Populations and Risk Factors
- Neonates during difficult vaginal deliveries — shoulder dystocia is the primary mechanism; large-for-gestational-age infants (>4 kg), gestational diabetes, and prolonged second stage of labor are independent risk factors; incidence approximately 1–2 per 1,000 live births
- Adults following high-energy trauma — motorcycle accidents, falls from height landing on the shoulder with the head forced contralaterally, sports tackles with forced lateral neck flexion
- Contact sport athletes — football, rugby, hockey, wrestling — forceful depression of the shoulder with simultaneous contralateral lateral flexion of the neck (overlaps with stinger mechanism but with greater force and structural injury)
- Individuals carrying heavy loads on one shoulder — military packs, heavy rucksacks — chronic traction on the upper trunk ("rucksack palsy")
- Prior clavicle fracture or shoulder dislocation — callus formation or displaced fragments may compress the upper trunk secondarily
- Cervical spinal stenosis — narrowed neural foramina reduce the reserve space for C5–C6 nerve roots, lowering the threshold for traction injury
Causes and Pathophysiology
Brachial Plexus Upper Trunk Anatomy
The brachial plexus arises from the ventral rami of C5–T1, organized into roots, trunks, divisions, and cords. The upper trunk forms from the union of C5 and C6 at Erb's point, located approximately 2–3 cm above the clavicle in the posterior triangle of the neck, between the anterior and middle scalene muscles. This convergence point is the most vulnerable segment of the upper plexus because:- Fixed proximal attachment: The nerve roots are tethered to the transverse processes and exit through the intervertebral foramina — they cannot slide proximally to accommodate stretch
- Exposed position: The upper trunk crosses the posterior triangle superficial to the middle scalene, with no bony or muscular protection — making it vulnerable to both direct compression and lateral traction
- Convergence point loading: When lateral traction is applied (head forced away from the ipsilateral shoulder), tensile force concentrates at the junction of C5 and C6 because this is where the two roots merge — stress is highest at the confluence point
Traction Injury Mechanism
The classic mechanism is forced lateral flexion of the neck away from the ipsilateral shoulder, increasing the distance between the cervical spine and the shoulder girdle beyond the nerve's elastic limit. The injury progresses through a predictable sequence:- Stretch within elastic limit (neurapraxia): The nerve is stretched but the axons remain intact — only the myelin sheath is disrupted at the point of maximal deformation. This produces a temporary conduction block. Recovery is complete, typically within 6–12 weeks, as remyelination occurs. This is the mechanism in most stingers and mild birth palsies.
- Stretch beyond elastic limit (axonotmesis): Greater force ruptures the axons within their endoneurial tubes, but the connective tissue framework (endoneurium, perineurium, epineurium) remains intact. Wallerian degeneration occurs distal to the lesion. Recovery is possible because intact endoneurial tubes guide regenerating axons to their original target muscles at approximately 1 mm/day.
- Root avulsion (neurotmesis): Extreme force tears the nerve root from the spinal cord. The ventral root (motor) is avulsed from the anterior horn, and the dorsal root (sensory) from the dorsal root ganglion. This injury is irreversible without surgical nerve transfer because central nervous system neurons cannot regenerate axons into peripheral pathways. Avulsion is more common in high-energy adult trauma than in birth injuries.
