# Shared Flashcard Set

## Details

Biomechanics Test 1
Test 1
84
Anatomy
09/12/2009

Term
 Apply Newton's First Law to the movements of the GH joint.
Definition
 Force is needed to start movement at the jt and the movement will continue in the same direction unless another force is applied to change the directions of movement. If shoulder flexors activate flx at GH jt, flx will continue until another force, say deltoid, applies and abduction force on the GH jt. The move direction will then change with the addition of this 2nd force.
Term
 Apply Newton's Second Law to an exercise for increasing elbow flx strength.
Definition
 If it is necessary to accelerate elbow flx motion during an exercise than greater force will be needed. If a wt is added to the hand, then the mass increases and this increase in mass will decelerate the motion unless more force is added. Rapid elbow flx requires more force and if the mass is also increased then even force is required.
Term
 Apply Newton's Third Law to gripping and holding an object in your hand.
Definition
 In flexing the fingers to grasp an object, the force from the finger flexors is greater than the resistance to flx and so the fingers move in flx. Once the fingers grasp and hold the object then the flx force of the fingers is equivalent to the resisting force of the object and motion of the fingers stops. The fingers flexors are still producing a flx force against the resistance of hte object to hold the object. Increased force by the finger flexor at this time may overcome the resistant forces of the object and hte object may break.
Term
 What is the difference between total and unit force?
Definition
 Total force is the total amt of force being applied to a surface while unit force is the force being applied per unit area on the surface. If there is a total force of 100N on a surface w/ an area of 100mm2 then the unit force would be 100N / 100mm2 or 1N per mm2.
Term
 What is the difference between loads and stresses?
Definition
 Loads are external applied to a structure.Stress is a force that occurs within that structure due to the external load.
Term
 What are the stresses occurring in a tendon when a tensile load is applied by the contraction of a muscle?
Definition
 There are tensile stresses being transmitted within the tendon, compressive stresses within the tendon resisting the tensile stresses and shear stresses resulting from the tensile-compression forces.
Term
 What are the stresses occurring in a vertebral disc when a compression load is applied by the vertebral bodies?
Definition
 Compressive stresses being transmitted in the disc, tensile stresses resisting the compression stresses, and shear stresses resulting for the tensile-compression forces.
Term
 What is the difference between stress and strain?
Definition
 Stresses are internal forces within a structure while strain is the deformation of the structure due to these tensile stresses.
Term
 What strains occur at a tendon when a tensile load is applied?
Definition
 Tensile stress produce tensile strain (elongation) of tendon. Resisting compressive stresses in the tendon produce compressive strain (contraction, squeezing) in the tendon. These 2 stresses produce shear stresses which produces shear strain (cutting, tearing) in tendon. Relative magnitude of the stresses determines overall strain on structures. If tensile stress > than compressive stresses structure will elongate.
Term
 What strains occur when a long bone is bending?
Definition
 Concave side of bend shows compressive stress and strain. Convex side show tension stress and strain. The forces for both are greatest at the periphery and decrease as the neutral axis in the center of the bone is reached.
Term
 What is the difference between work and power?
Definition
 Work is a function of the amt of force x the distance over which that force is applied. Work has no time component. Power is work divided by time. Unlike work, as the time interval changes the amt of power changes.
Term
 How would you determine the final resultant force and movement of a bone when three different muscles are applying forces (F1, F2, F3) at three different angles to the bone?
Definition
 Using a parallelogram, the resultant force FR1,2 can be determined for the combined action of F1 and F2 on the bone. After FR1,2 is resolved, this resultant force and F3 can be comined to fine the overall resultant force FR1,2,3
Term
 How can the component forces be determined from the line of action of a muscle?
Definition
 Represent the line of action of a muscle as a vector then construct a X and Y axis for the vector. X is along the bone that is moving and Y will be perpendicular to X. Using the line of action of the muscle as a hypotenuse, the X and Y components of muscle action can be derived. The muscle contracts and hte bone moves the line of muscle action usually changes.
