REVIEW OF ANATOMY UNDERLYING CARPAL TUNNEL

SYNDROME

CARPAL TUNNEL SYNDROME

Carpal tunnel syndrome is one of the most common workplaceinjuries. It results from compression of the median nerve as it passes into the hand and can be treated surgically by opening the carpal tunnel (decompression). Knowledge of the anatomy of the upper extremity and hand is essential in the diagnosis and treatment of carpal tunnel syndrome.

MEDIAN NERVE

Clavicle Scapula

Humerus

Radius Ulna

Carpal bones

Metacarpals Phalanges

BONES OF UPPER EXTREMITY

CARPAL BONES ARE LOCATED IN THE PROXIMAL PARTOF THE HAND

Styloid process of Ulna

Sesamoid bones

Distal phalanges

Middle phalanges Proximal phalanges

Metacarpal bones

Styloid process of Radius

Hook of hamate

AP RADIOGRAPH OF RIGHT HAND

CARPAL BONES

Wrist Joint

THUMB

CARPAL BONES FORM A 'TUNNEL' FOR PASSAGE OF STRUCTURES INTO THE HAND

TWO ROWS OF BONES: Order(lateral to medial)

Proximal Row -Scaphoid, Lunate, Triquetrum, Pisiform

Distal Row -Trapezium, Trapezoid, Capitate, Hamate

ANTERIOR VIEW OF LEFT HAND

MNEMONIC: SOME LOVERS TRY POSITIONS THAT THEY CAN'T HANDLE

Trapezium

Pisiform

Hook of Hamate

Trapezoid

Capitate

Hamate

Scaphoid Lunate

Triquetrum

Trapezium

Pisiform

Ulnar Styloid Process

Hook of Hamate

Radial Styloid Process

Trapezoid

Capitate

Hamate

ScaphoidLunate

Triquetrum

Radius Ulna

First Metacarpal

AP RADIOGRAPH OF WRIST OF LEFT HAND

THUMB

FLEXIONAT WRIST,FINGERS

SUPINATION =PALM UP (FORWARD)

MOVEMENTS OF FOREARM, HAND

EXTENSION/FLEXION SUPINATION/PRONATION

PRONATION=PALM DOWN (BACK)

EXTENSIONAT WRIST,FINGERS

MANY MUSCLES THAT MOVE THE HAND AND FINGERS ARE LOCATED IN THE FOREARM

FLEXIONAT WRIST

EXTENSIONAT WRIST

EXTENSOR/SUPINATORS

POSTERIOR FOREARM: WRIST, FINGER EXTENSORS

ANTERIOR FOREARM: WRIST,FINGER FLEXORS

FLEXOR/PRONATORS

SUPERFICIAL DEEP

Large muscles in forearm can produce powerful grip with the hand

TENDONS OF LONG FLEXOR MUSCLES PASS INTO THE HAND UNDER THE FLEXOR RETINACULUM - prevents bowstringing of tendons

INSERT - MIDDLE PHALANGES DIGITS 2-5

INSERT - DISTAL PHALANX OFTHUMB

FLEXOR DIGITORUMSUPERFICIALIS

ORIGIN - RADIUS,HUMERUS (MEDIALEPICONDYLE), ULNA

FLEXOR POLLICISLONGUS

ORIGIN - RADIUS,INTEROSSEUSMEMBRANE

FLEXOR DIGITORUMPROFUNDUS

ORIGIN - ULNA,INTEROSSEUSMEMBRANE

INSERT - DISTAL PHALANGES DIGITS 2-5

FLEXORRETINACULUM =TRANSVERSECARPAL LIGAMENT

SUPERIFICIAL LAYER DEEP LAYER

FLEXOR RETINACULUM (TRANSVERSE CARPAL LIGAMENT) ATTACHES TO CARPAL BONES

FLEXOR RETINACULUM - attaches CARPAL BONES DO NOT LIE FLAT BUT ARE ARCHED AND CREATE A TUNNEL

HAMATE

laterally toSCAPHOID,TRAPEZIUM TRAPEZIUM

plane ofcut

medially toPISIFORM,HOOK OFHAMATE

FLEXOR RETINACULUM

FLEXOR TENDONSIN CARPALTUNNEL

MEDIAN NERVETHUMB

COMMON SYNOVIAL SHEATHFOR FLEXOR DIGITORUMSUPERFICIALIS AND PROFUNDUS;EXTENDS UNDERFLEXOR RETINACULUM

SYNOVIAL SHEATHFOR FLEXOR POLLICISLONGUS

DIGITALSYNOVIAL SHEATHIN FINGERS

FIBROUS DIGITALSHEATH SURROUNDSSYNOVIAL SHEATH

SYNOVIAL SHEATHS SURROUND FLEXOR TENDONS

- SYNOVIAL SHEATHSSECRETE SYNOVIAL FLUID

- ACTS AS LUBRICANT

- REDUCES FRICTION WHEN TENDONSMOVE UNDERFLEXOR RETINACULUM

SYNOVIAL SHEATHS CAN BECOMEINFLAMED AND SWOLLEN WITHREPETITIVE MOVEMENTS

C5

C6

C7

C8

T1

Clavicle

1. Ulnar n.

4. Radial n.

3. Musculocutaneous n.

2. Median n.

Trunks

Divisions

Cords

BRANCHES

BRACHIAL PLEXUS - sensory and motor innervation of upper extremity

- PROXIMAL PART OF BRACHIAL PLEXUS INNERVATES SHOULDER AND BACK- FOUR LARGE BRANCHES INNERVATEARM AND HAND: MEDIAN, ULNAR, MUSCULOCUTANEOUS AND RADIAL NERVES

