elbow/forearm Flashcards
What are the articulations w/in the elbow and forearm?
Humero-ulnar joint
Humeroradial joint
Proximal radio-ulnar joint
Distal radio-ulnar joint
T/F: olecranon process is on the radius
F: ulna
Fovea of radial head =___, edge of head =___
Concave
Convex
Prox RU joint vs distal RU joint radius and ulna convex vs concave
Prox: convex radial head, concave ulna
Distal: convex ulnar head, concave radius
What restricts radial deviation?
Radial styloid process
What carpal bone is the most injured?
Scaphoid
The humero-ulnar joint is made up of what 2 structures?
Trochlear notch (proximal ulna)
Trochlea (humerus)
The humeroradial joint is made up what 2 structures?
Fovea (proximal radius)
Capitulum (humerus)
T/F: the humeroradial is less congruent compared to humero-ulnar joint
T
What type of joint is the elbow?
Modified hinge (ulna experiences slight ant axial rotation and side-side motion as flex/ext)
Elbow flex and extend near ___ axis of rotation
Medial-lateral
Varus is Latin for
Turned inward (ADD)
Valgus is Latin for
Turned outward (ABD)
T/F: the natural frontal plane angle made by the extended elbow is referred to as normal cubital varus
F: normal cubital valgus
T/F: carrying angle is another term for normal cubital valgus
T
Normal cubitus valgus of the elbow is at an angle of ___ from the longitudinal axis of the humerus
15 degrees
Excessive cubitus valgus is when the forearm is deviated laterally ___
30 degrees
Cubitus varus is when the forearm is deviated medially ___
5 degrees
T/F: women have greater valgus angulation compared to men by about 2 degrees
T
T/F: regardless of gender, valgus angle is larger on the non dominant arm
F: dominant arm
With a valgus force, which side is compressed? Tensed?
Compress= lateral
Tension (stretch)= med
Medial collateral ligament of elbow consists of
Ant, post and transverse fiber bundles
T/F: the posterior fiber bundles of the MCL are the strongest and stiffest
F: ant fiber bundles
T/F: ant and post fiber bundles of MCL provide significant resistance against a valgus (ABD) producing force
T
Ant fiber bundles of MCL provide articular stability throughout which plane?
Sagittal plane
T/F: ant fiber bundles of MCL are fan shaped
F: post fiber bundles
Ant fiber bundles are taut throughout _____, while post fibers are taut in ____
Full range flexion and extension
Extremes of elbow flexion
T/F: flexor carpi ulnaris is the dynamic medial stabilizer of the elbow
T
Dynamic stabilizers =
Flexors and pronators
T/F: MCL is susceptible to injury when the extended elbow is violently forced into extreme varus (fall outstretched and supinated UE)
F: valgus
T/F: MCL is susceptible to injury from non-weight bearing, repetitive, valgus producing strains placed on the elbow
T
What are the 2 fiber bundle branches of the lateral collateral ligament of the humerus?
Radial collateral lig
Lateral (ulnar) collateral lig
T/F: LCL also provides resistance against valgus forces
F: varus
LUCL is taut at full ___
Flexion
What 2 lig provide primary soft tissue resistance against varus and valgus mvt throughout full flex and ext?
LUCL (varus)
Ant fibers of MCL (valgus)
T/F: LUCL prevents excessive ER of proximal forearm relative to the humerus
T
LUCL provides stability at the elbow in which 2 planes?
Frontal and transverse planes
What is the position of comfort for individuals w/ inflammation and swelling
Intracapsular pressure is lowest at 80 degrees flexion
Close vs loose pack pos for humeroulnar
Close: full ext, supination
Loose: 70 deg flex, 10 deg sup
Close vs loose pack pos for humeroradial
Close: 90 deg flex, 10 deg sup
Loose: full ext, sup
Close vs loose pack pos for proximal, distal radioulnar
Close: full pronation, supination
PROX loose: 70 deg flex, 35 deg sup
DISTAL loose: 10 deg sup
Normal ROM = __ deg extension to __ deg flexion
5-145
If elbow flexor contracture, how many deg can you move?
Less than 30 deg
How many degrees is the functional arch (able to do most ADLs) of flexion?
