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The Elbow

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The Elbow Powered By Docstoc
					Elbow Joint
               Bones
              humerus

              ulna


              radius




                        1
Elbow Joint
  A very stable joint that assists shoulder
  in application of force and controlling
  placement of hand in space
                                  humeroulnar
                                  joint




                                     humeroradial
                                     joint
                                                    Asymmetrical structure
                                                    of trochlea creates
                                                    angulation of ulna
                                    proximal        when extended known
                                    radioulnar      as the carrying angle
                                    joint
                                                                     2
Elbow Structures
                 coronoid fossa
           radial fossa

 lateral epicondyle

trochlea

capitulum
                                         medial
                                         epicondyle
coronoid process


                                  Anterior View3
  Elbow Ligaments
              Anterior view of right elbow joint




                       Valgus                                   Varus

  annular ligament
  holds radius up
  into the elbow jt.                               medial/ulnar collateral resists valgus
                                                   stresses

lateral/radial collateral resists varus            ulnar collateral is taut in all joint
stresses                                           positions
                                                   valgus support very important since
because varus stresses are rare support            most forces are directed medially
from                                               (creating a valgus force)
these ligaments is less significant
                                                                                      4
 Elbow ROM


flexion/extension
       145º active, 160º passive
       need 100-140º to perform ADL’s
       (e.g., reach back of head to comb hair need 140º
               only 15º needed to tie a shoe)

supination/pronation
      85º supination; 70º pronation
      need 50º supination & 50º pronation to perform ADL’s




                                                          5
                       biceps brachii                           Elbow Flexors
                    multi-articular muscle
                    whose effectiveness
                    is dependent on                                  Flexors are almost
                    position of shoulder                             twice as strong as
                    & radioulnar jts                                 the extensors making
                                                                     us better pullers than
                                                                     pushers


                                                   brachialis
        brachioradialis
(Used more in rapid mvmts or against resistance)
                                                                Note: brachialis is the
                                                                MOST EFFECTIVE
                                                                elbow flexor!
                                                                biceps brachii not
                                                                effective when pronated
                                                                                              6
                      Elbow Extensors
     triceps brachii
            long head is bi-articular
            so its force production
            dependent on shoulder
            position

                   lateral head is strongest
                   yet is relatively inactive
                   unless acting against
                   resistance


anconeus

                         medial head is the
                         ‘workhorse’ of this group
                         active in all positions
                                                     7
                              biceps brachii           Radioulnar Joints
   supinator                      active in rapid
always active                     mvmts or          Supination   Pronation
                                  against
                                  large loads




 pronator teres
active in rapid mvmts
or against large loads
                         pronator quadratus
                                always active




                                                                         8
                                         Forearm muscle
 Biceps brachii & brachialis active to   contribution in throwing
 flex elbow (& abduct shoulder)




                                                             Biceps most
                                                             susceptible
                                                             to strain during this
                                                             phase


triceps brachii becomes active              triceps activity drops off sharply -
to extend elbow (some dispute this)         biceps brachii and brachialis
                                            quickly become active to
                                            decelerate elbow                         9
   Injury potential in forearm
Mainly a consequence of repetitive activities

dislocations are possible
   often accompanied by fracture
   of medial epicondyle

myositis ossificans of brachioradialis
  deposits of ectopic bone in muscle
  2nd most common site behind quads

high velocity overhead movements
   (e.g., throwing, tennis serve)
   large tensile forces developed medially
   large compressive forces developed laterally
   large shear forces developed posteriorly

   this is created by the development of a large
   VALGUS force on elbow during late cocking and
   early acceleration                              10
Medial Epicondylitis
linked to movements containing
high velocity valgus extension
mechanism

large valgus torque near maximal
external rotation resisted by
a large varus torque generated
by the soft tissue in the elbow




                                   11
                             Little Leaguer’s Elbow




• medial epicondylitis
  – medial strain imparted during the initial forward phase of
    throw as hand and elbow lag behind trunk and shoulder
  – curveball pitching will magnify this medial strain throughout
    pitch and therefore is not recommended for young pitchers   12
      Medial Elbow Injuries
    (“Little Leaguer’s Elbow”)
Sprain or rupture of
  ulnar collateral ligaments

medial epicondylitis

tendinitis of wrist flexors

avulsion fractures of medial epicondyle

osteochondritis dissecans to the capitulum
 (a lesion in the bone and articular cartilage)
 where the radial head is pushed up into
 the capitulum due to the compressive
 load developed from the valgus force             13
                     Tennis elbow
• lateral epicondylitis -
  inflammation/microdamage to tissues on the
  lateral side of the humerus, 30%-40% of
  tennis players will develop some amount of
  this injury
• causes include poor technique and
  equipment
   – e.g. off-center shots and rackets strung
      too tightly
• The pain is exacerbated by activities
  involving extension of the wrist. These
  include lifting a suitcase, shaking hands,
  turning doorknobs, etc
                                                14
  The Wrist                                Radiocarpal
  and Hand                                    Joint

 Distal                                                       I
 Radioulnar Joint
                            Carpals
WRIST - radiocarpal joint
condyloid joint
                                                                   II
ulna makes no contact withMetacarpals
carpals but floats on disc so                P
it does not influence wrist                      M
mvmt during                    Phalanges                          III
supination/pronation                                 D
                                                 V       IV
                                                                        15
                                                       The scaphoid may be
Radiocarpal jt is the articulation                     one of the most
between the scaphoid & radius                          important carpals
                                                       because it supports
            scaphoid                                   the weight of the arm
                                                       and transmits the
                                                       forces between the
                                                       hand and the forearm