AXILLARY NERVE

RADIALNERVE

MUSCULO-CUTANEOUSNERVE

MEDIANNERVE

RADIALNERVE ULNAR

NERVE

ULNARNERVE

BRANCHES OF BRACHIAL PLEXUS PROVIDE SENSORY INNERVATION TO SKIN OF ARM AND HAND

DORSALVENTRAL

MEDIAN NERVE INNERVATES MUSCLES OF FOREARM AND HAND,SENSORY TO SKIN OF HAND

MEDIAN NERVEarises from medialand lateral cords (M of brachial plexus)

MOTOR TO FLEXOR/ PRONATOR MUSCLES - innervates most muscles of anterior forearm

MOTOR TO SOME , IMPORTANT MUSCLES OF HAND - Median nerve innervates muscles of thenar (thumb) eminence and first two lumbricals

Passes under Flexor retinaculum to enter hand

SENSORY innervation to lateral palm and lateral 3.5 digits

PALMARSIDE

DORSALSIDE

LUMBRICALS1,2

MUSCLES OF THENAREMINENCE - Flexor pollicis brevisAbductor pollicis brevisOpponens pollicis

FLEX/EXTEND AB/ADDUCT

OPPOSE

IN HAND, MEDIAN NERVE INNERVATES MOST MUSCLES OF THE THUMB

DAMAGE TOMEDIAN NERVEPRODUCES LOSSOF OPPOSITIONOF THUMB

BRANCHES TO LUMBRICALS1,2

RECURRENT BRANCH OF MEDIAN NERVE - TO MUSCLESOF THENAR EMINENCE -Flexor pollicis brevis,Abductor pollicis brevisOpponens pollics

MOTOR BRANCHES OF MEDIAN NERVE TO MUSCLES OF HAND PASS THROUGH THE CARPAL TUNNEL

FLEXORRETINACULUM =TRANSVERSECARPAL LIGAMENT

MOST SENSORY BRANCHES OF MEDIAN NERVE PASS THROUGH CARPAL TUNNEL

Note: Palmar Cutaneousbranch of Median Nerve does not pass through carpal tunnel

Digital sensory branches of Median nerve pass through thecarpal tunnel

SENSORY innervation to lateral palm and lateral 3.5 digits (thumb to lateral side of ring finger); on dorsal side, skin over the distal phalanges of same digits

PALMARSIDE

DORSALSIDE

COMPRESSION OF MEDIAN NERVE IN CARPAL TUNNEL

MEDIANNERVE

FLEXORRETINACULUM

FLEXORTENDON

SYNOVIALSHEATH

CARPAL BONES

SWELLING OF SYNOVIAL SHEATHSPRODUCES COMPRESSION OF MEDIANNERVE BECAUSE FLEXOR RETINACULUMAND CARPAL BONES ARE RIGID AND DO NOTSTRETCH

Ulnar nervedoes not passthrough carpal tunnel

SYMPTOMS OF CARPAL TUNNEL SYNDROME: MOTOR WEAKNESSOR PARALYSIS

PARALYSIS OFMUSCLES OF THUMB -

due to damage to RecurrentBranch of Median nerve

Atrophy of muscles ofthenar eminence - musclesat base thumb look flattened

Loss of Opposition ofThumb

OPPOSE

Note: Palmar Cutaneousbranch of Median Nerve does not pass through carpal tunnel

Digital sensory branches of Median nerve

SYMPTOMS OF CARPAL TUNNEL SYNDROME: SENSORY LOSS

SENSORY LOSS - anesthesia or numbness in distal part lateral palm; lateral 3.5 digits (thumb to lateral side of ring finger); on dorsal side, skin over the distal phalanges of same digits

Note: Skin of proximal part of lateral palm may show no sensory loss (Palmar Cutaneous branch)

ULNAR NERVE IS NOT AFFECTED IN CARPAL TUNNEL SYNDROME

ULNAR NERVES DOES NOTPASS THROUGH CARPAL TUNNEL

Ulnar nerve innervates all other intrinsic muscles of hand (ex. interosseus muscles)

Sensory innervation to medialpalm and medial 1.5 digits

MEDIANNERVE

ULNARNERVE

RADIAL NERVE IS NOT AFFECTED IN CARPAL TUNNEL SYNDROME

RADIAL NERVE

- Innervates extensor musclesof arm and forearm (damage produces WRIST DROP)

- Sensory innervation to dorsum of arm, forearm and hand

In Hand: Radial nerve innervates no muscles

- only sensory to dorsum ofhand - does not pass through Carpal Tunnel

RADIALNERVE

POSTERIOR ARM FOREARM: WRIST, FINGER EXTENSORS

RADIALNERVE IN SPIRALGROOVE

MOTOR SENSORY

3) Median nerve

2) Flexor carpi radialis tendon

6) Flexor carpi ulnaristendon

5) Ulnar nerve and artery

1) Radial artery4) Flexor digitorum superficialis andPalmaris longustendons

THUMBISLATERAL

ORDER OF STRUCTURES AT WRIST: LATERAL TO MEDIAL

KNOW FORSURGERY,REPAIR