Joints - Skeletal Muscle Basics Flashcards
(63 cards)
1
Q
what is a joint?
A
- a point of contact
- articulation ⇢ articulating bones = 2 bones joined together to form a joint
⇢ usually bone and bone but tooth and bone also a joint - bones DO NOT actually contact one another ⇢ always connective tissue (CT) between surfaces on bone
2
Q
function of joints
A
- allow or limit movement (ex: bones of skull - no movement)
- facilitate growth
3
Q
joint classification
A
structural classifications: tissues that connect the bones
general rule: the more mobile a joint is, the less stable & vice versa
⇢ less stable = more clinically relevant
4
Q
structural classifications of joints
A
2 basic types:
- bones joined by solid masses of CT
⇢ fibrous, cartilaginous - bones joined by a CT capsule surrounding a lubricated (by synovial fluid) cavity ⇢ synovial
5
Q
ligaments
A
ligare = to bind ⇢ binding the bones
- bone to bone (unlike tendons)
- dense regular or irregular CT
-
intrinsic
- the ligament is what is binding the bones (ex sutural ligaments)
-
extrinsic
- supporting bands
- range of motion (ROM)
- extracapsular (outside joint) vs. intracapsular (within joint)
- ex: ACL - intracapsular
6
Q
fibrous joints
A
bones joined by solid mass of dense irregular connective tissue
- collagen fiber emerge from 1 bone ⇢ cross the space between bones ⇢ penetrate into other bone
- expanse of CT differs between joints and affects range of motion (ROM)
3 types:
- suture
- gomphosis
- syndesmosis
7
Q
fibrous joints: sutures
A
sutur = seam
only located between bones of the skill
sutural ligament – the connective tissue
juveniles ⇢ slightly movable (skull still growing)
adults ⇢ immovable – can become synostosis = bony joint
8
Q
fibrous joint: gomphoses
A
gompho = bolt or nail
tooth & bone ⇢ peg-and-socket
periodontal ligament (PDL) – fibrous
9
Q
fibrous joints: syndesmoses
A
- syndesmo = band
- more substantial and longer fibrous connections (ex: greater distance between articulating bones) ⇢ allows for more mobility
- interosseous membranes, fibrous cords
10
Q
cartilaginous joints
A
solid mass of cartilage(s) – CT forming joints
2 types:
- synchondrosis
- symphysis
11
Q
cartilaginous joints: synchondrosis
A
- connecting tissue is hyaline cartilage
- examples:
- between manubrium & 1st rib – permanent
- epiphyseal growth plates ⇢ become synostoses (bony joint) when cartilage is replaced by bone - growth of bone length – temporary
12
Q
cartilaginous joints: symphysis
A
- symphysis = growing together
- ends of bone covered with hyaline cartilage
- bones are connected by fibrocartilage
- midline ⇢ all symphyses located here
13
Q
synovial joint
A
4 structures common to most synovial joints:
- synovial (articular capsule)
- synovial (articular; joint) cavity ⇢ space present between articulating bones
- synovial fluid
- articular cartilage
14
Q
synovial capsule/articular capsule
A
- what unites articulating bones
- NOT a solid sheet of connective tissue
- encloses the articular cavity – like a sleeve
- fibrous capsule ⇢ outer layer
- dense irregular CT - collagen
- often exhibit thickening of collagen fibers (capsular ligaments)
- often reinforced/replaced by tendons
- synovial membrane ⇢ inner layer
- secretes synovial fluid
- occasionally accumulations of adipose tissues (articular fat pads) ⇢ in joints with a lot of stress - added cushion
- ex: knee joint
15
Q
synovial fluid
A
- ov = egg
- thin film over surfaces within the articular cavity
- functions:
- reduces friction
- absorbs shock
- contains phagocytic cells - take away structures
- supplies nutrients to articular cartilage
- located within articular cavity
- except over hyaline cartilage
- warm-ups: get synovial fluid to proper viscosity ⇢ allow joints to move properly, protect structures within
16
Q
articular cartilage
A
- hyaline cartilage
- NOT binding
- functions
- reduces friction between bones
- absorbs shock
- where ‘wear and tear’ occurs ⇢ avascular
17
Q
articular disc - accessory structures
A
- typically, complete discs of fibrocartilage
- divides synovial cavity
18
Q
meniscus
A
- incomplete, fibrocartilaginous disc (not completely circular)
- functions:
- improvement of fit (of bones)
- redistributes weight
- absorption of shock
- facilitation of combined movements
19
Q
labrum
A
- fibrocartilaginous lip
- ball & socket joints
- deepens the socket ⇢ better fit/protect
- shoulder & hip
20
Q
bursa
A
- bursa = purses
- sac-like structures similar to joint capsules
- found outside of joint
- lubricated
- main function: reduction of friction
- tendon/synovial sheaths
- tube-like bursae, wrapping around long tendons
21
Q
clinical connection: bursitis
A
- inflammation of bursa
- typically caused by irritation from repeated/repetitive use
- symptoms:
- pain
- swelling
- reduced range of motion
22
Q
angulation
A
angular movements
- discussed in respect to body in anatomical position
- palms face forward ⇢ radius & ulna are parallel rather than crossed over
