CHAPTER 12: HAND - NERVES AND TENDON TRANSFERS Flashcards
Describe the levels of the brachial plexus
Rob Tucker Drinks Cold Beer
Roots
• Enter post triangle between Scalenus anterior and Scalenus medius
• Plexus surrounded by fascial sheath axillary sheath from the prevertebral fascia.
Trunks
• Around 3rd part of subclavian artery, lower behind it
• Each trunk divides into anterior and posterior divisions.
• In posterior triangle
Divisions
• Behind clavicle
• Anterior divisions from upper and middle trunks form Lateral Cord
• Anterior divisions from the Lower trunk form the Medial cord
• All 3 Posterior divisions form the Posterior cord
Cords
• In axilla
• Cords lie above and lateral to the 1st part of the axillary artery.
• Medial cord crosses behind the artery to lie to the medial side of the 2nd part of the artery under pec minor.
• Post cord is behind the artery.
• Lateral cord lateral to the artery at this point.
• Cords leave the post triangle by descending behind the clavicle into axilla.
Branches
What are the myotomes of the branchial plexus?
Myotomes C5 Shoulder abduction C6,7,8 Shoulder adduction C5,6 Elbow flexion C7,8 Elbow extension C6,7 Wrist movements C7,8 Finger movements T1 Intrinsics
Which nerves originate from the roots of BP?
Long thoracic nerve descends behind the plexus and subclavian vessels crosses outer border of 1st rib and enters axilla. Supplies serratus anterior.
Dorsal scapular nerve pierces Scalenus medius and supplies levator scapulae and rhomboids.
Nerve to subclavius runs in front of plexus and 3rd part subclavian art. Behind clavicle and in front of subclavian vein to supply subclavius. May have accessory phrenic fibres which join the phrenic in the superior mediastinum if present this is called accessory phrenic nerve.
Which nerve emerges from the upper trunk?
Suprascapular nerve passes lat and down with suprascapular vessels. Enters the supraspinous fossa through suprascapular notch. Supplies supraspinatus and infraspinatus.
Which nerves originate from the lateral cord?
Lateral pectoral nerve pierces clavipectoral fascia and supplies Pec Major
Musculocutaneous supplies coracobrachialis in axilla, then biceps, brachialis and elbow joint in upper arm and becomes the lateral cutaneous nerve of forearm.
Which nerves originate from the medial cord?
Medial pectoral nerve supplies and pierces Pec Minor and supplies Pec Major
Medial cutaneous nerve of the arm joined by intercostobrachial nerve to supply sensation of medial side of arm.
Medial cutaneous nerve of the forearm descends in front of axillary artery.
Ulnar nerve descends between axillary arty and vein. No branches in axilla. Upper arm to elbow only. Forearm branches to FCU, FDP (medial) Palmar cut branch, Post cut branch - skin on dorsum of ulnar side of hand. PB, digital nerves, hypothenar muscles, Add P, 3 and 4 lumbricals, interosseii.
Which nerves originate from the posterior cord?
Upper and lower subscapular nerves supply the upper and lower parts of the subscapularis muscle. Lower subscapular also supplies teres major muscle.
Thoracodorsal nerve runs down on the subscapularis to lat dorsi. Accompanies the subscapular vessels.
Axillary nerve passes backwards through the quadrilateral space with the posterior circumflex humeral arty. It supplies shoulder joint, and divides into ant and post. Anterior division supplies Deltoid and regimental badge area of skin. Posterior division supplies deltoid, teres minor, then terminates as upper lateral cutaneous nerve of arm to skin over lower half of deltoid.
Radial Nerve direct continuation of Posterior cord lies behind axillary artery. Largest branch of plexus. In axilla gives off branches to long and medial heads of triceps and the post cut nerve of arm. Then goes on to supply the extensor compartment
What is the median nerve made up of?
Medial root of Median nerve is direct continuum of Medial Cord crosses in front of 3rd part of axillary arty to join lateral root.
Lateral root of median nerve is the direct continuum of the Lateral cord. Joins with medial root to make the main trunk of the median nerve. No branches in axilla, eventually supplies pronator teres, FCR, PL,FDS, thenar muscles, 1st 2 lumbricals and digital nerves. Branches Anterior Interosseous nerve to FPL,FDP (lateral) PQ and wrist joint. Palmar cutaneous branch.
What are the 5 stages of embryogenesis?