Term
 What is the difference between fixed and movable pulleys?
Definition
 Fixed pulleys change the direction of force but not the magnitude of the applied force. Moveable pulleys change both the direction of pull and decrease the magnitude of the applied force.
Term
 What is the difference between type I and type III levels?
Definition
 Type 1 lever has a central fulcrum with the wt side of the lever on one side of the fulcrum and the force side of the lever on the opposide side of the fulcrum. Type III lever- the fulcrum is at one end and the wt at the opposite end of the lever. The force lies between the fulcrum and the wt end. In this lever, wt arm is always longer than the force arm.
Term
 What is torque and how is it calculated?
Definition
 Torque is a rotational force and is calculated by multiplying the force or wt by the perpendicular distance of the force or wt from the center of rotation.
Term
 With a type I lever, what would the force be if dw=6 cm and dF=2 cm?
Definition
 F=3w
Term
 With a type I lever, what would the force be if the dW=3 cm and dF=9cm?
Definition
 F= 1/3W
Term
 With a type III lever, what would the force be if dW=10 cm and dF=2cm?
Definition
 F=5W
Term
 With a type III lever, what would the force be if the dW=20cm and dF=2cm?
Definition
 F=10W
Term
 How can the distance that the weight arm moves be increased relative to the distance that the force moves in a class I lever?
Definition
 The longer the wt arm relative to the force arm or the shorter the force arm relative to the wt arm, the greater and faster the movement of the wt end of the lever.
Term
 How can the distance that the weight arm moves be increased relative to the distance that the force arm moves in a class III lever?
Definition
 The longer the wt arm or the shorter the force arm, the greater and faster the movement of the wt end of the lever.
Term
 How does movement of the force arm only a short distance affect muscle contraction force?
Definition
 With a short force arm and long wt arm, small mvt at the force end of the lever produces a large mvt at wt end. Bc the mvt of the force end is small, the shorten (contraction) of the muscle is small. The small shortening keeps the muscle near the top of its length tension curve so force production by the muscle is high
Term
 What is the difference between osteokinematic and arthrokinematic movements?
Definition
 Osteokinematic are the mvts seen by the bone at a jt. These include flx, ext, abd, and add. Arthrokinematic mvts are those occuring at the articular surfaces of the bone making up the jt. These mvts are rotation, translation or combo.
Term
 Give an example of the plane types of synovial joints and there degrees of freedom.
Definition
 intercarpal jts which can have 1,2,or 3 degrees of freedom.
Term
 Give an example of hinge types of synovial joints and there degrees of freedom.
Definition
 Humeroulnar or IP jts which have 1 degree of freedom
Term
 Give an example of condyloid types of synovial joints and there degrees of freedom.
Definition
 Radiocarpal or MCP jts which have 2 degrees of freedom
Term
 Give an example of saddle types of synovial joints and there degrees of freedom.
Definition
 CMC jt of the thumb which has 2 degrees or the sternoclavicular jt which has 3 degrees.
Term
 What is the concave/convex rule?
Definition
 When a convex surface is moving on a fixed concave surface, arthrokinematic jt translation (glide) is opposite to thedirection of osteokinematic mvt. When a concave surface is moving on a fixed convex surface, arthrokinematic jt translation is in the same direction.
Term
 What is the difference between a loose pack and close pack position of a joint?
Definition
 In a loose pack, the jt show minimum congruency bw the match jt surfaces, the ligament nad capsule are loose and there is a max jt space. Good for dynamic jt mvt and jt mobilization but poor for static load bearing. Close pack position- jt shows max congruency, tightness of the jt capsule and L, minimal jt space. Good position for static load bearing but not for joint mobilization.
Term
 What movements of the clavicle occur at the SC and AC jt during clavicular elevation?
Definition
 elevation at the AC jt and depression at the SC jt.
Term
 What movements of the clavicle occur at the SC and AC jt during clavicular posterior rotation?
Definition
 posterior rotation at the SC and AC jts.