Birth Injury Mechanism
During a difficult vaginal delivery, shoulder dystocia traps the anterior shoulder behind the pubic symphysis. The obstetrician applies lateral traction to the fetal head to deliver the shoulder, which stretches the ipsilateral upper trunk. The force is concentrated at Erb's point because the shoulder is fixed against the symphysis while the head is pulled away. Approximately 80–90% of obstetric Erb's palsy cases are neurapraxic and recover spontaneously within 3–6 months. The remaining 10–20% involve axonotmesis or avulsion and may require surgical intervention (nerve grafting, nerve transfer, or muscle transfer).Waiter's Tip Posture Mechanism
The waiter's tip position is not a random posture — it is the predictable result of which muscles are lost and which remain functional:- Shoulder adducted and internally rotated: Loss of supraspinatus (C5–C6, abduction initiator) and infraspinatus (C5–C6, external rotator) leaves the subscapularis (C5–C6 but often partially spared via lower trunk contributions), pectoralis major (C5–T1, internal rotator), latissimus dorsi (C6–C8), and teres major (C5–C7) unopposed — the shoulder is pulled into adduction and internal rotation
- Elbow extended: Loss of biceps brachii (C5–C6) and brachialis (C5–C6) removes elbow flexion; the triceps (C6–C8, intact) holds the elbow in extension
- Forearm pronated: Loss of biceps (the most powerful supinator at 90° flexion) and supinator (C5–C6) leaves pronator teres (C6–C7, partially intact) and pronator quadratus (C8–T1, intact) unopposed
- Wrist flexed: Loss of brachioradialis (C5–C6) and the wrist extensors receiving C5–C6 input allows gravity and intact wrist flexors to pull the wrist into flexion
Signs and Symptoms
Acute Presentation (Neurapraxic — Recoverable)
- Waiter's tip posture: Shoulder adducted and internally rotated, elbow extended, forearm pronated, wrist flexed — the arm hangs limp at the side; in neonates, the affected arm does not participate in the Moro reflex
- Motor loss: Inability to abduct the shoulder (deltoid, supraspinatus), externally rotate the shoulder (infraspinatus), flex the elbow (biceps, brachialis), or supinate the forearm (biceps, supinator); grip may be preserved because hand muscles (C8–T1) are intact
- Sensory disturbance: Paresthesia or numbness over the lateral arm (axillary nerve, C5), lateral forearm (musculocutaneous nerve, C5–C6), and radial aspect of the hand (if C6 sensory root involved); the "regimental badge" area over the deltoid insertion is the classic C5 sensory test zone
- Reflex loss: Depressed or absent biceps reflex (C5–C6) and brachioradialis reflex (C5–C6); triceps reflex (C7) preserved
- Pain: Neck and shoulder pain at the time of injury; may include burning or lancinating pain radiating into the lateral arm from neural irritation at the injury site
Chronic Presentation (Axonotmesis / Avulsion — Variable Recovery)
- Persistent motor deficit: Months after injury, deltoid and biceps atrophy become visible; shoulder subluxation may develop from loss of supraspinatus and deltoid tone (the humeral head drops inferiorly); elbow flexion contracture may develop if the arm is splinted in flexion without range of motion exercises
- Compensatory patterns: Shoulder hiking (upper trapezius substitution for absent deltoid abduction), trunk lean to bring objects to the hand, scapular winging if long thoracic nerve (C5–C7) is also involved
- Contracture development: Unopposed internal rotators and adductors produce progressive glenohumeral internal rotation contracture — in neonatal Erb's palsy, this can lead to posterior glenohumeral subluxation and glenoid dysplasia if not addressed early
- Co-contraction patterns: During recovery, aberrant reinnervation may produce simultaneous activation of antagonist muscles (e.g., biceps and triceps firing together) — this is clinically frustrating but indicates active reinnervation
Assessment Profile
Subjective Presentation
- Chief complaint: Adult: "I can't lift my arm or bend my elbow since the accident"; neonate (parent report): "The baby doesn't move the arm — it just hangs there"; chronic: "My arm is weak and I can't reach overhead or turn a doorknob"
- Pain quality: Acute — sharp, burning, or lancinating pain in the neck and lateral shoulder/arm; chronic — deep aching in the shoulder from subluxation or capsular strain; neuropathic burning or shooting pain along the lateral arm if neural irritation persists
- Onset: Acute traumatic event (motorcycle accident, sports tackle, difficult delivery) with immediate arm weakness; or insidious onset over weeks with progressive weakness (suggests compressive lesion — space-occupying lesion at the posterior triangle)
- Aggravating factors: Any attempt at shoulder abduction, external rotation, or elbow flexion; carrying weight in the affected hand (stresses the subluxed shoulder); contralateral lateral neck flexion (reproduces traction on the upper trunk)
- Easing factors: Supporting the arm in a sling reduces gravitational stress on the subluxed shoulder and eliminates the pain of unsupported weight; rest eases neuropathic pain
- Red flags: Bilateral upper extremity weakness or lower extremity involvement → suspect cervical spinal cord injury or bilateral plexopathy; emergency referral; progressive weakness without trauma → consider Pancoast tumor compressing the plexus, metastatic disease, or radiation plexopathy; refer for imaging and neurological evaluation before treating
Observation
- Local inspection: Waiter's tip posture (acute); deltoid and biceps atrophy (chronic — compare bilateral muscle bulk); shoulder subluxation (inferior displacement of the humeral head visible as a sulcus sign under the acromion); scapular winging if long thoracic nerve is involved; in neonates, the affected arm does not participate in spontaneous movement or the Moro reflex
- Posture: Shoulder girdle depression on the affected side (loss of supporting muscle tone); compensatory upper trapezius hypertonicity (shoulder hiking to substitute for deltoid abduction); head may tilt toward the affected side to reduce traction on the healing plexus
- Gait: Not directly affected unless pain or arm immobilization produces a guarded gait pattern; observe for reduced reciprocal arm swing on the affected side
Palpation
- Tone: Upper trapezius and levator scapulae — hypertonic on the affected side from compensatory shoulder hiking. Scalenes — assess for hypertonicity contributing to upper trunk compression. Deltoid and biceps — hypotonic or atrophic, feeling soft and flaccid rather than firm. Supraspinatus and infraspinatus — reduced tone if C5–C6 supply is disrupted. Intact antagonists (pectoralis major, latissimus dorsi, subscapularis) may develop adaptive shortening from unopposed pull.