30-130 deg
What is needed for full flexion and extension
Extensibility and space
When __ = scarred, damages extension, ___= scarred, damages flexion
Olecranon process
Coronoid process
Injury at C5 spinal cord injury may result in
Being unable to pull, lift, feed and groom bc elbow flexors are paralyzed
T/F: in the hummer-ulnar joint, the trochlear notch is concave, while the trochlea is convex
T
What is the roll and glide for flexion of humeroulnar joint?
Roll and glide ant (ulna on humerus)
@ humeroulnar joint, what is stretched in extension? Flexion?
EXT: ant structures (post slacken)
FLEX: post structures (ant slacken)
T/F: humeroradial joint rolls and glides ant when ext
F: flex (radius on humerus)
(ext= post)
T/F:ulnar n = stretched when flexed
T
How is the central band oriented?
Distally and medially from radius to ulna
What is the primary role of central band of interosseous membrane?
Firmly bind radius to ulna
Attachment point for extrinsic muscles of hand
Transmit force proximally through upper limb
T/F: interosseous membrane helps w/ distraction forces
F: helps redistribute compressive forces fr radius –> ulna –> humerus
T/F: distractive forces shortens the IM and goes through musc
T
Proximal and distal radio-ulnar joints allows forearm to perform which mvts?
Pronation and supination
The axis of rotation of prox and distal radio-ulnar joints= ___ part of the joint
Convex
T/F: pronation supination allows independent rotation of the hand w/out obligatory rotation of radius and humerus
F: ulna and humerus
T/F: during pronation, distal ulna rotates on fixed radius
F: distal radius rotates on fixed ulna
Pronation= assoc w/ shoulder ___, supination= shoulder ___
IR
ER
Annular lig is a circular band of CT that attaches to __, holding proximal radius to ulna
Ulna on either side of the radial notch
Distal radio-ulnar joint is made up of ___ head of ulna and ___ ulnar notch on radius
Convex
Concave
T/F: radius and ulna are parallel when forearm = in pronation
F: supination
T/F: humeroulnar, humeroradial and proximal radioulnar joint share 1 articular capsule
T
T/F: annular lig= primary stabilizer of proximal radio-ulnar, TFCC= distal
T
Stabilizers of distal radio-ulnar joint
Triangular fibrocartilage complex (TFCC)
Pronator quadratus
Tendon of extensor carpi Ulnaris
Distal oblique fibers of interosseous membrane
T/F: pronator quadratus= primary stabilizer of distal radio-ulnar joint
F: TFCC (Triangular Fibrocartilage Complex)
T/F: loss in integrity of TFCC = clinical sign of advanced rheumatoid arthritis
T
Neutral pos/0 reference pos of forearm rotation is
Thumbs up (betw sup and pron)
Normal ROM = ___ degrees of pronation, and ___ degrees of supination
75
85
What is the functional arc for pronation and supination?
50 deg both
T/F: without the last 30 degrees of complete forearm rotation, one cannot perform ADLs
F: can still perform ADLs
Pron and sup can be compensated @ shoulder via ___ and ___ respectively
IR
ER
The elbow and forearm are innervated by
Musculocutaneous
Radial
Median
Ulnar
Musculocutaneous spinal nerve roots
C5-7
Musculocutaneous innervates what musc?
Biceps brachii
Coracobrachialis
Brachialis
Radial n spinal nerve roots
C5-T1
Radial n innervates
Triceps
Anconeus
Brachioradialis
T/F: radial n= main innervator of elbow
F: elbow and forearm
Median n spinal nerve roots
C6-T1
Median n innervates
Wrist flexors and pronators:
Pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis
Ulnar n spinal nerve roots
C8-T1
Ulnar n innervates
Flexor carpi ulnaris
Med half of flexor digitorum profundus
Intrinsic musc of hand
Elbow flexors are innervated by which nerves?
Musculocutaneous (biceps)
Radial (brachioradialis)
Median (pronator teres)
T/F: when lose 1/3 nerves innervate elbow flexors, you can still flex arm
T
Elbow flexors= innervated by 3 nerves, elbow extensors= ___
1: radial n
Pronators of forearm= innervated by
Median n
Supinator of forearms= innervated by
Musculocutaneous n
Radial n
HU and HR joints innervated by ___, Prox RU? Distal RU?
