High-yield overview

Supine | Head Turned to the Opposite Side | Phrenic Nerve on Anterior Scalene | Thoracic Duct at Risk on the Left

C5 to T1Plexus trunks exposed between the scalenes

Left sideThoracic duct at the venous angle

SupineBeach-chair, head turned to the opposite side

C3 to C5Phrenic nerve on anterior scalene

Critical Must-Knows

There is no true internervous plane - this is an intermuscular, interfascial approach and a classic examiner trap.
The phrenic nerve (C3 to C5) descends on the anterior surface of anterior scalene - identify it first and protect it; it is the key that leads to the trunks.
The subclavian artery and the plexus trunks lie between the anterior and middle scalene; the subclavian vein lies anterior to anterior scalene, separated from the artery by the muscle.
On the left side, the thoracic duct arches through the scalene fat pad to the venous angle - injury causes a chyle leak and chylothorax.
Position supine in the beach-chair, head turned to the opposite side, with the arm prepped free for intra-operative nerve monitoring.

When & Why

What it exposes. The supraclavicular approach is a supine, head-turned exposure through the posterior triangle of the neck that reaches the trunks and divisions of the brachial plexus (C5 to T1), the subclavian artery, and the anterolateral lower cervical and cervicothoracic spine by working between the scalene muscles just above the clavicle. For any lesion proximal to the clavicle, no other single exposure matches this reach. Why supraclavicular. The trunks of the plexus lie most superficially here, sandwiched between the anterior and middle scalene just above and behind the clavicle. A short transverse incision gives simultaneous access to the upper, middle and lower trunks, the divisions, the subclavian artery and the apex of the lung, and it is the anterior route for thoracic outlet decompression.

Supraclavicular (Phalen / Narakas)

Transverse incision above the clavicle to reach the trunks and divisions - the workhorse for plexus exploration, neurolysis and cable grafting.

Supraclavicular TOS decompression

Anterior scalenectomy, cervical rib excision and first rib resection for thoracic outlet syndrome.

Combined supra- plus infra-clavicular

A double approach for whole-plexus exposure in complete pan-plexus injuries from roots to cords.

Indications. - Supraclavicular brachial plexus exploration for traction or closed injuries of the upper, middle or lower trunks, divisions and roots C5 to T1

Nerve grafting and nerve transfer for post-ganglionic ruptures of the trunks (sural, medial antebrachial or other cable grafts)
Neurolysis or excision of benign plexus tumours (schwannoma, neurofibroma) at the trunk level
Thoracic outlet syndrome requiring anterior scalenectomy, cervical rib excision, or first rib resection via the anterior route
Cervical rib producing true neurogenic compression of the lower trunk
Anterolateral access to the cervicothoracic junction (C7, T1) for selected anterior decompression or biopsy Contraindications. - Active infection of the skin over the supraclavicular fossa
Medical unfitness for prolonged general anaesthesia or for the beach-chair position
A lesion clearly confined to the infraclavicular cords or terminal branches (use an infraclavicular or deltopectoral approach instead)
A predominantly distal peripheral nerve lesion (explore at the site of the lesion) Alternative and combined approaches. - Infraclavicular / deltopectoral approach for the lateral and posterior cords and terminal branches around the coracoid
Posterior (subscapular) approach for the infraclavicular plexus when anterior scarring is severe
Transaxillary first rib resection (Roos), an alternative route for TOS decompression that avoids a neck scar

The Exposure

Work from skin to trunks through the posterior triangle, protecting the superficial nerves and vessels, then develop the intermuscular plane along the anterior scalene - using the phrenic nerve as the guide - to open the interscalene gutter and display all three trunks and the subclavian artery.

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Image Needed: Clinical PhotoHigh Priority

Intra-operative photograph of the supraclavicular approach: a transverse clavicular-crease incision in the right posterior triangle, the sternocleidomastoid retracted medially and the scalene fat pad reflected laterally, a vessel loop protecting the phrenic nerve on anterior scalene, and the brachial plexus trunks and subclavian artery coming into view between the scalenes.

Context: A verified image is being sourced for this exposure.