- Tenderness: Erb's point — focal tenderness in the posterior triangle approximately 2–3 cm above the clavicle, between the anterior and middle scalenes; may reproduce radiating paresthesia into the lateral arm and forearm on palpation; referred path tenderness: with neural irritation, tenderness may extend along the lateral arm (axillary nerve territory) and lateral forearm (musculocutaneous territory) — this maps the C5–C6 distribution and should be correlated with sensory testing; cervicothoracic junction — tenderness from compensatory postural strain
- Temperature: Usually normal unless acute inflammatory response is present at the injury site (mild warmth in the posterior triangle); the affected hand may feel cool in chronic cases due to reduced sympathetic tone if the injury extends to involve T1 sympathetic fibers
- Tissue quality: Scalenes and upper trapezius — taut bands and trigger points from chronic compensatory loading. Deltoid and biceps — soft, atrophic tissue with reduced bulk compared contralaterally. Supraspinatus and infraspinatus fossae — muscle bellies feel flat and soft in chronic denervation. Glenohumeral capsule may feel lax inferiorly (subluxation) and tight anteriorly (internal rotation contracture).
Motion Assessment
- AROM: Shoulder abduction markedly reduced or absent (deltoid and supraspinatus loss); shoulder external rotation absent or trace (infraspinatus loss); elbow flexion absent or trace (biceps and brachialis loss); forearm supination weak or absent; wrist extension may be reduced; grip strength typically preserved (C8–T1 intact); the patient may demonstrate shoulder hiking (upper trapezius substitution) when attempting abduction — this is a compensatory trick movement, not true deltoid function
- PROM / end-feel: Shoulder PROM may be full if no contracture has developed — end-feel will be tissue stretch (tight internal rotators) on external rotation; in chronic cases, internal rotation contracture produces a capsular or firm end-feel at the external rotation limit; elbow PROM is typically full unless flexion contracture has developed from splinting; contralateral lateral cervical flexion PROM may reproduce upper trunk symptoms (lateral flexion away from the affected side stretches the plexus)
- Resisted testing: Shoulder abduction — weak or absent (C5: deltoid, supraspinatus); elbow flexion — weak or absent (C5–C6: biceps, brachialis); forearm supination — weak (C6: biceps, supinator); wrist extension — may be reduced (C6 contribution); grip and finger movements — normal (C8–T1); this pattern of proximal weakness with preserved distal function is the hallmark of upper trunk palsy and distinguishes it from a complete plexus injury
Special Test Cluster
| Test | Positive Finding | Purpose |
|---|---|---|
| ULTT1 (median nerve bias) (CMTO) | Shoulder abduction, elbow extension, wrist/finger extension, forearm supination reproduce burning or paresthesia in the lateral arm/forearm; symptoms change with cervical lateral flexion | Assess neurodynamic tension through the upper trunk and lateral cord; median nerve bias stresses C5–C6–C7 contributions |
| ULTT2a (musculocutaneous nerve bias) (CMTO) | Shoulder depression, elbow extension, forearm supination, wrist extension reproduce lateral forearm symptoms | Specifically stresses the musculocutaneous nerve (C5–C6) — the most direct upper trunk derivative; more specific than ULTT1 for upper trunk pathology |
| Shoulder depression test (CMTO) | Passive lateral flexion of the neck away from the affected side with simultaneous shoulder depression reproduces radiating pain or paresthesia into the lateral arm | Reproduces the traction mechanism on the upper trunk; high sensitivity for brachial plexus tension |
| Myotomal testing (C5–C6) (CMTO) | Weakness of shoulder abduction (C5), elbow flexion (C6), forearm supination (C6) with preserved grip (C8–T1) | Localizes the lesion to the upper trunk by demonstrating the specific myotomal pattern of deficit |
