Biomechanics 1 Flashcards
kinematics
description of motion, not about forces or torques
osteokinematics
gross body motion, around an axis of rotation, although axis isn’t often stationary during physiological motion
arthrokinematics
motions occurring between articular surfaces of joints
If moving segment is convex roll and glide will be …
opposite
if moving segment is concave roll and glide will be…
same direction
synarthrosis joints- fibrosis
not intended to move, skull
synarthrosis- cartilaginous
spinal disc, some movement
diarthrosis joint
synovial, most motion by far
DOF of hinge
1
DOF of pivot
1
DOF of elipsoid
2
DOF of ball and socket
3
DOF of planar
2
DOF of codyloid
1, but technically 6
DOF of saddle
2
ovoid joint
concave paired with convex
saddle joint
both parts have both concave and convexity
mechanical advantage
less force required
speed advantage
end moves way faster than the end
first class lever
teeter totter, OA joint
fulcrum in the middle
mechanical advantage depending on location of fulcrum
second class lever
wheelbarrow, not normal seen in the body
fulcrum, weight, force
ALWAYS mechanical advantage
third class lever
broom, common in the body
fulcrum, force, weight
Speed advantage
torque =
force x moment arm
newton’s 1st law
Inertia
a body remains at rest or in uniform motion unless impacted by a force
newton’s 2nd law
acceleration
F=m*a
force will accelerate mass
newton’s 3rd law
equal and opposite
balanced pair of forces
joint reaction force
muscle force will cause joint compression
center of gravity
point where gravity acts on a segment through the COM, draw a line down
composition vs. resolution of forces
composition is adding vectors, resolution is taking a force apart into vectors
positive torques are…. (counter/clcockwise)
counter
negative torques are… (counter/clockwise)
clockwise
muscle parts sizes big to little
muscle –> muscle fascicles –>muscle fiber –> myofibril –> my-filament
steps of muscle activation
- action potential traveling down the axon
- AP reaches the muscle cell
- AP travels across sarcolema
- AP travels into cell through T-tubules
- sarcoplasmic reticulum releases calcium
- Ca binds to troponin
- myosin stroke creates force
- Ca reabsorbed
- muscle inhibition/rehibition
pennate muscles have…
shorter fiber length
produce smaller joint excursions (can’t contract as much)
produce more torque
more often extensors
physiological cross sectional area (PCSA)
sum of all cross-sections of fibers in the muscle
directly proportional to max force
what does titin do?
provides 40% passive tension, bungee cord
size principle
smaller motor units recruited first
type 1 motor fibers
slow, (slow and steady wins the race)
type 2 motor fibers
fast twitch
rate coding
when subsequent action potentials begin before previous response has relaxed, the effect is summative
impulse =
force x time elapsed
work for concentric is ____ and eccentric is ___
concentric = positive (same direction) eccentric = negative (opposite direction force and motion)
force couple
type of synergy, two linear forces in different directions combine to produce rotation (ex: UT and SA)
active vs. passive insufficiency
active: inability to produce force at the extremes of joint motion
passive: muscles dont have enough length to allow full ROM at both joints
isotonic
constant effort
isokinetic
constant speed
sarcopenia
loss of muscle mass
strain
normalized change in dimension
stress
force/area
material property, independent of size of sample
direct vs. indirect attachment of ligaments
direct: continuous, gradual change from ligament to bone
indirect: merge into periosteal layer, not as strong
creep vs. stress relaxation
creep: strain changes over time with fixed stress
stress relaxation: stress reduces over time with fixed deformation
ligament injury grades
grade 1: pain, no instability
grade 2: some torn fibers, minimal instability
grade 3: completely torn
what is articular cartilage made of?
hyaline cartilage
primarily type 2 collagen
hematopoises
process of blood cell formation in red marrow in trabecular bone
osteoblasts
make bone
osteoclast
breakdown bone
osteocytes
mature cells that sense the load
cortical bone
outer shell
cancellous (trabecular) bone
spongy, inter-meshing
wolff’s law
bone remodels according to the loads and stresses to which it is subjected
angle of inclination of humerus
130-150 degrees superiorly
angle of torsion of the humerus
30 degrees posteriorly
during arm elevation, the clavicle ____, ___, ___ rotates
elevates, retracts, and posteriorly rotates
force couple for scapular movement
trap and SA
what articulates with the capitulum of the humerus?
the fovea on the head of the radius
what articulates with the trochlea of the humerus?