Pending image generation or sourcing

Exposure sequence

Step 1Position the patient

Supine beach-chair with a small sandbag or roll between the scapulae to drop the shoulder and gently extend the neck - this lifts the plexus toward the surgeon.
Turn the head 30 to 45 degrees to the opposite side onto a head ring to relax the sternocleidomastoid and open the posterior triangle.
Prep and drape the ipsilateral arm free into the field for intra-operative nerve monitoring and traction testing.
Establish somatosensory and motor evoked potentials and triggered EMG and confirm baseline readings before incision.

Step 2Mark the incision

A transverse skin-crease (Langer line) incision, about 6 to 8 cm long, placed one to two finger-breadths above and parallel to the clavicle.
Centred over the posterior border of sternocleidomastoid so the midpoint of the incision lies over the scalene mass.
The crease incision heals in the natural folds of the neck and is preferred cosmetically; for a combined whole-plexus exposure it can extend laterally over the clavicle toward the deltopectoral groove.

Step 3Skin and platysma

Incise skin and subcutaneous tissue in the line of the incision, then identify and incise the platysma in the same line.
Place retractors to expose the investing layer of deep cervical fascia. Platysma is supplied by the cervical branch of the facial nerve and must be repaired at closure.

Step 4The external jugular vein

The external jugular vein crosses the field obliquely over sternocleidomastoid; it is a reliable superficial guide.
It can usually be mobilised and retracted, but if it tethers exposure it should be ligated and divided between ligatures.

Step 5Protect the supraclavicular nerves

The supraclavicular nerves (C3 to C4) from the superficial cervical plexus emerge at Erb's point on the posterior border of sternocleidomastoid and fan out across the clavicle.
They are sensory. Identify, mobilise gently and retract them rather than sacrifice them, to avoid a numb patch over the clavicle and upper shoulder.

Step 6Open the posterior triangle

Incise the investing fascia along the posterior border of sternocleidomastoid and retract the muscle medially, preserving the spinal accessory nerve branch to it.
The omohyoid (superior belly) crosses the floor; mobilise and retract it, or divide it and mark the ends for later repair.
The transverse cervical and suprascapular vessels may cross the floor - ligate or coagulate them as needed.

Step 7Reflect the scalene fat pad (thoracic duct on the left)

Mobilise and retract laterally the fatty scalene (posterocervical) fat pad that fills the posterior triangle, exposing the anterior scalene muscle.
On the left side, take care: the thoracic duct ascends through this fat to reach the venous angle. Use meticulous blunt dissection and low ligation of any suspicious lymphatic channel.

Step 8Identify the phrenic nerve

Find the phrenic nerve (C3 to C5) on the anterior surface of anterior scalene, running from superolateral to inferomedial beneath the prevertebral fascia.
Gently free it and protect it with a vessel loop. It is the key that leads to the plexus - never divide a vertical structure on anterior scalene without confirming it is not the phrenic nerve.

Step 9Expose the trunks

Incise the prevertebral fascia along the lateral border of anterior scalene. The trunks come into view in the interscalene gutter.
Upper trunk (C5 to C6) superiorly, middle trunk (C7) in the middle, and lower trunk (C8 to T1) inferiorly, lying on the first rib close to the subclavian artery.
The subclavian artery lies with the trunks, posterior to anterior scalene; the subclavian vein lies anterior to anterior scalene, separated from the artery by the muscle.

Step 10Identify the branches

Trace and protect the suprascapular nerve from the upper trunk, often visible at the lateral upper trunk.
On the posterior aspect, be aware of the long thoracic nerve (Bell) penetrating and descending on middle scalene, and the dorsal scapular nerve (C5) piercing middle scalene - injury to Bell's nerve wings the scapula.

Identify the phrenic nerve before any dissection on anterior scalene

The phrenic nerve (C3 to C5) descends on the anterior surface of anterior scalene and is the single most important structure in this approach - it points the surgeon to the trunks and protects the hemidiaphragm. Identify it before any work on the muscle, sling it with a vessel loop, and use bipolar rather than monopolar diathermy in its vicinity. Never divide a vertical structure on anterior scalene until you have confirmed it is not the phrenic nerve.

The 'no internervous plane' trap

Examiners frequently ask for the internervous plane of this approach. The correct answer is that there is none - the dissection is intermuscular and interfascial. State this confidently, then explain that the safe deep dissection follows the anterior surface of anterior scalene, using the phrenic nerve as the guide to the trunks. Candidates who invent a plane lose marks for anatomy.