- change in angle between topographical axes of articulating bones
23
Q
flexion & extension
A
- typically occur in sagittal plane
-
flexion: decrease in angle between articulating bones
- flex = to bend
-
extension: increase in angle between articulating bones
- exten = to stretch out
- often to restore to anatomical position ⇢ but can hyperextend past
24
Q
abduction & adduction
A
- typically occurs in frontal/coronal plane
- abduction: typically, away from midline
- adduction: typically, toward midline
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circumduction
* circ = circle
* complex angular movement
* sequential
* flexion ⇢ abduction ⇢ extension ⇢ adduction
* or opposite order
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rotation
* a bone revolves around its own longitudinal axis
* ex: head turn R/L ⇢ rotation of C1/C2 around one another
* medial/internal rotation
* lateral/external rotation
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types of synovial joint
pivot, hinge, saddle, ball-and-socket, condyloid, plane
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pivot joint
between C1 and C2 vertebrae
capable of rotation
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hinge joint
elbow, knee (modified)
capable of flexion and extension
30
saddle joint
between trapezium carpal bone and 1st metacarpal bone
capable of flexion, extension, abduction, adduction, but NOT rotation
31
ball-and-socket joint
hip joint
most freely movable
capable of flexion, extension, abduction, adduction + medial and lateral rotation
32
condyloid joint
between radius and carpal bones of wrist
capable of flexion, extension, abduction, adduction but NOT rotation
33
plane joint
between tarsal bones
articulating surfaces ⇢ relatively flat
allowing sliding/gliding movement
34
clinical connection: arthritis
* form of rheumatism affecting joints
* rheumatism: painful disorder affecting any supporting tissues of the body but doesn't involve direct injury/infection
* joints are swollen, stiff, and painful
3 types:
1. _osteoarthritis (OA)_ ⇢ degenerative, irreversible “wear + tear” - breakdown of articular cartilage (avascular!); leads to the need for replacement
2. _crystal arthritis (gout)_ ⇢ occurs when sodium urate crystals become deposited in/among soft tissues of joint; food/drink high in uric acids can lead to higher levels/risk – first metatarsophalangeal joint = most common region
3. _rheumatoid arthritis_ ⇢ autoimmune disorder – immune system attacks its own joint linings ⇢ synovial membrane, sometimes cartilage; joints in hand = greater freq.
35
properties of muscular tissue - electrical excitability
* ability to respond to certain stimuli by producing electrical signals (**action potentials - AP**) ⇢ travel along muscle cells plasma membrane due to ion channels
* property of nerve cells as well
* electrical (cardiac autorhythmic muscle) & chemical (skeletal muscle, neurotransmitters)
36
properties of muscular tissue - contractility, extensibility, elasticity
* **contractility** \*\*
* contracts when stimulated by an AP
* generates tension while pulling on attachment points
* **extensibility**
* ability to stretch without being damaged (most muscle cells)
* **elasticity**
* ability to return to original length & shape after contraction
37
functions of muscular tissue
* producing body movements
* stabilizing body position - postural muscles
* storing & moving substances within the body
* particularly true for cardiac & smooth muscle
* GI system, blood/lymphatics
* producing heat - thermogenesis
* shiver ⇢ involuntary contraction
38
types of muscle tissue
1. **skeletal muscle cells**: attached to bone; striated & voluntary (consciously controlled)
2. **cardiac muscle cells**: unique to the heart (walls); involuntary & striated ⇢ heart has pacemaker (autorhythmic)
3. **smooth muscle cells**: extensible; non-striated & involuntary
39
formation of muscle cells (fibers)
* formed by fusion of 100+ myoblasts (small mesodermal cells)
* myo = muscle
* end result is a muscle cell (fiber)
* multinucleate - multiple nuclei
40
muscle growth
* once maturity is reached, cell division is not possible
* **hypertrophy**
* hyper = above/excessive
* trophy = nourishment
* enlargement of existing muscle fibers
* increased production of myofibrils and organelles
* results from forceful, repetitive muscular activity
* can result from hormones (like HGH) in juveniles
41
muscle cells/fibers/myofibers
42
components of myofibers
* sarcolemma
* sarc = flesh
* lemma = sheath
* plasma membrane ⇢ surrounding contents
43
components of myofibers (TT)
* transverse (T) tubules
* invaginations of the sarcolemma
* invaginate in from the surface toward center of cell
* allows APs to quickly spread through the myofiber - propagate
* superficial and deep parts
44
sarcoplasmic reticulum (SR)
* fluid-filled system of membranous sacs that encircle each myofibril
* stores Ca2+ in relaxed muscle ⇢ released when activated
* terminal cisterns
* dilated end sacs of SR
