Lab Objectives - Exam 1

Know common devices used to measure PROM

• Goniometers

• Tape

• Inclinometers

  • Bubble

  • Digital

• CROM & BROM

• Athrodial protractors

Goniometers

• Plastic, steel, gravity dependent, cheap

  • They use weighted pointer

• MOST COMMONLY USED

  • Measures almost any joint

• Alignment is key

  • Stationary arm, moveable arm, fulcrum

• Read the beginning and end ROM (represents angle created by proximal and distal bones of joint)

  • May lack good criterion-related validity but excellent reliability

  • Intra-rater

  • Peripherial joints

• No difference in small vs large

Tape

• C7 to S1

• Schober technique

  • Lumbrosacral junction

  • 10 cm above

  • .90 Correlation coefficient with roentgenograms

• Modified Schober Technique

  • Lumbrosacral junction

  • 10 cm above

  • 5 cm below

  • .90 Correlation coefficient with roentgenograms

Inclinometer

• Accurately measures ROM

• Bubble and digital

  • Fast & small

  • Repeatable, measuring all joints including composite movement of multiple joints

  • Active and passive measurements made by one person

• More expensive

CROM (cervical)/BROM (back)

• Intra-rater .75 to .91

• Inter-rater .41 to .88

• Measures forward head/ back ROM

Arthodial protractors

• Uncommon

• Measures device for joint flexibility

• Enables quick and accurate testing of ROM in all major joints

• Transparent heavy gauge aircraft plexiglass

• Large easy to read red and blue degree markings

Accurately measure PROM

• Align fulcrum with joint

  • Stationary arm parallel to proximal segment

  • Movable arm along distal segment

• Stabilize and move passively (outside force, no voluntary muscle contraction, quantity of the motion, quality of endfeel)

  • Manually

  • Mechanical (CPM)

Identify procedures to improve reliability

• Use preferred position and stabilize proximal joint component

  • Explain and demonstrate the desired motion to your patient

• Move joint passively to complete ROM

  • Determine end-feel and make a clinical estimate on ROM

• Palpate appropriate bony landmarks

• Align goniometer’s SA and MA with landmarks

  • Determine axis of motion

• Read and record measurement

  • Compare to opposite side

  • Re-measure at the same time of day when your patient returns for their follow-up visit

  • Successive measurements should be taken by same examiner (same force for end-feel)

  • Inexperienced examiners should take several measurements

Know how to document goniometric measurements

• Be specific and objective

  • Conicise

• Be familar with what is acceptable at clinic

  • Open-minded for differing opinions

• DO NOT USE WITHIN NORMAL LIMITS (age appropriate norms)

  • Relate to well-known test

• Record beginning and ending position using 0-180 degree notation method (use table)

• Do not use total joint ROM

Accurately perform isolated MMT of UE/LE/trunk

• Follow standard positions, stabilize proximal, apply resistance in line with muscle action

Accurately assign a strength grade using the Lynch/Modified Lovett scale

• Grade 0–1: No contraction/trace

• Grade 2: Movement in gravity-eliminated

• Grade 3: Movement against gravity

• Grade 4–5: Movement against gravity + resistance

Identify/eliminate substitutions

Example: During sit-ups, moving arms changes moment arms (shorter → easier, longer → harder). Substitutions change torque demand.

Apply alternate grading scales (calf, hand, trunk)

• Trunk: Lawn Chair sit-up progression grading

• Calf: Heel raise reps (noted as functional testing in lab discussions)

• Hand: Grip/pinch dynamometer (noted in muscle testing alternatives)

Explain basic concepts of osteokinematics

• Planes of motion→ axis of rotation→ movements

  • Sagittal plane→ mediolateral axis → flex/ext

  • Frontal plane→ anteroposterior axis→ abd/add

  • Horizontal plane→ vertical axis→ int/ext rotation

Glenohumeral joint

• Number of axis = 3

• Orientation of axis = mediolateral, vertical, anteroposterior

• Location passing through = humeral head

• Plane of motion = sagittal, horizontal, sagittal

• Movement = flex/ext

Humeroulnar joint

• Number of axis = 1

• Orientation of axis = mediolateral

• Location passing through = medial and lateral epicondyles of humerus

• Plane of motion = sagittal

• Movement = flex/ext

Radiocarpal joint

• Number of axis = 2

• Orientation of axis = mediolateral, anteroposterior

• Location passing through = head of capitate (may be scaphoid)

