Exam 4 Flashcards
how many bones in the axial skeleton ?
74 bones (skull, vertebrae, ribs)
How many bones in the appendical skeleton
126 bones (extremities, shoulder girdle, pelvis)
How many bones in the auditory ossicles?
6 bones
how many bones in the human body?
206
what are the 5 functions of bones?
- Support
- Protection
- Attachment
- Mineral Reserve
- Hemopoiesis
force distribution inside the body, related to pressure
stress
6 types of forces
- Compression
- Tension
- Shear
- Bending
- Torsion
- Combined loading
explain compression forces
act along the long axis of a bone, tending to push the ends of bone together
explain tension forces
opposite of compressive, stretching force
explain shear forces
sliding; force is parallel to the cross section of the bone
explain bending forces
application of an eccentric force to the end of the bone causing compression & tension at the same time. (ex/ rickets: tension on one side, compression on the other)
explain torsion forces
twisting around the long axis of bone
explain combined loading
including more than 1 of the previous force types
single force large enough to cause injury (ex: car tire rolling over the foot)
traumatic force load
multiple application of forces, usually with smaller magnitudes (ex: stress fracture)
repetitive force load
4 properties of bone structure
- stiffness
- compressive strength
- elasticity
- tensile strength
ratio of stress to strain
stiffness
stress = ?
F / area (force divided by area)
amount of change in the bone’s shape
strain
what is compressive strength?
a bones resistance to compression
what is elasticity?
a bone’s ability to regain it’s original shape after deformation, provided by collagen
what is tensile strength?
resistance to being pulled apart
where does longitudinal growth take place?
epiphyseal plates
explain longitudinal growth. what ages does this occur?
epiphyseal plates produce new bone cells on the diaphysis of the bone up to [ages 18-25]
explain circumferential growth
internal layers of the periosteum lay down concentric layers of bone
where does bone resorption occur?
around the medullary cavity
osteoclasts vs. osteoblasts
osteoclasts: resorb bone (take it away)
osteoblasts: make new bone
both remain in balance until 40-60 years of age
3 classifications of bone responses to stress
- wolfe’s law
- hypertrophy
- atrophy
what is wolfe’s law?
a bone grows or remodels in response to the forces of demands placed upon it
Hypertrophy
increased bone density based on loading
atrophy
loss of bone tissue (happens in astronauts)
what is a fracture?
a disruption in bone continuity (break/crack)
bone resists _______ the best
compression
5 types of fractures
- Avulsion
- Comminuted
- Impacted/compression
- Greenstick
- Stress fx
Avulsion fracture
occurs in tensile loading. bone chip pulled off. (kids jump off high objects, lift heavy objects)
comminuted fracture
results in many fragments [car accident, gun shot]
impacted or compression fracture
fracture pressed together by a compressive load (in spine; standing on a broken bone)
Greenstick fracture
incomplete fracture to to bending; most common in children (soft bones)
Stress fracture
small cracks caused by repeated low stresses (most common in tibia)
strong slightly extensible protein found in collagenous tissue
collagen [fibers allow flexibility]
elasticity of collagen determines differences in what?
joint ROM
a joint needs sufficient _______ for efficient & safe movement. Where does this come from?
- lubrication
- synovial fluid from bursae sacs
articular cartilage
1-7 mm thick coating over epiphyses at synovial joints
what does articular cartilage do?
spreads out the load at the joint, minimizes friction - no bones rubbing together [50% stress reduction]
where is articular cartilage located?
epiphyses (end of bone)
what helps prevent the loss of cartilage?
regular exercise
articular fibrocartilage can be found as either a ______ disc or ______ disc
fibrous or partial
articular fibrocartilage ______ and ________ loads
absorbs, distributes
what does articular fibrocartilage do for bones?
holds bones in place, minimizes slippage
what does articular fibrocartilage do for joint?
lubrication (synovial fluid)
improves joint congruency
examples of articular connective tissue
ligaments and tendons
what does the elastic limit of articular connective tissue mean?
stretched up to a point, then surgery is required
example of a ligament injury? tendon/muscle injury?
sprain; strain
joint stability is a joints ability to resist ______
dislocation
joint stability depends on what
shape of the articulating surfaces
the shape of the articulating surfaces of a joint is usually
concavoconvex [ball and socket]
what is closed pack position
a joint has maximum contact between articulating surfaces [example: knee in full extension]
what is loose packed position
a joint has the least contact between surfaces [example: 25 degree knee flexion]
more ligaments = more ____
stability
with muscle insertion, what are the 3 ligament components?