* 1 T tubule + 2 terminal cisterns = triad
* when triggered, Ca2+ will be released into sarcoplasm
* triggers muscle contraction
* action potential travels down T tubule
45
components of myofibers (sarcoplasm)
* sarcoplasm
* cytoplasm
* components within:
* myofibrils
* mitochondria ⇢ ATP production
* myoglobin ⇢ red color protein only found in muscle - bind O2 molecules which diffuse into muscle fibers from interstitial fluid – O2 released when needed by mitochondria for ATP production
* glycogen ⇢ stores glucose molecules – can be broken down when needed to help produce ATP
* sarcoplasmic reticulum
* ATP ⇢ organic compound that plays a role in energy transfer – vital for allowing muscle contraction to occur and to stop
46
myofibrils
* contractile elements
* one myofibril extend the entire length of muscle fiber
47
myofilaments
* small protein structures
* 3 main types:
* contractile
* regulatory
* structural
* do NOT extend entire length of muscle fiber
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contractile proteins
* converts ATP's chemical energy into mechanical energy of motion
* **myosin**: main component of thick filament
* myosin binding site (covered by tropomyosin) – allow myosin head to bind to actin
* **actin**: main component of thin filament
* 2 thin filaments for every thick filament
* overlap during various phases of muscle contraction
49
regulatory protein
* switch contraction process & off
* part of thin filament
* **tropomyosin**: blocks myosin head from binding to actin
* in _relaxed_ muscle
* **troponin**: holds tropomyosin in place
* moves when calcium is present
50
sarcomere
basic functional unit of a myofibril
51
sliding filament mechanism
* filaments do NOT shorten. they slide past one another
* sarcomeres shorten ⇢ causing shortening of the whole muscle
52
connective tissue associated with muscle: **endomysium**
* endo = inside
* surrounds each muscle fiber (cell)
* carries small vessels
* neurovasculature (nutrients)
53
connective tissue associated with muscle: **perimysium**
* surrounds fasicles
* continuous with endomysium
* fasicles
* fasicle = little bundle
* groups of muscle fibers/myofibers
54
connective tissue associated with muscle: **epimysium**
* epi = upon
* thick CT that surrounds the periphery of the muscle
* binds all fascicles together to form muscle belly
55
connective tissue associated with muscle
* all CT is continuous
* emerges from belly of muscle as **tendons**
* fibers are continuous with periosteum and blends/interweaves with collagen of osseous extracellular matrix
* muscle contract ⇢ bring tendon with ⇢ allow bone to move
* _tendons: connect muscle belly ⇢ bone_
* movement
56
tendons
* characteristics:
* highly organized/ordered collagen fibers
* poorly vascularized ⇢ slow to heal
* lacks muscle cells
* appear opaque
* different shapes and sizes
* aponeurosis
* apo = from
* neu = a sinew
* flat sheet of tendons
57
fascia
* fascia = bandage
* wraps around groups of muscles or structures
* dense irregular CT ⇢ unlike tendons
58
‘contraction’
* in muscle physiology, ‘contraction’ does not always mean shortening on a muscle
* **isometric contraction**: contraction without a change in length
* tension generates – not enough to exceed resistance
* rest, stabilizing joints, postural muscles
* **isotonic contraction**: contraction with a change in length
* tension in the muscle remains almost constant
* external movement
59
isotonic contraction
* _concentric_ contraction: muscle _shortens_
* *eccentric* contraction: muscle *lengthens*
ex: a weightlifter uses _concentric contraction_ when lifting a dumbell and *eccentric contraction* when lowering it
* most activities include both
60
eccentric contraction – muscle injuries
muscle injuries are more common during eccentric contraction – myotendonous injuries
⇢ especially repeated
⇢ mini tears in muscle/CT/tendons
61
muscle attachment sites
* **origin/proximal/superior attachment**
* attachment site of tendon to _stationary_ bone
* typically *proximal or superior*
* **insertion**
* attachment of tendon to _movable_ bone
* typically *distal or inferior*
62
functional groups of muscles (all typically happening)
* **prime mover (agonist)**: muscle that produces most of the force in a particular action – during a contraction
* most powerful concentric contractions
* **synergist**: a muscle that aids the prime mover
* may stabilize a joint and restrict certain movements
* modify the direction of a movement ⇢ coordinated
63
functional groups of muscles
* **antagonist**: muscle that opposes the prime mover
* some cases it relaxes to give prime mover almost complete control over action
* more commonly, maintains some tension on a joint
* limits speed and range of prime mover
* prevents excessive movement, joint injury, or inappropriate actions
* **fixator**: muscle that prevents a bone from moving
* to *fix* a bone means to hold it steady, allowing another muscle attached to it to pull on something else