| Spurling's test (CMTO — rule out) | Cervical extension, lateral flexion, and axial compression toward the affected side reproduce radicular symptoms in the C5–C6 distribution | Rule out cervical radiculopathy — Spurling's compresses the neural foramen; positive Spurling's suggests a foraminal lesion (disc, osteophyte) rather than plexus traction |
| Tinel's sign at Erb's point (supplementary) | Percussion over Erb's point (posterior triangle, 2–3 cm above clavicle) produces tingling radiating into the deltoid and lateral arm | Localizes neural irritability to the upper trunk; an advancing Tinel's (moving distally over weeks) indicates active axonal regeneration |
Cluster interpretation: A positive shoulder depression test + positive ULTT1/ULTT2a + myotomal weakness in C5–C6 with preserved C8–T1 function strongly localizes the injury to the upper trunk. If Spurling's is also positive, the cervical spine must be assessed as a concurrent or alternative lesion site. An advancing Tinel's sign at Erb's point over serial assessments indicates active nerve recovery.
Differential Diagnoses
| Condition | Key Distinguishing Feature |
|---|---|
| C5–C6 cervical radiculopathy | Neck pain with positive Spurling's test; symptoms reproduced by foraminal compression rather than lateral traction; dermatomal pattern may be identical, but radiculopathy typically presents with neck pain as a primary complaint and is often position-dependent |
| Rotator cuff tear (supraspinatus) | Shoulder abduction weakness with pain, but no elbow flexion deficit and no sensory loss; positive empty can test and painful arc; intact biceps reflex |
| Axillary nerve injury (isolated) | Deltoid weakness and regimental badge numbness only — no biceps, supraspinatus, or infraspinatus involvement; elbow flexion and forearm supination preserved; usually post-shoulder dislocation |
| Thoracic outlet syndrome | Symptoms predominantly in C8–T1 distribution (medial arm/hand); provoked by overhead positions (Roos test positive); vascular component (pallor, coolness, diminished radial pulse); upper trunk symptoms would be atypical for TOS |
| Pancoast tumor | Progressive brachial plexus symptoms without trauma; lower trunk involvement more common but can affect upper trunk; Horner's syndrome; shoulder/axillary pain; refer for chest imaging; do not treat as mechanical plexopathy |
CMTO Exam Relevance
- Classified as A4 neurological condition — brachial plexus upper trunk injury
- The waiter's tip posture is a classic exam stem — know which muscles are lost (deltoid, biceps, supraspinatus, infraspinatus, brachioradialis, supinator) and which are preserved (C8–T1 hand intrinsics, triceps)
- Erb's point is a testable anatomical landmark — junction of C5 and C6 in the posterior triangle, the most common site of upper plexus injury
- ULTT1 and ULTT2a (musculocutaneous bias) are the neurodynamic tests for upper trunk involvement; ULTT2a is more specific because the musculocutaneous nerve is a direct upper trunk derivative
- Distinguish from C5–C6 radiculopathy: both produce similar myotomal and dermatomal patterns, but the mechanism is different (traction/trauma for Erb's vs. foraminal compression for radiculopathy); Spurling's differentiates
- Birth palsy prognosis question: Biceps recovery by 3 months is the key prognostic indicator — if the infant does not demonstrate active elbow flexion by 3 months of age, surgical consultation is indicated
- The advancing Tinel's sign concept may be tested — distal migration of Tinel's along the nerve course over serial assessments indicates axonal regeneration proceeding at approximately 1 mm/day
Massage Therapy Considerations
- Primary therapeutic target: The compensatory muscle guarding pattern (upper trapezius, levator scapulae, scalenes) and the developing contracture in the intact antagonists (pectoralis major, subscapularis, latissimus dorsi). The denervated muscles (deltoid, biceps, supraspinatus, infraspinatus) cannot be directly strengthened through MT, but their tissue quality and elasticity can be maintained to support reinnervation.
