The Musculoskeletal System

Question 1

What are the functions of the musculoskeletal system?

Answer 1

• support
• protection of vital organs
• movement (limbs, chewing, breathing)
• production of red blood cells in bone marrow
  -calcium reserve

Question 2

How does the musculoskeletal system support the body?

Answer 2

Maintaining body shape and suspending organs.

Question 3

What type of tissue is bone?

Answer 3

Solid connective tissue.

Question 4

Name the two types of bone.

Answer 4

Cortical and cancellous bone.

Question 5

Describe cortical bone.

Answer 5

Compact/woven bone. Solid bone forming the outside of bone.

Question 6

Describe cancellous bone.

Answer 6

Spongy bone. A meshwork of bone that forms the inside.

Question 7

What are osteocytes, osteoblasts, and osteoclasts?

Answer 7

Cells within the bone.

Question 8

What is an osteocyte?

Answer 8

A cell.

Question 9

What is an osteoblast?

Answer 9

An active cell (builder).

Question 10

What is an osteoclast?

Answer 10

Destroyer (resorb old bone).

Question 11

When are osteoclasts most active?

Answer 11

During growth.

Question 12

How do osteoblasts work?

Answer 12

When blood calcium levels are high, they create new bone to store excess calcium.

Question 13

How do osteoclasts work?

Answer 13

When blood calcium levels are low, they break down areas of bone to release calcium into the blood circulation.

Question 14

What role do bone cells take in the event of a fracture?

Answer 14

Osteoclasts will destroy damaged bone and osteoblasts will produce new bone.

Question 15

What are the types of bone?

Answer 15

• long bones
• short bones
• flat
• sesamoid
• irregular

Question 16

What are sesamoid bones?

Answer 16

Small pebble-shaped bones that form in tendons.

Question 17

Explain parts of a long bone.

Answer 17

• Diaphysis – main shaft
• Epiphysis – prominences forming
  the ends
• Physis - also called the growth
  plate
• Metaphysis – area adjacent to the
  physis
• Medullary cavity – central cavity
  filled with bone marrow

Question 18

Name two types of bone development.

Answer 18

• intramembranous ossification
• endochondral ossification

Question 19

Where does intramembranous ossification occur?

Answer 19

In flat bones.

Question 20

Explain intramembranous ossification.

Answer 20

The outline of the bone is formed by membranes, bony tissue forms
between the membranes
A – The outline of the bone is formed by
membranes with stem cell inside
B – Stem cells become osteoblasts and
start producing bone matrix
C – Eventually, the entire area becomes
bone and the trapped osteoblasts become
osteocytes

Question 21

Where does endochondral ossification occur?

Answer 21

All other bones that aren’t flat bones.

Question 22

Explain endochondral ossification.

Answer 22

The outline of the bone is formed by cartilage, which is then gradually
replaced by bone from the inside out.
A – A cartilage model of the skeleton forms
B – Osteoblasts in the centre start to turn this model into bone
C – Secondary areas in the epiphyses also start to become bone
D – Gradually the entire model is replaced by bone except for the articular cartilage
covering the epiphyses and the physis (growth plate). The physeal cartilage will
continue to lengthen the bone until the animal is fully grown, at which point, the
physis ‘closes’ and also becomes bone.

Question 23

What are the four stages to bone healing?

Answer 23

1. Haematoma formation
   * Haemorrhage at the trauma site leads to the formation of a
   haematoma
2. Soft Callus
   * The fracture is fused together by fibrous tissue
3. Hard Callus
   * The fibrous tissue eventually becomes bone and forms a solid union
4. Remodelling
   * Over time, the hard callus is re-formed to produce a ‘normal’ bone

Question 24

What is bone tissue mostly composed of?

Answer 24

Calcium phosphate (CaPO4)

Question 25

What is needed in a diet to maintain a healthy skeleton? Where can these be found?

Answer 25

Calcium and phosphorus. Milk, eggs, and a bone meal.

Question 26

What is the ideal calcium : phosphorus ratio?

Answer 26

Between 1.1:1 and 1.3:1

Question 27

Which vitamin is needed for calcium and phosphorus absorption in the digestive tract?

Answer 27

Vitamin D.

Question 28

What can low levels of calcium, phosphorus, and Vitamin D lead to?

Answer 28

= reduced bone formation * Rickets - Poor and abnormal growth in puppies * Osteomalacia in adults = softened, brittle bone * Slow or incomplete fracture healing

Question 29

What type of tissue is cartilage and what is it composed of?

Answer 29

Solid connective tissue. Proteins and a few cells (chondrocytes).

Question 30

What can high levels of calcium, phosphorus, and Vitamin D lead to?

Answer 30

* Increased bone formation often causing tissue mineralisation. This can lead to kidney and digestive failure, and calcium deposits in the skin and muscle. * High blood calcium can also affect the heart

Question 31

What are the three types of cartilage?

