Biomechanics Final Review Flashcards
1
Q
What are statics?
A
Body is at rest
2
Q
What are dynamics?
A
Body is in motion
3
Q
What is the description of the movement of the human body as a whole?
A
Translation of the center of mass
4
Q
What is movement powered by?
A
Muscles that rotate the limbs
5
Q
What is rotation of a joint called in biomechanics? Why?
A
- Angular motion
Because it has an axis
6
Q
What is an axis?
A
The pivot point for angular motion of the whole body or body segments
7
Q
What is the motion of the rotating body at the axis?
A
zero
8
Q
What is a kinematic chain?
A
A series of articulated segmented links
9
Q
What are the two perspectives of a movement at a joint?
A
- proximal segment rotating on fixed distal segment
- distal segment rotating on fixed proximal segment
10
Q
What are the two persectives for knee flexion?
A
- femoral - on - tibial movement
- tibial on femoral movement
11
Q
What is roll in arthrokinematics?
A
multiple points along one rotating surface contact multiple points on another articular surface
12
Q
What is slide in arthrokinematics?
A
A singular point on one articular surface contacts multiple points on another articular surface
13
Q
What is the roll and slide of a convex on concave joint?
A
Rolls and slides opposite directions
14
Q
What is the rolls and slide of a concave on convex joint?
A
Rolls and slides same
15
Q
What are kinetics?
A
The effect of forces on the body
16
Q
What is a force?
A
A push or pull that can produce/arrest/ or modify movement
17
Q
What is the standard unit of force?
A
Newtons
18
Q
What is the force on the body?
A
Load
19
Q
What does force do?
A
Move, fixate, stabilize (also potential to deform/injure)
20
Q
What type of force can happen in a car accident?
A
Shear
21
Q
What kind of force happens to the anterior disc during neck flexion?
A
Bending
22
Q
What kind of force happens to the posterior disc during neck flexion?
A
Tension
23
Q
What kind of force happens with rotation and extension of the neck?
A
Combined loading
24
Q
What is the ability of the periarticular connective tissues to accept and disperse loads impacted by?
A
Aging, trauma, prolonged immobilization, disease
25
What is X in a stress strain curve?
The % increase in a tissue related to the original length
26
What is Y in a stress strain curve?
The internal resistance generated as it is resisting deformation
27
What is a toe region in a stress strain curve?
Collagen fibers are crimped
28
What is the elastic region in a stress strain curve?
return to original length and energy is recovered
29
What is the plastic region in a stress strain curve?
Plastic deformation - energy lost
30
What is the ultimate failure point for tendons?
8-13%
31
What is the yield point in a stress strain curve?
The point at which it turns from elastic to plastic
32
What is creep?
Increasing deformation under constant load
33
What is internal torque?
Internal force and internal moment arm
34
What is external torque?
External force (gravity) and external moment arm
35
What happen if internal torque and external torque are equal?
Rotary equilibrium
36
What is leverage?
Moment arm length possessed by a particular force, changes throughout the ROM
37
What is FY in a force diagram?
Force that rotates
38
What is F in a force diagram?
The muscle
39
What is FX in a force diagram?
Compressing or distracting joint
40
What is an isometric muscle activation?
Maintains a constant length; internal = external torque
41
What is a concentric muscle activation?
Muscle shortens; internal torque is more than external; rotation in direction of activated muscle
42
What is a eccentric force?
Muscle lengthens as it is being elongated by another more dominant force; external torque is more than internal torque; joint rotation is dictated by external torque
43
What is an agonist?
Muscle that initates or executes the particular movement
44
What is an antagonist?
Opposite action of a particular agonist
45
What is a synergist?
Cooperating muscles for execution of a particular movement
46
What is a force couple?
2 or more muscles produce forces in different linear directions - resulting torques act in same rotary direction
47
What is an evolute?
The path of serial locations for the instantaneous axis of rotation
48
What happens to the path of the evolute when the opposing joint surfaces are less congruent?
Longer and more complex
49
What are goniometric measures?
