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MSK 4 > UE Joint biomechanics > Flashcards

UE Joint biomechanics Flashcards

1
Q

What is the normal range for flexion and extension of the elbow joint?

A

Ext: 0 deg.
Flex AROM: 135-145 deg
Flex PROM: 150-160 deg

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2
Q

What prevents posterior displacement with elbow flexion?

What bony landmark prevents elbow hyperextension?

A

coronoid process sliding into coronoid fossa

olecranon locking into olecranon fossa

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3
Q

When is the elbow joint capsule at it’s maximum volume?

A

70-80 deg of flexion

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4
Q

What are the 3 parts of the MCL of the elbow?

-What are the characteristics of each?

A

Anterior: prevents valgus restraint through all elbow extension

Posterior: taut in full flexion

Transverse: no role in stability

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5
Q

What ligament is the primary restraint for elbow varus deviation and over supination?

What is the secondary restraint for these motions? When is each ligament tight?

What ligament restrains traction and lateral subluxation?

A

Elbow radial LCL

Lateral Ulnar Collateral Ligament and Annular Ligament
-tight in extreme flexion and any varus motion

Annular ligament

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6
Q

What is the usual carrying angle of the elbow joint? What is impacted if this angle is increased?

How does the elbow angle change with flexion and extension?

A

around 13 deg. of radial deviation but it is usually bigger in females and if the angle is increased it impacts the ulnar nerve

elbow laterally deviates in extension and medially deviates with flexion

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7
Q

What structures limit elbow extension?

What structures limit elbow flexion?

A

Extenion: anterior capsule, flexor muscles, and olecranon process/fossa

Flexion: soft tissue, posterior capsule, extensor muscles, radial head/fossa, coronoid process/fossa, also limited with forearm in mid-to-full pronation

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8
Q

When is the humero-ulnar joint in an open packed position?

When is it in the closed packed position?

A

Open: 70 deg. flexion and 10 deg supination

Closed: full extension and supination

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9
Q

When is the humero-radial joint in an open packed position?

When is it in the closed packed position?

A

Open: full extension and supination

Closed: 90 deg of flexion and 5 deg of supination

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10
Q

How does an injury typically impact the open and closed packed structures of the elbow?

A

closed-packed joints often fracture the associated bones

open-packed joints during injury typically dislocate

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11
Q

What is the role of the interosseous membrane (IOM)?

How is weight bearing from the hand transferred to the forearm?

A
  • binds radius to ulna
  • site for muscle attachments
  • transfers force from radius to ulna

weight bearing from hand to forearm is through radius and is shared to ulna through the IOM

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12
Q

What ligament supports the proximal radio-ulnar joint?

A

annular ligament which allows spin and prevents radial head displacement

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13
Q

In the distal radio-ulnar ligaments when is the palmar aspect tight? When is the dorsal lig. tight?

A

Palmar: tight in supination
Dorsal: tight in pronation

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14
Q

What portion of the TFCC is avascular?

A

central portion

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15
Q

What is the normal ROM for radio-ulnar pronation and supination?

What is the functional ROM for each?

A 
Pronation= around 75 deg.
Supination= around 85 deg.

Function ROM is 50 deg for each

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16
Q

What is the radial head motion during supination and pronation movements?

A

Supination: radial head spins in annular lig/radial notch and “unwinds” from the ulna

Pronation: radial head spins in annular lig/radial notch and rotates over ulna

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17
Q

True or False: The proximal and distal radio-ulnar joint does not follow typical roll/glide rules for manual therapy.

A

False, the distal RU joint the roll/glide is the same but the proximal RU joint the roll/glide is opposite

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18
Q

What limits supination movements?

What limits pronation movements?

A

Supination: pronator teres, pronator quadratus, TFCC, palmar DRUJ ligaments, and IOM

Pronation: Supinator, Biceps, TFCC, and Dorsal DRUL ligament

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19
Q

When is the Biceps Brachii most effective?

A

most effective as an elbow flexor at 80-100 deg. of elbow flexion and with shoulder extension

most effective as a supinator at 90 deg. flexion

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20
Q

When is the brachioradialis strongest?

A

strongest at 90-120 deg. of elbow flexion with forearm in mid-position

21
Q

When does the triceps brachii produce the most torque?

Which head of the triceps is most active?

A

in 90 deg. of elbow flexion

middle head is most active, other two heads only activate with higher load or greater speed of contraction

22
Q

What is the role of the anconeus muscle?

A

helps initiate elbow extension and may stabilize against varus force

23
Q

What muscles flex the elbow?

A

brachialis
biceps brachii
brachioradialis
pronator teres

24
Q

What muscles extend the elbow?

A

Triceps and anconeus

25
Q

What muscles supinate the forearm?

A

Supinator
biceps brachii
radial wrist extensors
brachioradialis

26
Q

What muscle pronate the forearm?

A 
pronator teres
pronator quadratus
flexor carpi radialis
palmaris longus
brachioradialis
27
Q

What is normal ROM for the wrist motions of flexion, extension, radial and ulnar deviation?

What are the functional wrist ROM positions?

A

Flex: 65-85 deg
Ext: 60-85 deg
RD: 15-21 deg
UD: 20-45 deg

Functional:

  • 20-35 deg ext
  • 10-15 deg ulnar deviation
28
Q

What is the capsular pattern for the wrist?

