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Kyla Rafols

問題数 100 • 2024/09/25

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<5 deg

Cubitus varus

>15 deg

Cubitus valgus

-15 deg

Gunstock deformity

Carrying angle is present during

elbow extension, forearm supination

Carrying angle is absent during

elbow flexion beyond 30 deg, forearm pronation

There is slight increase in the angle in the dominant arm compared to the nondominant arm

True

Carrying angle increaes until around age 14 or 15, when epiphyseal ______ occurs, then decrease slightly but becomes more consistent after age ____

closure, 15

Carrying angle is usually about _____ deg in full extension, with a range of ______

15, 8-15

An increased carrying angle beyond the normal range, which may be abnormal, esp if unilateral

Cubitus valgus

The carrying angle typically disappears when the forearm is supinated and flexed against the humerus

True

The carrying angle disappears at flexion beyond 30 deg, as found by

van roy

The configuration of the trochlear groove determines the pathway of the forearm during flexion and extension

True

Trochlear groove common configuration: ulna is guided medially from extension to flexion, so in full flexion the forearm aligns with humerus

True

Trochlear groove config: in extension, forearm moves _______ to a positional slightly ______ to the axis of the humerus

laterally

Different configurations of the trochlear groove can lead to variations in the forearm’s path during flexion, causing it to rest either medially or laterally to the humerus in full flexion

True

Factors affecting motion of elbow joint

type of motion, forearm position, body mass index, shoulder position

Passive flexion typically has a smaller range than an active motion due to muscle bulk limiting approximation between the forearm and humerus

False

Active flexion range

135-145 deg

Passive flexion range

150-160 deg

Flexion ROM is greater when the forearm is supinated compared to pronation or a neutral position

True

Higher BMI may limit elbow ROM. Studies show an increase of 2-3 deg for each z-score increase in BMI

First statement is true, second is false

Muscles crossing both the elbow and shoulder, such as the brachioradialis and brachialis, may restrict elbow motion when both jts attempt full ROM simultaneously

False

Joint surface configuration, ligaments and joint capsule all contribute to limiting ROM while providing stability

True

Closed pack position of humeroulnar jt

full extension

Closed pack position humeroulnar jt:

bony contact of olecranon process within olecranon fossa limits extension

Valgus resistance in closed pack position

medial collateral ligament, bony components, anterior joint capsule

Varus resistance in close pack position

bony structures, lateral collateral complex

In full extension, resistance to joint distraction is provided by soft tissue structures, particularly the

anterior joint capsule

Limits the extremes of flexion

coronoid process, radial head

At 90 degrees flexion, the anterior lart of the MCL provides primary resistance to both distraction and valgus stress

True

Varus stress at 90 deg flexion

osseous structures provide majority of resistance, LCL and joint capsule provide minor resistance

EMG

electromyography

Used to monitor the electrical activity produced by the firing of motor units

emg

Helps determine the relative proportion of motor units firing in a muscke during a specific contraction

emg

EMG can identify muscle activation patterns of agonists and antagonsists

True

Elbow flexors

brachialis, biceps brachii, brachioradialis, pronator teres, wrist flexors

Tasks requiring stability

uniarticular muscles>biarticular muscles

Uniarticular muscles

brachialis, triceps medial head

Biarticular muscles

triceps long head, biceps

Concave, located on the lat aspect of proximal ulna and mi ed with articular cartilage

ulnar radial notch

Encircles the radial head, lined with articular cartilage and attaches to the radial notch’s anterior and posterior edges

annular ligament

Connects to the ulna, capsule and collateral ligaments

articular disc

Collagen-rich, mostly avascular and articulates with ulnar head and carpal bones

articular disc

PRUJ ARTICULATING SURFACES

ulnar radial notch, annular ligament, radial head, humeral capitulum

DRUJ ARTICULATING SURFACES

ulnar radial notch , articular disc, ulnar head

PRUJ DISC SURFACES

convex, articulates with ulnar head

DRUJ DISC SURFACES

concave, articulates with carpal bones

PRUJ and DRUJ are mechanically linked, with motion in one joint affecting the other

true

Joints surfaces of radioulnar is optimal in maximal pronation/supination, with minimal contact in neutral position