• Plane of motion = sagittal, frontal

• Movement = flex/ext, ulnar/radial deviation

Hip joint

• Number of axis = 3

• Orientation of axis = mediolateral, vertical, anteroposterior

• Location passing through = femoral head

• Plane of motion = sagittal, horizontal, frontal

• Movement = flex/ext, int/ext rotation, abd/add

Tibiofemoral joint

• Number of axis = 2

• Orientation of axis = mediolateral (slight deviation), vertical

• Location passing through = lateral and medial epicondyles of femur, along the tibia

• Plane of motion = sagittal, horizontal

• Movement = flex/ext, int/ext rotation

Talocrual joint

• Number of axis = 1

• Orientation of axis = mediolateral (slight deviation)

• Location passing through = talus, or medial and lateral malleoli

• Plane of motion = sagittal

• Movement = dorsiflexion/plantarflexion (pronation/supination of subtalar joint)

Analyze open vs closed chain

• Standing from seated position & straighten the leg while sitting = knee extension

  • Open chain = straighten leg while sititng

  • Close chain = stand up from a seated position

Explain arthrokinematics and convex-concave rule

• Convex on concave = roll & glide opposite

• Concave on convex = roll & glide same

• Examples: shoulder (convex humeral head on concave glenoid) vs knee (concave tibia on convex femur).

Convex-on-concave movement

• Relatively fixed = concave

• Relatively mobile = convex

• Movement (roll & glide) = opposite

Concave-on-convex movement

• Relatively fixed = convex

• Relatively mobile = concave

• Movement (roll & glide) = same

Glenohumeral joint in open chain movement

• Fixed concave = glenoid fossa

• Mobile convex = humeral head

• Convex-on-concave

Humeroulnar joint in open chain movement

• Fixed convex = trochlea on humerus

• Mobile concave = trochlea notch

• Concave-on-convex

Wrist radiocarpal joint in open chain movement

• Fixed concave = radius distal end

• Mobile convex = carpal bones

• Convex-on-cave

Hip in open chain movement

• Fixed concave = acetabular fossa

• Mobile convex = head of the femur

• Convex-on-concave

Tibiofemoral joint in open chain movement

• Fixed convex = femoral condyles

• Mobile concave = tibial condyles

• Concave-on-convex

Talocrural joint in open chain movement

• Fixed concave = distal end of the tibia and both malleoli

• Mobile convex = trochlea and sides of the talus

• Convex-on-concave

Glenohumeral flexion

• Roll = superior

• Slide = inferior (or spin)

Glenohumeral extension

• Roll = inferior

• Slide = superior (spin)

Glenohumeral internal rotation

• Roll = anterior

• Slide = posterior

Glenohumeral external rotation

• Roll = posterior

• Slide = anterior

Glenohumeral abduction

Roll = superior

Slide = inferior

Glenohumeral adduction

• Roll = inferior

• Slide = superior

Humeroulnar flexion

• Roll = anterior

• Slide = anterior

Humeroulnar extension

• Roll = posterior

• Slide = posterior

Radiocarpal flexion

• Roll = anterior

• Slide = posterior

Radiocarpal extension

• Roll = posterior

• Slide = anterior

Radiocarpal radial deviation

• Roll = lateral

• Slide = medial

Radiocarpal ulnar deviation

• Roll = medial

• Slide = lateral

External torque with load (external force & moment arm)

Torque = Force × Moment Arm; gravity acts as external force, perpendicular distance as moment arm

External torque with effort (internal forces & moment arms)

• Internal torque = muscle force × internal moment arm; must balance external torque.

  • Largest external torque, due to longest external moment arm

  • Internal moment arm does not change among sit-ups

The component vector acting along the parallel line will result in a distraction/compression force (blue vector). How to differentiate whether this component vector will be distraction or compression force?

a. When the arrow head is pointing toward the hand, this component vector is pulling the forearm “away” from the joint center (i.e. AOR) distraction (example: C)
b. When the arrow head is pointing toward the joint center, this
component vector is pulling the forearm “toward” the joint center (i.e. AOR)  compression (example: A)

The component vector acting along the perpendicular line will result in a rotary/shear force. (orange vector)

Calculate muscle force using torque equilibrium

Equation: Muscle Force = (External Force × External MA) ÷ Internal MA

• Torque = force x moment arm

  • Internal torque = muscle forces

  • External torques = body weight or other external forces

  • Clockwise torque = counter-clockwise torque

How do you determine the external moment arm & what is moment arm? With 15 Newton-meter, how much force is required from therapist to resist maximal torque production?