Dangers & Extensions

Structures at risk, by layer

Danger structures and how to protect them
Layer / zone	Structure at risk	Protection
Anterior scalene surface	Phrenic nerve (C3 to C5)	Identify first, sling with a vessel loop, bipolar not monopolar diathermy
Left fat pad / venous angle	Thoracic duct (left side only)	Blunt fat-pad dissection, ligate suspicious channels, inspect before closure
Between the scalenes	Subclavian artery and vein	Proximal and distal control early; vascular injury needs immediate repair
Middle scalene	Long thoracic nerve of Bell (C5 to C7)	Avoid deep diathermy on middle scalene during scalenectomy or rib resection
First rib / lower trunk	Apical pleura (cupola) and stellate ganglion	Stay off the first rib groove unless resecting; chest radiograph post-operatively
Superficial field	Supraclavicular nerves (C3 to C4) and suprascapular nerve	Mobilise and protect to avoid clavicular numbness and shoulder-girdle motor loss

Complications and their management

Complications, prevention and management
Complication	Prevention	Management
Phrenic nerve injury	Identify first, vessel loop, avoid monopolar diathermy	Observe; most recover; rare diaphragmatic plication if symptomatic
Vascular injury (subclavian vessels)	Proximal and distal control, careful retraction	Immediate vascular repair; call vascular surgery early
Thoracic duct injury (left)	Blunt fat-pad dissection, inspect before closure	Suture ligation; fat-pad patch; medium-chain diet; re-explore if persistent
Pneumothorax	Stay off the cupola of the pleura	Chest drain; confirm on post-operative chest radiograph
Horner syndrome	Protect the lower trunk and stellate region	Usually incomplete and recovers; counsel pre-operatively
Winged scapula (Bell nerve)	Protect long thoracic nerve on middle scalene	Observe and physiotherapy; rare persistent deficit

Extensile options. Extend proximally along the posterior border of sternocleidomastoid toward the mastoid to convert the exposure toward the interscalene region, reaching the C5 and C6 roots and the upper trunk origin. Extend distally over the clavicle to the deltopectoral groove to reach the divisions and the lateral and posterior cords around the coracoid, or add a separate infraclavicular incision (combined double approach) for pan-plexus injuries. For the cervicothoracic spine, retract the carotid sheath medially and work along the longus colli to reach the C7 and T1 vertebral bodies for selected anterolateral decompression, respecting the inferior thyroid artery and recurrent laryngeal nerve medially. Closure and aftercare. Achieve meticulous haemostasis and, on the left, re-inspect the thoracic duct region for any chyle leak. Re-check that the phrenic nerve and all identified trunks and branches are intact, then repair omohyoid if it was divided. Close the platysma meticulously with absorbable suture - this layer is the key to a flat, cosmetic scar and protects against lymphatic collection - and close the skin with a running subcuticular suture. Place a suction drain if a large dead space remains or extensive neurolysis or rib resection was performed. Obtain a chest radiograph in recovery to exclude an apical pneumothorax, and document an upper-limb neurovascular examination against the pre-operative baseline.

Procedures Through This Approach

Brachial plexus exploration, neurolysis and cable grafting of trunk-level post-ganglionic ruptures, guided by intra-operative nerve action potentials
Nerve transfers that use supraclavicular donors (for example upper trunk to recipient nerves)
Excision of plexus tumours (schwannoma, neurofibroma) with a functioning nerve-sparing technique
Thoracic outlet decompression: anterior scalenectomy, cervical rib excision, division of congenital bands, and first rib resection when indicated
Anterolateral access to the cervicothoracic junction (C7, T1) for selected anterior decompression, biopsy or stabilisation

Viva & Exam Focus

Mnemonic

SCALPSSCALPS - safe sequence from skin to the trunks

Supine beach-chair

Head turned to the opposite side, arm draped free for monitoring

Clavicular-crease incision

Transverse, 6 to 8 cm, centred on the posterior border of SCM

Anterior scalene

The central landmark of the approach

Ligate the EJV

And protect the supraclavicular sensory nerves

Phrenic nerve

On anterior scalene - identify first and sling it

Subclavian artery

And the plexus trunks between the scalenes

Mnemonic

DANGERDANGER - the six layered hazards of the supraclavicular fossa

Duct

Thoracic duct on the LEFT at the venous angle

Artery and vein

The subclavian vessels - obtain proximal and distal control

Nerve, phrenic

On the anterior surface of anterior scalene

Ganglion, stellate

Sympathetic chain - Horner syndrome if injured

Emphysema

Pneumothorax from the apical pleura (cupola)