C6-C8
C6-7
C8
T/F: musc that attach distally on radius can flex/extend but unable to pronate/supinate
F: attach on ulna
(radius can do all 4)
Biceps brachii has greatest force during ___
Flexion and supination
T/F: biceps brachii = largest cross sectional area resulting in greatest force generated by any musc that innervates elbow
F: brachialis
Brachioradialis = ___ of all elbow musc
Longest
When brachioradialis shortens, it causes full elbow _____ and ___ of forearm to near neutral position
Flexion
Rotation
T/F: at elbow, flexor torque > extensor torques (opposite of knee)
T
Elbow flexor torque= greatest when forearm = ___. Why?
Supinated
Bc inc biceps flexor MA
Elbow flexors best torque, force and MA
90 deg torque
80 deg force
100 deg Internal MA
Elbow flexion and __ shoulder results in greater elbow flexion torque (biceps)
Extended
Ext shoulder and flex elbow, cxn velocity =___ and ___ force
Slows
Generates more
T/F: ant deltoid= synergist to biceps as ext shoulder and flex elbow
F: post delt
T/F: primary elbow extensors= triceps brachii
F: triceps and anconeus
T/F: long head of triceps can ADD shoulder
T
Anconeus= sm (little ext torque) but provides ___
Stability
T/F: elbow extension is typically paired w/ shoulder extension
F: shoulder flexion
Ant deltoid = imp synergist to triceps for ___, post deltoid = imp synergist to biceps for___
Push forward (shoulder flexion)
Shoulder extension
Triceps __ elbow or __ flexion
Extends
Prevents
Order of recruitment for elbow extensors (low lv -> high effort)
Anconceus
Medial triceps
Lateral triceps
Long triceps
Elbow extensors peak torque, greatest MA
90 deg
Full ext
What are the 2 classifications for musc to be pronators/supinators?
- attach prox: ulna/humerus and dis: radial/hand
- produce force acts w/ an internal MA about AoR for pron and sup
(MA= greatest when perpendicular to AoR)
Shoulder IR and ER + elbow pron and sup respectively, allows hand to rotate ___ deg in space compared to 170-180 deg pron and sup alone
360
What are the primary supinators?
Biceps brachii
Supinator
What are the secondary supinators?
Radial wrist extensors
Extensor pollicis longus
Extensor indicis
Brachioradialis (pronated pos)
What is between the 2 heads of supinator?
Radial n
Where do you notice weakness w/ radial n damage?
Finger and thumb extensors
T/F: excessive pronation @ supinator -> radial compression
F: supination
T/F: brachioradialis = secondary supinator and pronator
T
(pronated pos-> sup) (vv)
NS usually recruits what musc for low power tasks that only require supination?
Supinator
T/F: supinator shows sig EMG activity during mod/high power supination
F: biceps
As supinated forearm rotates towards pronation, ___ tendon wraps around prox radius and “unwinds” radius back - sup
Biceps
Biceps effectiveness as a supinator = greatest when elbow flexed @___
90 deg
When turning a screw, the triceps prevent the biceps from ___ the elbow and shoulder during every supination effort
Flexing
T/F: when turning a screw, triceps neutralizes biceps elbow flexion w/o interfering w/ supination task bc triceps= attached to ulna
T
Primary pronator musc
Pronator teres
Pronator quadratus
Secondary pronator musc
Flexor carpi radialis
Palmaris longus
Brachioradialis (supinated pos)
Median n passes through what 2 heads of musc?
Pronator teres (humeral and ulnar heads)
Median n injury ->
Pronator musc paralyzed
T/F: pronator teres= most involved pronator that’s involved during all pronation mvt regardless of power demands
F: pronator quadratus
(teres= greatest EMG activity @ high power pron)
Pronator quadratus stabilizes the distal radio-ulnar joint by ___
Compressing ulnar notch (radius) against ulnar head
T/F: pronator teres = activates during high power activities
T
___ (group) = stronger than ___ of elbow
Flexors and extensors
T/F: pronators as group= stronger than supinators
F: supinators>pronators