• Perpendicular distances between the line of pull of force and AOR

• EMA = solid brown line (cm)

  • 15 Nm/.15 m (15 cm) =100 N

  • 15Nm/.3 m (30 cm) = 50 N (smaller force)

Calculate the muscle forces required by shoulder abductors to hold 4 lb dumbell at 90 degree shoulder abduction.

• Weight of arm = 10 lb

• Weight of dumbell = 4 lb

• Internal torque = external torque

  • IF x IMA = EF x EMA

• IFmuscle x IMAmuscle = EFarm x EMA arm + EFobject x EMAobject

  • IF x 2 in = 10lbs x 12in + 4lbs x 25 in

  • IF x 2 in = 216 in/lbs → 108 lbs

Calculate the muscle forces required by shoulder abductors to hold 4 lb dumbell at 90 degree shoulder abduction.

• Weight of arm = 10 lb

• Weight of dumbell = 4 lb

• Internal torque = external torque

  • IF x IMA = EF x EMA

• IFmuscle x IMAmuscle = EFarm x EMA arm + EFobject x EMAobject

  • IFmuscle x 2 in = 10 lbs x 6 in + 4lbs x 12 in

  • IFmuscle x 2 in = 108 in/lbs → 54 lbs

Compared 90 to 30 degrees, which has larger muscle force from the shoulder abductors?

• 90 degrees

  • Longer moment arm increases the external torque, which must counteract by generating a greater internal torque

Understand concepts of stability including center of mass and base of support

• COM low and in BOS = most stable as force of gravity acts directly through BOS

• COM higher and closer to edge of BOS = most mbile as force of gravity is nearly outside the BOS

• Whole body COM = S2

  • Limb loss = COM will move away from loss of limb, superiorly and laterally from S2

• Compensate when weight is added or taken away

Apply concepts of stability to assit a patient with stair climbing

• Stay below patient (ascending behind, descending in front)

• Always have patient where gait belt tightly around smallest part of waist

  • One hand on belt, other on shoulder to prevent leaning forward

• Move one foot at a time to ensure larger BOS and so COM is distributed

  • Patient moves, then you move

  • Can ask to hold rail for extra BOS

Analyze moment arms at different forearm positions

• Biceps brachii has longest MA in supination, reduced in pronation.

  • Pronation = closer to AOR (short perpendicular distance)

  • Supination = flexion (bias) maximize MA

• Brachialis: constant MA.

  • Pronation/suppination don’t affect the MA

  • Pronation (bias) minimize MA

Bony land marks to identify AOR for elbow flexion and extension?

• Passes through trochlea and capitulum of humerus

• Medial and lateral epicondyle is used to identify

Biceps brachii

• O: supraglenoid tubercle (long) & coracoid process (short)

• I: radial tuberosity

• A: flex elbow, supinate radio-ulnar, flex glenohumeral

Brachialis

• O: distal anterior humerus

• I: Ulnar tuberosity

• A: flex elbow

Brachioradialis

• O: lateral supracondylar ridge of humerus

• I: styloid process radius

• A: flex elbow, pronate/supinate radio-ulnar depends on forearm position

Supinated forearm

• Bias biceps brachii

• Maximize MA on biceps

• 20-25% greater elbow flexor torque (increased MA)

Pronated forearm

• Bias brachialis

• Minimize MA on biceps

• No effect on MA of brachialis

Neutral forearm

• Bias brachioradialis

• Maximize MA of brachioradialis

Analyze torque generation at different elbow positions

• Peak torque at ~90° flexion (largest MA + optimal length-tension relationship)

• Weaker at full extension/flexion due to smaller MAs

Supinator action

• Supinate forearm

• Rotates radius to turn palm anteriorly or superiorly if elbow is flexed

Extensor indicis action

• Extends 2nd digit

• Helps extend hand at wrist

Extensor pollicis longus action

• Extends DIP at thumb

• Extends MCP

• Extends carpometacarpal joints

Pronator quadratus action

• Pronates forearm

• Deep fibers bind ulna and radius together

Brachioradialis action

• Weak flexion of forearm

• Maximal flexion when forearm is midpronated

Pronator teres action

• Pronate forearm

• Flex forearm

Flexor carpi radialis action

• Flexes hand

• Abducts hand

Palmaris longus action

• Flexes hand

• Tenses palmar aponeurosis

Biceps brachii action

• Both = supinate forearm (most powerful) when supine & flex forearm

• Long = weak arm flexor

• Short = resists dislocation of shoulder

Review muscle actions

• Pronators: pronator teres, pronator quadratus

• Supinators: supinator, biceps brachii

Role of triceps brachii when turning a screw

• Cancels biceps’ elbow flexion torque during supination, providing stability.