- Cell differentiation
- Morphogenesis
- Pattern formation
- Apoptosis
- Development and Growth
What is the embryology of the upper limb?
wk 4
limb bud begins to develop
limb bud elongates
wk 5
hand paddle well-formed
nerve trunks enter arm
wk 6 fingers separate (by apoptosis)
wk 7
upper limbs rotate by 90deg & elbow flexes
wk 9-10
finger nails start to form and resembles adult limb
What happens in the process of cell differentiation?
The process by which individual cells under genetic control become specialised for carrying out specific functions
CONNECTIVE TISSUE (mesoderm) – forms skeletal elements – bone, joints, tendon, ligaments, fascia
MUSCLE migrates in from somites and connects w dorsal & ventral tendons already in limb
VESSELS (Median artery, basilic & cephalic veins) grow in from vascular axis (aorta and cardinal vein). Median artery degenerates (persistent in 10%)
NERVES grow in from the CNS – last to enter – motor axons grow into dorsal & ventral muscle masses before they divide
What is morphogenesis?
Morphogenesis - formation of shape - e.g. that of individual bones and muscles
- Dorsoventral WNT Pathway
- Wingless = Wnt-7a gene = dorsal patterning
- Engrailed 1 = ventral patterning
- loss of Wnt → double palm, loss of engrailed → double dorsum - Ulnar-Radial (antero-posterior) axis – ZPA
- Sonic Hedgehog gene & retinoic acid signals here
- thumb to little - Proximodistal – AER
- Mesenchymal Interaction
- remove AER - limb development ceases
- duplications and deletions - Hox A-D gene clusters
- mediated by 1-3
- Mutations in Hox d13 are assoc with central polydactyly
- Gli 3 is another gene in limb development→ variety of polydactylies
What is apoptosis?
- Programmed cell death
- Interdigital mesenchymal cells are inhibited from forming cartilage by ectoderm
- Persistence - syndactyly
When does development and growth occur? What are the developmental milestones after birth?
In Utero
Foetal period growth – 9-40/40
After Birth At birth → grasp reflex 3 months → power grip with ulnar digits 5 months → finger grip with adducted thumb 7 months → thumb opposition 9 months → small object pinch 10 months → fine pinch 3 – 4 yrs → hand preference established
What is the course of the median nerve?
Axilla - C5-T1 roots
Arm - initially lateral to brachial artery then → medial
Forearm - under bicipital aponeurosis, b/t 2 heads of PT, emerges & gives off AIN, travels under fibrous arch FDS, b/t FDS & FDP
AIN - Passes downwards on IO membrane between FPL and FDP accompanied by AI artery, Ends on anterior surface of carpus
Wrist - lies b/t PL & FCR
PCBMN arises 6cm proximal to wrist crease
Carpal Tunnel - 10 structures = MN, FPL, 4xFDS, 4xFDP
Hand - enters palm passing behind TCL & divides into muscular, lateral and medial branches
What is the nerve of Berettini?
Nerve of Berettini - Communication between 4th web CDN (ulnar) and 3rd web CDN (median) just distal to carpal tunnel
What branches come off the median nerve?
Muscular branches in cubital fossa
- PT, FCR, PL and FDS
Articular to elbow
Anterior Interosseous Nerve
- FPL, radial FDPs, PQ. Wrist, DRUJ, carpus
- IO membrane and radial periosteum
Palmar cut branch
- 6cm prox to TCL → palmar triangle
Recurrent motor branch
- recurrent around lower border of TCL ~1cm distal to scaphoid tubercle
- supplies OP,APB,FPB.
Variations in anatomy. (Lanz 1977) Extraligamentous branch emerging distal to flexor retinaculum and recurrent to thenar muscles (50%).
Sub-ligamentous – under flexor retinaculum and recurrent (30%)
Trans-ligamentous – emerging beneath flexor retinaculum and piercing it (20%)
What happens to median nerve after TCL?
Lateral branch gives off -
- Muscular to 1st lumbrical
- Cutaneous branch to both sides of thumb and radial side index
Medial branch gives off
- Muscular branch to 2nd lumbrical
- Cutaneous branches to ulnar side of index and both sides of middle and radial side of ring finger
What connections may exist b/t ulnar & median nerves?
Martin-Gruber Anastomosis
Ulnar intrinsic fibres travel with the median nerve to the forearm (can come from median trunk or anterior interosseous) before crossing to join the ulnar nerve → in high ulnar lesion the intrinsics may be spared.
Riche-Cannieu Anastomosis
Ulnar Nerve fibres contribute to Median Nerve more distally in palm
How do you examine the median nerve?
