Musculoskeletal Flashcards
What type of muscle is the only voluntary type?
Skeletal muscle
What accounts for the difference in the length-tension relationship when comparing skeletal and cardiac muscle?
This is due to difference Ca2+ intracellular concentrations
What causes the movement of tropomyosin to free the myosin binding sites on actin?
The combination of Ca2+ ions and TroponinC (TpC)
What neurotransmitter is used at a neuromuscular junction?
ACh
What 3 structures make up cardiac muscle’s own excitatory system?
SA node, AV node and bundle of His
T-tubules are present in both cardiac and skeletal muscle. True or false?
True; action potential propagate along t-tubules in both types of muscle
Define Pharmo-contraction coupling.
Contraction that occurs in smooth muscle in the absence of electrical activity via hormones or neurotransmitters.
What type of neurones innervate skeletal muscle cells?
Alpha-motor neurone (I.e. somatic neurones)
Where are somatic neurones cell bodies located?
The ventral horn of the spinal cord
What is the function of SERCA pumps?
To maintain calcium ion storage in muscle cells
List the 4 steps involved in the sliding-filament model.
- ATP is hydrolysed when myosin head is unattached.
- ADP + P are bound to myosin as the myosin head attaches to actin
- ADP+P release causes myosin head to change position; the actin filament moves
- Binding of ATP causes the myosin head to return to the resting position
CYCLIC PROCESS
Define ‘tetanic contraction’ and the different between complete and incomplete.
Tetanic contraction is the sustained contraction resulting from high frequency stimulation (I.e. summation). Complete is where there is no relaxation of the contraction (graph: fused) and incomplete is where there is partial relaxation of the contraction (graph: infused).
What is the difference of isometric and isotonic muscle contraction?
Isometric contraction involves the muscle contraction without any visible movement of the joint of muscle, whereas, isotonic contraction is when the muscle contracts and shortens.
Compare and contrast the two types of muscle fibres: slow and fast twitch fibres.
Slow twitch fibres *red *type I *lots of mitochondria *high levels of myoglobin; oxygen binding *highly aerobic *fatigue resistant; endurance Fast twitch fibres *white *type II *fewer mitochondria *glycolytic metabolism *fatigue quickly *rapid, intense, short duration contraction
What metabolites cause muscle fatigue?
Lactic acid, inorganic phosphate, increase ADP, reactive oxygen species and an ionic imbalance (of sodium and potassium)
Describe dystrophy and name an example disease.
Dystrophy is a muscle destroying disease that is the progressive degeneration of muscle fibres.
Define autoregulation
The intrinsic ability of an organ/tissue to maintain a constant blood pressure despite changes in perfusion pressure.
What type of nerve fibres richly innervate skeletal muscle?
Sympathetic vasoconstrictor fibres.
What has more control over arterial pressure during strenuous exercise: metabolic or nervous control?
Metabolic; increase of tissue metabolism = increase blood flow
What portion of oxygen does muscle extract from blood at rest compared to during exercise?
At rest: 25-30%
During exercise: 80-90%
What does oxygen debt during exercise result in?
Post-exercise hyperaemia (due to a fall in vascular resistance - vasodilation)
Why does increased production of lactic acid result in pain after exercise?
The increases lactic acid levels stimulate nociceptive C fibres which result in the sensation of pain
Name some functional adaptations of vascular beds in order to maintain adequate blood flow to muscles and skin.
- Variable oxygen extraction
- Participation in vascular reflexes
- Dominant metabolic vasodilation
- Vasodilator response to adrenaline
- Skeletal muscle pump
Name the 3 functional adaptations of cutaneous circulation.
- Sensitivity to ambient temperature
- Cold-induced vasodilation
- Rise in core temperature to reduce body temperature
What are the 3 classifications of joints based on their range of movement?