• Synergist for vigorus supination and pronation

  • Attaching to ulna neutralize flexion tendency of biceps with supination task

Biceps and triceps are

• Synergists for supination

• Antagonists for elbow flexion and extension

Role of anterior deltoid when pushing a door

• Synergist

• Produces flexion torque that drives the limb forward and neutralizes the shoulder extension of long head of triceps

Review arthrokinematics of pronation & supination

• Radius rotates around ulna

• Pronation

  • Proximal RU = radial head rolls anteriorly, slides posteriorly against radial notch of ulna (internal rotation)

  • Distal RU = distal radius rolls anteriorly and glide anteriorly against the head of ulnar

  • HR = spin of fovea of radial head against capitulum of humerus

• Supination

  • Proximal RU = radial head rolls posteriorly and glide anteriorly against the radial notch of ulna (external rotation)

  • Distal RU = distal radius rolls posteriorly and glide posteriorly of the ulnar

  • HR = spin of fovea of radial head against capitulum of the humerus

Compare the effect of muscle forces of the deltoid at the GH joint

• Vector resolved into:

  • Parallel to humerus: superior shear force → pulls humeral head upward (risk of impingement).

  • Perpendicular to humerus: abduction torque → initiates and drives GH abduction.

• If acting alone: inefficient abduction, superior migration of humeral head, impingement of subacromial structures, poor stability.

Compare the effect of muscle forces of the rotator cuff at the GH joint

• Provide compression force → centers humeral head in glenoid.

• Provide inferior-directed shear force (especially infra/teres minor/subscapularis) → offsets deltoid’s superior translation.

• Assist with fine-tuning rotation (external rotation to clear tubercle under acromion).

• Complementary role: Deltoid drives motion; rotator cuff stabilizes and controls arthrokinematics.

Explain scapulohumeral rhythm by describing the osteo- and arthro- kinematics at the glenohumeral joint during arm elevation

• First half of elevation (0-90) & second half of elevation (90-180)

  • Osteo: 60 degrees abduction

  • Arthro: humeral head rolls superiorly and glides inferiorly

Explain scapulohumeral rhythm by describing the osteo- and arthro- kinematics at the scapulothoracic joint during arm elevation

• First half of elevation (0-90) & second half of elevation (90-180)

  • Osteo: 30 degrees upward rotation (contributed by SC and AC joint)

  • Arthro: N/A

Explain scapulohumeral rhythm by describing the osteo- and arthro- kinematics at the sternoclavicular joint during arm elevation

• First half of elevation (0-90)

  • Osteo: 20-25 degrees elevation

  • Arthro: Clavicle rolls superiorly and glides inferiorly

• Second half of elevation (90-180)

  • Osteo: 25 degree posterior rotation (limited elevation)

  • Arthro: Clavicle spinning on sternum

Explain scapulohumeral rhythm by describing the osteo- and arthro- kinematics at the acromioclavicular joint during arm elevation

• First half of elevation (0-90)

  • Osteo: 5-10 degrees upward rotation

  • Arthro: N/A

• Second half of elevation (90-180)

  • Osteo: 25-30 degrees upward rotation

  • Arthro: N/A

What’s the effect of the deltoid muscle force on the joint surface of the GH joint during arm elevation?

a) How do you decide the two axes to resolve your vector into?

• One axis will be along (parallel to) the moving segment (humerus in this case)

• Other axis will be perpendicular to the humerus.

  • The two axes will intersect at the insertion of the deltoid (the tail of the vector)

What are the effects of the deltoid muscle force acting at the GH joint on each of the axes you identified in a)?

• Parallel to the humerus: pulling the humeral head superiorly (superior shear force)

• Perpendicular to the humerus: abduction of the GH joint

What are the consequences if the deltoid is the only muscle activated during shoulder abduction?

• If the deltoid is the only muscle activated during shoulder abduction

  • the movement may be inefficient and potentially harmful.