Term
 What movements of the clavicle occur at the SC and AC jt during clavicular protraction?
Definition
 anterior translation of the clavicle at the SC and AC jt
Term
 What are the benefits of upward scapular rotation during arm flexion and abduction?
Definition
 Increases ROM in flexion and abduction, maintenance of the subacromial space, permits the deltoid, supraspinatus and coracobrachialis muscles to function near the top of the length tension curve so that they can produce high forces over a large portion of the motion.
Term
 What is scapular rhythm?
Definition
 Ratio of GH motion to scapular motion. Commonly given a 2:1 (2 degrees of GH to 1 degree of scapular motion). Using the 2:1, 90 degrees of osteo flexion or abd is the result of 60 degrees of GH mvt and 30 degrees of scapular mvt.
Term
 When in phase II of scapular movement and what movements occur during this phase?
Definition
 occurs after 90 degrees of shoulder flx and abduction. Scapular and clavicular elevation occuring in Phase I stops and the scapula upwardly rotates and the clavicle rotates posteriorly.
Term
 What can decrease the size of the subacromial space?
Definition
 subacromial bursitis, calcium deposits in the esubacromial bursa, thickening of the coracoacromial L, inflammation of the RC of the tendon of the long head of the biceps, thickening or hooking for the acromion process.
Term
 What are the movements of the shoulder complex structures during flexion?
Definition
 0-60, scapular and clavicle elevate, the humeral head glides inferiorly and rotates posteriorly.60-90: humeral head is seated in the glenoid fossa and rotates posteriorly, clavicle and scapula continue to elevate and scapula begins to upwardly rotate90-180: scapular upwardly rotates, clavicle rotates posteriorly and humeral head rotates posteriorly while seated in glenoid fossa.
Term
 What are the movements of the shoulder complex structures during extension?
Definition
 180-90: seated humeral head rotates anteriorly, scapula downwardly rotates and clavicle rotates anteriorly90-69: seat humeral head continues to rotate anteriorly, scapula stop downward rotation and depresses. Clavicle stops its anterior rotation and depression.60-0: humeral head rotates anteriorly and glides superiorly and scapula and clavicle depress.
Term
 What are the movements of the shoulder complex structures during ER?
Definition
 Humeral head rotates laterally and glides anteriorly, clavicle translates posteriorly and scapula retracts.
Term
 What scapular and clavicular movements are produced by the upper trapezius?
Definition
 elevation of the scapula and clavicle, posterior rotation of the clavicle, upward rotation of the scapula
Term
 What muscles produce downward rotation of the scapula?
Definition
 pec minor, rhomboid major and minor, levator scapulae.
Term
 What muscles produce upward rotation of the scapula?
Definition
 upper trapezius, lower trapezius, serratus anterior
Term
 What are the actions of the deltoid?
Definition
 GH flexion, ext, abd, IR, ER
Term
 What muscles produce GH adduction and IR?
Definition
 pec major, latissimus dorsi, teres major, subscapularis (slight adduction)
Term
 What muscles produce an inferior glide of the humeral head?
Definition
 infraspinatus, teres minor, subscapularis
Term
 What muscle is the main GH abductor from 0-60 degrees?
Definition
 supraspinatus is the main abductor for 0-60 degrees
Term
 What muscle is the main GH abductor from 90-180 degrees?
Definition
 the deltoid is the main abductor above 90 degrees.
Term
 What muscle are involved during GH flexion from 0-60 degrees?
Definition
 upper trapezius: scapular and clavicular elevationSubscapularis, infraspinatus, teres minor: GH inferior glideCoracobrachialis (initiates):GH posterior rotationanterior deltoid and biceps: GH posterior rotation
Term
 What movements and muscle actions are common during GH extension (180-0) and adduction (180-0)?
Definition
Term
 What muscles are involved for GH flexion from 60-90 degrees?