- Synarthroses: do not move at all (e.g. sutures in skull)
- Amphiarthroses: limited movement (e.g. pubic symphysis)
- Diarthroses: movement on several planes (e.g. knee joint)
What are the 6 types of synovial joints?
Ball & socket, hinge, pivot, gliding/plane, saddle and condyloid.
Name and describe the two membranes of an articular capsule of a synovial joint.
- fibrous membrane: composed of dense irregular connective tissue and forms the outer layer of the articular capsule
- synovial membrane: composed of a specialised connective tissue and has a rich capillarity network and contains synovial-fluid producing cells called synoviocytes. It has no epithelial lining but still have good regenerative powers.
Compare and contrast the two types of synoviocytes.
TYPE A: macrophage-like cell and acts by removing debris via phagocytosis. They are derived from bone marrow and contribute slightly to the production of synovial fluid.
TYPE B: fibroblast-like cells which an abundant rough ER. They are the main producer cells of synovial fluid.
How can synovial fluid be used to diagnose certain joint diseases?
An arthrocentesis can be preformed where a sample of synovial fluid is taken from the patient and the physical, chemical and microscopic characteristics of the fluid are analyses to, hopefully, lead to a diagnosis.
Why is it important to warm up being completing exercise to protect your joints?
The synovial fluid present in synovial joints plays an important role as a shock-absorber for the body. It is important to warm up before exercise as this thickens the synovial fluid to a gel-like consistency and is therefore a more efficient shock absorber.
Define proprioception.
The ability to know where our joints are without needing to see them (both in static and dynamic positions).
What type of muscle spindle is adapted to detecting rapid rates of change in joint angulation and stretch in muscles?
Gamma-motor neuron
What type of Golgi tendon receptor measures tension in tendon to gauge force generated by a muscle?
Type 1 beta-sensory Afferents
What neuronal structure processes information collect by receptors of joint angulation (e.g. muscle spindles, Golgi tendon receptors, pacinian corpuscles)
The thalamus; acts as the relay centre
What 2 fields of physics are explored in the science of Biomechanics?
Newtonian mechanics and Continuum mechanics
State the 1st law of Newton’s Laws of Motion.
An object that is at rest will stay at rest and an object in motion will not change its velocity (magnitude or direction) unless an external force acts upon it
State the 2nd law of Newton’s Laws of Motion.
Net force on an object is equal to the mass of the object multiplied by its acceleration
Net force = Mass x Acceleration
F = m(kg) x a(m/sec^2) = newtons
State the 3rd law of Newton’s Laws of Motion.
For every action, there is an equal and opposite reaction
Define ‘Centre of Mass Location’.
The unique point in space around which the mass of an object is equally distributed
Define ‘Moment of Inertia (I)’.
The measurement of an objects rotation inertia
I = mass - distance^2
What is a lever in biomechanics?
A rigid beam which rotates about a support called a fulcum.
What type of lever is an eccentric bicep curl an example of?
A second class - the load is situated between the fulcrum and force
What type of lever is the Atlanta-occipital joint an example of?
A first class lever - the fulcrum is located between the applied force and load
What type of lever is the concentric flexion of the biceps brachii an example of?
A third class - the force is applied between the fulcrum and the load
What type of joint is the sternoclavicular joint?
A synovial ball and socket joint between the manubrium notch and medial end of the clavicle.
Where does the interclavicular ligament run between?
The 2 medial ends of both clavicle; superior to the manubrium
What type of joint is the acromioclavicular joint?
A synovial gliding joint between the acromion process and lateral end of the clavicle.
What supporting ligament of the acromioclavicular joint is responsible for the majority of the weight-bearing abilities of the shoulder?
The coracoclavicular ligament that runs between the coracoid process of the scapula and the inferior surface of the acromion end of the clavicle.
What group of muscles supply stability to the glenohumeral joint?
The rotator cuff muscles: teres minor, supraspinatus, infraspinatus and subscapularis.
