Kines wrist and hand

KINESIOLOGY

• Joint includes
  • ulnohumeral joint
  • radiocapitellar joint
  • proximal radioulnar joint
• Elbow function
  • crucial for activities of daily living
  • acts as a lever arm when positioning the hand
  • functions as a fulcrum for forearm lever
• Functional ROM
  • 30° to 130 flexion/extension
    • total ROM is 0-150 degrees
  • 50° supination/supination
• Normal carrying angle

• normal valgus carrying angle
  • ? for males
  • ? for females
  • this diminishes with flexion
• Axial loading
  • in extended elbow
    • 40% of weight is through ulnohumeral joint
    • 60% of weight is through radiohumeral joint
• Muscles of the elbow
  • Flexors
    • biceps
      • the distal biceps attachment is at the level of the radial tuberosity
    • brachialis
      • the attachment of the brachialis 11 mm distal to the tip of the coronoid
    • ?
  • Extensors
    • triceps
• Primary static stabilizers
  • ulnohumeral joint (coronoid)
    • loss of 50% or more of coronoid height results in elbow instability
  • medial (ulnar) collateral ligament (MCL)
    • overview
      • the MCL is composed of the anterior, posterior and transverse bundles
      • the MCL provides resistance to valgus and distractive stresses
    • anatomy
      • origin
        • ?
      • insertion
        • ?
    • components
      • anterior bundle of MCL
        • most important restraint against valgus stresses
          • radial head is second most important
      • posterior bundle of MCL
        • the posterior bundle forms the floor of the cubital tunnel
        • primary restraint to valgus stress in maximal elbow flexion
        • if this is contracted, flexion may be limited
      • transverse bundle of MCL
  • lateral collateral ligament complex (LCL)
    • overview
      • consists of the
        • radial collateral ligament (RCL)lateral ulnar collateral ligament (LUCL)
          • function?origin ?
            • posterior lateral epicondyle
            insertion
            • crista supinatoris of proximal ulna
          accessory collateral ligament
          • some believe that the the accessory collateral ligament and the radial collateral ligament contribute substantially to lateral elbow stability
          annular ligament
          • provides stability to the proximal radioulnar joint
      • anatomy
        • the LCL arises from isometric point on lateral aspect of capitulum
      • function
        • optimal stability is conferred with an appropriately tensioned LCL repair
• Secondary static stabilizers
  • radiocapitular joint
    • this functions as an important constraint to valgus stress
      • the radial head provides approximately 30% of valgus stability
      • this is most important at 0-30 deg of flexion/pronation
  • capsule
    • greatest contribution the capsule on stability occurs with the elbow extended
  • origins of the flexor and extensor tendons
• Dynamic stabilizers
  • includes muscles crossing elbow joint
    • anconeus
    • brachialis
    • triceps
    • biceps
  • they provide compressive stability
• Nerves: Review
• Musculocutaneous nerve 
  • origin
    • lateral cord of the brachial plexus
  • anatomy at elbow
    • it exits laterally, distal to the biceps tendon
    • it will terminate as the LABC (forearm), which is found deep to the cephalic vein
  • innervation at elbow
    • it supplies the biceps and brachialis
      • the nerve runs between these muscles
• Radial nerve
  • origin
    • posterior cord of the brachial plexus
  • anatomy at elbow
    • it leaves the triangular interval (teres major, long head of triceps and humeral shaft)
    • found in spiral groove 13 cm above the trochlea
    • pierces lateral intermuscular septum 7.5 cm above the trochlea
      • this is usually at the junction of the middle and distal third of the humerus
      • lies between the brachialis and the brachioradialis
    • distally it is located superficial to the joint capsule, at the level of the radiocapitellar joint
• Median nerve
  • origin
    • medial/lateral cords of the brachial plexus
  • anatomy at elbow
    • it courses with brachial artery, running from lateral to medial
    • lies superficial to brachialis muscle at level of elbow joint
  • innervation at elbow
    • it gives branches to elbow joint
    • it has no branches in upper arm
• Ulnar nerve
  • origin
    • medial cord of brachial plexus
  • anatomy at elbow
    • runs medial to brachial artery, pierces medial intermuscular septum (at the level of the arcade of Struthers) and enters posterior compartment
    • it traverses posterior to the medial epicondyle through the cubital tunnel
  • innervation at elbow
    • it gives branches to elbow joint
    • it has no branches in upper arm
    • first motor branch to FCU is found distal to the elbow joint
•  