An estimate of the average axis of rotation that is used
50
When is the estimate of the IAR more accurate?
The smaller the angular range
51
What is collagen made up of structurally?
A triple helix
52
If stress is always in the same direction, what will the collagen fibers do?
Orient themselves to run paralell
53
If the stress is in different directions, it leads to what? ( in terms of collagen)
Interlaces lattice effect
54
What are the 2 basic elements of connective tissue?
Cells and extra-cellular matrix made of fibrous components and ground substance
55
What is ground substance?
A water saturated matrix or gel
56
What gives ground substance physical resilience?
GAGs
57
What is associated with the matrix? Why?
A large quantity of water - as a function is to enable diffusion of nutrients and waste products and friction free movement of fibers
58
What does the ground substance do?
Transmits loads
59
What is the composition and role of the matrix determined by?
The stress that impacts the cells
60
What do GAGs do?
Give physical resiliance
61
What are GAGs?
Glycoaminoglycans - large protoglycan complex
62
How does cartilage get nutrition?
Milking action via synovial fluid caused by intermittent joint loading
63
What happens to the large proteoglycan complexes in regards to nutrition of the cartilage?
They are trapped, attract water, but repel eachother
64
What helps the PGs protect the cells from outside forces?
The stiffness and hydrophilic nature of the sugar chains
65
What does the nutrition to the cartilage do?
Increases the capacity for loads
66
What do bone spurs form from?
Increased spinal stresses
67
Where is bone laid down?
Areas of high stress
68
Where is bone reabsorbed?
Areas of low stress
69
What are obeoblasts constantly doing?
Synthesizing ground substance/collagen; deposition of salts
70
What do osteoclasts do?
Remove bone
71
What do osteoblasts do?
Lay down new bone
72
What happens with immobilization?
marked changes in the structure and function of connective tissues - loss of mass, volume, and strength
73
What happens with mechanical strength with immobilization?
Reduced
74
How long until mechainical strength is lost with immobilizaiton?
within days
75
What should we know about the recovery after immobilizaiton?
Slow - often incomplete
76
What is aging accompanied by?
A slowing of the rate of fibrous proteins and proteoglycan replacement and repair in all periarticular tissues and bone
77
What does aging cause us to use in terms of forces?
Loss of ability to restrain and disperse forces - microtrauma
78
How can we mitigate the effects of aging?
Physical activity and resistance training
79
What is endomysium?
A thin layer of connective tissue that surrounds an individual muscle cell/fiber; external to the sarcolemma
80
What does endomysium do?
Helps transfer the contractile force inside it from the actin/myosin to the tendon
81
What is the perimysium?
A sheath of connective tissue surroudning a bundle of muscle fibers (fascicle)
82
What does the perimysium do?
Provides a conduit for blood vessels and nerves; tough and resiliant to stretch
83
What is the epimysium?
A sheath of fibrous elastic tissue surrounding a muscle belly
84
What should we know about the epimysium ?
Resistant to stretch
85
What are contractile proteins?
Actin
myosin
86
What are non-contractile proteins?
Cytoskeleton within muscle fibers
supportive structure between fibers
87
What do non-contractile proteins do?
Play a role in transmission of force but do not contract
88
What provides passive tension within the muscle cell?
Titin
89
What stabilizes the alignment of adjacent sarcomeres?
Desmin
90
What is a fusiform muscle?
Fibers run parallel to one another and to a central tendon
91
What are fusiform muscles designed for?
Mobility, low force over long range
92
What are pennate muscles?
Fibers approach their central tendon obliquey, contain a larger number of fibers per area
93
What do pennate muscles do?
generate larger forces
94
What type of muscle are most muscles in the body?
Pennate
95
What does a physiologic cross-section area tell us?
The amount of active proteins available to generate active force
96
What is a max force potential of a muscle proportional to?
the sum of the cross sectional area of all its fibers
97
What is a pennation angle?
The angle of orientation between the tendon and the fibers
98
Which type of muscle fires quicker?