LOOK
- wasting of thenar muscles
- sudomotor changes in radial digits
FEEL
- moving 2pd
MOVE At elbow - Palpable tendon of FCR with resisted wrist flexion Anterior interosseous sign – ‘O’ sign – FDP index and FPL. - Pronation of the forearm with elbow extended to neutralise PT (PQ) Motor Branch of Median - APB - Opposition Thumb little OP
Compression tests
What are the compression tests of the median nerve?
Pronator syndrome
- Ligament of Struthers – resisted elbow flexion
- Lacertus fibrosis – resisted elbow flexion with forearm pronated
- Pronator Teres 2 heads – resisted pronation with elbow extended
- FDS arch - resisted FDS flexion of the middle finger
Carpal tunnel
- Tinel’s - paraesthesia
- Phalen’s
- carpal compression (if wrist stiff)
- reverse Phalen’s
What do you find with a median nerve injury at the elbow?
Motor
- Pronator muscles, wrist & finger flexors paralysed except FCU and ulnar FDPs.
- Forearm supinated, weak wrist flexion with ulnar deviation.
- No index and middle DIPJs flexion, weak ring - and little flexion.
- Weak MCPJ flexion from interossei.
- No thumb IPJ flexion, thenar eminence wasted. Thumb laterally rotated and adducted. Hand flattened and ape-like.
Sensory
o No sensation radial side of hand and palm.
o Vasomotor – areas warmer and dryer than normal. Due to arterial dilatation and absence of sweating resulting from loss of sympathetic control.
Trophic changes
o Skin dry and scaly, nails crack easily and atrophy of finger pulps.
What do you find with a median nerve injury at the wrist?
Motor
o Thenar muscles paralysed and wasted. Simian thumb. APB & OP not possible.
o 2 Lumbricals paralysed (make a fist slowly middle and index will lag behind ring and little)
Sensory
o As for elbow lesions.
What compression syndromes are there of the median nerve?
- Pronator Syndrome - PAIN
- Anterior Interosseous syndrome - MOTOR
- Carpal Tunnel Syndrome (P&N, palm spared)
What is pronator syndrome and what are the signs?
Pain in proximal volar forearm ↑ with activity, ↓ median sensation
Tinels at PT
4 sites of compression
- Between 2 heads of PT
- Ligament of Struthers
- Beneath bicipital aponeurosis (lacertus fibrosus)
- Under arch of FDS
Distinuish from CTS by
- Altered sensation in the palmar triangle → PCBMN
- Tinels +ve over forearm not wrist
- Phalen’s negative
- NCS ↑ latency at elbow or forearm (or no change as intermittent compression)
What is the treatment for pronator syndrome?
Conservative Splint (pronation and slight wrist flexion) and change habits
Surgical
dissect out the median nerve from 5cm above elbow to below the bicipital aponeurosis. Release one head of PT, FDS bridge and anything else compressing.
What is anterior interosseous syndrome?
- Compression neuropathy of ant interosseus nerve. (FPL, PQ and radial FDP)
- Rare <1% of upper limb compressions.
What is the aetiology of AIN syndrome?
Tendinous bands o deep head of PT o Origin of FDS of middle o Origin of a palmaris profundus o Accessory bicipital aponeurosis
Accessory muscles o from FDS to FDP o Gantzer’s muscle (accessory head of FPL) o Palmaris Profundus o Flexor Carpi Radialis Brevis
Vascular
o Thrombosis of ulnar collateral vessels
o Aberrant radial artery
Other
o Enlarged bicipital bursa
What are the symptoms and signs of AIN syndrome?
Symptoms
- Writing gone off
- post-viral
- purely motor paresis but - ache in forearm
- Weak pinch grip esp. FPL weakness
Signs
FPL – absent or weak IPJ flexion
FDP – absent/weak DIPJ flex of index or less commonly middle finger, can’t make O sign
PQ – pronate with elbow flexed to reduce power of PT
FDS Middle finger – flexion test
Multiple compression sites in proximal forearm
NCS ↑latency in upper forearm
What is the treatment of AIN syndrome
wait 6-12wks
Surgical
- dissect out AIN from origin to lower 1/3 of forearm +/- detach 2 heads of PT
If it doesn’t resolve
- internal neurolysis
- tendon transfers
Carpal tunnel syndrome
Paget 1954
most common upper limb compression synd
1-10% popn, 60% w repetitive grip tasks
50% b/n 40 – 60, F>M 6:1, 40% bilateral
Do you know a classification system for CTS severity?
Classification (Chang & Dellon, J Hand Surg 1993, 18B, 467.) No impairment 0. Paraesthesia – intermittent 1. Threshold - mild (SWM = 2.83 - 3.84) 2. Abduction - weak 3. Threshold - severe (SWM >3.84) 4. Paraesthesia - persistent 5. S2PD - mild (7-10mm) 6. Atrophy - mild 7. S2PD - severe (>10mm) 8. Anaesthesia 9. Atrophy – severe
How do you examine for CTS?
