Musculoskeletal System

Question 1

What is the locomotor system?

Answer 1

Musculoskeletal system that allows wide range of animal movement.

Question 2

What are the components of the locomotor system?

Answer 2

Bones, joints and muscles.

Question 3

Define cursorial.

Answer 3

Having limbs adapted for running.

Question 4

What are the key adaptations of the locomotor system in cursorial animals?

Answer 4

1. Reduced pectoral skeleton - allows more cranial/caudal movement.
2. Elongation at proximal end of limb - scapula lies laterally.
3. Elongation at distal end of limb - long metacarpals, walk on toes or hooves.

Question 5

Describe how the pectoral skeleton reduced.

Answer 5

In cursors the clavicle is usually absent or vestigial; there is no skeletal component attaching the forelimb to the trunk.

Question 6

How is the scapula attached to the body in a cursor?

Answer 6

Joint is purely muscular and is called a synsarcosis. This particular joint is called the omothoracic junction.

Question 7

What is a consequence of increasing leg length?

Answer 7

Increase stride length - energy efficient way to cover the ground more quickly.

Question 8

Define flexion.

Answer 8

Folding limb

Question 9

Define protraction.

Answer 9

Moving limb forwards.

Question 10

Define extension.

Answer 10

Stretching limb

Question 11

Define retraction.

Answer 11

Moving limb backwards or fixing limb and moving trunk forwards relative to limb.

Question 12

In which species is trunk contribution limited.

Answer 12

Herbivores with roughage diets e.g. horses –> rely more on limbs elongation.

Question 13

In which species is trunk contribution higher.

Answer 13

Carnivores with small-volume, consuming meat diet have flexible trunks, multipurpose limbs e.g. cat.

Question 14

What are the four gaits and their beats?

Answer 14

1. Walk - 4 beat
2. Trot - 2 beat
3. Canter - 3 beat
4. Gallop - 4 beat

Question 15

Name and describe the two components of the domestic species internal skeleton.

Answer 15

1. Axial skeleton - bones of vertebral column, skull and ribcage.
2. Appendicular skeleton - all bones of fore and hind limbs.

Question 16

Name the 4 main bone classifications.

Answer 16

1. Flat
2. Long
3. Short
   4 Sesamoid

Question 17

Describe flat bones and give examples.

Answer 17

• Large surface area for muscle attachment.
• Protection of underlying structures.
• Scapula/pelvis

Question 18

Describe long bones and give examples.

Answer 18

• Support and leverage in limbs
• humerus/femur

Question 19

Describe short bones and give examples.

Answer 19

• Large range of movement
• Ant-concussive
• Carpus/tarsus

Question 20

Describe sesamoid bones.

Answer 20

• Embedded in tendons
• Change in angle over bony surface –> redirect forces, reduce friction so prevent damage

Question 21

Describe the general features of bones.

Answer 21

1. Smooth surface areas: passage of structures/tendons
2. Specific bony contours: provide site for attachment of important structures
3. Rough surface areas: general muscle attachment

Question 22

Define the periosteum.

Answer 22

• Covers outer surface of bone (except articular surfaces).
• Contains blood vessels and nerves.
• Important for fracture healing.

Question 23

What are the epiphysis and diaphysis in a long bone?

Answer 23

Epiphysis: Ends of the bone, spongy for shock absorption.
Diaphysis: Shaft, compact for strength.

Question 24

How do primary and secondary ossification centers differ?

Answer 24

Primary: Forms in diaphysis during fetal development.
Secondary: Forms in epiphyses after birth.

Question 25

How do growth plates appear on radiographs?

Answer 25

In young animals: Visible as dark (radiolucent) lines.
In adults: Closed and fully ossified, no longer visible.

Question 26

What are growth plates?

Answer 26

Growth plates, or epiphyseal plates, are areas of hyaline cartilage located between the ossification centres.

Question 27

How do growth plates contribute to bone growth?

Answer 27

• Chondrocytes in the proliferation zone divide and push older cells toward the diaphysis.
• Older chondrocytes hypertrophy, the matrix calcifies, and osteoblasts lay down new bone, elongating the bone.

Question 28

What are the structural components of skeletal muscle?

Answer 28

• Muscle fibers arranged in fascicles.
• Connected to bone via tendons.
• Rich blood supply and innervation.

Question 29

What is the origin of a muscle?

Answer 29

The fixed or stationary attachment point of a muscle.

Question 30

What is the insertion of a muscle?

Answer 30

The movable attachment point of a muscle.

Question 31

How can muscles attach to bone?

Answer 31

1. Directly to bone
2. Via tendons
3. Via aponeurosis (limited access to bone)