Fusiform
99
Most muscles have pennation angles between __ and __
0 and 30
100
What is a series?
All components are connected end to end forming a single path
101
What is a parallel?
All components connected across each other
102
What is a series elastic component?
Tissues attached end to end with the active proteins: tendon, titan
103
What is a parallel active component?
Tissues lie parallel with active proteins: epi/peri/endomysium
104
What does a stretched muscle do?
Has elasticity and temporarily stores a fraction of the energy that created the stretch
105
Muscle is viscoelastic, what does this mean?
Time changes its behaviour
106
What is elasticity in terms of protection?
Dampening mechanism, protects muscle
107
When are muscles loaded? (what action)
Eccentric action
108
What does increasing the stretch load do?
Increases intensity
109
What are the components of plymetric exercise?
Elasticity and viscoelasticity
110
What is the ultimate force generator?
The sarcomere
111
What are muscle fibers and cells composed of?
Myofibrils
112
What are repeating subunits of myofibrils known as?
Sarcomeres
113
What are dark bands / A bands?
Thick myosin
114
What are light bands/ I band?
Thin actin
115
What helps keep sarcomeres aligned?
Structural proteins, also provide mechanical stability
116
How do all the structural proteins disperse forces?
Longitudinally and laterally
117
What does the shortening of sarcomeres in unison do?
Creates movement
118
What forms a cross bridge?
Each myosin head attaches to an adjacent actin filament
119
What does the amount of force in a sarcomere depend on?
the simultaneously formed cross bridges & the length at any moment
120
What length gives the greatest possible crossbridges?
Resting
121
What is an action potental?
A sum of all competing inhibitory/excitatory inputs
122
What is rate coding?
The rate of sequential activation - smooth increasing muscle force
123
What happens with smaller sized units?
Less force/more fine motor control
124
What happens with larger units?
Larger force and high innervation ratio
125
What is recruited first? small or large?
Smaller recruited before larger
126
What is the rate coding and recruitment of the motor unit specific for?
highly specific to demand
127
Which muscle activation requires less units and more cross bridges?
Eccentric
128
What do concentric movements require?
more motor units for same muscle force
129
What is muscle fatigue?
Exercise-induced decline in max voluntary muscle force despite max effort
130
What is the basis of neuromuscular overload and adaptation training?
muscle fatigue
131
What reverses muscle fatigue normally?
Rest
132
What is rate of fatigue specific to?
Task and rest-work cycle
133
What do high intensity short duration activities do in terms of fatigue?
Rapid fatigue, recover after a few minutes of rest
134
What does low intensity low duration activity require afterwards?
longer rest
135
Are women or men less fatiguable?
Women
136
Are older of younger people less fatiguable with isometrics?
Older
137
When does DOMS peak?
24-72 hours
138
What is a 1RM used for?
Quantify strength gains
139
What does strength training do with sarcomeres?
Added in parallel
140
When does atrophy occur?
Within first few weeks (3-6% in first week)
141
What does immobility do to muscle type?
Increase slow twitch
142
What does Excursion do? (jaw)
Serves as a pivot point with contralateral condyle making a wider arc of rotation
143
What do protrusion and retrusion do?
Follow slope of articular prominence
144
What is depression and elevation of the jaw?
combo rotation and translation, axis contantly moving, no set ratio of rot/translation
145
What happens during the early phase (jaw)?
35-50% primarily rotation, posterior rotation on concave inferior surface of the disc; mandible goes inferior/posterior
146
What happens during late phase?
Final 50-65%, primarily translation, condyle and disc slide forward and inferior along articular eminence
147
What are the primary muscles of mastication?
Masseter, temporalis, medial pterygoid, lateral pterygoid
148
What is the neutral zone?
The amount of intervertebral movement that occurs with the least passive resistance from the surrounding tissues
149
What increases the neutral zone?
Injury or weakness of surrounding tissues
150
What is spinal instability?
Loss of intervertebral stiffness that can lead to abnormal and increased interverterbal motion
151
Where can core stability also be viewed from?
