Appendicular Skeleton

What does the appendicular skeleton consist of?

fins or limbs, and girldes

What is the anterior girdle?

the pectoral girdle or shoulder

What is the posterior girdle?

the pelvic girdle or hip

What are the main functions of fins?

propulsion and stabilization

Barbel

a fleshy projection from the lip or head

Adipose fin

a small fin on the top mid-line of the body near the tail fin

Anal fin

fin along the lower mid-line of the body near the tail fin

Caudal fin

tail fin

Dorsal fin

the fin or fins along the top-midline of the body

Pectoral fin

the paired fins nearest the head, corresponding to front arms or legs

Pelvic fin

the paired fins nearest the tail, corresponding to hind legs

Scales

overlapping outgrowths of the skin

What is considered stylopodium?

bones of the upper arm and thigh (i.e. humerus and femur)

What is considered zeugopodium?

bones of the forearm and shank (i.e. radius & ulna, tibia & fibula)

What is considered autopodium?

bones of the manus or pes (carpals, metacarpals, phalanges; tarsals, metatarsals, phalanges)

Do amphibians have a clavicle?

it’s variable

Do birds have a clavicle?

Birds have paired clavicles that fuse with an unpaired interclavicle to form the furcula (wishbone)

Do mammals have a clavicle?

posterior coracoid fuses to the scapula; clavicle is variable

List some animals with clavicles

• humans

• monkeys

• cats

• mice

• rabbits

• rats

• bullfrogs

List some animals that do not have clavicles

• dogs

• horses

• cattle

• sheep

Describe the pectoral girdle

It is the scapula and clavicle that associate with the humerus of the upper extremity

Describe the evolution of the pelvic girdle

The pelvic girdle is a single bone in fish, and was a single bone in very early tetrapods. In later tetrapods, it become three bones. All of the bones are endochondral.

What are the three bones of the pelvic girdle?

• ilium: site of attachment to the vertebral column

• ischium

• pubis

What joins the two os coxa of the pelvis together?

a pubic symphisis

What can account for morphological changes to the appendicular skeleton?

Morphologic changes to the appendicular skeleton occur to facilitate different modes of locomotion.

Cursorial

running

Fossorial

burrowing/digging

Saltatorial

hopping

Aerial

flying/gliding/sailing

Arboreal

lives in trees

Sprawled limb posture is common in ________

amphibians and most reptiles

What change in limbs reflects a shift to more efficient and rapid locomotion?

shift to limbs under the body in later therapsids; digits placed more in line with the direction of travel through the torsion of the limb bones

limb motion became more pendular and efficient

The shift in limb position resulted in ______.

the scapula being used more as a supportive structural element

Plantigrade

walks on the entire flat of the foot (ex. humans, bears)

Digitigrade

walks on digits (ex. dogs and cats)

Unguligrade

walks on tips of phalanges (ex. horses)

For animals that engage in cursorial locomotion, what adaptations occurred over time?

• lengthening of distal limb segments

• reduction in bones, digits

Longer distance fliers tend to have what?

longer radius and ulna

What are sesamoid bones?

• small, rounded bones imbedded within tendons

• reinforce and decrease stress on tendons by redistributing the forces on that tendon

• ex. patella, proximal sesamoid bones in horse hooves, sesamoid bones of the metacarpals and metatarsals

Where is bone marrow collected from in dogs?

the wing of the ilium and the proximal end of the femur

Where is a common collection site for bone grafts?

top of the humerus and wing of the ilium