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37 notecards = 10 pages (4 cards per page)

Viewing:

Biomech Exam #2: Wrist

front 1

Wrist into

back 1

  • 8 carpal bones
  • Act as a “spacer” between the forearm and the hand

front 2

2 primary articulations

back 2

  1. Radiocarpal joints
  2. Midcarpal joints

front 3

Terminology / directional terms

back 3

  1. Palmar & volar = anterior
  2. Dorsal = posterior

front 4

Osteology

back 4

  1. Distal forearm
  2. Carpal bones
  3. Carpal tunnel

front 5

Osteology: Distal Forearm

DORSAL

back 5

  • several grooves & raised areas that stabilize tendons coursing to the wrist/hand
  • Example: Dorsal(Lister’s)Tubercle => separates the ECRB from the EPL

front 6

Osteology: Distal Forearm

PALMAR

back 6

  • Proximal attachments of wrist capsule & thick palmar radiocarpal ligaments

front 7

Osteology: Distal Forearm
• distal articular surface of the radius

back 7

  • concave in both ML & AP directions
  • Two important boney configurations
    • Medial (ulnar) angulation of ~25 degrees = “ulnar tilt”
    • Palmar angulation of ~10 degrees = “palmar tilt”
  • ulnar deviation & flexion > radial & extension

front 8

Osteology: Carpal Bones (proximal)

back 8

  • scaphoid, lunate, triquetrum, pisiform
  • Joined “loosely”

front 9

Osteology: Carpal Bones (distal)

back 9

  • Bound tightly = stable base for articulation with metacarpal bones
  • trapezium, trapezoid, capitate, hamate

front 10

Osteology Proximal Bones: scaphoid

back 10

  • Most fractured
  • • Greek for “boat duetoit’sdistalroundedsurface(likeahull)
  • Has a tubercle
  • Articulateswithbothproximal&distalrow
  • Scapholunateligamentisimportant;morelater

front 11

Osteology Proximal Bones: Lunate

back 11

  • most instable; 2nd most fractured
  • Latinfor“moon”

front 12

Osteology Proximal Bones: Triquetrum

back 12

  • 3rd most fractured! • “triangle bone
  • Easily palpated with radial deviation

front 13

Osteology Proximal Bones: Pisiform

back 13

  • shaped like pea
  • EmbeddedwithinthetendonofFCU;sesamoid bone
  • Attachmentforotherligaments
  • Easytopalpate!

front 14

Osteology Distal Bones: capitate

back 14

  • largest of all carpals
  • Latin for “head”
  • Stable anchor at the base of the third metacarpal = longitudinal stability of hand; axis for all wrist motion

front 15

Osteology Distal Bones: Trapezium

back 15

  • Articulates with thumb; saddle joint.
  • Has a tubercle
  • Along with tubercle of scaphoid; serves as attachment point for transverse carpal ligament

front 16

Osteology Distal Bones: trapezoid

back 16

Nothing to notes

front 17

Osteology Distal Bones: hamate

back 17

  • Articulates with base of 4th & 5th = allows for cupping motion of hand
    • Has a hook = medial attachment for the transverse carpal ligament!

front 18

Osteology: The carpal tunnel

back 18

  • Thick band = transverse carpal ligament
  • Palmar cavity made by carpal bones and transverse CL
  • Restrains enclosed tendons from springing out (anteriorly)

front 19

Arthrology: Radiocarpal

back 19

Between ulnar+radius and triquerium+lunate+scaphoid

front 20

Arthrology: Midcarpal

back 20

Between finger bones and hamate+capitate+trapezoid+trapezium

front 21

Arthrology: Intercarpal

back 21

  • synovial plane joints that connect the carpal bones
  • 3 sets/rows of joints

front 22

Arthrology: Intercarpal (ligaments)

back 22

front 23

Arthrology: Intercarpal (extrinsic ligaments)

back 23

front 24

Arthrology: Intercarpal (intrinsic ligaments)

back 24

front 25

Osteokinematics

back 25

  • 40 flexion
  • 40 extension
  • 10 radial deviation
  • 30 ulnar deviation

front 26

Arthrokinematics: flexion + extension (limp+back wrist)

back 26

  • ROLL + SLIDE = same direction
  • concave + convex
  • limp wrist forward (extension) OPPOSITE with flexion
    • dorsal radiocarpal ligaments slacken + parlmar RC lig is tight

front 27

Arthrokinematics: ulnar + radial deviation

back 27

  • roll + slide = same direction of deviation
  • concave-convex
  • waving motion

front 28

"Double V" ligaments with ulnar+radial deviation

back 28

  • Upper V shape = medial + lateral of palmar intercarpal ligament
  • Lower V shape = palmar ulnocarpal+ palmar radiocarpal ligaments

front 29

Primary Muscular Actions

back 29

attach distally within the carpus; act on the wrist only

front 30

Secondary Muscular Actions

back 30

cross the carpus and attach to the digits = act on wrists & hand

front 31

Muscular actions map

back 31

front 32

Muscular Actions: Wrist Extensors Muscles

back 32

  • Extensor Carpi Radialis Longus
  • Extensor Carpi Radialis Brevis
  • Extensor Carpi Ulnaris
  • (Extensor digitorum // finger extension + torque at wrist)
  • Extrinsic finger extensors

front 33

Muscular Actions: Wrist Extensors in action

back 33

  • extrinsic finger flexors contract (Fl. digit.sup+ profundus) and fex fingers but creates wrist flexion torque
  • carpi radialis brevis BLOCK wrist flexion tendency (caused by finger flexor muscles)
  • => wrist extensor maintains good length+flex fingers better

front 34

Muscular Actions: Wrist Flexors muscles

back 34

  • Flexor Carpi Radialis
  • Flexor Carpi Ulnaris
  • Palmaris Longus
    • Absent in 10-15% of people
  • (Extrinsic finger flexors): produce more torque than wrist muscles, depending on wrist position

front 35

RIGHT CARPAL TUNNEL: Cross sectional area, position, and length of moment arms (muscles that cross wrist @capitate head level)

back 35

  • each muscle's moment arm for a particular action is equal to the perpendicular distance between the axis and the muscle tendon's position

front 36

Muscular Action: Radial Deviations

back 36

  • 15% more torque than ulnar
  • Extensor carpi radialis brevis+Longus (ECRB & ECRL)
  • extensor pollicis longus + brevis (EPL & EPB)
  • flexor carpi radialis (FCR)
  • abductor pollicus longus (AbPL)
  • flexor pollicis longus (FPL)

front 37

Muscular Action: Ulnar Deviations

back 37

  • extensor carpi ulnaris (ECU)
  • flexor digitorum profundus and superficialis (FDP & FDS)
  • extensor digitorum (ExDigi)