Elbow
Cubitus varus vs valgus and mention other common wrist disorders

WRIST AND HAND

I. BONES

1. Head of ulna
2. Styloid process of ulna
3. Styloid process of radius
4. Tubercle of radius – Lister’s tubercle; serves as a landmark for locating several tendons in this region
5. Carpal bones
   1. Proximal row – scaphoid, lunate, triquetrum, pisiform
   2. Distal row – trapezium, trapezoid, capitate, hamate

* Scaphoid – most frequently fractured bone carpal (navicular)

• Articulation: proximally – radius; distally – trapezium and trapezoid; medially – lunate and capitate

* Lunate – most frequently dislocated carpal bone

• Articulation: proximally – radius; distally – capitate and hamate; laterally – scaphoid; medially – triquetrum

* Triquetrum – Articulation: anteriorly – pisiform; laterally – lunate;

distally – hamate; proximally – articular disc

* Pisiform – smallest carpal bone; lies on different plane anterior to

triquetrium; last to ossify.

* Trapezium – Articulation: proximally – navicular; distally – first

metacarpal; medially – trapezoid & 2^nd metacarpal

* Trapezoid – lesser multangular

* Capitate – largest carpal bone & second most frequently fractured

carpal bone (Os magnum)

–   located at the center of the wrist & together with lunate  and 3^rd digit forms central axis of hand

• 1^st carpal bone to ossify
• Articulation: proximally – lunate & scaphoid; distally – 2^nd to 4^th metacarpal; laterally – trapezoid; medially – hamate

* ? – has hook-like process volarly for attachment of transverse

carpal ligament, pisohamate ligament and FCU.

• 2^nd carpal bone to ossify
• Articulation: 4^th & 5^th MC, triquetrum, lunate and capitate.

6. Five metacarpals – note the tubercle at the base of the 5^th MC that serves as distal attachment of ECU.
7. Phalanges – 14; proximal, middle, distal; for thumb – proximal & distal

II. JOINTS

1. Wrist Joint

– provides wide mobility of the hand along with great structural stability.

– classified as condyloid joint with 2 degrees of freedom.

– 15 bones with 17 joints

– consists of 3 joints: radiocarpal, intercarpal & midcarpal articulations.

1. Radiocarpal Joint

– formed by articulation of radius with scaphoid & lunate

– condyloid or ellipsoid joint

– primary movements of this joint are flexion-extension with minimal radial & ulnar deviation.

– triangular fibrocartilaginous disk attaches the distal end of radius & ulna to the triquetrium.

1. Intercarpal Joints

– plane joint

– articulation between individual carpal bones

1. Midcarpal Joints

– formed by proximal and distal carpal bones; also a plane joint

– ulnar & radial deviation primarily occurs here with minimal flexion & extension also takes place

– scaphoid articulates with the trapezium, trapezoid and capitate

– lunate articulates with the capitate

– triquetrium with the hamate

1. Carpometacarpal Joints

– bones of 2^nd-4^th MCs articulates with the distal row of carpal bones

– motions of the individual joints are small but important for hand function and provide a large change in the shape of the transverse arch of the hand

1. CMC Joint of Thumb

– formed by trapezium and base of the 1^st MC

– sellar or saddle joint

– motions are abduction-adduction, flexion-extension and opposition

– reposition or retroposition – reverse of opposition

1. MCP joints

– condyloid type with degrees freedom

– convex heads of MCs articulate with concave base of proximal phalanges

– fibrocartilaginous volar plates found at the base of the phalanges

1. IP joints

– thumb – IP joint only

– digits 2 – 4 have PIP & DIP

– classified as hinge joint with 1 degree of freedom

– has volar plate mechanism with check rein ligaments which prevent hyperextension

* LIGAMENTS OF THE WRIST and HAND

• Cover the volar, dorsal, radial & ulnar areas of the wrist.
• Functions to stabilize joints, to permit and guide motion of bones.
• To limit joint motion and transmit forces from the hand to the forearm.
• Prevent dislocation of carpal bones with movement.
• Ligaments of the wrist:
  • Dorsal radiocarpal
    • O: radial styloid process, I: lunate & triquetum
    • Primary fxn: maintain contact between lunate & radius
  • Ulnar & radial collateral
    • Radial – O: radius, I: scaphoid, trapezium, 1^st MC
    • Ulnar – O: Ulna, I: pisiform & trapezium
  • Volar Radiocarpal
    • 3 distinct bands: radiocapitate, radiotriquetral, radioscaphoid
  • Ulnocarpal
    • O: fibrocartilaginous complex
    • I: directly – ulnolunate band, ulnocapitate, indirectly – ulnotriquetral, capitotriquetral
  • Scaphotrapezial ligament complex
  • Scapholunate interosseous
• Ligaments of the fingers
  • Deep transverse MC ligament
    • Attached to the volar plate & was between the MC heads to connect adjacent sides of MC 2-4 thus limiting the spread of the bones.
  • Medial & Lateral collateral
    • O: MCP head, I: bases of the phalanges
    • Function: ?
  • Volar plate – fibrocartilage that is attach to the base of proximal phalanx
    • Functions:
      • Reinforce the joint capsule
      • Adds to the amount of surface contact with MCP head.
      • ?
      • ?
      • ?