• The deltoid initiates abduction, but without support from other muscles—especially the rotator cuff muscles, the humeral head may migrate superiorly

  • Leading to impingement of the subacromial structures

  • Lack of stabilization from the rotator cuff can compromise joint integrity, increasing the risk of shoulder instability or injury

What’s the effect of the supraspinatus (single muscle) and infraspinatus, teres minor and subscapularis (the three combined) acting at the glenohumeral joint during arm elevation (frontal plane only)?

• Supraspinatus: Superior roll (abduction) & compression

• Subscapularis, infraspinatus, and terest minor: Compression

Supraspinatus

• Drives the abduction with superior roll of the humeral head

• Compresses the humeral head

• There is a small superior translation force which is negligible.

  • In addition, supraspinatus creates a semi-rigid spacer above the humeral head, restricting excessive superior translation of the humerus

• Advantage: the superior roll contributes to the abduction of the GH joint, the compression force contributes to joint stability

Infraspinatus, teres minor, and subscapularis

• Inferior glide of the humeral head

• Compresses the humeral head

• Advantage: the Inferior directed force is needed to neutralize the strong superior translation force from deltoid, the compression force contributes to joint stability

Infraspinatus and teres minor

• Externally rotate the humerus

• Advangtage: the external rotation increases the clearance between the greater tubercle and acromion

Using a TheraBand to represent the muscle force of the anterior deltoid on a skeleton model, are you able to “see” the change of the moment arm when you elevate the arm of the skeleton?

• The muscle fiber of the anterior deltoid almost passes through the anterior-posterior axis of rotation

  • Arm is < 30 degrees of abduction.

• As we elevate the arm of the skeleton model, the distal end of the theraband moves superior

  • The perpendicular distance between the line of pull and AOR increase

How does the changes in the moment arm of the deltoid compare to the supraspinatus?

• The moment arm of the deltoid increase from 0-120 degrees of arm abduction.

• The moment arm of the suprapinatus stays consistent from 0-120 degrees of arm abduction.

Compare the mechanical advantages between the suprapinatus and the deltoid muscle

• Supraspinatus has a greater mechanical advantage at the initial (<30º abduction) or later range (>60º) of abduction

• Deltoids has a greater mechanical advantage at the initial (<30º abduction) or later range (>60º) of abduction

What are other movements that occur throughout 0-180 degrees?

• Clavicle retracts at SC joint (≈ 15°)

• Upwardly rotating scapula posteriorly tiles (≈ 20°)

  • Less consistently, externally rotates (≈ 10°)

• GH joint externally rotates about (≈ 45°)

Locate key anatomical features of the shoulder girdle via palpation and outlining the structures.

• Sternum: jugular notch, xiphoid process, sternoclavicular joint.

• Clavicle: outline entire clavicle, mark SC and AC joints.

• Scapula: outline entire scapula; spine, acromion, AC joint, supraspinous fossa, infraspinous fossa, medial & lateral borders, superior & inferior angles, coracoid process.

• Humerus: greater tubercle, lesser tubercle, intertubercular groove.

Postural assessment (partner): look for scapular deviations: elevated/depressed, upward/downward rotation, adducted/abducted (protracted/retracted), tipped/tilted, or winged scapula.

Analyze collective muscle actions at the scapulothoracic joint based on the knowledge of the origins, insertions and line of pull of the muscles

Muscles	Scapular Action

a

Upper trapezius + Lower trapezius + Serratus anterior

Upward rotation

b

Upper trapezius + Middle trapezius + Rhomboids

Retraction + elevation

c

Rhomboids + Levator scapulae

Downward rotation + elevation + retraction

d

Lower trapezius + Pectoralis minor

Depression

Upper trapezius

O: Occipital bone & upper cervical spinous process

I: Lateral clavicle, acromion

A: Upward rotation & elevation of scapula

Middle trapezius

• O: Upper thoracic SP

• I: Scapular spine

• A: Retract scapula

Lower trapezius

• O: Lower thoracic SP

• I: Medial scapular spine

• A: Upward rotate, depress, retract scapula

Serratus anterior

• O: Lateral surface of the ribs

• I: Medial border scapula

• A: protract and upward rotate scapula

Rhomboids

• O: Lower cervical SP (minor) & upper thoracic SP (major)

• I: Medial border scapula below scapular spine

• A: Retract, elevate, downward rotate scapula

Levator scapulae

• O: Transverse process of upper cervical

• I: Superior angle scapula

• A: Elevate & downward rotate scapula