Respiratory nerve

Long thoracic (Bell) on middle scalene wings the scapula

Clinical Decision Scenarios

Practise clinical reasoning and management decisions out loud

Viva scenarioStandard

Clinical prompt

“A 24-year-old motorcyclist presents three weeks after a closed right shoulder trauma with weakness of shoulder abduction and external rotation, and preserved hand function consistent with an upper trunk (C5 to C6) lesion. MRI shows a pseudomeningocele at C5 and C6 and a thickened upper trunk. How would you plan and execute a supraclavicular exploration?”

Practical approach

I would treat this as a closed traction injury of the upper trunk requiring systematic work-up and a planned supraclavicular exploration. I would confirm the level and the pre- versus post-ganglionic status with high-resolution MRI of the plexus and serial electrodiagnostic studies at three to four weeks, looking for denervation and evidence of root avulsion. Absence of clinical and electrical recovery by three to four months in a pre-ganglionic pattern, or a post-ganglionic rupture, is an indication to explore. I would position the patient supine in the beach-chair position with the head turned to the opposite side and the arm free for monitoring. Through a transverse clavicular-crease incision deepened through platysma, I would protect or divide the external jugular vein and supraclavicular nerves, mobilise omohyoid, and reflect the scalene fat pad. I would identify the phrenic nerve on anterior scalene first and sling it, then open the prevertebral fascia to expose the upper, middle and lower trunks. I would use intra-operative nerve action potentials and evoked potentials to distinguish a conduction block (neurolysis) from a non-conducting rupture (resection and cable grafting with sural nerve), reserving nerve transfers for irreparable root avulsions.

Key clinical points

Confirm level and pre- versus post-ganglionic status with MRI and serial electrodiagnostics

Operate if no recovery by three to four months or for a documented post-ganglionic rupture

Supine beach-chair, head turned opposite, arm free for monitoring

Transverse clavicular-crease incision centred on the posterior border of SCM

Identify and protect the phrenic nerve on anterior scalene first

Expose the trunks by opening the prevertebral fascia lateral to anterior scalene

Use nerve action potentials to decide neurolysis versus grafting

Reserve nerve transfers for irreparable avulsions

Common pitfalls

Operating too early before confirming the lesion will not recover spontaneously

Dividing a vertical structure on anterior scalene before confirming it is not the phrenic nerve

Failing to use intra-operative nerve action potentials to guide the decision

Not counselling the patient about realistic recovery times of one to three years

Further questions

“How do nerve action potentials change your intra-operative management, and what donor nerves would you consider for transfer in an upper trunk avulsion?”

Viva scenarioChallenging

Clinical prompt

“A 35-year-old woman has slowly progressive thenar wasting and numbness on the ulnar side of the hand with a positive elevated-arm stress test and electrophysiological evidence of a lower trunk lesion. Imaging shows a cervical rib. Discuss the role and execution of supraclavicular surgical decompression.”

Practical approach

This is true neurogenic thoracic outlet syndrome with lower trunk (C8 to T1) compression, here caused by a cervical rib and its fibrous band. I would first confirm the diagnosis with careful electrodiagnostics showing a chronic lower trunk lesion and imaging demonstrating the bony or band abnormality, having excluded carpal and cubital tunnel compression. Non-operative measures are appropriate first line for mild or equivocal cases, but established motor wasting with a demonstrable compressive structure is an indication for surgical decompression. I prefer the supraclavicular route because it gives direct visualisation of the anterior and middle scalenes, the cervical rib, any fibrous band, and the brachial plexus. Through the standard transverse incision I would identify and protect the phrenic nerve, remove the anterior scalene insertion (scalenectomy), excise the cervical rib and any offending band down to the first rib, and confirm the lower trunk is decompressed. I would watch for the thoracic duct on the left, the long thoracic nerve on middle scalene, and the subclavian vessels, and obtain a post-operative chest radiograph.

