure releases the foul smell?

Answer 8

musk glands (sacs on either side of anus, just ventral to the tail)

Question 9

What is the platysma? Function?

Answer 9

a cutaneous muscle derived from the hyoid (neck) musculature that controls
facial muscles that control eyelids, lips, nose, pinnae

Question 10

What two salivary glands are located close to the hyoid venous arch?

Answer 10

mandibular gland and parotid gland

Question 11

What are the two components of the trapezius? What are their functions?

Answer 11

trapezius cervicis=protracts the shoulder

trapezius thoracis=retracts the shoulder

Question 12

in general, where do dorsal muscles of the shoulder usually insert?

Answer 12

humerus

Question 13

What are the two components of the extensor carpi?

Answer 13

radialis and ulnaris

Question 14

Which is the largest thigh muscle?

Answer 14

biceps femoris

Question 15

What is the fascia latae?

Answer 15

covers the lateral surface of the thigh, attached to the tensor fasciae latae

Question 16

Which is the largest muscle along the caudolateral surface of the shank?

Answer 16

gastrocnemius-lateralis

Question 17

High gear vs low gear muscles.

Answer 17

high gear=low force

low gear=high force

Question 18

Which muscle is fan-shaped?

Answer 18

serratus ventralis

Question 19

What is the relative size of temporalis and digastric in herbivores compared to carnivores?

Answer 19

temporalis is smaller in herbivores

digastric larger in herbivores

Question 20

What are the two portions of triceps brachii?

Answer 20

longus and laterallis

Question 21

True or false. Gluteus superficialis is larger in quadripeds.

Answer 21

True

Question 22

What allows young mammals to nurse?

Answer 22

facial muscles

Question 23

Match.
Scalenus, rectus thoracis, serratus ventralis, longus colli

retracts ribs, suspends pectoral girdle, flexor of neck, pulls ribs towards head

Answer 23

scalenus: pulls ribs towards the head
rectus thoracis: retracts ribs
serratus ventralis: suspends pectoral girdle
longus colli: flexor of neck

Question 24

Which muscles insert on humerus?

Answer 24

teres major, subscapularis, scapuldeltoideus

Question 25

Which muscles insert on femur?

Answer 25

adductor femoris

Question 26

Match the muscle to its origin.
masseter, cleidomastoideus, rectus thoracis, scalaenus, sartorius

illium, clavicle, cervical vertebra, sternum, zygomatic arch

Answer 26

masseter-zygomatic arch
cleidomastoideus-clavicle
rectus thoracis-sternum
scalaenus-cervical vertrebra
sartorius-ilium

Question 27

Match.
Teres major, sternomastoideus, tensor fascia latae, semitendinosus

retracts and rotates brachium, flexes shank, depresses or rotates head, abducts and protracts thigh

Answer 27

teres major-retracts and rotates brachium
sternnomastoideus-depresses or rotates head
tensor fascia latae-abducts and protracts thigh
semitendinosus-flexes shank

Question 28

Serratus ventralis is composed of what two parts?

Answer 28

cervicis and thoracis