Anatomy week 3 and 4 Flashcards
(18 cards)
MACROscopic and Microscopic muscle structure
MACROscopic anatomy: Connective tissue wrappings support, protect, & separate portions of muscle & whole muscles -Fibres -Endomysium -Fascicles -Perimysium -Epimysium -Musculotendinous -Muscle belly (FEFPEMM)
Microscopic anatomy: -Sarcolemma -Sarcoplasm -Nuclei -Myofibrils -Sarcomere -Transverse tubules -Sarcoplasmic reticulum (ssnmsts)
Properties of muscle
-Extensibility
stretch without sustaining damage by the application of force
lengthen when relaxed
-Elasticity
return to original shape after lengthening or shortening
Maintains a specific shape & geometry in muscles despite malleable nature
-Excitability
respond to a stimulus (electrical signals) from nerves
contract & function
-Conductivity
propagate electrical signals, including action potentials
Allows action potential to be transmitted along muscle cell, activating tissue & initiating muscle contraction
-Contractility
shorten & thicken, thus producing force, in response to a specific stimulus
force production & movement
-Adaptability
change in response to how it is used
Enlarge (hypertrophy) with increased work; atrophy if deprived of work
Contractile elements of a sacromere
functional unit of muscle fiber; their shortening causes contraction
Sliding filament theory
Action potential (discussed later) travels to sarcoplasmic reticulum & releases calcium ions into sarcoplasm
Calcium ions then bind with troponin, moving aside tropomyosin protein strands covering binding sites on actin filament
Myosin heads are charged with energy from breakdown of ATP (able to move)
Energy binds myosin heads to active receptor sites on actin filament, making connections called cross-bridges
Ratcheting action (power stroke) occurs as myosin heads pull sarcomere together, shortening the strand
Myosin heads bind more ATP, providing energy needed to release hold on actin strand; process creates contractions
Action potentials and factors affecting muscle activation
-Muscle force is produce in two ways
# of motor units (neuron + skeletal muscle fibres) that are activated
-All or none principle
-Frequency of stimulation
-How does frequency affect contraction strength? - linear
Action potentials and factors affecting muscle activation
-Muscle force is produce in two ways
# of motor units (neuron + skeletal muscle fibres) that are activated
-All or none principle
-Frequency of stimulation
-How does frequency affect contraction strength? - linear
Motor unit structure
Single motor neuron Ventral horn of the spinal cord Activates multiple muscle fibres -Large motor units in the lower limb muscles ~2000 fibres gastrocnemius Powerful contractions -Small motor units in the eye muscles ~10 fibres Allows accurate movement One motor unit = One fibre type
Muscle fibre types
I – slow twitch
IIa – fast twitch
Iib – fast twitch (inefficient, fatigue quickly)
Slow Twitch Fibers
Contract slowly but are resistant to fatigue
Rely on aerobic energy production
Used for long-duration activities (walking, jogging)
Fast Twitch Fibers
Contract rapidly & powerfully but fatigue quickly
Larger in diameter than slow twitch fibers due to having more myofilaments
Rely on anaerobic energy production
Used for short-duration activities (sprinting, lifting)
Ordered recruitment
MU recruited by spinal mechanisms
Small motor units recruited first
Fine motor control
Larger motor units recruited later when high forces required
Also first to be ‘derecruited’
Sensory receptors and stimuli
Sensory receptors:
Main sensory receptors in musculoskeletal system
Exteroceptors (sight, smell, hearing, taste, touch)
Interoceptors
Temp., pain, pressure
Proprioceptors
Stimuli:
Automatic responses to stimuli
Aff / Eff feedback loops
Do not require cognitive control
First ‘port of call’ for environmental interaction
Reduces demand on conscious control of movement
Essentially excite or inhibit muscle contractions
Sensory receptors and stimuli
Sensory receptors:
Main sensory receptors in musculoskeletal system
Exteroceptors (sight, smell, hearing, taste, touch)
Interoceptors
Temp., pain, pressure
Proprioceptors
Stimuli:
Automatic responses to stimuli
Aff / Eff feedback loops
Do not require cognitive control
First ‘port of call’ for environmental interaction
Reduces demand on conscious control of movement
Essentially excite or inhibit muscle contractions
Basic Spinal reflexes
Monosynaptic reflexes Biceps brachii, triceps brachii, brachioradialis, quadriceps femoris, triceps surae reflexes
Polysynaptic reflexes Upper abdominal, lower abdominal, cremasteric, plantar, anal reflexes
Upper limb joint motion (elbow) degrees of movement
Flexion (140 degrees) / extension (0 degrees)
Pronation (85-90 degrees) /Supination (85-90 degrees)
Scapulohumeral rhythm of the shoulder complex
-Synergy - total effect is greater than the sum of the individual effects.
-Synergistic movements of the;
-Sternoclavicular
-Acromioclavicular
-Glenohumeral joints
Very common and important for healthy function
Comparable to the pelvic movements with hip
List and describe the shoulder injuries
Clavicular Fracture
- Impact related (trauma)
- Direct landing force on Acromion Process
- Limited DOF for energy dissipation – easier to break
Rotator Cuff Impingement
-Tendons travel in small space between acromion and humeral head
-Specifically supraspinatus
-Narrowing of space can cause impingement; inflammation,
tendon thickening, pathological scapulohumeral rhythm
Describe finger dislocation injuries
Finger Dislocation
-Common in Ball Sports
-Finger Movements
Flexion/Extension
Abduction/Adduction
49% of all finger injuries in football (Miller & Friedrich, 2020)Epicondylitis injuries
Lateral epicondylitis – “Tennis elbow”
-Forehand/backhand, radial flexion & extension
Medial epicondylitis – “Golfer’s elbow”
-Downswing; ulnar flexion & flexion
- Both are repetitive stress injuries.
- Microtraumas or tears in muscle & soft tissue at proximal attachments.
E- athletes common injuries
Hand/figure/wrist pain
Eye fatigue
Back/neck pain
