Wrist and Hand

What movements do the wrist and hand allow for?

• Fine motor control ( writing and typing)

• Power movements (gripping and lifting)

What bones make up the wrist?

1. Radius

2. Ulna

3. 8 Carpal bones

What is the main loading bearing bone in the wrist?

Radius

What are the 8 carpal bones?

• Scaphoid

• Lunate

• Triquetrum

• Pisiform

• Trapezium

• Trapezoid

• Capitate

• Hamate

What bones make up the hand and how many?

• Metacarpals (5)

• Phalanges (14)

What bone is the most commonly fractured?

Scaphoid due to the poor blood supply

What bone is the central stabilizer of the hand?

Capitate

What are the main joints of the wrist?

1. Radiocarpal joints

2. Midcarpal joints

3. Intercarpal joints

What type of joint is the radiocarpal joint?

condyloid/ellipsoid joint

What type of joint is midcarpal joint?

plane joint

what type of joint is the intercarpal joint?

13 plane joint

How is the midcarpal joint seperated?

Into the medial and lateral compartment

What is the function of the medial and lateral compartment of the midcarpal joint?

Medial: Large part formed by hamatyer, captitate, triquetrum, lunate and scaphoid has SLIGHT more movement than lateral

Lateral: trapezoid, trapezium, scaphoid

What joint does most force go through at the wrist?

Radiocarpal around 80% of force go through radius

What is the midcarpal joint major function?

Adds motion between carpal rows

What is the intercarpal joint major function?

It is a small stabilizing joint

Why does injury in one area affect entire wirst?

Because wrist motion is distributed across multiple joints and not one single joint does all movement

What are the hand joints?

• metacarpophalangeal joint

• carpometacarpal joint

• interphalangeal joint

• distal interphalangeal joint

• Proximal interphalangeal joint

what type of joint are the distal interphalangeal joint and the Proximal interphalangeal joint

hinge joint

What type of joint is the interphalangeal joint?

hinge joint

What type of joint is carpometacarpal joint

all are plane except the 1st metacarpal that is a saddle joint

\Wrist bone to hand bone

What type of joint is the metacarpophalangeal joint?

condyloid joint

What tradeoff does the wrist ligament have?

Because it is highly mobile it has less stability

What is the characteristics of extrinsic (long ligaments) ?

Connect forearm to carpals

What type of ligament is the radial collateral and what does it do?

Extrinsic

Holds scaphoid to radius

What type of ligament is the palmar radiocarpal ligament and what does it do?

extrinsic

frontal surface of wrist that resist extension of wrist

What type of ligament is the palmar ulnocarpal ligament and what does it do?

extrinsic

stabilizes gripping holds triquetrum and lunate to wrist

What type of ligament is the ulnar collateral ligament and what does it do?

extrinsic

holds pisiform to ulna

What type of ligament is the dorsal radiocarpal/ulnocarpal ligament and what does it do?

extrinsic

prone to injury due to hyperextension

holds triquetrum and lunate to wrist

What is the characteristics of intrinsic ligaments?

Ligament that has to do with stabilization of carpal to carpal

What are the groupings of the intrinsic ligaments?

Short

intermediate

Long

What is the function of the short ligament group?

Stabilizes distal low carpal

• hamatoocapitate

• trapezoidcapitate

• Trapeziotrapezoid

What is the function of the intermediate ligament group?

Stabilize proximal carpal row

• lunotriquetral

• scapholunate

What is the function of the long ligament group?

provides overall stability across carpal bone on dorsal and frontal side

• dorsal intercarpal ligament

• palmar intercarpal ligament

What is the passageway of the wrist referred to as and what does it contain?

Carpal tunnel

Contains:

• Flexor tendons

• Median nerve

What ligament makes of the carpal tunnel and what is its characteristics?

Transverse carpal ligament

• flexor on palmar side

• band shape and works as pathway for nerves

• holds pisiform to scaphoid

What is carpal tunnel syndrome and what are symptoms?

Compression of median nerve

Symptoms:

• Numbness

• Tingling

• Weak grip

What are the causes of carpal tunnel syndrome?

• Caused by:

  • Repetitive motion

  • Inflammation

• Important concept:

  • Limited space → any swelling = compression

What makes up the central column?

Radius → Lunate → Capitate → 3rd metacarpal

What is the function of the central column?

The main force transmission line

• It’s used analyze movement and understand injury pattern

What movements occur at the wrist?

• Flexion / Extension

• Radial deviation (toward thumb)

• Ulnar deviation (toward pinky)

What movements does not occur at the wrist?

pronation and supination

Where do the extensors muscles at the wrist originate from?

• five on the lateral epicondyle

• Two on ulna

• One on radius

What are the muscles that extend the wrist that are inserted at finger?

• Extensor Digitorum

• Extensor Digit Minimi

• Extensor Indicis

What are the muscles that extend the wrist that are inserted at the thumb ?

• extensor pollicis longus

• Extensor pollicis brevis

What do all the extensor muscles have in common?

They all run down the Extensor retinaculum a fibrous connective tissue band that runs across dorsal side

What results from weak extensors?

poor grip strength

Where do the flexor muscles of the wrist originate from?

• 4 on the medial epicondyle

• 1 on ulna

• 1 on radius

What extensor muscles originate on the medial epicondyle?

• Palmaris longus

• flexor digitorum superficialis

• flexor carpi ulnaris

• Flexor carpi radialis

What are the muscles that flex the wrist that are inserted at the fingers?

• Flexor digitorum superficialis

• Flexor Digitorum profundus

What are the muscles that flex the wrist that are inserted at the thumb ?

Flexor pollicis longus

What are the muscles that flex the wrist that are inserted at the metacarpals?

• Flexor carpi radialis

• Flexor carpi ulnaris

• palmaris longus

What muscle does ~79% of the population have bilaterally?

Palmaris longus

What forms the roof of the carpal tunnel?

Flexor retinaculum

What can the same muscles of the wrist do to fingers?

Can move both wrist and fingers

What are the intrinsic hand muscle groups?

• Thenar (thumb)

• Hypothenar (pinky)

What are the thenar muscles?

• Abductor pollicis brevis

• Flexor pollicis brevis

• Opponens pollicis

What are the hypothenar muscles?

• Abductor digiti minimi

• Flexor digiti minimi brevis

• Opponens digiti minimi

What do intrinsic muscle do functionally?

WOrk with fine motor control

What do extrinsic muscle do functionally?

work with power

What type of joint is the thumb and what does it do functionally?

Saddle joint

Precision of movement, force control and grip

What does grip position depend on?

Grip strength depends on wrist position

• Best grip = ~30° extension

• Worst grip = full flexion

Compare radial and ulnar deviation

Radial deviation:

• Slightly stronger (~15% more torque)

Ulnar deviation has:

• Greater range

• Used more in functional tasks