What position is closed packed for the wrist?

A

capsular pattern: equal limit to flex and extend

Close pack: full extension

29
Q

What is associated with an ulnar styloid which is more proximal?

What is associated with a more distal ulnar styloid?

A

associated with Keinbock’s disease

associated with TFCC impingement

30
Q

Which row of the carpal bones is most mobile?

What are the key intrinsic ligament for this row?

What muscles attach to this row?

A

the proximal row

scapholunate interosseous and Lunotriquetral interosseous

flexor carpi ulnaris

31
Q

What is the commonly fractured bone during a FOOSH MOI? (falling on outstretched hand)

What is the most commonly dislocated carpal bone?

What bone exerts a flexion moment on the proximal row?

Which bone exerts an extension moment on the proximal row?

A

Scaphoid

Lunate

Scaphoid

Lunate

32
Q

What are characteristics of the extrinsic wrist ligaments?

What are the characteristics of the intrinsic ligaments?

A
  • connects radius/ulna to carpals
  • connects carpals to metacarpals

Intrinsic:

  • stronger
  • carpal to carpal
  • slow healing-lie with synovial lining
33
Q

What movement causes a dorsal intercalated segment?

Which ligament is disrupted by this segment?

A

lunate tips dorsally due to the connection to the triquetrum

scapholunate ligament disrupted

34
Q

What movement causes a Volar intercalated segment?

Which ligament is disrupted by this segment?

A

lunate dips palmarly due to connection to scaphoid

lunotriquetral ligament is disrupted

35
Q

How does the lunate and capitate move as the wrist is put into extension?

How do these motions change with flexion?

A

lunate rolls dorsally and slides volarly on distal radius

capitate rolls dorsally and slides volarly on lunate

Reverse motions from extension

36
Q

How do the carpals move as the wrist goes into ulnar deviation? Radial deviation?

A

ulnar deviation: proximal row rolls ulnarly and slides radially

Radial deviation: prox row rolls radially and slide ulnarly

37
Q

True or False: The flexors of the wrist work almost 2x as much as the extensors of the wrist and the radial deviators work more than the ulnar deviators.

A

True

38
Q

What are the three main arches of the hand?

A

Proximal Transverse Arch : through the carpals, capitate is the key, more stable than mobile

Distal Transverse Arch: goes through the MC heads and is more mobile than the proximal arch

Longitudinal Arch: connects the transverse arches

39
Q

True or False: All CMC joints between digits 2-5 are planar joints that allow for flexion and extension.

A

False, the 5th is a saddle joint that also allowed for abd/add

40
Q

What are the open and closed pack positions for the thumb CMC joint?

What is normal ROM for the thumb CMC joint flexion/extension? abduction?

A

closed: opposition
Open: neutral

Flex/Ext: around 50 deg total
Abd: around 40 deg total

41
Q

What is the closed pack and open packed positions for the MCP joints?

What is normal ROM for the MCP joints for flexion, extension, and abduction?

A

Closed: full flexion
Open: slight flexion

Flex: 90 deg at 2nd and progresses to 110 at 5th MCP
Ext: 30-40 deg AROM but 90 deg PROM
Abd: around 20-30 deg in neutral; restricted in flexion

42
Q

What is the normal ROM for flexion and extension of the thumb MCP joint?

A

Flexion: 60 deg
Extension: 0 to very slight hyperextension

43
Q

What is the open and closed packed position for the finger interphalangeal joints?

What is the normal ROM for flexion and extension of the proximal and distal PIP joints? How is this different from the thumb IP joint?

A

closed: full extension
Open: slight flexion

PIP: flexion-100-110 deg extension-0 deg
DIP: flexion 80 deg extension-20 deg
Thumb IP: flexion-80 deg. extension: 20 deg

44
Q

When are the radial and ulnar collateral ligaments of the fingers at max tension?

A

In 70 deg. of flexion

45
Q

What is the only muscle capable of extending the MCP?

What can this muscle not do?

A

Extensor digitorum

cannot extend PIP and DIP alone, it needs assistance from the intrinsic muscles, if no assistance from intrinsics then the IP/DIP joints will flex

46
Q

How does the PIP joint extend?

How is this different for the DIP joint?

A

PIP:
-intrinsice muscles (lumbricals) produces extension through lateral bands

DIP:
-oblique retinacular lig. tightens due to PIP extension which pulls on terminal tendon to extend DIP

47
Q

What is the flexor mechanism for the interphalangeal joints?

A
  • flexor digitorum profundus initiates DIP flexion
  • DIP flexion pulls terminal tendon and lateral bands distally
  • extensor hoods pulled distally, relaxing central tendon for PIP flexion
  • pull of flexor digitorum profundus and absence of extensor digitorum activity causes intrinsics to impart flexion at PIP
48
Q

What is prehension?

What are the two types?

A

grasping objects between any 2 surfaces in the hand

Power Grip:
-flexion at all fingers

Precision Handling:

  • finger-finger or finger-thumb skilled placement
  • two jaw chuck (using 2 digits)
  • three jaw chuck (using 3 digits like when using a pencil)
49
Q

What is the functional hand position?

A

Wrist in 20-30 deg. extension
MCP in 34-45 deg flexion
PIP/DIP in 15-30 deg. flex
thumb CMC in 35-45 deg flex

MSK 4 (14 decks)

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