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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