PNS: Tibial Nerve

• The tibial nerve is formed from the L4-S3 nerve roots
• Fibers of the tibial nerve are contained within the sciatic nerve until the popliteal fossa
• Distal to the popliteal fossa, the tibial nerve divides into medial and lateral plantar nerves, as well as calcaneal nerves
• The tarsal tunnel is located underneath the flexor retinaculum of the ankle, between the medial malleolus and calcaneus

Contents of the Tarsal Tunnel

• Tibial nerve
• Posterior tibial artery
• Posterior tibial vein
• Tendons of tibialis posterior
• Flexor digitorum longus tendon
• Flexor hallucis longus tendon

Palpation of the Tibial Nerve

• The tibial nerve is contained within the sciatic nerve until proximal to the popliteal fossa, where it divides into its own connective tissue sheath
• The nerve runs through the popliteal fossa with little overlying tissue, pressure should be applied carefully within the popliteal fossa
• Applying pressure in the popliteal fossa can compress and aggravate the tibial nerve
• Immediately distal to the popliteal fossa, the sural nerve branches off, running superficially between the two heads of the gastrocnemius
• This sensory branch is distinct from the tibial nerve and is palpable between the gastrocnemius bellies
• The main trunk of the tibial nerve passes deep to the plantaris and gastrocnemius, piercing the tendinous arch of the soleus
• The nerve runs over the posterior surface of the tibialis posterior within the deep posterior compartment
• It passes posterior to the medial malleolus and under the flexor retinaculum in the tarsal tunnel
• The tibial nerve gives off a sensory branch (Baxter's nerve) proximal to the flexor retinaculum, serving the calcaneus and connective tissue, and implicated in calcaneal or Achilles' tendon issues
• Distal to the tarsal tunnel, the tibial nerve divides into medial and lateral plantar nerves, innervating the intrinsic foot muscles and providing sensory innervation

Palpation of Affected Tissue

• Assess tone and tissue health in the posterior compartments of the leg and intrinsic foot muscles
• Similar to the median nerve, the tibial nerve has a high number of autonomic fibers
• Tibial nerve injuries can lead to trophic changes (affecting skin, nails, hair), changes in sweating, or autonomic dysfunction

Motor Function of the Tibial Nerve

• Gastrocnemius
• Soleus
• Plantaris
• Popliteus
• Tibialis Posterior
• Flexor Digitorum Longus
• Flexor Hallucis Longus
• Plantar flexion and Inversion
• Medial and lateral plantar nerves innervate the intrinsic muscles of the plantar surface of the foot, producing flexion, abduction, and adduction of the pedal digits

Sensory Function of the Tibial Nerve

• Innervates most of the plantar surface of the foot

Chronic Compartment Syndrome

• Neuropraxia condition from increased pressure within lower leg fascial compartments
• Can occur with or without neurological symptoms like muscle fatigue, pain, or paresthesia, especially during activity or in a dependent position
• The anterior compartment is most commonly affected (45% of cases), followed by the deep posterior compartment (40%)

Anterior Compartment Contents

• Tibialis anterior
• Extensor hallucis longus (EHL)
• Extensor digitorum longus (ED)
• Tibial artery and vein
• Deep peroneal nerve

Deep Posterior Compartment Contents

• Tibialis posterior
• Flexor digitorum longus (FDL)
• Flexor hallucis longus (FHL)
• Posterior tibial artery and vein
• Tibial nerve

Chronic Compartment Syndrome - MOI

• Overuse

Chronic Compartment Syndrome - Manifestation

• Occurs with exercise, relieved by rest
• Increased blood flow can increase muscle volume by 20%
• Compression on capillaries causes ischemia and pain
• Tight, achy, crampy feeling in the compartment
• Paresthesia in the leg or foot
• May be bilateral, often worse on one side

Chronic Compartment Syndrome - Assessment

• ROM restricted by pain
• Shortened antagonists during length tests
• Check for stress fractures by tapping on the bone to recreate sharp, localized pain
• Rule out DVT or vascular claudication

Chronic Compartment Syndrome - Treatment

• Myofascial release (MFR) for posterior compartment
• Thorough treatment to all sides of lower leg
• Increase ROM with joint mobilizations or PROM, or hold-relax with agonist contract stretch
• Nerve glides include SLR with tibial nerve bias (dorsiflexion and eversion), common peroneal nerve bias (plantar flexion and inversion), or sural nerve bias (dorsiflexion and inversion)
• Treat similarly to venous insufficiency with elevation, hydro shunt, unidirectional strokes, and PROM

Tarsal Tunnel Syndrome

• Compression of the tibial nerve in the tarsal tunnel
• Sources of compression include the tendons of FDL, TP, FHL, the flexor retinaculum, and the abductor hallucis muscle (affecting plantar nerves)

