Palmar view: major bones + joints

Palmar view: external landmarks

Osteology: metacarpals

Radial view of bones in third ray

• metacarpals
• phalanges
• capitate bone of wrist

Osteology: Phalanges

• palmar and lateral view

Osteology: The Arches of the Hand

• natural concavity of palm
  1. longitudinal arch system
  2. transverse arch system (x2)

AROM of hand

1. finger motion (A-D)
2. thumb motion (E-I)
   1. finger adduction // thumb flexion // thumb exension
3. Thumb abduction
4. Thumb adduction
5. thumb opposition

Arthrology: CMC joints (moblity)

• mobility across 5 carpometacarpal joints
  • peripheral joints (1,4,5) MORE MOBILE than central 2 joints

Arthrology: CMC joints (articular surfaces)

• A. surfaces of 2nd-> 5th carpometacarpal joints (ligaments = cut)

Arthrology: CMC joints and ligaments

Arthrology: The 1st carpometacarpal

• exposed to show saddle-shaped appearance
• right thumb

Arthrology: The 1st carpometacarpal (ABD/ADD)

• stretched: intermetacarpal ligamet (IML), radial collateral ligament (RCL), and adductor pollicis muscle
• CONCAVE+CONVAX = ROL + SLide in same direction

Arthrokinematics of the 1st CMC: Flex/Ext

• flexion: slight medial roation + RCL elongation + slack oblique anterior ligament
• extension: slight lateral rotation + oblique anterior ligament elongation

Arthrokinematics of the 1st CMC: Opposition

• 2 Phases of opposition
  • abduction and flexion with medial rotation
  • tight posterior oblique ligament + contraction opponents pollicis

Metacarpophalangeal joints: radial

• radial collateral ligament and connective tissues
  • (metacarpophalangeal, proximal interphalangeal, distal interphalangeal points)

Metacarpophalangeal joints: periarticular connective tissues

• periarticular connective tissues at metacarpophalangeal joints

Arthrokinematics: MCPs (FLEX/EXTEN)

• flexion: activation of flexor digitorum profundus muscle
  • tendon at A1 and A2 pulleys
  • tight=> dorsal capsule and R.ColLig.
  • ROLL SLIDE = SAME DIRE
• Extension: extensor digitorum+ intrinsic muscle activate
  • tight= palmar plate
  • slack= RCL cord

Arthrokinematics: MCPs (ABDUCTION)

• first dorsal interosseus muscle (DI1)
  • tight= U.Col.Lig
  • slack= R.Col.Lig
• ANTERIOR POSTERIOR DIRECTION

General features of proximal interphalangeal ligaments (IPs)

IPs: Arthrokinematics

• active flexion
  • metacarpophalangeal and interphalangeal joints (thumb)
  • Powered by flexor pollicis longus +PLong. brevis
• CONCAVE+CONCAVE = same direction

Muscular Function of the hand: intrinsic

• all attachments within the hand
• themear eminence // hypothenar eminence // other

Muscular Function of the hand: Extrinsic muscles

• proximal attachments outside of the hand
• flexor of the digits
• extensors of fingers
• exntensors of thumb

Extrinsic flexors of the digits: muscles

• Flexor digitorum superficialis
• FDP
• Flexor pollicis longus

Palmar view of the hand (sheath/ligaments/muscles/bones)

Muscle activation for proximal interphalangeal joint flexion (pulling finger down/in)

• force by the flexor digitorum superficialis = flexion torque on all joint it crosses
  • flexor torques progressively increase in the proximal direction
• Isoloate only flexion => extensor digitorum+ extensor carpi radialis brevis RESIST flexion effect (on wrist and metacarpal joints)

Tenodesis

• wriust extends/moves back (palm up) => thumb and fingers automatically flex (b/c extrinsic digital flexors stretch)

Extrinsic extensors of the digits Muscles

1. Extensor digitorum (communis)
2. Extensor indicis
3. Extensor digit minimi

Extrinsic extensors of the digits Muscles (with arm)

Extrinsic extensors of the thumb (muscles)

1. Extensor pollicis longus
2. Extensor pollicis brevis
3. Abductor pollicis longus

Intrinsic muscles of the hand

Thenar eminence (muscles)

1. Abductor pollicis brevis
2. Flexor pollicis breview
3. Opponens pollicis

Hypothenar eminence (muscles)

1. Flexor digiti minimi
2. Abductor digiti minimi
3. Opponens digiti minimi
4. Palmaris brevis

Thenar & Hypothenar

• used during the opposition of thumb and small finger

Adductor Pollicis

• combo of flexion and adduction torque at the base of the thumb
• oblique and transverse head

Lumbricals & Interossei

Lumbricals

• innervated: median nerve (laterally) + ulnar nerve (medially)
• distal attachments: oblique fibers of dorsal hood (externsor mechanism on lateral band)
• Contractile: generate small force over long distance
• primary actions: MCP joint flexion and PIP and DIP joint extension

Dorsal Interossei

• innervated: ulnar nerve
• distal attachments: oblique fibers of dorsal hood (side base of proximal phalanx)
• Contractile: small force over shortdistance
• primary actions: Abduction of MCP joint flexion and PIP and DIP joint extension

Palmar Interossei

• innervated: ulnar nerve
• distal attachments: oblique fibers of dorsal hood (side base of proximal phalanx)
• Contractile: nondistnct
• primary actions: Adduction of MCP joint flexion and PIP and DIP joint extension

Adduction and Abduction of hand

Combined actions of lumbricals and interossei

• shown as flexors at the metacarpophalangeal joint + extensors at the interphalangeal joints

Extensor Mechanism & Interaction
between extrinsics and intrinsics

• Intrinsic plus: fingers flat across
  • MCP joint flexion and IP joint extension
• Extrinsic plus: fingers curled back
  • extrinsic muscles => MCP joint hyperextension and IP joint flexion
• Opening and closing the hand

Full extension of finger

1. Early phase: extensor digitorum extends metacarpophalangeal joint
2. Middle phase: intrinsic muscles+ extensors dig. to extend proximal+distal interphalangeal joints
   1. flexor torque prevents E.dig from hyperextending the metacarpal joint
3. Late Phase: muscle activation continues thru full finger extension

Full flexion of finger

1. Early phase: flexor dig. superficial and interosseus muscles flex joints
   1. inactive lumbrical
2. Late Phase: muscle action = unchanged, lumbricals stretched across both ends,

hand grips

1. power grip
2. precision grip (egg)
3. precision grip (baseball)
4. Precision grip (with alternating concavity of distal transverse arch)
5. power key pinch
6. tip-to-tip prehension pinch
7. pad-to-pad prehension pinch
8. hook grip