* MOTIONS OF THE FINGERS and THUMB

1. MCP – 20 degrees of abduction, 90 degrees of flexion & 45 degrees of extension
2. MCP of Thumb – 45 – 60 degrees of flexion & 20 degrees of hyperextension
3. In thumb

– 2 sesamoid bones attached to the volar plate

– attachment of adductor pollicis and first dorsal interosseous tendons ulnarly & FPB & APB radially.

– sesamoid mechanism produces a dynamic rotation at the thumb segment for precision of the pinch.

– CMC jt – flexion (0-15˚); extension (0-20˚); abduction (0-70˚)

– MCP jt – flexion & extension (0-50˚)

* MOTIONS and AXES OF THE WRIST

* Motions of the wrist occur at the radiocarpal and midcarpal joints

* Midcarpal joint – ½ of radial abduction & 1/3 of the ulnar abduction with

remaining motions occur at the radiocarpal joint.

* Wrist flexion – radiocarpal jt. (50˚) & midcarpal jt. (35˚)

* Full extension – radiocarpal jt. (35˚) & midcarpal jt.(50˚)

* Axis of motion through the capitate

* In flexion-extension, the axis of motion for extension is distal to axis of flexion

caused by motions of scaphoid & lunate (rotational & translatory motions)

NOTE:  Wrists movements are in a direction opposite to the finger motions.

III. MUSCLES

1. Muscles acting on the wrist – ECU, ECRB, ECRL, FCR, FCU & PL
2. Role of wrist extensors in grasping. (Discuss)
3. Role of wrist flexors in extension of fingers (Discuss)
4. Muscles acting on the digits

* Extrinsic – FDS, FDP, FPL, ED, EI, EPL, EDM, EPB & APL

* Intrinsic – 4 Lumbricals, 3 palmar interossei, 4 dorsal interossei, Thenar muscles, Hypothenar muscles & Palmaris brevis

* Considerations on muscles acting on the thumb

• Extrinsic – FPL, EPL, EPB, APL
• Intrinsic – AdP, FPB, APB, OP, lateral head of 1^st dorsal interossei

* Hypothenar Muscles – ODM, ADM, FDMB

1. Role of long finger flexors in grasping
2. Role of intrinsic muscles in grasping

IV. EXTENSOR ASSEMBLY

• distal attachments of the extensor muscle, lumbricals, interossei and thenar & hypothenar muscles & a retinacular system of fascia & ligaments.

* Purpose:

1. Extend the digits in different positions
2. Provide shortcuts for the extensor tendon
3. Permit full flexion of the digits

1. TENDON SYSTEM:
2. Extensor tendons – a) Central band – base of middle phalanx
3. b) 2 lateral bands – courses of side PIP joint & inserts to distal phalanx
4. Interossei muscles
5. a) base of the proximal phalanx
6. b) volar plate
7. c) lateral bands
8. d) base of the middle phalanx
9. Lumbricals – inserts into lateral bands

B. RETINACULAR SYTEM

• fibrous hood or dorsal expansion encloses the MCP joints & retains the tendons crossing the joint.
• Attachment: Palmar sides at the junction of the volar plate & transverse intercarpal ligament.

1. FLEXOR PULLEY

                                                –     retinacular system connected to the flexor compartment

• FDS & FDP tendons are enclosed in synovial lined tunnels
• Prevents bowstringing of long flexor tendons
• Severance of these pulleys causes loss of finger motion
• Attaches to shafts of phalanges

                        2 types:

• Annular pulley
• Cruciate pulley

1. PREHENSILE PATTERNS
2. Napier:
   1. Power grip
   2. Precision grip
3. Schlesinger:
   1. Hook grasp
   2. Cylindric grasp

• Fist grasp

1. Spheric grasp
2. Tip prehension
3. Palmar prehension

• Lateral prehension
  • Holding a key