What Is Neural Tension?

Understanding the Nervous System as a Mechanical Structure

The nervous system is not merely an electrical signalling network — it is also a continuous mechanical structure that occupies, traverses, and depends upon the same anatomical spaces as muscles, fascia, and joints. From the brain and spinal cord, peripheral nerves extend through the intervertebral foramina, pass between muscles, travel beneath retinacular bands, and ultimately terminate in skin, muscle, and viscera. Across every centimetre of this journey, the nerve must accommodate the movements of the body around it: bending, stretching, compressing, and gliding in synchrony with the tissues it passes through. Neural tension — more precisely termed adverse neural mechanosensitivity — describes what occurs when this mechanical accommodation is impaired, producing pain, altered sensation, or restricted movement along the neural pathway.

How Nerves Accommodate Movement Normally

Under normal physiological conditions, peripheral nerves possess considerable mechanical resilience. They are surrounded by epineurium — a fibrous outer sheath that protects the fascicles within — and the nerve itself can elongate by up to 20% of its resting length before intraneural tension compromises axonal transport and blood flow. During full forward trunk flexion combined with knee extension, the sciatic nerve and its contributing roots elongate by approximately 9 centimetres. The nerve accomplishes this through two mechanisms: elongation — genuine tensile elongation of the neural tissue — and excursion, whereby the nerve glides longitudinally through its surrounding connective tissue bed, redistributing the mechanical load along its length rather than concentrating it at any single point. When either mechanism is restricted — by scar tissue, fascial thickening, postural compression, or inflammatory change — the load cannot be distributed, and mechanical sensitivity develops at the site of restriction.

How Neural Sensitisation Develops

Neural tissue is normally not a significant source of pain in the absence of compression or ischaemia. What renders a nerve painful is sensitisation — an upregulation of nociceptive activity within the nerve trunk itself, a process called peripheral neurogenic sensitisation. This arises from several mechanisms. Compression reduces intraneural venous drainage, producing localised ischaemia and oedema within the epineurium. The hypoxic environment stimulates the release of inflammatory mediators including bradykinin, prostaglandins, and neuropeptides that lower the mechanical threshold of the axonal membrane. Repeated or sustained mechanical loading further upregulates sodium channel density, making the nerve more electrically excitable. The result is a nerve that fires in response to stimuli — stretch, pressure, movement — that would ordinarily be subthreshold, producing the characteristic pain, tingling, or dysaesthesia of neural sensitisation.

Clinical Assessment of Neural Tension

Neurodynamic tests are the primary clinical tool for assessing adverse neural mechanosensitivity. These tests progressively tension the neural pathway from both ends, assessing the reproducibility and quality of symptom response. The straight leg raise (SLR) tests the sciatic nerve and lumbosacral nerve roots — a positive test reproduces concordant symptoms in the leg between 30 and 70 degrees of hip flexion, further sensitised by adding ankle dorsiflexion or cervical flexion. The upper limb neurodynamic tests (ULNT1–4) test the median, radial, and ulnar nerves respectively. A positive test reproduces the patient's familiar arm, forearm, or hand symptoms and demonstrates sensitisation when a remote body part — such as cervical lateral flexion away from the test side — increases the symptoms. This remote sensitisation is the hallmark of true neural involvement.

Treatment Principles

Treatment of neural tension addresses both the site of restriction and the sensitisation of the nerve itself. Neural mobilisation — comprising slider techniques that alternately tension and unload the nerve to improve excursion, and tensioner techniques that apply progressive elongation to desensitise the sensitised tissue — is the primary intervention. Manual therapy to joints and soft tissues that compress or tether the nerve (foraminal joints, scalene muscles, piriformis, tarsal tunnel) reduces the mechanical load on the neural pathway. Education regarding the neurobiological basis of neural pain reduces catastrophising and facilitates active participation in recovery. Progressive loading of the sensitised pathway through graduated neurodynamic exercises restores mechanical tolerance. Neural tissue, like musculoskeletal tissue, responds to appropriate loading — the goal is not permanent unloading but progressive restoration of normal mechanical capacity.