A segmental or a whole spine level
152
What makes the neutral zone decrease?
muscle force
153
What are the sagittal plane kinematics of the neck ?
120-130 degrees combined
80 degrees ext
40-50 flex (20-25% total at OA/AA, rest C2- C7)
Medial -lateral axis
154
When is the vertebral canal greatest?
Full flexion, least in ext
155
What creates restraint in the neck in flexion?
Ligamentum nuchae, interspinous ligaments in flexion, compression forces on anterior margin of AF
156
What creates restraint in the neck in extension?
Approximation of apophyseal joints, compression forces on posterior margin of AF
157
What are the arthrokinematics of the AO joint?
Occipital condyles roll backwards in ext/ forwards in flexion, slide in opposite direction
158
How much flexion and ext at the AA joint?
15 degrees
159
What are the arthrokinematics of C2-C7?
Follows plane of facets, overall 90-100 degrees of motion
160
What are the arthrokinematics of extension an C2-C7?
Inferior facets slide inferior and posterior 55-60 degrees and load inferior apophyseal joints
161
What are the arthrokinematics of flexion of the c2-c7 joints?
Inferior facets slide superiorly and anteriorly, 35-40 degrees, stretches capsule and less joint surface contact
162
What percentage of flexion of the neck do we need to back up while driving?
42-48% flexion
163
What degree of flexion on each side do we need to drive?
65-75 degrees and 50-60% axial rotation
164
What is the AA designed for?
rotation
165
How much rotation each direction at the AA joint?
35-40
166
What slides and what is the axis at the AA joint?
Atlas slides, axis is dens
167
What does full rotation stretch?
Both vertebral arteries
168
What is the movement at C2-C7 guided by?
Facets at 45 degrees
169
What is the glide at C2-C7 joints?
Inferior glides posteriorly/inferiorly same side, opposite is anterior and superior
170
What are the arthrokinematics of side bending of the neck in the frontal plane?
Inferior facets slide inferiorly and slightly postieriorly, lateral flexion side moves superiorly and anteriorly
- small rolling @ occipital condyles, slide opposite
171
What are the ostrokinematics of elevation of the SC joint?
Frontal plane
A-P axis
35-45 degrees elevation
10 degrees degression
172
What are the arthrokinematics of elevation and depression at the sc joint?
- longitudinal diameter
- elevation: convex surface rolls superiorly and slides inferiorly
- depression: convex surface rolls inferiorly and slides superiorly
173
Which shoulder joint is not a true joint?
ST joint
174
What are the arthrokinematics of abduction and adduction of the shoulder?
- frontal plane, AP axis
- convex head of humerus rolls superiorly and slides inferiorly along the longitudinal diameter of the fossa, adduction is opposite
175
Why does the large humeral head not roll off?
Sliding
176
Where is the ICL stretched? (Shoulder movement)
in 90 degrees of abduction
177
What is the ratio of the scapulohumeral rhythum?
2:1 - every 3 degrees of abduction: 2 degrees at GH joint/ 1 at ST upward rotation
178
What is the 60 degrees of the scapula during full abduction a result of?
Simultaneous elevation of the clavicle at the SC joint combined with upward rotation of the scapula at the AC joint
179
What does the clavicle do during full abduction?
Retracts at the Sc joint
180
Where is the clavicle to start?
Horizontal about 20 degrees posterior to frontal plane
181
How much does the clavicle retract during abduction?
15-20 degrees
182
What does the scapula do with full abduction?
Tilts posteriorly and slightly rotates outward
183
What does the postierior tilt and external rotaion of the scapula help with?
Keeps scapula flush with the thorax, orients the fossa, moves the coracoacromial arch away from the advancing humeral head
184
How much does the clavicle rotate during full abduction?
20-35 degrees
185
What is the most predominant motion of the clavicle with abduction?
rotation
186
What does the natural external rotation of the humerus during abduction allow for?
the greater tubercle on the humerus to pass posterior to the acromion
187
What are the retractors?
middle trap, rhomboids, lower trap
188
What are retractors essential for?