Key clinical points

Confirm true neurogenic TOS with electrodiagnostics and imaging, excluding distal entrapments

Trial non-operative therapy for mild or equivocal cases

Established wasting plus a compressive structure is an indication to operate

Supraclavicular route gives direct visualisation of scalenes, rib, band and plexus

Protect the phrenic nerve and the long thoracic nerve throughout

Perform anterior scalenectomy, cervical rib and band excision down to the first rib

Watch the thoracic duct on the left and the subclavian vessels

Post-operative chest radiograph to exclude pneumothorax

Common pitfalls

Operating on non-specific symptoms without objective neurological or imaging findings

Failing to exclude carpal and cubital tunnel compression first

Injuring the long thoracic nerve during middle scalene work

Not recognising a chyle leak on the left side post-operatively

Further questions

“How do you distinguish true neurogenic TOS from the more common disputed form, and how would you manage a post-operative chyle leak?”

Viva scenarioChallenging

Clinical prompt

“During a left supraclavicular plexus exploration you notice milky fluid welling up from the fat pad near the venous angle. How do you proceed?”

Practical approach

This is a thoracic duct injury. I would manage it methodically. I would optimise the field with good lighting, suction and retraction to identify the source in the fat pad near the junction of the left subclavian and internal jugular veins. I would look for the injured lymphatic channel and ligate it directly with non-absorbable fine ties or oversew the area, because the thoracic duct and its tributaries are best controlled by suture ligation rather than diathermy, which is unreliable on thin-walled lymphatics. I would place a fat-pad or muscle patch over the region if the leak persists. Before closure I would re-inspect with a Valsalva manoeuvre to confirm control, and place a suction drain. Post-operatively I would start a low-fat medium-chain triglyceride diet, monitor the drain output, and obtain a chest radiograph to exclude a chylothorax. A persistent high-output leak beyond several days, or a progressive chylothorax, would prompt return to theatre for re-exploration and definitive ligation in consultation with the thoracic team.

Key clinical points

Recognise a thoracic duct injury by milky fluid near the left venous angle

Optimise exposure with suction and good lighting before attempting repair

Control by direct suture ligation rather than monopolar diathermy

Use a fat-pad or muscle patch if the leak persists

Confirm control with a Valsalva test before closure

Place a drain and start a low-fat medium-chain triglyceride diet post-operatively

Chest radiograph to exclude chylothorax

Return to theatre for persistent high-output leak or progressive chylothorax

Common pitfalls

Attempting to control a lymphatic with monopolar diathermy, which is unreliable

Closing without confirming control with a Valsalva manoeuvre

Missing an evolving chylothorax by omitting the chest radiograph

Delaying re-exploration in the face of a persistent high-output leak

Further questions

“When would you involve the thoracic or vascular team, and what are the metabolic consequences of a persistent chyle leak?”

Exam day cheat sheet

Supraclavicular approach - exam-day essentials

Patient position

Supine beach-chair with a roll between the scapulae to drop the shoulder
Head turned 30 to 45 degrees to the opposite side onto a head ring
Arm prepped and draped free for intra-operative nerve monitoring
Gentle neck extension lifts the plexus toward the surgeon
Establish somatosensory, motor evoked potentials and triggered EMG at baseline

Incision and landmarks

Transverse skin-crease incision 6 to 8 cm, one to two finger-breadths above the clavicle
Centred over the posterior border of sternocleidomastoid
External jugular vein crosses SCM obliquely - ligate or retract
Omohyoid (superior belly) crosses the floor - mobilise, retract or divide
Scalene fat pad reflected laterally to reveal anterior scalene

Key deep landmarks

Anterior scalene is the central landmark
Phrenic nerve (C3 to C5) descends on the anterior surface of anterior scalene
Trunks lie between anterior and middle scalene - upper C5 to C6, middle C7, lower C8 to T1
Subclavian artery posterior to anterior scalene with the trunks
Subclavian vein anterior to anterior scalene, separated by the muscle

Structures at risk

Phrenic nerve - identify first, sling, protect the hemidiaphragm
Thoracic duct on the LEFT at the venous angle - chyle leak risk
Subclavian artery and vein - obtain proximal and distal control early
Long thoracic nerve (Bell) on middle scalene - winged scapula if injured
Apical pleura (cupola) - pneumothorax; stellate ganglion - Horner syndrome

