2.1 Structure + Function of Skeletal Muscles + Joints

Question 1

The skeletal system is composed of bones and cartilage and has two main parts. What are they and what areas do they represent?

Answer 1

1. Axial skeleton = Bones of head, neck, and trunk
2. Appendicular skeleton = Bones of the limbs

Question 2

Cartilage is an avascular semi-rigid connective tissue that obtains nutrients + oxygen via diffusion. What are the 2 types of cartilage and their different functions?

Answer 2

Costal cartilage = forms where more flexibility is required in skeleton

Articulating cartilage = found on articulating points, esp synovial joints, to form frictionless surface

Question 3

What are the functions of bone?

Answer 3

1. Protection
2. Structural + mechanical support
3. Basis for movement
4. Storage (salts + calcium)
5. Regeneratign supply of new blood cells (produced by marrow)

Question 4

What is compact bone and what role does it play?

Answer 4

Forms external hard layer of all bones + srrounds medullary cavity (bone marrow)

Provides protection + strength for weight bearing

Question 5

What is spongy bone and what role does it play?

Answer 5

Forms inner layer of bones and consists of lamellae bone cells

Blood cells + platelets are formed in these spaces

Reduces bone density

Question 6

Bones are classified based on shape. What are the 5 primary categories of bone?

Answer 6

1. Long bones = tubular/cylindrical
2. Short bones (cuboidal, ONLY in akles + wrists)
3. Flat bones = thin + curved, protective
4. Irregular bones = complex shapes
5. Sesamoid bones = small + round, found in certain tendons to prevent excessive wear

Question 7

Articulations, projections, and holes make up the 3 types of bone markings. What kind of markings do they refer to?

Answer 7

1. Articulations = two bone surfaces come together to articulate (form a joint)
2. Projection = area of bone that projects above bone surface (muscle attachment)
3. Hole = opening / groove in bone that allows passage of blood vessels or nerves

Question 8

What is the periosteum?

Answer 8

A connective tissue which covers the bone surface (except at joint) and envelopes a rich supply of blood vessels + nerves

Question 9

A joint is an articulation or place of union between two or more bones. What are the three types of joint?

Answer 9

1. Fibrous joint
2. Cartilaginous joint
3. Synovial joint

Question 10

What are fibrous joints?

Answer 10

Joints united by fibrous tissue

Movement is limited to length of fibres connecting the articulating bones

Question 11

What is a gomphosis joint?

Answer 11

Peg + socket joint (tooth + socket)

Type or fibrous joint

Question 12

What are cartilaginous joints?

Answer 12

United by hyaline cartilage or fibrocartilage

Greater movement than fibrous joints, but less than synovial joints

Question 13

Synchondroses and symphyses are both types of cartilaginous joints. What are the differences between them?

Answer 13

Synchondroses = tmeporary, united by hyalline cartilage

Symphyses = cartilage fused to fibrocartilage pad/plate, strength + flexibility eg intervertebral discs

Question 14

Synovial joints are the most common joint and have more movement than other types. What are synovial joints?

Answer 14

Bones separated by a space containing synovial fluid

Synovial fluid lubricates and nourishes cartilage + joint surface

External reinforcement = accessory ligament, internal reinforcement = thickened connective tissue on capsule

Question 15

The temporomandibular joint (TMJ) is an atypical synovial joint. How is it divided?

Answer 15

Divided into superior + inferior synovial cavities by the TMJ disc (meniscus)

Question 16

What kinds of movement can a synovial joint perform?

Answer 16

Pivot, ball + socket, plane, hinge, saddle, condyloid

Question 17

These are three types of muscle fibres (muscle cells), what are they?

Answer 17

1. Skeletal striated muscle
2. Cardiac striated muscle
3. Smooth muscle

Question 18

Skeletal muscle has two main components, what are they?

Answer 18

1. Fleshy contractile component
2. Non-contractile portion (collagen bundles) known as tendons or aponeuroses

Question 19

Muscle contraction is the shortening of muscle fibres. What are 3 types of contraction?

Answer 19

1. Reflexive = automatic involuntary (heart)
2. Tonic = slight muscle contraction to provide tone (small back msucles)
3. Phasic contraction

Question 20

Phasic contraction can be isometric or isotonic. What does this mean?

Answer 20

Isometric = muscle length stays the same (maintain position)

Isotonic = muscle length changes to produce movement

Question 21

What are the 2 types of isotonic contraction?

Answer 21

1. Concentric = muscle shortens (deltoid raising arm)
2. Eccentric = muscle lengthens (deltoid lowering arm)

Question 22

The function of skeletal muscle is to initiate movement or position the body. How are the different skeletal muscles classified accordinng to their role in achieving this function?

Answer 22

1. Prime mover (agonist) = movement is main functions, concentric
2. Fixator = steadies proximal part, isometric
3. Synergist = complements prime mover
4. Antagonist = opposes an action (triceps antagonist to biceps)