Bio-mechanics

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Author:
wolfgar
ID:
113648
Filename:
Bio-mechanics
Updated:
2011-11-01 11:36:20
Tags:
hand
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Description:
biomechanics of the hand
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  1. What type of joint is the thumb cmc, what motions can it produce and in what planes?
    Joint type - saddle

    • Motions -
    • flexion/extension = frontal plane
    • Abduction/adduction = saggital plane
    • opposition
  2. What tissues stabilize the CMC joint of the thumb?
    • Oblique ligaments
    • dorsal and palmar carpometacarpal ligaments
  3. What does the obliwue ligaments of the cmc joint of the thumb limit?
    • Extension
    • Abduction
    • opposition
  4. What are the motions, planes and arthokinematics of the the 1st cmc? of all the MCP joints? of all the IP joints?
    • CMC
    • Flexion/extension - roll/glide same
    • Abduction/adduction - roll/glide opposite

    • MCP
    • thumb - flexion/extension
    • 2-5 fingers - flexion/extension (saggital plane), abd/adduction (frontal plane)
    • roll/glide same (open chain)

    • IP
    • thumb - flexion/extension - frontal plane
    • 2-5 digits - flexion/extension - saggital plane
    • roll/glide same (open chain)
  5. What type of joint are the MCP joints?
    Condyloid
  6. Name all the stabilizing tissues of the the 2-5 mcp joints, and what there components resist?
    Palamr plates - which resists hyperextension

    Collateral (radial and ulna) ligaments - which have to components

    • Cord - resits flexion
    • accessory resists extension
  7. Name all the stabilizing tissues of the thumb?
    Extensor pollicis longus - reinforces forsal capsule

    • Collateral ligaments - limit abd/adduction
    • palamar plate - limits extension
    • sesmoid bones - limit extension
  8. What tissues stabilize the ip joint of the thumb?
    Palmar check rein ligament resists - hyperextension

    Palamr plates - which resists hyperextension

    Collateral (radial and ulna) ligaments - which resist abd/adduction depending on location.

    • Cord - resits flexion
    • accessory resists extension
  9. Name the stabilizing tissues of the ip joints of the 2-5 digits and give what each tissues reists?
    Collateral (radial and ulnar ligament ) - reists abd/adduction depending on location.

    • cord - resits flexion
    • accessory - resists extension

    Palamr plates resist - hyperextension

    palamr check-rein ligament resists - hyper extension
  10. List all the tissues that contribute to movement of the hand and what they do?
    Digital flexor tendon sheath - synovial fluid reduces the friction on the tendons and help provide them with nutrition.

    retinacula - bind flexor tendons close to bones and act as a pulley system, to prevent the tendon from bowstringing which would Decrease ROM by up to 1/2.

    Extensor hood mechanism - helps keep the tendons in the poper positions and aids in creating a good moment arm in active finger extension.
  11. What are the 9 componets of the extensor hood mechanism and what do they do?
    Extensor digitorum tendon - inserts into the base of the proximal phalanxs.

    dorsal hood - is composed of two sets of fibers that run around the MCP joint.

    Transverse fibers - wrap around the MCP joint and attach to the palamr plate - they act as a sling and aide in extension at the MCP joint.

    Oblique fibers - run distally and merge into the central tendon and lateral bands - they serve as an attachment site for the lumbricals and interossei. They also tranfer the force of the hands intrinsic muscles to the lateral band and central tendon.

    central tendon -is continuation of the central band of the ED tendon and it transmits force fro the ED , interosseo and limbrical to the middle phalanx were it inserts.

    lateral bands - comes of the central tendon at the middle of the proximal phalanx and it transmits force from the ED , interossei and lumbricals to the distal phalanx.

    terminal tendon - the merging of the two lateral bands which insert onto the base of the distal phalanx.


    oblique retinacular ligament - runs from the flexor sheath to the lateral bands - and helps to coordinate the movement of the PIP and DIP joints of the fingers.

    intrinsic hand muscles - the lumbricals dorsal and palamr interossei - extend the PIP and DIP joints.
  12. What are some problems that extrinsic muscle have when acting on the hand?Why do the extrinsic muscle need the intrinsic muscles of the hand?
    Because the extrinsic muscles of the hand are dependant on wrist position for optimal length-tension. They can be dimished by failure of the sheath and pulley systems.

    They need synergist ( often intrinsic muscle) to create finger flexion.
  13. What muscles flex the MCP, the PIP and DIP joints?
    MCP flexion - FDS is recruited first due to longer moment arm ( this is because it crosses fewer joints)

    PIP and DIP - if unresisted the FDP is recruited first if resisted the FDS is then recruited to help.
  14. What muscles help in MCP extension? in IP extension?
    MCP extension - ED

    • IP extension -
    • ED (if MPC if extending)
    • Interossei - are able to extend the ip due to their insertion in the dorsal hood.
    • Lumbricals -help by creating slack in FDP so it doesn't limit motion through passive tension.
  15. What muscles are involved in a cylindrical grip?
    FDP - flexes fingers around the object and may recruit FDS if the grip is tightened.

    Interossei - will flex the mcp joints

    Thumb - flexes and adducts around object - FPL, FPB, AP may all be rectruited.
  16. What muscles are involved in pad to pad prehension?
    • Thumb - cmc joint - opposition
    • OP, FPL, APL, FPB, APB

    thumb MCP+IP - flexion - FPL, FPB

    Fingers - MCP and PIP - FDP or FDS (depends on what happens at the DIP) , interossei (helps in MCP flexion),

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