Muscular System Flashcards
Understand the functions and properties of muscle tissue
Functions
1. Produce movement
- Skeletal muscle for all locomotion and manipulation
- Cardiac muscle pumps blood
- smooth muscle propels substances (food, urine etc.)
- Maintains posture and body function
- Skeletal muscles maintain posture, counteract gravity - Strengthen & Stabilise Joints
- Generate heat as they contract
Properties of Muscle tissue enabling their function:
1. Electrical excitability: respond to stimuli to produce action potentials
2. Contractility: contract forcefully when stimulated
3. Extensibility: the ability to stretch without being damaged (eg. stomach stretching with food)
4. Elasticity: ability to return to the original length and shape after contraction and extension
Describe the structure of skeletal muscle
- Approx 700 skeletal muscles
- Affected by age, health and body biomechanics
Composed of:
1. Muscle
- Individual muscle cells, blood vessels, nerves
- Wrapped in epimysium
2. Fascicle
- A bundle of individual muscle cells
- Wrapped in perimysium
3. Fibre
- Individual muscle cell
- Wrapped in endomysium
Name the common patterns of muscle fascicle arrangement and explain how ROM and power of a muscle is impacted by fasicles/fibres.
- Muscles have different shapes due to the arrangement of their fascicles
- Muscles generate power by contracting their fibres
- The more fibres per unit of a cross-sectional area, the more power the muscle can produce - Muscle fibres contract and shorten or lengthen ONLY in the direction of their fascicles
- The longer the fibres of that muscle the greater the ROM it can produce
- Different fascicle patterns have different functional capabilities
1. Circular
2. Convergent
3. Parallel
4. Pennate
Understand skeletal muscle attachment points
- Most skeletal muscles span joints and attach to bones in at least two places (hence attach to two tendons as well)
- The two attachments are called the origin (stationary point/proximal end of muscle) and the insertion (movable point/distal end of muscle)
-Muscle contraction causes movement at the joint
o The moveable bone/insertion (near the joint) moves toward less movable/origin bone
- Can have more than one of each for same muscle (insertions and origins are interchangable)
Understand the types of muscular contractions produced
- Isometric (plank)
- Muscle length remain the same
- No movement occurs but muscle force is increased
- Resists gravity or antagonist force of other muscles - Isotonic
a. Concentric (raising barbell in a bicep curl)
- Movement occurs as a result of muscle fibres shortening
b. Eccentric (lowering barbell from bicep curl)
- Muscle lengthens in the direction of its fascicles
- Undergoes controlled and general relaxation
- E.g. placing a cup of water down
Understand terminology for the naming of muscles
Differentiate between superficial and deep fascial structures
Describe the principles of the neurovascular supply of muscles
Distinguish between the three types of muscle tissues by body location, voluntary/involuntary and cell shape & appearance.
- Skeletal muscle
- Attaches and covers the skeleton, voluntary contraction for overall body motility
- single, very long, cylindrical, multinucleate cells with obvious striations (long-thin parallel streaks) - Cardiac muscle
- only exists in the heart, involuntary (contracts without stimulation from the nervous system)
- branching chains of cells; uni or binucleate striations - Smooth muscle
- present in the walls of hollow organs (stomach, intestines, trachea), involuntary contractions (ANS stimulated)
- single, fusiform (lemon-shape), uninucleate, no striations
Describe & give an example of each type of fascicle arrangement
- Circular fascicle arrangement
- Fascicles arranged into concentric rings
- Muscles surrounding external body openings (sphincters)
- Contraction closes the opening of these circular fibre arrangements (e.g. mouth), as those muscle fibres contract, the circumference of that circle closes in and affects the closing/opening of the muscle fibre - Convergent fascicle arrangement
- Broad origin, fascicles converge toward a single tendon of insertion (indirect insertion)
- Triangular or fan shaped
- Strongest contraction - Parallel fascicle arrangment
- The length of fascicles runs parallel to the long axis of the muscle
- Greatest shortening of length during contraction
- Either straplike (e.g. sartorius) or spindle-shaped with an expanded belly (fusiform e.g. biceps brachii) - Pennate fascicle arrangement
- Fascicles are short and attach obliquely
- Unipennate
Fascicles insert onto only one side of the tendon
- Bipennate
Fascicles insert onto the tendon from the opposite sides of the muscle
- Multipennate
Fascicles insert onto the tendon from many directions – many feathers side-by-side (eg. Deltoid)
Describe the types of connective tissue with skeletal muscle
- Ligaments: fibrous connections between bones, composed of collagen fibres, usually blend with the periosteum of bones at the joint
- Tendon: fibrous tissue linking a muscle belly to the attachment site at bone
- Aponeurosis: broad, flat connective tissue linking muscle belly to site of attachment; spread over a greater area than tendon
- Raphe: line of fibrous tissue where one muscle joins another’ usually a long attachment
Understand the principles of muscle action
- Muscle fibres contract and shorten or lengthen ONLY In the direction of their fascicles
- Antagonising muscle groups work in opposition
o Contraction of agonist/prime mover and concurrent relaxation in the antagonist - Muscles contract in response to nerve activation
o Innervation
Describe the types of movement associated with prime movers, synergists, antagonists and fixators and provide examples of each
- The arrangement of muscles permits them to work together or in opposition to produce movements
- Prime mover: main muscle responsible for producing a specific movement – concentric contraction
o E.g. biceps brachii prime mover of elbow flexion - Synergist: Compliment action of prime mover by:
o Adding extra force to the same movement
o Reducing undesirable or unnecessary movements
o E.g. brachialis synergist of biceps in elbow flexion - Antagonist: Muscle that opposes action of another muscle – eccentric contraction
o E.g. triceps brachii opposes biceps during elbow flexion
o Sometimes regulate action of primer mover by providing resistance to slow/stop movement - Fixator: steadies proximal parts of a limb while movements occur in distal parts – isometric contraction
o E.g. rotator cuff muscles stabilise shoulder during elbow flexion
Describe how the action of a muscle can be inferred by the position of the muscle relative to the joint it crosses
- A muscle that crosses the anterior side of a joint produces flexion
- A muscle that crosses the posterior side of a joint produces extension
- A muscle that crosses on the lateral side of a joint produces abduction
- A muscle that crosses on the medial side of a joint produces adduction
