Wrist & Hand

Distal landmarks of radius and ulna

Radius:

• styloid process

Ulna:

• styloid process

• head

Carpal Bones (listed radial to ulnar)

8 Carpal Bones - Straight Line To Pinky, Here Comes The Thumb

Proximal Row:

• Scaphoid

• Lunate

• Triquetrum → 3rd listed = TRI-quetrum

• Pisiform

Distal:

• Trapezium (most lateral and distal from body) → trapeze artist

• Trapezoid

• Capitate - touches middle finger

• Hamate

Landmarks of Carpals

• Hook of hamate → tells image is anterior

  • Pinky side

• Pisiform is a sesamoid bone in the tendon of the flexor carpi ulnaris

Motions of the wrist

• Flexion

• Extension

• Radial deviation

  • “abduction”

    • Fingers point lateral

• Ulnar deviation

  • “adduction”

    • Fingers point middle

Wrist articulations (joints)

• Distal radioulnar joint - pivot diarthroidal

• Radiocarpal joint - ellipsoidal diarthroidal

• Intercarpal joints - gliding diarthroidal joints

Joint capsule of the wrist

Contains all carpal bones

Ligaments of the wrist

• Radial collateral ligament

  • Connect the radius to the scaphoid and trapezium

  • Affected by varus stresses

• Ulnar collateral ligament

  • Connects ulnar styloid to the triquetrum

  • Affected by valgus stresses

Need to know intercarpal ligament

Scapholunate ligament

Triangular Fibrocartilage Complex (TFCC) meaning

• Triangular = shape

• Fibrocartilage = material in which the structure is comprised

• Complex = complicated

  • many liagmentous structures attach to the cartilage

Functions of the TFCC

• Suspends the carpals from the ulna

• Cushions the forces transmitted through the ulnocarpal axis

• Connects the ulna to the carpals

Bones of the hand

• Digits numbered 1-5 from radial to ulnar

• Metacarpals (5): MCP = metacarpophalangeal

  • long bones of hand

• Phalanges (5)

• Phalanx (14): DIP = distal interphalangeal; PIP = proximal interphalangeal

  • 2 in the thumb

    • PIP & DIP

  • 3 in digits 2-5

    • PIP

    • Middle (intermediate)

    • DIP

Landmarks on all metacarpals and & phalanges

• Base

  • Proximal end

• Shaft

  • Diaphysis

• Head

  • Distal end

Carpometacarpal joints (CMC) + Thumb motions

• Joints 2-5 = gliding joints

  • minimal motion

• 1st joint (thumb) = saddle joint

  • flexion/extension

  • abduction/adduction

  • opposition/reposition

Metacarpophalangeal (MCP) joints

• Condyloid joints

  • Joints 2-5

    • Flexion/extension

    • Abduction/adduction

  • 1st:

    • Flexion-Extension

Interphalangeal (IP) joints

• Fingers 2-5

  • Proximal = PIP

  • Distal = DIP

• Thumb

  • Interphalangeal joints

• Hinge joints

  • flexion/extension

MCP & IP Joint Stability

• Articular cartilage in between

• Has MCL and LCL

  • Can have varus/valgus forces

Finger Motions

• Flexion/Extension

  • MCP

  • PIP

  • DIP

• Adduciton/Abduction

  • Named relative middle of hand

  • MCP only

Anterior forearm muscles (Superficial and deep layers)