- Sequencing logic: Release compensatory shoulder girdle hypertonicity first (upper trapezius, levator scapulae) to reduce mechanical strain on the healing plexus → release scalenes carefully to decompress the upper trunk at the posterior triangle → address internal rotator and adductor shortening (pectoralis major, subscapularis, latissimus dorsi) to prevent contracture → gentle tissue maintenance to the denervated muscles (deltoid, biceps, supraspinatus, infraspinatus) to preserve elasticity for reinnervation. This order protects the healing nerve by reducing compressive forces before addressing contracture.
- Safety / contraindications: Avoid deep pressure directly over Erb's point — the injured upper trunk is superficial and vulnerable in the posterior triangle; do not apply aggressive stretching to the denervated muscles (they lack protective reflex and can be overstretched without the patient's awareness); areas of sensory loss require reduced pressure and visual monitoring because the patient cannot provide accurate feedback; acute traumatic injury within the first 2–4 weeks — limit to gentle effleurage and positioning only until the inflammatory phase resolves; if bilateral symptoms or progressive weakness is present without a clear traumatic mechanism, do not treat — refer for neurological evaluation
- Heat/cold guidance: Moist heat to the compensatory muscles (upper trapezius, levator scapulae, scalenes) before treatment to improve tissue pliability; avoid heat over the posterior triangle injury site in the acute phase (may increase neural edema); cool pack post-treatment to the posterior triangle if the area is reactive after scalene or upper trapezius work
Treatment Plan Foundation
Clinical Goals
- Reduce compensatory shoulder girdle hypertonicity (upper trapezius, levator scapulae, scalenes) to minimize mechanical compression of the healing upper trunk
- Prevent internal rotation and adduction contracture by addressing adaptive shortening in the pectoralis major, subscapularis, and latissimus dorsi
- Maintain tissue elasticity and circulation in denervated muscles (deltoid, biceps, supraspinatus, infraspinatus) to support potential reinnervation
- Reduce neuropathic pain and neural mechanosensitivity through gentle neurodynamic mobilization
Position
- Supine with the affected arm supported on a bolster at the side in a neutral position (slight abduction, neutral rotation) — avoids gravitational traction on the subluxed shoulder and keeps the upper trunk in a slack position
- Side-lying on the unaffected side for posterior shoulder and scapular work — bolster the affected arm anteriorly to prevent it from falling into adduction and internal rotation
- Avoid prone positioning if shoulder subluxation is present — the weight of the arm hanging off the table places traction on the plexus
Session Sequence
- General effleurage to the cervical spine, upper trapezius, and shoulder girdle — assess tissue state, identify compensatory hypertonicity and trigger points; establish parasympathetic tone before targeted work
- Sustained compression and myofascial release to the upper trapezius and levator scapulae — reduce compensatory shoulder hiking pattern; work within pain-free tolerance; these muscles are chronically overloaded from substituting for absent deltoid function
- Scalene release — gentle sustained compression and cross-fiber work to the anterior and middle scalenes; this decompresses the upper trunk at the posterior triangle; monitor for paresthesia reproduction — if tingling radiates into the arm, reduce pressure and reposition
- Pectoralis major and latissimus dorsi release — address adaptive shortening from unopposed internal rotation and adduction; myofascial release and sustained longitudinal stripping; critical for contracture prevention
- Subscapularis release — axillary approach with the arm in slight abduction and external rotation; gentle sustained compression to the subscapularis through the axillary fold; this is the primary internal rotator and the deepest contributor to internal rotation contracture
- Gentle effleurage and myofascial maintenance to the deltoid, biceps, supraspinatus, and infraspinatus — preserve tissue elasticity and circulation in the denervated muscles; do not apply deep pressure (the muscles lack protective tone and sensory feedback may be impaired)
- Gentle neurodynamic mobilization — ULTT1 or ULTT2a position taken to the first onset of neural tension, then oscillated gently within a pain-free range; performed last, after all soft tissue decompression is complete; defer if the nerve is acutely irritable [subacute and chronic cases only]
Adjunct Modalities