- rotary component [causes movement]
- stabilizing component [more stable]
- dislocating component [less stable]
what is fascia?
sheet of fibrous connective tissue enveloping, separating, or binding muscles and organs
what does fascia do?
increases origin or insertion sites of muscle
technique used by therapists in regards to fascia
myofascial release
another type of connective tissue besides fascia that protects muscles
skin
what 4 things does joint flexibility rely on?
- shape of articular surfaces
- intervening muscle or fat
- muscle tension
- extensibility of collagenous tissue
ACSM guidelines on stretching
- 10 minutes long
- 4 or more reps per muscle group
- 2-3 days per week
what is the minimum stretching technique to improve flexibility?
2 to 4 repetitions for 10-30 seconds [totals 1 min per muscle group]
5 types of stretching
- active
- passive
- static
- ballistic
- PNF [proprioceptive neuromuscular facilitation-both active & passive]
what make up the functional unit of the spine
2 adjacent vertebrae & the soft tissue between them
which is the primary site of biomechanical analysis of the spine
L5/S1 {lumbosacral joint}
primary curves of the spine
present at birth; thoracic and sacral
secondary curves of the spine? what are the developed for?
cervical and lumbar, developed to support body weight
spinal curvature can be changed by …
pathology or repeated load - wolfe’s law
3 possible pathological curves
- Excessive lumbar lordosis
- Excessive kyphosis
- Scoliosis
lumbar lordosis is also called
sway back
explain lumbar lordosis
abs can’t support pelvis so anterior pelvic tilt occurs (tight back)
pathological spinal curvature common in pregnancy
functional lordosis
what is excessive kyphosis?
exaggerated thoracic curvature [hunch back, as seen in computer or desk jobs**]
what is swimmers back?
functional kyphosis due to muscle development/use
what stroke causes swimmers back
butterfly stroke
what is scheuermann’s disease? what condition is it related to?
- wedge shaped vertebrae due to agnormal epiphyseal plate
- kyphosis
what is scoliosis
- lateral curvature [C or S curve] of the spine
- disorientation of articulating facets
what determines movement capabilities in scoliosis
spinous & transverse processes
_____ _______ discrepancy is common in scoliosis
leg length [unequal]
what are intervertebral disks
cushions between vertebrae
what do intervertebral disks do?
- shock absorption
- sponges (fill with water in a horizontal position, compresses when standing)
intervertebral disks make up ____ height of a healthy spine
1/4 of height
we lose ____ of height by the end of each day due to water loss from disks [gravity] & gain height back when sleeping
1 cm
astronauts can gain ____ of height in space
5 cm
what is annulus fibrosis
outer ring of fibrous cartilage of the disk that protects the disc from bending/torsion
what is nucleus pulposus
gelatinous center of the disk that resists compression
spinal flexion = ?
spinal extension = ?
lateral flexion = ?
spinal rotation = ?
- forward bending
- backward bending
- side bending
- twisting
what movements cause compression & tension forces
flexion, extension, lateral flexion
what movement causes shear & torsional stress (disk rupture)
spinal rotation [twisting]
the pumping action of a disc makes up for its ______ nature
avascular
What helps prevent disc degeneration
exercise
we lose fluid in our discs beginning at age…
35
the elderly have lost ___% of fluid content in discs therefore they lose _____
35%, height
what is the most expensive workman’s comp. injury?
low back pain
how much of the population suffers from low back pain?
70-80%
most common injured sights in LBP (low back pain)
L4/L5, & L5/S1
11 factors related to injury development
- Skeletal Alignment
- Muscle strength
- Muscle endurance
- Joint flexibility
- Joint Alignment
- Bone mineral density
- Previous injury
- Muscle firing patter
- Body composition
- Body mass (weight)
- Psychological factors
“She Makes Music. John Joins. Beats Prevent My Boyfriend from Becoming Pissed”
Affects the pattern of stress imposed upon tissues
Skeletal alignment
Affects the magnitude of loading and shock absorption
Muscle strength
(Current level of fatigue) affects magnitude of loading & shock absorption
muscle endurance
Affects loading pattern of segments. Influenced by tissue temperature
Joint flexibility
Affects area of force distribution
Joint alignment
Affects strength of bone to withstand stress. Influenced by diet and hormone levels.
bone mineral density
Affects tissue threshold
Previous injury history
Affects magnitude of load and pattern of imposed load
muscle firing pattern
Affects magnitude of imposed load.
body mass/weight
Affects magnitude of imposed load
body composition
Affects pain threshold. Higher threshold of pain vs. others, etc.
psychological factors
5 extrinsic factors
- Task
- Environment
- Equipment
- Level of participation
- Rules
3 characteristics of task
- nature of task
- intensity of performance
- frequency of performance
Affects the magnitude of loading and recovery. Single bout vs. repetitive (continuous) activity. Movement pattern
nature of the task
Affects magnitude of loading
intensity of performance
Affects recovery time
frequency of performance
Environment involves playing surface. What are 3 points to consider in choosing playing surface or environment?