• Superficial layer

  • Pronator teres - median nerve

  • Flexor carpi radialis - median nerve

  • Palmaris longus - median nerve

  • Flexor carpi ulnaris - ulnar nerve

  • Flexor digitorum superficialis - median nerve

• Deep layer

  • Flexor digitorum profundus - ½ median, ½ ulnar

  • Flexor pollicu longus - median nerve

  • Pronator quadratus - median nerve

Pronator Teres origin/insertion/action/innervation

O: coranoid process, medial epicondyl

I: middle lateral radius

A: pronation

• weak elbow flexion

N: median nerve

Flexor carpi radialis origin/insertion/action/innervation

O: medial epicondyle

I: second metacarpal

A: wrist flexion & radial deviation

N: median nerve

Palmaris Longus origin/insertion/action/innervation

O: medial epicondyle

I: apponerosis and palmer retinaculum

A: tightens palmar aponeurosis

• wrist flexion

N: median nerve

What percent of the population does not have a palmaris longus

14%

Anterior wrist muscles do what motion

Wrist flexion

Flexor carpi ulnaris origin/insertion/action/innervation

O: medial epicondyle, olecranon process

I: hook of hamate, 5th metacarpal

A: wrist flexion

• wrist ulnar deviation

N: ulnar nerve

Flexor digitorum superficialis origin/insertion/action/innervation

O: medial epicondyle, superior anterior radius

I: palmar aspect of middle phalanges of anterior of phalanges 2-5

A: PIP and MCP flexion

N: median nerve

To the foot’s flexor digitorm longus/brevis, the hand’s flexor digitorum ______ is?

• Superficialis

• Profundus

Flexor digitorum profundus origin/insertion/action/innervation

O: proximal, medial, anterior surface of ulna; interosseous membrane

I: palmar aspect of distal phalanges 2-5

A: DIP flexion

N: ½ median, ½ ulnar

Flexor pollicis longus origin/insertion/action/innervation

O: anterior radius; interosseous membrane

I: base of distal phalanx of thumb

A: thumb flexion (all joints - IP & MCP)

N: median nerve (anterior interosseous nerve)

Pronator quadratus origin/insertion/action/innervation

O: distal anterior surface of ulnar

I: distal ¼ of anterior surface of radius

A: pronates forearm

N: median nerve

Posterior forearm muscles (superficial and deep)

• Superficial

  • Brachioradialis – radial nerve

  • Extensor carpi radialis longus – radial nerve

  • Extensor carpi radialis brevis – radial nerve

  • Extensor digitorum – radial nerve

  • Extensor digiti minimi – radial nerve

  • Extensor carpi ulnaris – radial nerve

  • Anconeus – radial nerve

• Deep

  • Supinator - radial nerve

  • Abductor pollicis longus — radial nerve

  • Extensor pollicis brevis – radial nerve

  • Extensor pollicis longus – radial nerve

  • Extensor indicis – radial nerve

Extensor carpi radialis longus origin/insertion/action/innervation

O: supercondylar ridge

I: dorsal base of 2nd MC

A: wrist extension

• wrist radial deviation (scooping muscles

• N: radial nerve

Extensor carpi radialis brevis origin/insertion/action/innervation

O: lateral epicondyle

I: dorsal base of 3rd MC

A: wrist extension

• wrist radial deviation

N: radial nerve

Extensor digitorum origin/insertion/action/innervation

O: lateral epicondyle

I: extensor expansion of digits 2-5

A: extension of MCP, PIP, and DIP joints

N: radial nerve

Extensor digiti minimi origin/insertion/action/innervation

O: Lateral epicondyle

I: extensor expansion of the 5th digit

A: wrist extension (synergist)

• wrist ulnar deviation

N: radial nerve

Extensor carpi ulnaris origin/insertion/action/innervation

O: lateral epicondyle

I: dorsal aspect of 5th MC

A: wrist extension

• wrist ulnar deviation

N: radial nerve

Supinator origin/insertion/action/innervation

O: lateral epicondyle, radial collateral ligament, annular ligament, supinator fossa, crest of ulna

I: proximal posterior radius

A: forearm supination

N: radial nerve

Abductor pollicis longus origin/insertion/action/innervation

O: posterior ulna and radius, interosseous membrane

I: base of 1st metacarpal

A: thumb abduction (CMC)

N: radial nerve

Extensor pollicis longus origin/insertion/action/innervation

O: posterior ulna and interosseous membrane

I: base of 1st distal phalanx

A: extension of 1st IP, MCP, and CMC joints

N: radial nerve

Extensor pollicis brevis origin/insertion/action/innervation

O: posterior distal radius, interosseous membrane

I: base of 1st proximal phalanx

A: extension of 1st MCP and CMC joints

N: radial nerve

Extensor indicis origin/insertion/action/innervation

O: Posterior distal 1/3 of ulna and interosseous membrane

I: extensor expansion of the 2nd finger

A: extension of 2nd finger

• wrist extension

N: radial nerve

Anterior compartment group and innervation

• Flexor/pronator group

• Median & ulnar nn.