Pulling activities
189
What do the retractors do?
Anchor scapula to axial skeleton
190
What are the upward rotators of the ST joint essential for?
elevation of the UE
191
What do the upward rotators provide?
Stable attachments for the more distal mobilizers
192
What are the athrokinematics of abduction at the GH joint regarding the supraspinatus?
Supraspinatus rolls the humeral head superiorly toward abduction while also compressing the joint for added stability
193
What muscles do shoulder IR?
subscapularis
pec major
lat dorsi
teres major
anterior deltoid
194
What muscles do shoulder ER?
Infraspinatus
Teres minor
posterior deltoid
195
What is kinematics?
Describes the motion of a body without regard to the forces or torques that may have produced the motion
196
What is kinetics?
Describes the forces or toruqes that act on or within a body
197
What muscles activation is used when slowing lowering a book to a table?
Eccentric to decelerate the descent of the book
198
What is a force?
The magnitude of a push applied against a patients skin
199
What is a pressue?
The force divided by the contact area
200
What can a force do when applied to a small surface area?
create large and potentially damaging pressure (also called stress)
201
Why does bone heal better than articular cartilage?
Bone has blood supply and a well developed periosteum and endosteum
202
Describe two natural effects of aging on connective tissues?
- slower rate of synthesis of fibrous proteins and proteoglycans
- tendons of muscles become less stiff and unable to quickly and effectively transmit stabilizing forces
203
What is the function of synovial fluid?
Provides nutrients to the articular cartilage, act as a lubricant that reduces the coefficient of friction between joint surfaces
204
What happens with a smaller pennation angle?
More force able to be generated
205
What tissues are responsible for a muscles passive length-tension curve?
- extracellular connective tissues
- structural proteins
206
Do myofiliments contract with the muscle?
NO, they slide past one another (sliding filament theory)
207
What is tetanization?
To sustain a force beyond the twitch duration, the muscle fibers must receive additional action potentials before the muscle force from the previous action potential is lost
208
What does tetanization allow?
a muscle fiber to accumulate tension
209
What happens as a muscle starts to fatigue from prolonged submax effort?
The EMG from the agonist muscle progressively increases
210
What will the EMG amplitude be for a muscle during eccentric vs concentric
eccentric will be less than that for lifting the same load (concentric)
211
How does the nervous system increase muscle force?
- recruitment
- rate coding
212
What is a motor unit?
A single alpha motor neuron and all its innervated muscle fibers
213
What is the Henneman size principle?
Motor units are naturally recruited by the nervous system in order of increasing size - smaller before larger
214
What does immobilization increase?
fast twitch fibers
215
Adding sarcomeres in parallel increases...
Skeletal muscle hypertrophy and contractile force
216
What does adding sarcomeres in seres increase?
The speed of contraction of the muscle fiber
217
What is efferent innervation?
Nerves traveling from the CNS to a muscle
218
What is afferent innervation?
Nerves traveling from the muscle towards the CNS
219
Which variable is most responsible for the magnitude and direction of the joint reaction force at the elbow?
Muscle force
220
What is the mass determined by?
the number of particles
221
What does the mass moment of interia depend on?
Mass and how it is distributed relative to the axis of rotation
222
Where is the COM in the human bodY?
Anterior to S1
223
Would a muscle force through the axis of rotation create torque?
NO
224
What is a clinical example of Mechanical advantage?
MMT
225
What is the arthrology of the HU joint?
Contributes to flexion/extension and stability
226
What is the arthrology of the HR joint?
Contributes to flexion/ext; is a MODIFIED hinge joint
227
What is excessive cubitus valgus?
20-25 degrees
228
What does the elbow capsule incompass?
3 joints - HR, HR, prox RU
229
What do the ligaments in the capsule of the elbow provide?
Multiplanar stability
230
What can injury to the MCL cause?
Compression Fx, ulnar nerve injury, anterior capsule, medial musculature at epicondyle
231
What can cause a NWB MCL injury?
Repetitive valgus producing strain, overhead athletes
232
What is tommy john surgery?
