Appendicular skeleton

Question 1

What are 3 major components of the appendicular skeleton?

Answer 1

pectoral girdle
pelvic girdle
limbs

Question 2

What are the 2 components of the pectoral girdle?

Answer 2

endochondral/cartilage replacement
dermal bone

Question 3

What are the bones in the cartilage replacement of the pectoral girdle?

Answer 3

coracoid
scapula
suprascapula

Question 4

What are the bones in the dermal investing of the pectoral girdle?

Answer 4

clavicle
cleithrum
supracleithrum
post-temporal

Question 5

T or F: cartilaginous fishes like Chondrichthyes have a pectoral girdle composed of bone

Answer 5

false! only cartilaginous elements

Question 6

What modification do bony fish have that Chondrichthyes lack?

Answer 6

dermal elements of the pectoral girdle (bones)

Question 7

Describe the pectoral girdle in frogs

Answer 7

lost most of the dermal bones (ex. cleithrum)

humeral muscles moved to dorsal part of girdle

Question 8

Describe the pectoral girdle in non-bird reptiles

Answer 8

dermal elements (clavicle and sometimes cleithrum) and replacement elements (scapula and part of coracoid) present

Question 9

Describe the pectoral girdle in birds

Answer 9

clavicles (dermal) retained and fuse to form furcula (wishbone)
paracoracoid and scapula present
scapula dorsal to rib cage

Question 10

Describe the pectoral girdle in mammals

Answer 10

loss of coracoid

only two bones present:
- scapula (replacement)
- clavicle (dermal)

Question 11

What type of mammals may have reduced or absent clavicles?

Answer 11

running mammals ex. cats

Question 12

Which pectoral girdle element is retained in all mammals? what does it look like?

Answer 12

scapula - broad, flat plate

Question 13

What is the function of the scapula?

Answer 13

muscular attachment

Question 14

What composes the pelvic girdle?

Answer 14

cartilage replacement bone only

Question 15

T or F: the pelvic girdle has dermal elements

Answer 15

false

Question 16

In which group is the pelvic girdle a single element and unattached to the vertebral column?

Answer 16

fish

Question 17

What are the 3 main ossification areas of the pelvic girdle in most tetrapods?

Answer 17

ilium - wing
ischium - back
pubis - front

Question 18

in more advanced vertebrates, which becomes the largest pelvic element?

Answer 18

the ilium

Question 19

Pubic fusion occurs in most vertebrates, except which group?

Answer 19

birds

Question 20

What is the largest foramen in the tetrapod body?

Answer 20

the obturator foramen in the pelvic girdle = nerve passage, blood vessels, and muscle connections

Question 21

Is the pelvic girdle of amphibians attached to the vertebral column?

Answer 21

yes

Question 22

Describe the difference between salamander and frog pelvic girdles

Answer 22

salamanders have short and more rectangular
frogs have elongated iliums

Question 23

How is the pelvic girdle modified to allow frogs to jump?

Answer 23

a ligament between ilium and sacral vertebra = frees ilium to move separately and strong muscle attachment = strong jumps

Question 24

Describe the pelvic girdle in non-bird reptiles

Answer 24

mostly reduced and fenestrated

large gap between pubis and ischium = leg muscle attachment

ilium is elongated

legless lizards have vestigial pelvic girdle

snakes have lost pelvic girdle entirely

Question 25

Which group of reptiles have lost the pelvic girdle entirely?

Answer 25

snakes

Question 26

Which group of vertebrates have a mostly reduced pelvic girdle?

Answer 26

non-bird reptiles

Question 27

Why is it beneficial for birds to lack pubic bone fusion?

Answer 27

to produce larger eggs

Question 28

How do birds compensate for the lack of pubic bone fusion?

Answer 28

their pelvic bones (ilium, ischium, pubis) are fused together = innominate bone and is fused to the sacrum

Question 29

What are the 3 pelvic bones?

Answer 29

ilium ischium pubis

Question 30

What is the innominate bone?

Answer 30

the result of the 3 pelvic bones fusing together

Question 31

Which vertebrate groups have an innominate bone?

Answer 31

birds and mammals

Question 32

What allows birds to be bipeds?

Answer 32

their expanded ilium and ischium to allow for enlarged muscles for walking on two legs

Question 33

Describe the mammalian pelvic girdle

Answer 33

made from the fusion of the 3 pelvic bones = innominate bone pubic symphysis

Question 34

How does the pelvic girdle of quadruped mammals differ to that of bipeds?

Answer 34

quadruped pelvic girdle has an elongated pelvis for more muscle attachment

Question 35

What are the major bones in the forelimb?

Answer 35

humerus - upper limb radius - larger, anterior lower limb ulna - smaller, posterior lower limb carpals - wrist bones metacarpals - proximal digits phalanges - distil digits

Question 36

What are the major bones of the hindlimbs?