- slope
- hardness
- material condition
part of environment that affects magnitude and direction of loading
slope
part of environment that affects magnitude of loading and friction
hardness & material condition
footwear falls under the equipment category; what are 2 traits to take into consideration with footwear?
- Outsole materials
2. Midsole materials
which footwear trait affects magnitude & friction? which affects the amount of cushioning & padding?
outsole materials; midsole materials
Level of participation affects ______ of _______ ______
magnitude of forces imposed
two aspects of “Level of recreation”
- recreational vs. competitive
2. skill level of components
rules affect the _____ and ______ of loading and the ______ of ____ distribution
- magnitude, frequency
- pattern of force
4 properties of muscle
- extensibility
- elasticity
- irritability
- contractility
ability to stretch
extensibility
ability to return to normal shape
elasticity
ability to respond to stimuli
irritability
ability to develop tension
contractility
muscle tension is a _____ force that creates joint ______
pulling; torque
3 types of tension/contraction
concentric (shortening)
isometric (no movement)
eccentric (lengthening)
single muscle cell
muscle fiber
basic contractile unit of muscle
sarcomere
muscles have varied lengths & _______
diameters
longest muscle? Largest?
longest: sartorius
Largest: latissimus dorsi
what comprises a motor unit?
motor neuron & all the fibers it innervates
fibers of motor units can be _______ with those of other motor units
interspersed
motor units are confined to a single muscle, how many do large muscles have?
1,000 - 2,000 fibers per motor unit
why do small muscles such as in the eye have a smaller amount of fibers/motor unit?
for precise control (<100)
3 longitudinal/parallel muscles
sartorius, biceps femoris, biceps brachii
direction of longitudinal/parallel muscle pull
toward each other in y [vertical] direction
3 pennate muscles
tibialis posterior, rectus femoris, deltoid
direction of pennate muscle pull
in x & y direction
the greater the angle of ______, the ___ force produced by the muscle
pennation, less force
in pennate muscles, there are more _____/______ so it (may/may not?) make a large difference in force production
- fibers/aerobic
- may not
2 types of muscle fibers
- slow twitch fibers
- fast twitch fibers
describe slow twitch fibers
- type 1
- ~50%
- oxidative, aerobic
Fast-twitch fibers, also known as type II fibers, have 3 categories. Explain them what are they
Type IIa, IIx and IIc
Type IIa fibers
25%, fast oxidative glycolytic (FOG), aerobic & anaerobic
Type IIx fibers
~25%, fast glycolytic (FG), anaerobic
Type IIc fibers
1-3%, limited information known
3 factors affecting muscle force
- velocity of shortening
- duration of muscle contraction
- muscle length-tension relationship
a higher muscle ______ decreases force
velocity
the longer the ______ of muscle contraction, the more force produced
duration
a muscle can develop tension from ______ of resting length
60-160%
greatest active tension is at…
resting length
what is active insufficiency in muscles?
function of 2 joint muscles; inability for them to achieve full joint ROM at same time
what is an example of active insufficiency?
cannot bend wrist down with fingers in a fist, instead fingers open up
muscle strength is related to what 5 things?
- cross sectional area
- training state
- innervation [neural adaptation]
- angle of muscle attachment
- moment arm length
what is the equation for muscle power??
muscle force X muscle velocity
maximal muscle power occurs at approximately ____ to ____ max velocity of muscle shortening
1/3 to 1/2
max power of a muscle is affected by
movement squad
muscle power is important in what type of sports
explosive
a ______ athlete will give a better performance
powerful
Ability to exert tension over a period of time
muscle endurance
5 factors affecting muscle endurance
- muscle fiber type
- force & speed requirements
- fatigue in muscle (lack of ATP, no contraction)
- neurologic fatigue
- no action potential generated
temperature affects performance. What do higher temperatures increase?
- max isometric tension
- velocity of shortening
- strength power endurance
- reduced motor units required for work
- optimal muscle temperature