Repair of the anterior fibers of the UCL through a tendon graft from palmaris longus, gracillis, or plantaris
233
What is a terrible triad injury?
FOOSH and supinated
- elbow joint dislocation ( lig injury)
- fx radial head
- fx coronoid process
234
What problems can the terrible triad cause?
persistent instability, nerve damage, heterotopic ossification, stiffness
235
What happens during flexion of the elbow? (roll and slide)
radius rolls and slides up
236
How many joint capsules are there for the RU, HU, and HR joints?
one joint capsule shared
237
What holds the radial head by the ulna?
fibro-osseous ring; radial notch and annular ligament
238
What stabalizes the distal RU joint?
TFCC, pronator quadratus, ECU tendon, distal oblique fibers interosseous membrane
239
What do the radius and carpal bones do during rotation?
Rotate around the fixed humerus and ulna
240
What happens proximally do the raidus during supination?
rotation of the radial head in the fibro-osseous ring
241
What happens distally to the radius during supination?
Radius rolls and slides the same way - articular discs proximal surface slides across ulnar head
242
What do the radius and carpal bones do during prontation?
Rotate around the fixed humerus and ulna
243
What does the proximal surface of the disc do during pronation?
Slides across the ulnar head
244
What does the HR joint do during pronation?
The fovea of the radial head spins against the capitulum
245
What muscles do supination?
Biceps brachii, supinator
246
What bones are in the proximal row of carpals?
scaphoid, lunate, triquetrum, pisiform
247
What bones are in the distal row of carpals?
Trapezium, trapezoid, capitate and hamate
248
What is the arthrology of the RC joint?
Concave radius and disc and convex scaphoid and lunate
249
What is the arthrology at the Midcarpal joint?
Between proximal and distal rows, continuous capsule
250
How many joints make up the midcarpal joint?
13
251
How many degrees of freedom at the wrist?
2 - flx/ext, u/r dev
252
Where is the axis of the wrist?
Through the head of the capitate
253
What directs the osteokinematics of the entire hand?
the rotation of the capitate
254
What occurs with radial deviation?
Extension
255
What are the central columns of the wrist formed by?
Linkages between radius and lunate, medial compartment of midcarpal joint
256
What are the roll and slide during extension of the wrist?
- Convex lunate rolls dorsally and slides in a palmar directon
- head of capitate rolls dorsally on lunate and slides in a palmar direction
257
What is carpal instability?
Excessive mobility between carpals, usually laxity or ruptured ligaments
- can be static or dyamic
258
What is the rotational collapse of the wrist?
Mechanically proximal carpals are a row of mobile bone between two relative rigid segments; collapse due to compression
259
What is the most frequently dislocated carpal bone?
Lunate
260
When is activation of the wrist extensors necessary?
To block the wrist flexion caused by the activated finger flexor muscles
261
When does maximal grip force occur?
At about 30 degrees of extension
262
What are the kinematics of the abduction/adduction of the CMC joint?
Convex surface of the thumb metacarpal is moving on fixed concave trapezium - rolls palmar and slides dorsally
263
What are the kinematics of the flexion/ext of the CMC joint of the thumb?
Concave metacarpal on convex trapezium - flexion: metacarpal rolls and slides in ulnar direction
- extension: slide/glide in lateral direction
264
What happens with the opposition of the CMC thumb?
full opposition is closed packed position
265
What are the general features of the MCP joints?
Ovoid convex head of metacarpals and shallow concave proximal phalanges
266
Where do the collateral ligaments attach?
Proximal attachment at tubercle, cord part (thick and strong)
267
What are the volar plates?
Dense, thick, fibrocartilage; runs base of proximal phalnx; thinner elastic portion to MC
268
What are the fibrous digital sheaths?
Form tunnels or pulleys for extrinsic finger flexors are anchored on plates
269
What are the kinematics of the DIP and PIP?
