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MSK > Joints - Skeletal Muscle Basics > Flashcards

Joints - Skeletal Muscle Basics Flashcards

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
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2
Q

function of joints

A
  • allow or limit movement (ex: bones of skull - no movement)
  • facilitate growth
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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

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4
Q

structural classifications of joints

A

2 basic types:

  1. bones joined by solid masses of CT
    ⇢ fibrous, cartilaginous
  2. bones joined by a CT capsule surrounding a lubricated (by synovial fluid) cavity ⇢ synovial
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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
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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
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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

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8
Q

fibrous joint: gomphoses

A

gompho = bolt or nail

tooth & bone ⇢ peg-and-socket

periodontal ligament (PDL) – fibrous

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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
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10
Q

cartilaginous joints

A

solid mass of cartilage(s) – CT forming joints

2 types:

  1. synchondrosis
  2. symphysis
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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
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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
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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
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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
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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
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16
Q

articular cartilage

A
  • hyaline cartilage
  • NOT binding
  • functions
    • reduces friction between bones
    • absorbs shock
  • where ‘wear and tear’ occurs ⇢ avascular
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17
Q

articular disc - accessory structures

A
  • typically, complete discs of fibrocartilage
  • divides synovial cavity
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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
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19
Q

labrum

A
  • fibrocartilaginous lip
  • ball & socket joints
    • deepens the socket ⇢ better fit/protect
    • shoulder & hip
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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
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21
Q

clinical connection: bursitis

A
  • inflammation of bursa
  • typically caused by irritation from repeated/repetitive use
  • symptoms:
    • pain
    • swelling
    • reduced range of motion
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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
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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
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24
Q

abduction & adduction

A
  • typically occurs in frontal/coronal plane
  • abduction: typically, away from midline
  • adduction: typically, toward midline
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25
Q

circumduction

A
  • circ = circle
  • complex angular movement
    • sequential
  • flexion ⇢ abduction ⇢ extension ⇢ adduction
    • or opposite order
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26
Q

rotation

A
  • 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
27
Q

types of synovial joint

A

pivot, hinge, saddle, ball-and-socket, condyloid, plane

28
Q

pivot joint

A

between C1 and C2 vertebrae

capable of rotation

29
Q

hinge joint

A

elbow, knee (modified)

capable of flexion and extension

30
Q

saddle joint

A

between trapezium carpal bone and 1st metacarpal bone

capable of flexion, extension, abduction, adduction, but NOT rotation

31
Q

ball-and-socket joint

A

hip joint

most freely movable

capable of flexion, extension, abduction, adduction + medial and lateral rotation

32
Q

condyloid joint

A

between radius and carpal bones of wrist

capable of flexion, extension, abduction, adduction but NOT rotation

33
Q

plane joint

A

between tarsal bones

articulating surfaces ⇢ relatively flat

allowing sliding/gliding movement

34
Q

clinical connection: arthritis

A
  • 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
Q

properties of muscular tissue - electrical excitability

A
  • 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
Q

properties of muscular tissue - contractility, extensibility, elasticity

A
  • 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
Q

functions of muscular tissue

A
  • 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
Q

types of muscle tissue

A
  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
Q

formation of muscle cells (fibers)

A
  • formed by fusion of 100+ myoblasts (small mesodermal cells)
    • myo = muscle
  • end result is a muscle cell (fiber)
    • multinucleate - multiple nuclei
40
Q

muscle growth

A
  • 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
Q

muscle cells/fibers/myofibers

A
42
Q

components of myofibers

A
  • sarcolemma
    • sarc = flesh
    • lemma = sheath
    • plasma membrane ⇢ surrounding contents
43
Q

components of myofibers (TT)

A
  • 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
Q

sarcoplasmic reticulum (SR)

A
  • 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
Q

components of myofibers (sarcoplasm)

A
  • 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
Q

myofibrils

A
  • contractile elements
  • one myofibril extend the entire length of muscle fiber
47
Q

myofilaments

A
  • small protein structures
  • 3 main types:
    • contractile
    • regulatory
    • structural
  • do NOT extend entire length of muscle fiber
48
Q

contractile proteins

A
  • 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
Q

regulatory protein

A
  • 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
Q

sarcomere

A

basic functional unit of a myofibril

51
Q

sliding filament mechanism

A
  • filaments do NOT shorten. they slide past one another
    • sarcomeres shorten ⇢ causing shortening of the whole muscle
52
Q

connective tissue associated with muscle: endomysium

A
  • endo = inside
  • surrounds each muscle fiber (cell)
  • carries small vessels
    • neurovasculature (nutrients)
53
Q

connective tissue associated with muscle: perimysium

A
  • surrounds fasicles
  • continuous with endomysium
  • fasicles
    • fasicle = little bundle
    • groups of muscle fibers/myofibers
54
Q

connective tissue associated with muscle: epimysium

A
  • epi = upon
  • thick CT that surrounds the periphery of the muscle
  • binds all fascicles together to form muscle belly
55
Q

connective tissue associated with muscle

A
  • 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
Q

tendons

A
  • 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
Q

fascia

A
  • fascia = bandage
  • wraps around groups of muscles or structures
  • dense irregular CT ⇢ unlike tendons
58
Q

‘contraction’

A
  • 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
Q

isotonic contraction

A
  • 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
Q

eccentric contraction – muscle injuries

A

muscle injuries are more common during eccentric contraction – myotendonous injuries

⇢ especially repeated

⇢ mini tears in muscle/CT/tendons

61
Q

muscle attachment sites

A
  • 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
Q

functional groups of muscles (all typically happening)

A
  • 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
Q

functional groups of muscles

A
  • 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

MSK (6 decks)

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