Lesson 1Course of radial nerve in the axilla and proximal arm: relations to axillary vessels, humeral head, and latissimus dorsiHere we follow the radial nerve in the axilla and proximal arm, detailing its relation to the axillary artery, humeral head, latissimus dorsi, and surrounding fascia, with emphasis on compression sites, trauma risk, and surgical exposure corridors.
Relations to axillary artery and veinCourse around humeral head and neckRelations to latissimus dorsi and teres majorFascial tunnels and potential compression sitesSurgical approaches in the proximal armLesson 2Key landmarks for bedside localization and surgical exposure: lateral epicondyle, radial head, spiral groove, supinator tunnelThis section identifies reliable surface and deep landmarks for localizing the radial nerve and its branches, guiding bedside examination, ultrasound, and surgical exposure around the lateral epicondyle, radial head, spiral groove, and supinator tunnel.
Palpation of lateral epicondyle and radial headLocating the spiral groove on the humerusIdentifying the supinator tunnel regionUltrasound landmarks for radial branchesSafe windows for surgical approachesLesson 3Relevant microanatomy: epineurium, perineurium, endoneurium, vasa nervorum and implications for injury and recoveryWe detail radial nerve microanatomy, including epineurium, perineurium, endoneurium, and vasa nervorum, explaining how these layers respond to stretch, compression, and laceration, and how they influence regeneration, neuroma formation, and repair strategies.
Epineurial structure and surgical handlingPerineurium and fascicular organizationEndoneurial tubes and axonal supportVasa nervorum and ischemic vulnerabilityMicroanatomy and regeneration patternsLesson 4Brachial plexus roots and contribution to radial nerve (C5–T1): posterior cord formation and anatomical variantsThis section reviews how C5–T1 roots form the posterior cord and radial nerve, highlighting spatial relations in the neck and axilla, frequent anatomical variants, and how these patterns influence weakness, sensory loss, and electrodiagnostic findings.
C5–T1 root contributions to radial nerveTopography of trunks, divisions, and cordsPosterior cord formation and branching patternCommon root and cord anatomical variantsClinical impact of high or low root lesionsLesson 5Posterior interosseous nerve (PIN): entry through supinator (arcade of Frohse), motor branches to forearm extensors, typical branching patternHere we focus on the posterior interosseous nerve, from its entry through the supinator and arcade of Frohse to its motor branches for forearm extensors, describing typical and variant branching patterns and their role in selective palsies and surgical planning.
Entry beneath ECRB to supinatorArcade of Frohse anatomy and variantsIntramuscular course within supinatorMotor branches to wrist and finger extensorsPatterns in selective PIN palsiesLesson 6Spiral (radial) groove anatomy: position relative to humerus, branches to triceps and anconeus, vascular relationsThis section analyzes the spiral groove segment, describing its position on the posterior humerus, relations to triceps and anconeus branches, nearby vascular structures, and why this zone is vulnerable in fractures, entrapment, and surgical procedures.
Surface and radiographic localizationRelations to triceps and anconeus branchesContact with posterior humeral cortexRadial collateral and profunda brachii vesselsRisk zones in humeral shaft fracturesLesson 7Terminal motor and sensory territories: extensor compartment muscles, triceps, brachioradialis, anconeus, finger extensors, and dorsal hand sensory mapThis section maps terminal motor and sensory territories, linking each radial nerve branch to specific extensor muscles, triceps, brachioradialis, anconeus, and dorsal hand skin zones, to support precise bedside localization and electrodiagnostic interpretation.
Motor map of triceps and anconeusInnervation of wrist and finger extensorsBrachioradialis and ECRL innervation zonesDorsal hand and thumb sensory territoriesPatterns of overlap with median and ulnarLesson 8Common anatomical variants influencing clinical presentation: high bifurcation, accessory branches, variable innervation of brachioradialis and ECUWe review common radial nerve anatomical variants, including high bifurcation, accessory branches, and variable innervation of brachioradialis and ECU, emphasizing how these patterns alter clinical signs, nerve conduction studies, and surgical expectations.
High radial bifurcation patternsAccessory branches to triceps or brachialisVariable innervation of brachioradialisECU and ECRB innervation variantsImpact on EMG and nerve conduction testsLesson 9Division at lateral epicondyle/elbow: superficial sensory branch and deep branch (posterior interosseous nerve) anatomical detailsWe examine the radial nerve division near the lateral epicondyle, contrasting the superficial sensory branch and deep motor branch (PIN), their fascicular organization, relations to the radial head, and implications for entrapment, injections, and surgical decompression.
Anatomy at the lateral epicondyleBranching into superficial and deep branchesRelations to radial head and joint capsuleFascicular topography at the bifurcationEntrapment and iatrogenic injury risksLesson 10Forearm course of superficial branch: subcutaneous path, branches to dorsum of hand and anatomic snuffboxThis section follows the superficial radial nerve along the forearm, detailing its subcutaneous course, fascial planes, branches to the dorsum of the hand and anatomic snuffbox, and how this anatomy guides sensory testing, blocks, and surgical incisions.
Course deep to brachioradialisTransition to subcutaneous positionBranches to dorsum of hand and fingersAnatomic snuffbox relations and branchesSites of Wartenberg syndrome compression