Answer 36

femur - thigh tibia - larger, anterior shank bones fibula - smaller, posterior shank bones tarsals - ankle bones metatarsals - proximal digit bones phalanges - distil digit bones

Question 37

Which component of the appendicular skeleton are most tetrapods' limbs more firmly attached? which group(s) is excluded?

Answer 37

pelvic girdle fish = more strongly connected to pectoral

Question 38

Which component of the appendicular skeleton are fishes limbs more firmly attached?

Answer 38

pectoral girdle

Question 39

What are fish fins/limbs made of?

Answer 39

spines or rays (not the same bones as in fore and hindlimbs of other groups)

Question 40

How are fish fins supported? (ie., are they connected to the skeleton)?

Answer 40

except for the caudal fin, there's no connection between fins and the spine fins are supported only by muscle

Question 41

What is the function of pectoral fins in fish?

Answer 41

allow fish to maintain depth in water by producing lifting forces in some fish, fins are specialized for 'walking' or 'flying'

Question 42

What is the function of pelvic fins in fish?

Answer 42

change direction stop or turn quickly

Question 43

How are the limbs of amphibians distributed on the body?

Answer 43

aside from Caecilians amphibians have 4 legs spread out on both sides of the body

Question 44

How many digits do amphibians have on their forelimbs? hind limbs?

Answer 44

forelimbs: 4 digits hind limbs: 5 digits

Question 45

How are limbs modified in jumping or swimming frogs?

Answer 45

hind limbs are larger than forelimbs

Question 46

How are limbs modified in running or walking amphibians?

Answer 46

both fore- and hind limbs are short and similar in length

Question 47

Which vertebrates can regenerate limbs?

Answer 47

frogs and salamanders

Question 48

How are non-bird reptile limbs situated on the body?

Answer 48

to either side of the body at right-angles

Question 49

T or F: the common ancestor of all reptiles had 4 limbs

Answer 49

true

Question 50

Is the lack of limbs in snakes a derived or lost characteristic?

Answer 50

secondarily lost characteristic the common ancestor of all reptiles had 4 limbs

Question 51

Are birds quadrupeds like other reptiles, or bipeds like some mammals?

Answer 51

bipeds

Question 52

How have bird forelimbs been modified? What has this been useful for?

Answer 52

evolved into wings - useful for flight

Question 53

How have the hind limbs of birds been modified to support bipedalism?

Answer 53

many bones are fused to increase strength

Question 54

What are the 3 different walking/weight bearing types?

Answer 54

plantigrade digitigrade unguligrade (2 types)

Question 55

Describe plantigrades and give an example

Answer 55

animals that bear weight on the entire sole of their foot ex. humans, bears

Question 56

Describe digitigrades and give an example

Answer 56

animals that bear weight on only their digits ex. cats

Question 57

Describe unguligrades and give an example

Answer 57

animals that bear weight only on the tip of their digits/toes ex. horse

Question 58

What are the two types of unguligrades?

Answer 58

digit III only - ex. horse digit III + IV - ex. pig, cow, deer

Question 59

What type of -grade are birds?

Answer 59

plantigrades - they use all 4 digits to bear weight when they walk

Question 60

How many digits do birds have in their hind limbs?

Answer 60

4 digit I: back digits II-IV: forward

Question 61

How is the scapula different between quadrupeds and bipeds?

Answer 61

quadrupeds: scapula is vertical because forelimbs are beneath the body bipeds: scapula is horizontal because forelimbs are beside the body

Question 62

How is a vertical scapula an advantageous adaptation for animals that walk on two legs and climb?

Answer 62

horizontal scapulas can move with arms/forelimbs as they move forward and backward when running or climbing

Question 63

How are the forelimbs attached in bipeds? how is this evolutionary advantageous?

Answer 63

to the sternum via the clavicle beneficial for animals that climb because it allows arm and chest muscles to pull body weight

Question 64

How are the forelimbs attached in quadrupeds like cats? how is this evolutionary advantageous?

Answer 64

there is no connection between clavicle and sternum cat clavicles are very reduced instead, forelimbs are connected to sternum via compressible ligaments cat's have stronger hind limbs than forelimbs, so there doesn't need to be strong connection to joints for forelimbs

Question 65

How are quadruped (ex. cat) hind limbs modified for walking on 4 legs?

Answer 65

hind limbs are more muscular than forelimbs = provide most of the forward momentum hindlimbs connect to vertebral column via joints between the innominate bone and the sacrum (3 fused vertebrae) = increases muscular power

Question 66

How is the reduced clavicle in cats beneficial?

Answer 66

they can land on their forelimbs from high heights without hurting themselves because there's no clavicle = instead, soft tissues in the collar and shoulder absorb the landing shock