false

Radius crosses over ulna

pronation

Radial head spinning within annular ligament and radial notch

pronation

Ulnar head rests against the palmar aspect of the ulnar notch

supination

Subluxation/dislocation of the radial head from the annular ligament

pulled elbow

Limits the spin of the radius

quadrate ligament

Taut in supination

oblique cord

Runs from ulna to radius

oblique cord

Forms 4/5 of ring

annular ligament

No direct attachment to the radius

annular ligament

Attached to ulna and rotates around the radiak head and attaches back to the ulna

annular ligament

Found anteriorly

volar radioulnar ligament

Found posteriorly

dorsal radioulnar ligament

2 divisions of radioulnar ligament

volar, dorsal

Stabilizes the PRUJ and DRUJ

interosseous membrane

Interosseous membrane structure

central band, membranous portion, dorsal oblique cord

Encircles four-fifths of the radial head, covered with cartilage, blending with joint capsule and reinforced by LCL

annular ligament

Connects the ulna’s radial notch to the neck of the radius, reinforcing the inferior joint capsule and limiting radial head spin during forearm rot

quadrate ligament

Extends from below the ulna’s radial notch to the bicipital tuberosity of radius

oblique cord

its function may be to prevent separation of the radius and ulna

oblique cord

Thick, collagen rich, maintains spacing between radius and ulna during rotation

central band

Thin, soft, adjacent to the central band

membranous portion

Runs counter to central band, from the ulna to the middle radius

dorsal oblique cord

Runs from the ulnar notch of the radius to the ulnar fovea and styloid process

Dorsal and palmar radioulnar ligaments

Remains taut during rotation, preventing radial-ulnar separation and helps transfer wrist loads to the forearm

central band

Primary muscles for pronation and supination

pronator teres, pronator quadratus, biceps brachii, supinator

Anconeus may also assist in supination and pronation

true

Ulnar head moves distally and dorsally

pronation

Ulanr head moves proximally and medially

supination

The axis of motion for pronation and supination is a longitudinal axis extending from the center of the radial head to the center of the ulnar head

true

The motion of proximal ulna is less in magnitude compared to that of the radius and is opposite in direction

false

Elbow injuries

compression, distraction, varus or valgus, others

Pronator teres

primary action at the radioulnar jts, also contributes to elbow flexuon due to its two jt nature, stabilizes the PRUJ by helping maintain contact between radial head and capitulum

Pronator quadratus

one jt muscle unaffected by elbow position, active in both unresisted and resisted pronation, regardless of speed, deep head contributes to dynamic stabilization, maintaining compression at DRUJ

Supinator muscle acts alone during unresisted slow supination in any elbow or forearm position. But it cannot act alone during fast supination with the elbow extended

First statement is true, second is false

Supination torque increaes as the forearm moves into pronation, peaking at about 20 deg of pronation

true

Biceps brachii is involved during resisted supination or fast supination with the elbow flexed

true

Maximum torque values for supinators are found in the ________ deg range of pronation

40-50

Isometric testing shows that pronators are stronger than supinators, highlighting the functional distinctions between these muscle groups

false

DRUJ stability muscular support

pronator quadratus, ECU, ECRB

taut in pronation

dorsal ligament

Taut in supination

palmar ligament

Prevent separation of ulna and radius, allowing about 5 mm of movement before resisting distraction

dorsal and palmar RU ligaments

Stabilizes the DRUJ, taut in pronation and loose in supination, protecting the ulnar head

interosseous membrane

Cushions compressive forces from the carpal to the ulna and stabilizes the ulnar side, bearing strain based on FA position

articular disc

Elbow stabilization muscles

FCU, flexors, extensors

Elbow flexion ROM

30-130 deg

Forearm rotation

100 deg

The diarthrodial joint of the radioulnar system allows for pronation and supination, enhancing hand mobility but compromising stability. Muscles like the extensor carpi radialis brevis and extensor carpi ulnaris attach at the distal humerus, creating a functional link between the elbow, wrist, and hand.

Both statements are true

Aging reduces pennation angles and fascicle lengths, leading up to 50% muscle function loss. Passive stretching can counter this by increasing fascicle length

First statement is true, second is false

Older adults: less type 2 fibers, same type 1 fiber percentage

false

100

Muscle mass and contraction tyoe influence performance loss, with isometric contractions being least affected

true