Posterior compartment group and innervation

• Extensor/ supinator

• Radial nn.

What view is this cross section?

Top down view

Common Flexor Attachments

• Medial Epicondyle

  • PT

  • FCR

  • FDS

  • Palmaris longus

  • FCU

• Doesn’t include FDP or FPL

Common extensor attachment

• Lateral epicondyle

  • ECR brevis

  • Extensor digitorum

  • EDM

  • ECU

  • Supinator

• Doesn’t include brachioradialis, ECR longus, or extensor indicis

Extensor muscles of forearm separated into 3 functional group

1. muscles that extend hand at wrist

   1. ECR longus & brevis, ECU

2. Muscles the extend medial 2 digits

   1. Extensor digitorum

   2. Extensor indicis

   3. Extensor digiti minimi

3. Muscles that extend or abduct them

   1. APL

   2. EPB

   3. EPL

Anatomical snuff box: borders and contents

Borders:

• APL and EPB laterally, EPL medially

Contents:

• radial artery

• radial styloid

• scaphoid

• trapezium

Which carpal bone is the most frequently fractured & which carpal bone is most commonly dislocated

• Scaphoid

• Lunate

Carpal tunnel contents

Ten major anatomical structures:

• flexor digitorum superficialis tendons (4)

• flexor digitorum profundus tendons (4)

• flexor pollicis longus tendon

• median nerve

Carpal tunnel borders

• Medial - pisiform and hamate

• Lateral - scaphoid and trapezium

• Palmar - flexor retinaculum

  • “transverse carpal ligament”

Common cause of carpal tunnel

Frequent flexion

Muscles of the Hand (pinky)

• Hypothenar Eminence (small finger)

  • Abductor digit minimi - ulnar n.

  • Flexor digiti minimi brevis - ulnar n.

  • Opponens digiti minimi - ulnar n.

Muscles of the hand (thumb)

• Thenar Eminence (thumb)

  • Abductor pollicis brevis - median n.

  • Flexor pollicis brevis - median n.

  • Opponens pollicis - median n.

Muscles of the hand (MCP) action and innervation

Lumbricals

• Action (bye-bye motion)

  • Flex MCP

  • Extend IP

• Innervation

  • 1,2 — median n.

  • 3,4 — ulnar n.

Finger (2-5) Extensor Muscles

• EDC

  • all

• Extensor indices

  • 2nd only

• Extensor digiti minimi

  • 5th only

• Lumbricals

  • IP joints only, place in writing position

Finger (2-5) Flexor Muscles

• MCP joints

  • Lumbricals

  • FDS

• PIP joints

  • FDS

• DIP

  • FDP

Finger (2-5) Abduction/Adduction Muscles

Interossei

• 4 Dorsal (DAB)

  • 1st - abduct index

  • 2nd - abduct middle

  • 3rd - abduct middle

  • 4th - abduct ring

• 3 Palmar (PAD)

  • 1st - adduct index

  • 2nd - adduct ring

  • 3rd - adduct little

• Innervate: Ulnar n.

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

What musculature does the radial nerve innervate

• Triceps

  • Lateral/long/medial

• Anconeus

• Brachioradialis

• Extensor carpi radialis longus (ECRL)

• Extensor carpi radialis brevis (ECRB)

• Supinator

• Extensor digitorum

• Extensor digiti minimi

• Extensor carpi ulnaris

• APL, EPL, EPB, EI

INNERVATES EXTENSORS

What musculature does the median nerve innervate

• Pronator teres

• Flexor carpi radials

• Palmaris longus

• Flexor digitorum superficialis

• FPL

• FDP (lateral 1/2)

• PQ

• Distal to carpal tunnel

  • 3 thenar muscles

  • first 2 lumbricals

What musculature does the ulnar nerve innervate

• In the forearm:

  • Flexor carpi ulnaris

  • Flexor digitorum profundus (medial ½ - digits IV and V)

• IN the hand:

  • Muscles of hypothenar eminence

  • 3rd and 4th lumbricals

  • DAB and PAD

  • Palmaris brevis

  • Adductor pollicis