MSK 2 - Basic Concepts in MSK Flashcards
What are the 3 major tissue components of the MSK?
Which germ layers are all 3 derived from?
1) Bones (+ Joints)
2) Muscles
3) Connective Tissues
- All are derived from the mesoderm
What are the major functions of bone?
- Support
- Protection (of underlying muscles/structures)
- Metabolic (regulation of calcium + phosphate)
- Storage (of calcium + phosphate)
- Movement
- Haematopoiesis (creation of new blood cells)
What are the major functions of skeletal muscle?
- Locomotion
- Posture
- Metabolic - e.g.: storage of glycogen
- Venous return (skeletal muscle pump)
- Heat production (shivering + exercise)
- Continence
What are the main connective tissues and their major functions? (6)
- Tendons - force transmission from muscle to bone
- Ligaments - connects bone to bone
- Fascia - compartmentalisation of muscle + protection
- Cartilage - articular (decreases friction) + fibrocartilage (shock absorber)
- Synovial membranes - secrete synovial fluid for joint + tendon lubrication
- Bursa - synovial fluid sacs to protect tendons, ligaments from friction
What are the 3 main specialised cell types of bone and their roles?
1) Osteoblasts - lay down new bone, create EC matrix and deposit mineral components
2) Osteocytes -trapped within bone matrix to maintain/monitor bone
3) Osteoclasts - secrete acidic vesicles and enzymes to dissolve mineral/collagen component during bone remodelling (work alongside osteoblasts)
What are the 5 main types of bone and their functions?
1) Long - provide movement/levers for force
2) Short - stability and give better ROM
3) Flat - protection + attachment of muscles
4) Irregular - protection of underlying structures
5) Sesamoid - embedded within tendons for protection
Name 4 surface features of bones and their roles
1) Bony prominences - e.g.: greater trochanter, where muscles attach
2) Grooves/lines - where they’re associated with nerves/vessels
3) Depressions - attachment of other bones
4) Holes - where nerves/blood vessels can pass through
What 2 groups of blood vessels does a typical long bone have?
What is avascular necrosis?
1) Epiphyseal artery (supplying the ends)
2) Periosteal artery (supplying the shaft)
- When a bone is deprived of a blood supply, often leading to death of the bone.
What is the role of joints?
How is ROM and stability related to each other in joints?
What are the 3 main types of joint and what are their relative ROM’s?
- Connects one bone to another
- There is a trade off between ROM and stability - a joint with a low ROM has a high stability and vice versa
- Fibrous (low ROM) - collagen fibres joining bones, found where great strength/stability is required
- Cartilaginous (medium ROM) - “glue” holding bones together, found at the ends of growing bones or midline of adult bones
- Synovial (high ROM) - highly mobile, that cap the end of separate bones (egg like fluid)
How do synovial joints form?
- Joints form within a cartilage model
- Where the joint is going to form, there is cell death
- This leaves a gap between two bones which is the synovial joint (interruption of cartilage model).
What are the 3 classes of joint levers?
1) First-class = see-saw like, fulcrum in the middle of effort and load, e.g.: head balancing on neck
2) Second-class = Load in the middle of fulcrum and effort, e.g.: gastrocnemius in plantar flexion
3) Third-class = most common, effort in between load and fulcrum, e.g.: biceps curl
What is the origin and insertion of a muscle?
Why is muscle contraction “symmetrical”?
- The origin is a stationary proximal anchor point
- The insertion is a mobile distal attachment point
- Equal force is exerted on the origin and insertion.
Do muscles push or pull?
What can muscles act on only?
What is the action of a muscle on a joint a function of?
- Muscles can only pull, they CANNOT push
- Muscles can only act on the joints they cross
- The action of a muscle on a joint is a function of the orientation of its fibres and the relation of those fibres to the joint.
NB: muscles work together and almost never in isolation
What is concentric, eccentric and isometric contraction?
What do muscles within the same fascial compartment share?
Concentric = muscle pulls while shortening (e.g.: biceps curl) Eccentric = muscle pulls while lengthening (e.g.: knee extensors when walking downhill) Isometric = muscle pulls while staying the same length (e.g.: carrying a load)
- A common innervation and generally a common action.
What are the 5 main types of muscle and which one can contract the most powerfully?
1) Parallel
2) Fusiform
3) Circular (sphincter)
4) Triangular
5) Pennate (uni, bi and multipennate)
- Pennate
