Wrist & Hand

The ____ fine-tunes hand position

wrist

Radius (landmarks)

\-Body

\-Styloid Process

\-Ulnar Notch

Ulna (landmarks)

\-Body

\-Styloid Process

\-Ulnar Head

How many carpal bones are there?

8 (4 in proximal row, 4 in distal row)

What are the proximal row? (carpal bones)

\-Scaphoid

\-Lunate

\-Triquetrum

\-Pisiform

What are the distal row? (carpal bones)

\-Trapezium

\-Trapezoid

\-Capitate

\-Hamate

How many metacarpal bones are there?

5 (long bones of the hand, # 1-5)

How many phalangeal bones are there?

\-14

\-Thumb (Proximal, Distal)

\-Fingers 2-5 (Proximal, Middle, Distal)

\-Landmarks (Base, Body, Head)

Sesamoid Bones

\-Maybe 1 or 2 sesamoid bones (free floats) on the palmar aspect of 1st MCP joint

\-Typically lie in the opponens pollicus muscle

Distal Radioulnar Joint

\-Head of the ulna articulates with the ulnar notch of the radius

\-Interosseous membrane holds these bones together in the forearm

\-Motions: Pronation/Supination

Radiocarpal Joint

\-Distal radius articulates with proximal carpals (Scaphoid, Lunate, Triquetrum{slight})

\-Motions: Flexion/extension, Radial/ulnar deviation

\-Joint capsule and ligaments stabilize

Triangular Fibrocartilage

\-Ulna is separated from the proximal row of carpals by fibrocartilaginous disc

green part

Midcarpal Joints

\-Joints between adjacent carpal bones

\-Functional joint exists between proximal and distal rows of carpals

\-Gliding motions

\-Dozens of individual ligaments

Carpometacarpal Joints

\-1st MC & Trapezium (Separate joint cavity)

\-2nd MC & Trapezoid

\-3rd MC & Capitate

\-4th MC & Hamate

\-5th MC & Hamate

1st Metacarpophalangeal Joint

\-Extreme Mobility

\-Saddle Joint

\-Flexion/extension

\-Abduction/Adduction

\-Opposition/Reposition

2-5 Metacarpophalangeal Joints

\-Condyloid Joint

\-Flexion/extension

\-Abduction/adduction

Interphalangeal Joints

\-Hinge Joints: Thumb has one IP joint; Fingers each have PIP and DIP joints

\-Flexion/extension

Thenar Eminence

-Muscle mass on radial side of palm (squishy muscles on palm, thumb side)

• Abductor pollicis brevis

• Flexor pollicis brevis

• Opponens pollicis

• (Pollicis → related to thumb)

Hypothenar Eminence

\-Muscle mass on ulnar side of palm (fat pad on pinky side)

\-Abductor digiti minimi

\-Flexor digiti minimi brevis

\-Opponens digiti minimi

Anatomical Snuffbox

\-Contents → Scaphoid Bone

\-Radial Border → EPB tendon & Abd. PB tendon

\-Ulnar Border → EPL tendon

(PIC: Bottom → EPB tendon, Middle → Abd. PB tendon, Top → EPL tendon

Carpal Tunnel

\-Contents: Median nerve, FPL tendon, 4 tendons of FDS, 5 tendons of FDP

\-Floor: Carpal Bones

\-Roof: Transverse carpal ligament (aka flexor retinaculum)

(PIC: supinated view)

Tunnel of Guyon

\-Contents: Ulnar nerve

\-Borders: Hook of hamate & Pisiform bone

\-Lies superficial to transverse carpal ligament

Muscle which spinate

\-Supinator : O → L. epicondyle; I → Anterior Radius

\-Bicep brachii

Muscles which Pronate

\-Pronator Teres: O → M. epicondyle, I → lateral radius

\-Pronator quadratus

Wrist Extensor Muscles

-All originate off L. epicondyle via common extensor tendon

• ECRB

• EDC

• ECU

• EDM

• ECRL: O → Humerus, I → 2nd MC

Wrist Flexor Muscles

-Originate off M. epicondyle via common flexor tendon

• FCR

• Flexor Digitorum Superficialis

• Palmaris Longus

• FCU

• Flexor Digitorum profundus: O → Proximal ulna, I → distal phalanges of 4 fingers

Radial Deviation Muscles (moving toward thumb)

\-FCR

\-ECRB

\-ECRL

\-Abductor pollicus longus

\-Extensor pollicus longus

\-Extensor pollicus brevis

Ulnar Deviation Muscles

\-FCU

\-ECU

Finger (2-5) Extensor Muscles

\-EDC → all

\-Extensor indices → 2nd only

\-Extensor digiti minimi → 5th only

\-Lumbricals → IP joints only, place writing position

Finger (2-5) Flexor Muscles

\-MCP joints: Lumbricals, FDS

\-PIP joints: FDS

DIP joints: FDP

Finger (2-5) Abduction & Adduction Muscles

-MCP joints

• Dorsal interossei

  • ABD

• Palmar interossei

  • ADD

Thumb Extensor Muscles

\-EPL

\-EPB

Thumb Flexor Muscles

\-FPL

\-FPB

Thumb Abductor Muscles

\-APL

\-APB

Thumb Adductor Muscles

\-Adductor Pollicus

Thumb Opposition Muscles

\-Opponens Pollicus

Thumb Reposition Muscles

\-EPL

\-EFB

\-APL

\-APB

Nerve Supply

\-Ulnar Nerve

\-Median Nerve

\-Radial Nerve

Functional Movements of Wrist & Hand

-Strength of Grip

• Males grip strength on average 2× greater than females of similar age.

• Studies vary, but overall, ~6% stronger grip on dominant side.