Definition
 Upper trapezius: scapular and clavicular elevationupper and lower trapezius, serratus anterior: start of upward scapular rotationrhomboids:stabilize scapula and control upward scapular rotationsubscapularis, infraspinatus and teres minor: hold seated humeral head in glenoid fossasupraspinatus: assists in holding humeral head in glenoid fossacoracobrachialis, anterior deltoid, biceps: GH posterior rotation
Term
 What muscles are involved in GH flexion 90-180 degrees?
Definition
 scapula and clavicle stop elevationupper and lower trapezius, serratus anterior: upward scapular rotationrhomboids: stabilize scapula and control upward scapular rotationupper trapezius: posterior clavicular rotation subscapularis, infraspinatus and teres minor: hold seated humeral head in glenoid fossasupraspinatus: assists in holding humeral head in glenoid fossa coracobrachialis, anterior deltoid, biceps: GH posterior rotation
Term
 What are the shoulder muscles group strength from strong to weak?
Definition
 adductors >_ IR > extensors > flexors > abductors > ER
Term
 Why is the MCL of the elbow more developed than LCL and what movements do the MCL resist?
Definition
 Most ADLs involving the elbow apply a valgus strain that tenses the MCL. This tensile strain stimulates the production of collagen and thus the MCL develops more than the LCL which has less strain applied to it. the MCL has an anterior nad a posterior band. The superior fibers of the anterior band resist elbow ext and the inferior fibers of the anterior band resist flexion. The posterior band resists flexion beyond 90 degrees.
Term
 What is the best way to test the MCL and the jt capsule of the elbow joint?
Definition
 Place the elbow at 90 degrees of flexion and apply distraction to the joint. To test the jt capsule is to place the elbow in a 0 degrees position and apply distraction to the jt.
Term
 How much elbow movement is needed for most ADLs?
Definition
 Flexion/ ext 20-130 degrees; pronation- 50 degrees from neutral and 50 degrees of supination from neutral.
Term
 What arthrokinematic movements are common at the humeroulnar and humeroradial joints during flexion? What movements are not common?
Definition
 During elbow flx, both ulna and the radius rotate and glide anteriorly, but only the radius moves cranially on the ulna and the ulna guides the forearm in adduction as its trochlear ridge follows the throchlear groove of the humerus.
Term
 What arthrokinematics movements occur at the proximal radioulnar joint during pronation of the forearm?
Definition
 During forearm pronation, only the radius is moving. It rotates medially and the head glides laterally.
Term
 If the musculocutaneous nerve is damaged, what muscles could still flex the elbow?
Definition
Term
 What is the main flexor of the elbow and why?
Definition
 Brachialis. It shows the largest strength and work capacity, it is active regardless of shoulder position, and its active during resistive and non-resistive flexor at both rapid and slow elbow flexion.
Term
 What are the differences in the action of the three heads of the triceps?
Definition
 It is affected by the position of the shoulder but the medial and lateral heads are not. The lateral and long heads are active with resisted but not non resisted movements while the medial triceps is active with resisted and non resisted movements. The long head shows its greatest activity during rapid and high resistive movements.
Term
 What is the main pronator of the forearm and why?
Definition
 Pronator quadratus as it is not affected by elbow position as the pronator teres is and hte pronator quadratus is active during resisted and non resisted movements and during rapid and slow pronation. Pronator teres is active with rapid and resistive pronation but not with slow and non resistive pronation.
Term
 What are the roles of the intrinsic and extrinsic ligaments of the wrist?
Definition
 Provide stability for the radiocarpal, ulnocarpal, midcarpal and intercarpal jts. Resist mvts by tightening and allow mvts by loosening. Tightening and loosing allows certain bones to move while at the same time restricts other bones from moving. Results are wrist flx, ext, radial and ulnar deviation.
Term
 How much wrist movement is needed for most ADLs?
Definition
 10 degrees of palmar flexion and 35 degrees of ext are needed.
Term
 What is the movement sequence during wrist ulnar deviation?
Definition
 Distal carpal row moves ulnarly, the proximal row slightly radially and the scaphoid and lunate move dorsally.
Term
 How does radial deviation differ for ulnar deviation?