the ulna
normal carrying angle of the elbow?
about 18 degrees
valgus = more bent
varus = more straight
parts of the medial collateral ligament of the elbow
anterior: strongest, tight throughout ROM
posterior: tight in extreme flexion
transverse: minimal stability
parts of the lateral collateral ligament of the elbow
radial
lateral (ulnar): tight with full flexion
which elbow flexor is most active during rapid movements?
brachioradialis
which elbow flexor provides the greatest force throughout the range?
brachialis
is pronator teres an elbow flexor?
yes
what is anconeus for?
low level activity and humeroulnar stability
triceps recruitment order
medial head, lateral head, long head
does the interosseous membrane prevent radial distraction?
no, it is on slack… the oblique cord might help, but mostly its the annular ligament
in the proximal radioulnar joint, roll and glide happen in _____ direction
the opposite
in the distal radioulnar joint, roll and glide happen in ______ direction
the same
TFCC
disc, capsular ligaments and ulnar collateral ligament
which muscle is recruited for forceful supination or pronation
supination: biceps brachii
pronator: pronator teres
nerves that innervate elbow flexors
- musculocuateous (biceps, brachialis)
- radial (brachioradialis)
- median nerve(pronator teres)
which is stronger elbow flexors or extensors?
flexors
which is stronger elbow supinators or pronators?
supinators
radial inclincation or ulnar tilt
angle of distal end of radius toward ulna
palmar tilt
sagittal plane inclination of of distal radius
which row of carpal bones is more mobile?
proximal row
what goes through the carpal tunnel?
FDS, FDP, FPL, and median nerve
close packed position of the radoiocarpal joint
extension (palmar ligaments are thicker)
the axis of rotation of wrist movement is centered through…?
the capitate
ROM of the wrist
flexion: 80-90
extension: 70-80
radial dev: 15
ulnar dev: 30-45
wrist extensor compartments
1: extensor pollicis brevis, abductor pollicis longus
2: extensor carpi radialis longus and brevis
3: extensor pollicis longus
4: extensor digitorum and extensor indicis
5: extensor digiti minimi
6: extensor carpi ulnaris
hand interossei and lumbricals have what action
MCP flexion, PIP and DIP extension
extensor digitorum motion
extends PIP, MCP, and wrist
flexion/extension of CMC roll and glide is in the ______ direction
same.
this is in the plane of the palm
abduction/adduction of the CMC roll and glide is in the _____ direction
opposite
what two motions make up opposition
flexion and internal rotation
arches of the hand
proximal transverse: distal row of carpals
distal transverse: through MCP joints
longitudinal: Shape of 2nd and 3rd rays
what connects the vertebral body to the vertebral arch?
the pedicle
posterior elements of the vertebra
transverse process, laminae, spinous process
cervical plexus levels
C1-C4
which cervical vertebra has the most prominent transverse processes?
C1
which cervical vertebra has no body?
C1
which cervical vertebra has a dens?
C2
which cervical vertebra has the largest spinous process?
C7
which ligaments provide stability to the dens?
transverse and alar ligamanets
is the dens anterior or posterior?
anterior
the nuchal ligament is an extension of what ligament?
supraspinous ligament
where is the ligament flavum
immediately posterior to the spinal cord
tectorial membrane is the continuation of which ligament?
posterior longitudinal ligament
what motion does the alar ligament check?
axial rotation
which two ligaments make up the cruciform ligaments?
transverse ligament and vertical cruciate
what type of joints are facet joints?
plane joints
normal cervical flexion and extensions and side bend
flexion: 45-50
extension: 80-85
side bend: 35-40
the most cervical flexion occurs at these two joints
C4-C5 and C5-C6, possibly more prone to injury
costal facet patterns
T1: 1 full and 1 demi
T2-T8: 2 demis
T9: 1 demi superiorly
T10-T12: 1 full, no costotransverse
normal thoracic motion
flexion: 30-40
extension: 25-30
rotation: 30-35
sideband: 25-30
arthrokinematics of thoracic rotation
superior facet slides towards direction of motion
arthrokinematics of thoracic sidebend
ipsilateral slides inferior, contralateral slides superior
lumbosacral angle
cranial surface of S1 and the horizontal plane (L5 dips below horizontal FYI)
normal in standing is 30-40 degrees
normal range for lumbar spine
flexion: 40-50
extension: 15-20
sideband: 20
rotation: 5-7
arthrokinematics of lumbar rotation
ipsilateral gapping, contralateral approximation