Internervous plane

There is NO true internervous plane
An intermuscular, interfascial dissection
Superficially between platysma and SCM, then into posterior triangle fat
Deep plane developed along anterior scalene using the phrenic nerve as guide
Prevertebral fascia incised lateral to anterior scalene to expose the trunks

Closure and aftercare

Re-attach omohyoid if divided
Meticulous platysmal closure for a flat cosmetic scar
Suction drain if large dead space or rib resection
Chest radiograph to exclude apical pneumothorax
Document and compare upper-limb neurovascular examination with baseline

References

Guidelines, registries and global practice. Management of brachial plexus and thoracic outlet pathology is delivered in specialist units worldwide, and the principles converge across examination systems (advanced orthopaedic practice and advanced orthopaedic practice, DNB and MS, MRCS, SICOT). The supraclavicular route is the standard exposure for trunk-level plexus lesions and for anterior thoracic outlet decompression, taught in the major hand, nerve and spine atlases (Millesi, Narakas, Kline and Hudson, Mackinnon and Novak). - AO Foundation / orthopaedic nerve surgery consensus - explore closed traction injuries that show no clinical or electrical recovery by three to four months; use intra-operative nerve action potentials to decide neurolysis versus grafting.

British / European hand and peripheral nerve societies - microsurgical interfascicular cable grafting for post-ganglionic ruptures; nerve transfers for irreparable avulsions; specialised centralised care.
International thoracic outlet consensus - true neurogenic TOS with objective neurological and imaging findings warrants decompression; the supraclavicular route offers direct visualisation of the compressing structures. Population and clinical evidence. Adult brachial plexus traction injuries are most frequent in young men after motorcycle trauma, with a supraclavicular (upper-trunk-predominant) pattern in roughly half of significant injuries. Cervical ribs are present in a small proportion of the population (commonly quoted at well under 5 percent) and are asymptomatic in the majority; only a minority produce true neurogenic compression. Outcome after grafting and transfer depends on the level of the lesion, the interval to surgery and the specific nerves involved, with shoulder and elbow functions recovering more favourably than hand intrinsics. Global practice variation. In well-resourced centres, microsurgical cable grafting, nerve transfers and intra-operative electrophysiology are standard. In resource-limited settings the same surgical principles are applied with selective grafting and an emphasis on tendon transfers to restore critical function, reflecting both implant and electrophysiology availability. Consent (globally applicable). Discuss phrenic nerve injury and diaphragmatic paralysis, vascular injury to the subclavian vessels, chyle leak and chylothorax on the left side, pneumothorax, Horner syndrome, winged scapula from long thoracic nerve injury, and the long and often incomplete recovery of nerve function.

Evidence

Transaxillary approach for first rib resection to relieve thoracic outlet syndrome

Roos DB • Annals of Surgery (1966)

Introduced first rib resection as a surgical solution for thoracic outlet syndrome by removing the common bony fulcrum compressing the neurovascular bundle, and remains a foundational reference for operative decompression of thoracic outlet compression.

Evidence

The treatment of brachial plexus injuries

Narakas AO • International Orthopaedics (1985)

Defined a systematic surgical approach to traumatic adult brachial plexus injuries including the supraclavicular exploration of the trunks, and laid the groundwork for combining nerve grafting and nerve transfers in plexus reconstruction.

Evidence

Brachial plexus injuries - management and results in 171 cases

Millesi H • Clinical Orthopaedics and Related Research (1988)

Established microsurgical interfascicular cable nerve grafting as the standard for post-ganglionic plexus ruptures, using the supraclavicular corridor to reach trunk-level ruptures and reporting better return of proximal than distal function.

Evidence

Operative management of selected brachial plexus lesions

Kline DG, Judice DJ • Journal of Neurosurgery (1983)

Used intra-operative nerve action potentials to distinguish conducting lesions suitable for neurolysis from non-conducting lesions requiring resection and grafting, making electrophysiology central to intra-operative decision-making in plexus surgery.

Evidence

Thoracic outlet syndrome

Mackinnon SE, Novak CB • Current Problems in Surgery (2002)

Comprehensively reviewed the classification, diagnosis and surgical management of thoracic outlet syndrome and described the supraclavicular decompression including scalenectomy and first rib resection with protection of the phrenic and long thoracic nerves.