Definition
 Mvts of the distal and proximal carpal rows and mvt o the scaphoid and lunate during ulnar deviation are opposite those occurring during radial deviation.
Term
 Why are radial and ulnar deviations limited when the wrist is in full ext?
Definition
 Radial and ulnar deviations require mvts bw the proximal and distal carpal rows at the midcarpal jt. With the wrist is full ext, the scaphoid, hamate, capitate, and trapezoid form a closed pack ridged mass that blocks mvt at the midcarpal jt. Midcarpal mvt blocked, radial and ulnar deviation are also blocked and thus very limited or no deviation is permitted.
Term
 What muscles produce wrist extension?
Definition
 ext. carpi radialis longus and brevis, ext carpi ulnar, ext digitorum, ext indicis, ext. digiti minimi.
Term
 What muscles produce wrist flexion and ulnar deviation?
Definition
 flexor carpi ulnaris
Term
 What muscles produce wrist flexion?
Definition
 flexor carpi radialis, flexor carpi ulnaris, flexor digitorum superficialis, palmaris longus
Term
 What muscles produce wrist ext and radial deviation?
Definition
Term
 Which muscles stabilize the ulnar side of the wrist when the wrist is in a neutral position?
Definition
 flexor carpi ulnaris, ext carpi ulnaris
Term
 Which muscles stabilize the radial side of the wrist when the wrist is in a neutral position?
Definition
Term
 Which muscles stabilize the ulnar side of the wrist when the wrist is in extension?
Definition
 flexor carpi ulnaris
Term
 In what way does arthrokinematic abduction and adduction of the CMC jt of the thumb differ from arthrokinematic mvts at the other jts of the fingers?
Definition
 The direction of rotation and glide are opposite hte osteokinematic mvt where as at the other jts the direction of rotation and glide are in the same direction as the osteokinematic mvt.
Term
 What joints are flexed by contraction of the flexor digitorum superficialis?
Definition
 wrist, carpometacarpal, metacarpophalangeal, proximal interphalangeal
Term
 How would you differentiate between flexor digitorum superficialis and profundus?
Definition
 The profundus flexes the distal interphalangeal joint but the superficialis does not.
Term
 How would you differentiate between flexor pollicis longus and brevis?
Definition
 The longus flexes the interphalangeal joint of the thumb and the brevis does not.
Term
 How would you differentiate between the extensor pollicis longus and brevis?
Definition
 The longus extends the interphalangeal joint of the thumb and the brevis does not.
Term
 What muscles are needed to fully extend a finger and why are multiple muscles needed for this action?
Definition
 The extensor digitorum, ext indicis, ext digiti minimi, lumbricles, palmar and dorsal interossei are the muscles needed for full ext of the finger. Bc of the strength of the flex digitorum superficialis and profundus and the lack of strength of extensors, the lumbricles and interossei are needed.
Term
 How does the extensor assembly extend the PIP and DIP?
Definition
 Tension applied to the extensor hood by the ext digitorum (indicis and minimi), lumbricles and interossei is transmitted to the central slide and lateral bands. Tension of hte central slip produced ext of hte PIP. Tension on the lateral bands is transmitted to the terminal tendon to extend the DIP
Term
 What is the difference between a power grip and a precision grip?
Definition
 The thumb is adducted in a power grip but abducted in a precision grip.
Term
 What is the difference between a tip pinch and a lateral pinch?
Definition
 Tip pinch: tips of the two fingers are used and the forces are greater at the PIP jt than the MCP jt. With a lateral pinch, the palmar aspect of the distal thumb is pressing a object against the distal radial aspect of the index finger and forces at the MCP are greater than the PIP.
Term
 If you are mobilizing a joint and are applying 5 lbs of compression to the thumb, how much compression force is occurring at each joint of the thumb?
Definition
 5 lbs of compression force on the thumb will produce 10-15 lbs of force at the IP, 25-30lbs of force at the MCP, and 30-60 lbs at the CMC jt.
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