Answer 31

1. Hyaline cartilage – found covering the articular surfaces (the ends of bones within joints) 2. Elastic cartilage – found in the pinna and larynx 3. Fibrocartilage – found in cartilaginous joints

Question 32

What is the difference between tendons and ligaments?

Answer 32

Ligaments - A band or ring of connective tissue, attaching two bones together Tendons - A narrow band of connective tissue linking a muscle to a bone

Question 33

What is aponeurosis?

Answer 33

A wide sheet of connective tissue attaching a muscle to either a bone or another muscle.

Question 34

What is the periosteum?

Answer 34

The connective tissue layer surrounding a bone, adhered tightly to it surface

Question 35

What is bone marrow and where is it found?

Answer 35

Haemopoietic tissue found inside the medullary cavity of long bones.

Question 36

How does bone marrow differ in neonates?

Answer 36

In the neonate, red bone marrow fills the whole medullary cavity. Over time this is gradually replaced by fatty tissue, called yellow marrow. In the adult, bone marrow is only present in the ends of long bones.

Question 37

Name the three types of joints.

Answer 37

Fibrous, cartilaginous, and synovial.

Question 38

Explain fibrous joints.

Answer 38

These can also be called fused joints. They are immovable. Bones meet and are joined together with fibrous tissue. Over time this becomes bone and the bones are fused together. Example – bones of the skull

Question 39

Explain cartilaginous joints.

Answer 39

Two bones are joined together by fibrocartilage. There are two types. Cartilaginous joints with no movement Solid fibrocartilage forms between the two bones and forms a stable union. Example – mandibular symphysis Cartilaginous joints with small amount of movement Fibrocartilage joins the two bones and in the centre is a gelatinous pulp that allows some movement. Example – Inter-vertebral discs

Question 40

Explain synovial joints.

Answer 40

Movable joints.

Question 41

What are the ends of the bones in a synovial joint covered with and why?

Answer 41

Hyaline cartilage for smooth movement.

Question 42

What is a synovial capsule filled with and why?

Answer 42

Synovial fluid for lubrication.

Question 43

Where are intra-capsular ligaments found?

Answer 43

inside the synovial capsule.

Question 44

Where are extra-capsular ligaments found?

Answer 44

Outside or within the wall of the synovial capsule.

Question 45

Define menisci.

Answer 45

These are fibrocartilaginous pads that provide shock absorption and protection.

Question 46

What are the types of synovial joints?

Answer 46

Plane joints – flat bone surfaces that have a gliding motion. One bone slides in a parallel direction over the other bone. Hinge – allows movement in one direction, i.e. bending and straightening Condylar – curves surfaces fit together, allows movement in two planes. Ball and Socket – sphere of bone (the ball) fits into a depression (the socket) in other bone, allows movement in all 3 planes Pivot – a peg of bone fits into a ring or semi-circle of bone, allows rotation

Question 47

What are the three types of muscle?

Answer 47

Skeletal, smooth, and cardiac.

Question 48

What else can skeletal muscle be known as and why?

Answer 48

Striated muscle because it appears stripy under a microscope

Question 49

Describe skeletal muscle.

Answer 49

Skeletal muscle cells (also called fibres) are very long and are bundled together and bound by connective tissue to form a muscle. Skeletal muscle is attached to the skeleton. It is voluntary muscle (consciously controlled). It creates limb and trunk movement, including walking, chewing and breathing.

Question 50

Describe smooth muscle.

Answer 50

Smooth muscle cells are very small. Smooth muscle is involuntary (unconsciously controlled). Smooth muscle is found forming layers within organs. Examples – small intestine, bladder, blood vessels, iris of the eye, pilo-erector muscles.

Question 51

Describe cardiac muscle.

Answer 51

Cardiac muscle is only found in the heart. Cardiac muscle is also involuntary. It has its own internal pacemaker but can be controlled by unconscious parts of the brain and some hormones.

Question 52

Explain muscle contraction.

Answer 52

Skeletal muscle cells are filled with layers of overlapping proteins called myofibrils. When the muscle is stimulated to contract, these layers slide over one another and shorten the muscle.

Question 53

What are antagonists?

Answer 53

Muscles often work in pairs or groups to provide opposite actions. These are called antagonists.

Question 54

What movements can muscles produce?

Answer 54

* Flexion - bending of a limb joint (decrease the angle) * Extension - straightening of a limb joint (increase the angle) * Protraction - moves the limb cranially * Retraction - moves the limb caudally * Abduction - moves the limb laterally * Adduction - moves the limb medially Keep in mind – a muscle is only active when it is contracting. The movement a muscle makes is only when the muscle is contracting, i.e. shortening in length.