What portion of the humerus is covered by the glenoid cavity?
1/3
What is the glenoid labrum made of and what is its primary function?
It is made of fibrocartilage and acts by deepening the glenoid cavity to allow for a better fit.
What are the 3 attachment sites of the glenohumeral joint’s synovial capsule?
- Scapula; beyond the supraglenoid tubercle
- Margin of labrum
- Anatomical neck of the humerus
Name the 4 bursae involved in the glenohumeral joint.
Subacromial, subscapular, subdeltoid and subcoracoid bursae.
Name the 4 shoulder ligaments that help the stability of the joint.
Coracoacromial, coracohumeral, glenoumeral and transverse humeral.
What are the 5 anatomical names of the digits?
I - Pollex II - Index forefinger III - Digitis medius IV - Ring annularis V - Little minimus
What are the two types of movements possible of the hand? Name some examples of each
- non-prehensive movments - with a flat hand; hitting, pushing
- prehensive movements - dependent on position of the fingers; grasp, grip
What 2 sets of muscles are involved in power the power and precision grip?
The extrinsic flexor muscle and intrinsic palm muscles
At what joint in the hand does the ‘bye-bye‘ Movement occurs at?
The metacarpophalangeal joints (I.e. the knuckles)
What bones are involved in the synovial saddle joint of the thumb and are responsible for its range of movements?
The trapezium and proximal end of the 1st metacarpal bone.
What 3 instrinsic hand muscles are hypothenar?
Opponents digiti minimi, flexor digiti minimi & abductor digiti minimi
What intrinsic hand muscles are thenar?
Abductor pollicis brevis, flexor pollicis brevis, opponens pollicis & adductor pollicis
What does the anterior fibrous reticiulum form?
The flexor retinaculum; carpal tunnel
What does the posterior fibrous retinaculum form?
The extensor retinaculum
What nerve runs through the carpal tunnel?
Median nerve
What are the 5 classifications of bone?
Long, short, flat, irregular and seasamoid
What are the 2 layers of long bones?
Outer compact bone and an inner spongy layer of bone (diploë)
What are the 3 areas of long bones?
Diaphysis: proximal shaft that runs between the distal and proximal end of the bone
Epiphysis: the wider section of each end of the bone that is filled with spongy bone
Metaphysis: the region where the diaphysis joins with the epiphysis via mature bone. It also contains the epiphyseal plate (hyaline cartilage) in growing bone
Where is the endosteum located in long bones?
The delicate membrane is located lining the medullary cavity and is essential for bone growth,repair and remodelling
Where is the periosteum located for bones and what does it contain?
The fibrous membrane covers the outer surfaces of bones and contain blood vessels, nerves and lymphatic vessels that nourish the outer compact bone
What are the 2 main components of bone tissue?
Osteon (Haversian system of living cells) and a mineralised matrix
Compare and contrast the inorganic and organic portions of bone.
Inorganic portion (65%) contains phosphate salts (hydroxyapatite) and provides strength to the bone Organic portion (35%) contains collagen fibres and proteoglycans. It provides Flexibility
What can a deficiency in the organic portion of bone lead to?
Brittle bones
What can a deficiency in the inorganic portion of bones lead to?
Rickets; deficiency can be a lack of calcium
Where are osteocytes found?
In the lacunae between the lamellae of the bone matrix
Is compact/ cortical bone vascular or avascular?
Vascular
What do osteoclasts develop from?
Monocytes and macrophages
What is the bone immature stem cell called? And where are they found?
Osteogenic cells are found in the periostenum and bone marrow
What are the main functions of osteocytes?
To maintain the mineral concentration of the matrix via the secretion of enzymes
Where do blood vessels enter the bone?
The nutrient foramen (small opening in the diaphysis)
What are the 3 main types of vessels that supply blood to bone?
Nutrient artery (arise from main circulation), metaphyseal and epiphyseal arteries and periosteal arterioles
