Unit 1 - Applied Anatomy Flashcards
What is a joint?
A joint occurs where two or more bones articulate.
What are the 3 types of joints?
Fibrous - connected by dense connective tissue, fixed/immovable, found in skull
Cartilaginous - bones are entirely joined by cartilage, less movement than synovial, found in spine
Synovial - between bones that move against each other (limbs)
Explain the structure of muscles (more magnified).
Muscle fibers made of myofibrils, myofibrils surrounded by sarcoplasmic reticulum which stores calcium, myofibrils broken down into repeating segments (sarcomeres consist of actin and myosin).
Epimysium
outer layer, covers entire muscle
Perimysium
bundles of muscle fibers
Endomysium
Layer of fascia that surrounds individual fibres
Myofibril
threads found in striated muscle cells
Sarcomere
Structural unit of a myofibril in striated muscle cells
Actin and Myosin
Protein forms filaments of muscle cells
Muscle Fibre
composed of myofibrils
Sliding Filament Theory
- Sarcoplasmic Reticulum stimulated to release calcium ions
- Calcium ions bind to troponin thus moving both troponin and tropomysium (same structure) to expose binding site on actin filament
- ATP uses energy to connect myosin head to actin filament (creating cross-bridge) while breaking down into ADP, phosphate ion is produced.
- Power stroke occurs, Z-lines come closer to one another, making the H-zone smaller (this is the contraction as actin filaments are closer together and sarcomere has shortened)
- Cholinesterase breaks down Ach and the muscle fiber relaxes.
Axial Skeleton
Provides protection and support for vital organs, 80 bones. Also surface for attachment of muscles. Strong and limited movement, fused.
e.g.: ribs, sternum, cranium, vertebrae
Role of cholinesterase
Allows muscle to relax by breaking down Ach in 5 milliseconds. Repolarizes membrane immediately.
Anatomical terminology
Superior - higher
Inferior - lower
Posterior - behind
Anterior - Front
Proximal - close to origin
Distal - further from origin
Medial - close to middle
Lateral - further from middle
4 Types of Bones
Long - long, slightly curved for strength (arms and leg bones)
Short - small, (tarsals, carpals)
Flat - thin and flat, protects vital organs (skull, sternum, scapula)
Irregular - (vertebrae, sacrum)
Muscle Fibre Type 1
- slow twitch
- red due to large volumes of myoglobin, more blood vessels
- very resistant to fatigue (high prevalence of mitochondria)
- high capillary density (increased oxygenation)
- low ATP stores
low glycogen stores - longer to contract, not as explosive (long-distance)
Types of Muscle
Smooth - (in walls of internal organs, involuntary) spindle-shaped, non-striated, single nucleus, no tension sensors or stretch receptors
Cardiac - (in walls of heart, involuntary) striated, branched, single nucleus, no tension sensors or stretch receptors
Skeletal - (attached to muscle via tendons, voluntary) striated, multinucleated, cells bound together by fascia, tension sensors or stretch receptors
Appendicular Skeleton
Locomotion, balance and attachment. 126 bones. (clavicle, humerus, femur…)
Reciprocal Inhibition
Muscle must relax on one side of joint (antagonist) to allow for a muscle on the other side (agonist) to contract effectively. For safety otherwise a muscle tear would likely occur.
Role of Acetylcholine (Ach)
-increases membrane permeability to sodium ions
-opens motor end plate channels
-released from nerve endings and binds to receptors on muscle surface
-causes depolarization, enabling calcium to be released
Isotonic Muscle Contraction
Change in length
Concentric - muscle shortens
Eccentric - muscle lengthens
Isometric Muscle Contraction
No change in length when contracting (plank, handstand)
Isokinetic Muscle Contraction
develops tension and changes length at a constant speed (cycling, breastroke)
Delayed Onset Muscle Soreness (DOMS)
Pain and stiffness felt in muscles 24-72 hours after strenuous or unaccustomed exercise. Associated with inflammatory reactions, overstretching, overtraining and structural muscle damage. Can be prevented/minimized by reducing the eccentric component, gradually increasing intensity. Can be produced by micro tears, osmotic pressure, overstretching, etc.
Origin
Attachment of a muscle tendon to a stationary bone
Insertion
Attachment of a muscle tendon to a moveable bone
Muscle Fiber Type 2a
-fast oxidative fibres
- red due to large no. of mitochondria and myoglobin
- more prone to fatigue
- fast, strong muscle contractions (med force and speed)
(mile run, swimming, cycling)
Muscle Fiber Type 2b
- anaerobic
-highly developed sarcoplasmic reticulum
-high ATP stores - fast glycolytic fibers
white due to low levels of myoglobin and mitochondria
-rapid fatigue
-shot, fast bursts of power
(sprinting, weightlifting)
Functions of connective tissues
Cartilage - coats surface of bones in joints. shock absorber, keeps motion fluid (bone to bone)
Tendon - allows flexion and extension (muscle to bone)
Ligament - holds structures together, stability for synovial (bone to bone)
Types of Synovial Joints
Hinge - up and down (elbow)
Ball and Socket - rotation (shoulder)
Condyloid - front and back, nearly full rotation (wrist and fingers)
Pivot - single axis (neck)
Gliding - all directions, limited mobility (vertabrae)
Saddle - multiple axis (thumb)
Structure of a Long Bone
epiphysis - rounded end
spongy bone - ends, lighter + less dense
articular cartilage - smooth white tissue covers ends
diaphysis - long central shaft
compact bone - dense hard external layer
bone marrow - soft spongy tissue center of bones
marrow cavity - central cavity
blood vessel - controls aspects of bone formation
periosteum - ligaments and tendons attach to this dense layer of connective tissue
Characteristics common to muscle tissue
Contractibility - ability to shorten
Extensibility - ability to shorten
Elasticity - return to normal size
Atrophy - waste away of muscle tissue
Hypertrophy - increase in size
Controlled by nerve stimuli - requires an impulse
Fed by capillaries - blood will be redistributed to muscles when they are working
Features of a Synovial Joint
Articular cartilage - covers ends of bone
synovial membrane - holds synovial fluid in place
synovial fluid - provides smooth movement
bursae - fluid-filled sacs, reduce friction
meniscus -shock absorber
ligament
articular capsule - surrounding a synovial joint