Concave base rolls and slides in the palmar direction
270
What does the radial nerve innervate? (generally)
Extensive extensor muscles
271
What does the median nerve innervate? (generally)
Most of the extrinsic flexors
272
What does the ulnar nerve innervate?
medial half of FDP, hypothenar muscles
273
Where are the flexor pulleys?
Embedded within the fibrous digital sheath
274
How many pulleys are there for each finger?
5 annular pulleys
275
Where are the major pulleys?
At A2 and A4 attached to the shafts (mid and prox)
276
Where are the minor pulleys?
A1, 3, 5, attached to palmar plates
277
Where/What are the cruciate pulleys?
C1-3 thin crisscross over tendons where digital sheaths bend during flexion
278
What happens without the flexor pulleys?
Get 'bowstring'; A2 A4 reduce torque significantly if injured
279
What percentage of climbers have pulley injuries?
20%
280
What must act to prevent MCP and wrist flexion?
FDS PIP flexion requires ext; extensor digitorum must act
281
What are tendons connected by in the hand?
Juncturae tendinae - stabilize the angle of approach
282
What is the extensor mechanism?
Primary distal attachment of ED, EDM, EI and most intrisics
283
What does the extensor mechanism allow for?
Allows the extensor force to transfer distally throughout the entire finger
284
What is the dorsal hood?
Thin aponeurosis perpendicular to tendon, stabilizes the tendon at the MCP, slings around the proximal phalanx, assists ED in extending the MCP joint
285
What do the lumbricals and interossei attach to? What do they do?
The hood, assist ED with extension of PIP and DIP
286
What does the isolated ED get the MCP to do?
Ext, but needs intrinsics to get PIP and DIP ext
287
EPL and APL are radial deviators at wrist - so during thumb extension _______ _________ muscles must be activated to stabilize the wrist against unwanted radial deviation
Ulnar deviator
288
How many intrinsic muscles of the hand are there?
20
289
Lumbricals are ...
4 slender muscles off tendons of FDP
2 lateral, 2 medial
290
What do the lumbricals do?
Flexion at MCP, extension at PIP and DIP
291
Lumbricals have .... muscle spindles
high levels
292
What do the palmar interossei do?
Adduct
293
What do the dorsal interossei do?
Abduct
294
What happens with grip with a ulnar nerve injury?
38% reduction in max grip effort
295
What happens if wrist extensors are paralyzed?
Wrist flexion not neutralized and tendons overstretched in ED
296
What does the broad triangular medial collateral ligament of the elbow allow for?
Fibers to pass anterior and posterior to the ML axis of rotation of the elbow
297
What are the arthrokinematics at the HR joint during elbow flexion and supination?
Combined spin and a roll and slide in similar directons
298
How many nerves innervate the primary muscles that flex the elbow?
three - musculocutaneous, radial, median
299
What does the deltoid do during a pushing action?
Flexes shoulder, produces a shoulder flexion torque that neutralizes the shoulder extension torque potential of the long head of the triceps
300
What muscle is the antagonist of the brachialis?
Medial head of triceps
301
What happens during flexion at the RC joint?
Proximal carpal bones roll palmarly and slide dorsally; capitate rolls palmar direction and slides dorsally
302
What happens during extension at the RC joint?
The proximal row of carpal bones rolls dorsally and slides in a palmar direction
303
Which muscle is the most direct antagonist to the FCU?
Extensor pollicis longus or extensor carpi radialis brevis
304
What happens with flexion of the wrist?
Ulnar deviation
305
What muscles attach at the lateral epicondyle of the humerus?
Brachioradialis
ECRB
ECBL
ECU
ED
anconeus
supinator
- all innervated by radial nerve
306
What happens with the FCU and the FCR during active flexion of the wrist?
Both produce flexion, but each muscle neutralizes the others frontal plane actions
307
What does ulnar neuropathy cause?
Atrophy in the hypothenar eminence, the interosseous spaces, and the web space of the thumb
308
What does median neuropathy cause?
atrophy in the thenar eminence
309
What is the opposition of the thumb a combination of?
Abduction and flexion
310
What ligaments help prevent a valgus elbow?
The MCL of the elbow