- Hydrotherapy: Moist heat to the upper trapezius, levator scapulae, and scalene region before treatment (steps 2–3) to improve tissue pliability; moist heat to the pectoralis major and axillary region before subscapularis release (steps 4–5); avoid heat directly over the posterior triangle in acute cases; cool pack to the posterior triangle post-treatment if reactive
- Joint mobilization: Inferior glenohumeral glide — if shoulder subluxation is present, gentle Grade I–II inferior glide followed by gentle distraction may help reduce capsular guarding; lateral glide of the cervical spine away from the affected side may gently decompress the neural foramen at C5–C6 [subacute/chronic only; contraindicated if cervical instability is suspected]
- Remedial exercise (on-table): Passive range of motion through shoulder abduction, external rotation, and elbow flexion to maintain joint mobility and prevent contracture — performed by the therapist moving the arm through available range while monitoring for pain; active-assisted range of motion for movements the patient can partially perform [as reinnervation progresses]; gentle pendulum exercises with the arm hanging freely to decompress the glenohumeral joint
Exam Station Notes
- Demonstrate bilateral comparison of deltoid and biceps bulk before selecting treatment approach — visible atrophy changes the prognosis discussion and treatment intensity
- Show awareness of Erb's point location and avoid deep direct pressure during scalene release — verbalize the reasoning
- Perform myotomal testing (C5 abduction, C6 flexion/supination) pre- and post-treatment as outcome markers
- Position the arm in neutral (not adduction/internal rotation) during treatment and explain the contracture prevention rationale
Verbal Notes
- Posterior triangle and scalene work: inform the client that treatment near the base of the neck may temporarily reproduce their familiar arm tingling — this is expected because the nerve is being decompressed; if tingling intensifies or persists, the technique will be adjusted immediately
- Axillary access for subscapularis: explain that accessing the muscle under the armpit is necessary to address the internal rotation pattern; ensure verbal consent before proceeding; draping maintained throughout
- Denervated muscle work: explain that the weak muscles will be treated gently to maintain tissue health during nerve recovery — deep pressure is avoided because sensation may be reduced and the muscles cannot protect themselves
Self-Care
- Passive range of motion exercises — shoulder abduction, external rotation, and elbow flexion performed by the unaffected hand or a caregiver, 3–5 repetitions through full available range, 2–3 times daily; essential for contracture prevention
- Positioning guidance — avoid prolonged shoulder adduction and internal rotation (e.g., sling wear should be balanced with supervised abduction/external rotation positioning to prevent contracture)
- Pendulum exercises — stand at a table edge, lean forward, let the affected arm hang freely and swing in small circles; decompresses the glenohumeral joint and maintains joint lubrication
- Nerve gliding exercise — gentle cervical lateral flexion toward the affected side (slackening the plexus) followed by slow lateral flexion away (tensioning the plexus), oscillated gently within pain-free range; 5 repetitions, 2 times daily [subacute/chronic only; defer if neuropathic pain is provoked]
Key Takeaways
- Erb's palsy results from C5–C6 upper trunk injury at Erb's point — the waiter's tip posture (adducted/internally rotated shoulder, extended elbow, pronated forearm, flexed wrist) is the predictable result of losing deltoid, biceps, supraspinatus, infraspinatus, brachioradialis, and supinator while C8–T1 hand muscles remain intact
- The mechanism — forced lateral neck flexion away from the ipsilateral shoulder — concentrates tensile stress at Erb's point because the nerve roots are tethered proximally at the intervertebral foramina
- Birth palsy accounts for the majority of cases (1–2 per 1,000 live births) with 80–90% recovering spontaneously if neurapraxic; absence of biceps recovery by 3 months of age indicates surgical consultation
- The advancing Tinel's sign at Erb's point is the clinical indicator of active axonal regeneration — serial assessment showing distal migration of the Tinel's response indicates the nerve is recovering at approximately 1 mm/day
- Internal rotation and adduction contracture is the primary musculoskeletal complication — the intact antagonists (pectoralis major, subscapularis, latissimus dorsi) shorten unopposed, requiring proactive stretching and positioning
- Bilateral upper extremity weakness or progressive weakness without trauma are red flags for spinal cord injury or tumor — do not treat as a plexus injury without neurological clearance
- ULTT1 and ULTT2a (musculocutaneous bias) are the neurodynamic tests for the upper trunk; Spurling's test differentiates cervical radiculopathy from plexus injury