Tarsal Tunnel Syndrome - Associated/Predisposing Factors

• Repetitive stress activities like running or excessive walking/standing
• Trauma, like fracture, dislocation, or stretch injuries
• Heel varus or valgus
• Excessive calcaneal eversion causes collapse of the medial longitudinal arch (over-pronation)
• This puts traction stress on the posterior tibial nerve and compression by the flexor retinaculum
• Fibrosis
• Excessive weight gain (e.g., during pregnancy)
• Space-occupying lesions in the tarsal tunnel region, such as ganglions, tumors, edema, or osteophytes
• Tendonitis
• Systemic diseases causing ankle inflammation or nerve compromise (e.g., diabetes mellitus, arthritis)
• 20-40% of cases are idiopathic

Tarsal Tunnel Syndrome - Presents As

• Pain or paresthesia is experienced in the posterior tibial, lateral plantar, and/or medial plantar nerve distributions
• Burning, tingling, or pain in the medial portion of the ankle and/or plantar aspect of the foot, along with local tenderness behind the medial malleolus
• Muscle weakness of the toe abductors and flexors in progressed or chronic cases

Tarsal Tunnel Syndrome - Timing

• Can present as night pain

Tarsal Tunnel Syndrome - Assessment

• Check for arch stability
• Gait analysis to check for excessive inversion or eversion
• Sensory testing on the plantar surface of the foot
• Tenderness to palpation between the medial malleolus and Achilles tendon
• Tinel’s sign elicited by tapping over the tunnel
• Dorsiflexion-Eversion test

Tarsal Tunnel Syndrome - Treatment

• Ice for inflammation
• Decompress tissue around the medial malleolus and tarsal tunnel
• Perform tibial nerve SLR nerve glides
• Neuromuscular technique (NMT) to the deep posterior compartment and abductor hallucis
• Focus on soleus, especially at the proximal medial border of the tibia
• Strengthen the medial arch/tibialis posterior if foot posture or strength is a provocative factor

Morton's Neuroma

• Entrapment of the interdigital nerve (from medial & lateral plantar nerves, from the tibial nerve)
• Most common location is between the 3rd and 4th metatarsals, but can occur between 2nd & 3rd, or 1st & 2nd
• Not a true neuroma (overgrowth of nerve tissue) but perineural fibrosis and nerve degeneration
• Entrapment causes thickening of endoneurium and perineurium, as well as demyelination of the nerve

Morton's Neuroma - Contributing Factors

• Excessive pronation stretches the nerve in terminal stance
• High heels shift weight onto the forefoot
• Narrow toe box in shoes
• Thin-soled shoes allow ground forces to push up against the transverse metatarsal ligament
• Jogging, especially on hard services

Morton's Neuroma - Assessment

• Perform squeeze test
• Firmly squeeze the metatarsal heads with one hand while applying direct pressure to the dorsal and plantar interspace with the other hand
• The squeeze test may elicit radiating neuropathic pain
• Pain localized only to the plantar aspect of the webspace may be consistent with Morton's neuroma
• Passive and active toe dorsiflexion may aggravate symptoms

Morton's Neuroma - Treatment

• Consult a podiatrist/podorthist
• Massage therapy: focus on stretching exercises for superficial and deep posterior muscles of the leg
• Ice reduces inflammation
• Neuroma is a local contraindication (CI), meaning work around the neuroma, avoiding direct techniques that cause compression

Straight Leg Raise - Tibial Nerve Bias

• Position & Procedure: Extends the knee, everts the foot, extends toes, flexes hip, dorsiflexes the ankle Sensitizing test uses ankle dorsiflexion (if not used above) or cervical flexion (if ankle is already dorsiflexed)
• Positive: Recreation of symptoms in the tibial, medial plantar, or lateral plantar nerve distribution

Morton's Neuroma Metatarsal Squeeze Test

• Position & Procedure: Patient seated, therapist compresses foot by applying pressure to medial & lateral aspects of foot at MTP joints
• Positive: Sharp pain at the site of the neuroma, typically between the 3rd & 4th metatarsals

Dorsiflexion-Eversion Test

• Position & Procedure: Patient is supine or seated, bring the foot into max dorsiflexion and eversion and includes toe extension, hold for 5 seconds and tap over the tarsal tunnel
• Positive: Recreation of tibial nerve pain

Plantar Flexion and Inversion Muscles (MMT or RROM)

• Gastrocnemius
• Soleus
• Plantaris
• Popliteus
• Tibialis Posterior
• Flexor Digitorum Longus
• Flexor Hallucis Longus

Sensory Testing location

• Sole of foot