                                          Midcarpal joint


                                     Wrist ROM
                                     flexion: 70-90º need 10-15º for ADL’s
                                     extension: 70-80º need 35º for ADL’s
                                     ROM reduced when fingers are flexed

                                                                               16
Radial & Ulnar Deviation
proximal row of carpals
glides over distal row

ROM
radial dev. 15-20º
ulnar dev. 30-40º


                      17
                                    CMC of thumb is a saddle
                                    jt that allows flex/ext,
Carpometacarpal (CMC) jt            ab-/adduction & rotation

                                    these movements permit
                                    thumb to touch each finger
                                    (known as opposition)

                                    opposition is very
                                    important in all gripping &
                                    prehension tasks




                     Concave transverse arch metacarpals
                     to facilitate gripping
                                                                  18
Metacarpophalangeal (MCP) jts




                                      MCP of thumb is a hinge
                                      jt allowing only flex/ext




                           MCP of fingers is a condyloid jt
                           permitting flex/ext and ab-/adduction


                                                           19
               extensor carpi
                radialis longus



                                                     extensor
                                                     digitorum
extensor carpi
 radialis brevis




   Wrist Extensors                extensor carpi
   NOTE: Origin                   ulnaris
   on lateral               Because the extensors act
   epicondyle               on the elbow jt, elbow jt pos.
                            will influence extensor output       20
   flexor carpi
   radialis                                        flexor carpi
                                                   ulnaris
                       Wrist Flexors
                       all fusiform muscles
                       NOTE: Origin
                       on medial
                       epicondyle

palmaris                                      strongest flexor
longus                                        strength increased by
                                              encasing the pisiform in
                                              its tendon such that it
                                              becomes a sesamoid bone
                                              that improves the mechanical
                  Absent in 13%               advantage of the muscle
                  of population
                                                                             21
Radial Deviation - created by the radial muscles

                                     Extensor carpi radialis longus
                                       & brevis

         Flexor carpi radialis




  Ulnar Deviation - created by the ulnar muscles
        Extensor carpi ulnaris




                                                  Flexor carpi ulnaris

                                                                      22
Most of the muscles acting on wrist                Tendons are held in place
& fingers originate outside of the hand            on the dorsal and palmar
in the region of the elbow so they are             sides by the extensor &
known as extrinsic muscles                         flexor retinaculum respectively
                                                   (a thick band of fibrous tissue
                                                   running transversely across
                                                   the wrist)




                                     intrinsic muscles of the hand include
                                     4 muscles on thumb forming the
                                     thenar eminence and 3 muscles on the pinky
                                     forming the hypothenar eminence

                                                                                     23
Grip strength
related to wrist position
 strongest when wrist is slightly ulnar deviated and hyperextended
 grip @ 40º extension is 3X stronger than in 40º flexion
 neutral grip is safest position that minimizes strain on wrist structures

power grip utilizes extrinsic muscles
precision grip utilizes intrinsic muscles


Thumb position greatly influences grip
 thumb in plane of the hand in an
 adducted position such that fingers
 flex around object a power grip is
 created

 thumb is positioned perpendicular to
 hand and moved into opposition a
 precision grip is created

                                                                             24
Wrist actions in activities

 dynamic actions
        golf/baseball swing: active radial and ulnar
        deviation in the preparatory and power phases respectively

 static actions
           piano playing/typing: must maintain a stable, static
           position in order to maximize finger action




                                                                     25
Wrist/Hand Injuries
falls - broken with outstretched hand
 forces wrist into position of extreme
 extension or flexion

  sprain wrist ligaments
  strain wrist flexors
  fracture schaphoid
  fracture distal radius
    one of the most frequently fractured
    areas of the body because of its
    lower density and the size of the
    forces it usually accommodates
Overuse injuries - repetitive strain injuries
tenosynovitis of radial flexors and thumb muscles
 from canoeing, rowing, tennis, and fencing
medial epicondylitis due to overuse of wrist flexors



                                                       26
Carpal Tunnel Syndrome
 repeated wrist flexion/extension may inflame
 wrist flexor tendons to the point that
 they apply pressure and constrict
 the median nerve which innervates
 the radial side of the hand (thenar muscles)

wrist stabilization in a neutral position is
 recommended as treatment or prevention
 often using an external device

Ulnar Nerve Injuries
 occurs due to trauma to the elbow
 note that this nerve is not encased in the
 carpal tunnel
                      Carpal Tunnel
                      tunnel formed by the carpals
                      (floor and walls) and the roof is
                      formed by a transverse ligament
                      and retinaculum
                                                          27
Basic Steps in Open Carpal Tunnel Release

Step 1
  A small incision, usually less than 2 inches, is
made in the palm of the hand. In some severe cases,
the incision needs to be extended into the forearm
another 1/2 inch or so.
Step 2 After the incision is made through the skin,
a structure called the palmar fascia is visible. An
incision is made through this material as well, so
that the constricting element, the transverse carpal
ligament, can be seen.
Step 3 Once the transverse carpal ligament is
visible, it is cut with either a scalpel or scissors,
while making sure that the median nerve is out of
the way and protected.
Step 4 Once the transverse carpal ligament is cut,
the pressure is relieved on the median nerve.
Step 5 Finally, the skin incision is sutured. At the
end of the procedure, only the skin incision is
repaired. The transverse carpal ligament remains
open and the gap is slowly filled by scar tissue.



                                                        28

				
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