Signs
LOOK
thenar muscle atrophy, sudomotor
FEEL
- sensation in median nerve distribution, test palmar triangle
MOVE
Abd PB
Provocation tests
Tinels
Phalen’s (+ve if signs <40 sec) - forearm supinated on pillow
Reversed Phalen’s palms together and raising elbows as high as possible
Median nerve compression test
What investigations may be appropriate for CTS?
Electrophysiological changes median nerve distal motor latency >4ms is diagnostic (present in 2/3 of compressed nerves) but normal latency does not exclude TS – 10% NCS are false negative
ESR (if high check for RhA and collagen disorders), Blood sugar, Uric acid, TFTs.
X-rays for compressing source – Carpal tunnel view.
What is the aetiology of CTS?
Reduction in size of tunnel or ↑ in contents.
o ↓ tunnel → Acromegaly, Trauma, OA
o ↑ contents → swellings (ganglion, lipoma), inflammation (tenosynovitis, gout, amyloid) Endocrine (pregnant, diabetes, thyrotoxicosis,)
Congenital - rare o median art o long FDS belly o abnormal lumbrical o palmaris profundus
Trauma
o Direct – Carpal #, CMC dislocation, lunate disloc
o Indirect – hand trauma / burn → swelling
Swellings
o Ganglion, Fibroma, Lipoma, Aneurysm of median artery
Inflammatory
o RhA Synovitis, Gout, TB, gonorrhoea, Scleroderma, Amyloid
Metabolic
o Pregnancy, Diabetes, Thyroid - Myxoedema, Peripheral neuropathy, vit B6 deficiency
Obesity?
Iatrogenic
Idiopathic
o fibrous hyperplasia of flexor synovium
What are the non-operative treatments for CTS?
Non operative
- Activity Modification
- Steroid injection 25mg hydrocortisone
- 80% initial relief
- 1/3 still better at 3/12
- 22% at 12/12
- 11% still better at 18mths
- classical indication is temporary reversible CTS (pregnancy)
- Futuro splint night and protective
- NSAIDs
- Diuretics
How do you perform CTS release? What other additional procedures can be done?
Marking
o Fingers adducted, 3rd web to PL
o Longitudinal release of flexor retinaculum (Brain 1947)
o Synovectomy where indicated
o External neurolysis or epineurotomy– not recommended even in selected pts
Endoscopic release
o 1-2 portal technique
o Indications as for open
o Grip strength back quicker. No difference in low-demand hands
Complications
o sensitive volar scar (common) nerve injury, pillar pain, flexion weakness, pisotriquetral pain syndrome, CRPS type 1 (or 2 if nerve injury)
Adjuncts
o Epineurolysis
o Decompress the motor branch if APB weak.
o PL to APB transfer (Camitz opponensplasty) in patients with thenar wasting
o Internal Neurolysis – NO benefit.
How do patients recover after OCTR?
- Immediate relief of pins and needles
- s2pd = 2/52
- sensory and motor nerve latencies = 3-6 months
- pinch and grip strength = 6-9 months
What are the differences b/t CTS and pronator syndrome?
- Both have numb/paraesthesia in median distribution
- Both have weak thenar muscles
- Both have pain in wrist and forearm
- CTS more night problems
- Pronator syndrome = no Tinels at wrist, NCS not delayed at wrist
- Pronator get dysaesthesia in palmar triangle
- But Phalen’s +ve in 50% of pronator syndrome.
What causes recurrent CTS and how can it be treated?
Causes – incomplete release, scar causing new compression, flexor tenosynovitis
Explore if - +ve Phalen’s, night symptoms, +ve NCS after 6 months
Surgery - Re-release TCL, external neurolysis, synovectomy, revascularise nerve with PQ turnover flap
What is affected in high and low median nerve palsy?
High = Proximal to the origin of AIN (PT, FCR, FDS, radial FDPs, FPL, PQ + Thenar) Low = Distal to AIN (only Thenar muscles
What are the causes of median nerve palsy?
Congenital: absence of thenar muscles, Syringomyelia, Charcot-Marie-Tooth (AD hypertrophic neuropathy
Infection: Polio, Leprosy
Trauma, Compression
Spinal Muscular Atrophy
What tendon transfer is required for low median nerve palsy?
OPPONENSPLASTY
- Ring FDS → through palmar fascia → APB or EPB (Royle Thompson)
- EIP rerouted around ulnar side of hand → APB or EPB (Burkhalter 1973)
- ADM across palm → APB/EPB (Huber 1921)
- PL lengthened with strip of palmar fascia → APB (Camitz 1929)
- Others: ECU (EPB tendon attached to it), ECRL, EDM
What tendon transfers are used for high median nerve palsy?
- FCU split to restore balanced wrist flexion
- Re-route biceps to restore pronation
- BR→FPL for thumb flexion
- Opponensplasty using EI or ADM → thumb abduction and opposition
- Suture together ulnar FDPs to median FDPs to get mass action finger flexion
What is the course of the ulnar nerve?
C8, T1 +/- C7
Arm: medial to brachial artery, pierces medial fascial septum with superior ulnar collateral artery and enters post compartment
Medial intermuscular septum - medial epicondyle → coracobrachialis
Arcade of Struthers - 8cm prox to medial epicondyle. Made up of corachobrachialis insertion/fascia and superficial muscle fibres of triceps/ intermuscular septum
Elbow: passes behind medial epicondyle (humerus) - Osbournes canal
Forearm: b/t 2 heads of FCU. Supplies FCU, FDP little ring, elbow joint
Pierces flexor-pronator aponeurosis
Travels medial to ulnar artery
Wrist - b/t FCU & FDS, enters palm superficial to TCL & radial to pisiform. Divides into superficial & deep branches in Guyon’s canal
What branches come off ulnar nerve?
What communications may exist b/t ulnar and median nerves?
Elbow - FCU, FDP ring & little
Articular br to elbow
Palmar cutaneous to palm - mid forearm
Dorsal or Posterior Cutaneous Branch – from distal 1/3 forearm - dorsum of ulnar side of hand.
Superficial Branch - in palm between pisiform and hook of hamate. Ulnar artery = radial. 2 branches: muscular to PB and cutaneous to ring and little fingers.
Deep Branch - Runs backwards between ADM and FDM before it pierces ODM. Supplies palmar and dorsal interossei, 3rd and 4th lumbricals and Adductor Pollicis.
Examination of the ulnar nerve
LOOK Interosseous guttering and 1st dorsal IO wasting Hypothenar wasting Ulnar claw hand Sudomotor skin changes
FEEL
Moving S2PD, sharp/blunt, note sensation of dorsal cutaneous branch
MOVE
- Froment’s test – Add Pollicis
- Individual Froment’s for fingers – Palm IO
- Resisted abduction of index finger (1st Dorsal IO) and little (ADM)
- Flex MCPJ of little with PIPJ straight (FDM)
- Absent flexion at DIPJs of ring and little
- C-Spine – Spurling’s test for radiculopathy - Extend neck and rotate head toward affected shoulder whilst exerting pressure on head (axial load on spine)
What compression tests can be performed?
Cubital Tunnel syndrome
Phalen’s test (flexion of elbow)
Tinels unreliable
Note lack of claw due to FDP denervated
Ulnar tunnel syndrome (Guyon’s canal)
Pressure over canal
What deficits are observed when the ulnar nerve is injured at the elbow?
LOOK
Ulnar guttering, 1st WS & hypothenar wasting
Ulnar forearm wasting
FEEL
paraesthesia in ulnar distribution including dorsum
MOVE
- FCU and medial 2 FDPs paralysed
- radial wrist deviation
- DIPJ flexion little & ring - Froment’s sign
- Inability to wriggle middle finger side to side with palm on table
- Ulnar claw (main en griffe)
- MCPJ’s hyperextend due to paralysis of lumbricals and interossei (normally flexes MCPJ & extends PIPJ) & unopposed extrinsic extensors
- Fingers don’t claw if MCPJs cannot hyperextend - Wartenberg’s sign: persistent abducted & extended little finger - due to EDM’s indirect insertion into abductor tubercle on prox phalanx
Bouvier manoeuvre - manually block MCPJ in 90 deg flexion and ask pt to extend fingers.
Bouvier +ve = finger extends ok → need anticlaw procedure only, because long extensors and IPJs are ok.
Bouvier –ve = finger does not extend at IPJs then it is either
- Passive Positive – can extend IPJs passively = extensor apparatus incompetent
- Passive Negative – can’t passively extend = skin short or flexor adhesions or volar plate contracture etc
What deficits are observed when the ulnar nerve is injured at the wrist?
FEEL
Main nerve and palmar cut branch usually divided
Posterior cutaneous branch intact - arises 7 cm above the pisiform.
MOVE
Paralysed small muscles of hand
Claw hand MORE obvious as the FDP is not paralysed so there is marked flexion of the DIPJs = Ulnar Paradox
