SEARCH RESULTS FOR: Brachial-Plexus

Brachial Plexus Injury

**See corresponding Calgary Guide slide Legend: Brachial Plexus Injury: Pathophysiology and clinical findings High impact collision (ex. motorcycle accidents, sports) Fetal complications during labor & delivery** (ex. shoulder dystocia) Author: Merry Faye Graff Reviewers: Taylor Krawec Emily J. Doucette Jean K. Mah* *Indicates MD at time of publication Upward traction of arm with forced widening of scapulohumeral angle (lower brachial plexus injured first) Downward traction of arm with forced widening of shoulder-neck angle (upper brachial plexus injured first) Surgical trauma Direct trauma (i.e. gunshot wound, penetrating injuries) Pancoast tumour** Nerves are stretched or torn Nerves are severed or crushed Brachial Plexus Injury Damage to brachial plexus nerves that may cause weakness, decreased sensation or loss of movement in the shoulder, arm or hand Injury or compression demyelinates nerves without causing axonal injury (neuropraxia) Injury demyelinates nerves & severs axons (axonotmesis) Injury completely transects nerves (neurotmesis) Demyelination slows & disrupts nerve signal conduction Basal lamina tubes (axon scaffolds) are preserved Basal lamina tubes are severed Nerves are torn proximal to attachment at spine (post-ganglionic rupture) Nerve roots are torn from spinal cord (pre-ganglionic avulsion) ↓ Efferent signals (motor) ↓ Afferent signals (sensory) Inflammatory mediators sensitize primary afferent neurons Abnormal ectopic firing of nerves at or near nerve lesion Neuroma (benign growth or thickening of nerve tissue at lesion) during healing Breakdown of axon(s) & myelin distal to nerve lesion (Wallerian degeneration) Connection to central nervous system (CNS) lost Muscle weakness or loss of function in affected myotomes Paresthesia (numbness or tingling) in affected dermatomes Hyperalgesia (extreme sensitivity to touch) Neuropathic pain (burning, stabbing, electric-like pain) Neuroma blocks distal nerve conduction No conduction in affected nerves or nerve roots Repeated pain signals sensitize CNS Afferent signals are not transduced Efferent signals are not transduced Paravertebral sympathetic chain is disrupted (if C8 & T1 involved) Central sensitization Numbness Paralysis Horner’s syndrome** Shortening & hardening of muscles & tendons ↓ Muscle use Widespread pain Allodynia (normal touch perceived as painful) Contractures Muscle atrophy Note: Specific signs & symptoms vary based on nerves affected. Complications Published May 14, 2025 on www.thecalgaryguide.com Pathophysiology Mechanism Sign/Symptom/Lab Finding

Brachial Plexus

Brachial Plexus: Anatomy and physiology Elevates, retracts & inferiorly rotates scapula Innervates supraspinatus & infraspinatus Stabilizes, abducts & laterally rotates at glenohumeral joint Inferiorly rotates & protracts scapula Innervates rhomboids & levator scapulae Dorsal scapular nerve Suprascapular nerve C5 Superior C6 Nerve to subclavius Innervates subclavius Anchors & depresses clavicle Middle C7 Long thoracic nerve Innervates serratus anterior Protracts scapula C8 Inferior T1 Innervates pectoralis minor Innervates acromioclavicular & glenohumeral joints Lateral pectoral nerve Lateral Stabilizes & medially rotates at glenohumeral joint Extends, adducts & medially rotates at glenohumeral joint Innervates subscapularis Innervates teres major Superior subscapular nerve Inferior subscapular nerve Posterior Thoracodorsal nerve Innervates latissimus dorsi Extends, adducts & medially rotates at glenohumeral joint Innervates skin of inferior portion of medial side of arm Innervates skin of arm overlying biceps brachii, & medial side of forearm Medial brachial cutaneous nerve Medial antebrachial cutaneous nerve Medial Adducts & medially rotates at glenohumeral joint, inferiorly rotates, protracts & draws scapula anteriorly Innervates pectoralis major & minor Medial pectoral nerves Innervates adductor pollicis Innervates interossei of hand Adducts thumb Abducts & adducts digits 2-5 Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Author: Merry Faye Graff Reviewers: Mitchell Chorney, Ryan Dion, Emily J. Doucette, Jean Mah* * MD at time of publication Roots à Trunks à Anterior & Posterior Divisions à Cords à Terminal Branches Innervates anterior compartment of arm Supinates at radioulnar joint, flexes at elbow & flexes & adducts at glenohumeral joint Musculocutaneous nerve Lateral cutaneous nerve of forearm Innervates skin of lateral forearm Innervates teres minor & deltoid Stabilizes, laterally & medially rotates, adducts, abduct & flexes at glenohumeral joint Axillary nerve Innervates skin of lateral shoulder Innervates most of anterior compartment of forearm Flexes, adducts & abducts at wrist, flexes digits 1-5 & pronates forearm Innervates thenar compartment of hand Opposes, abducts & flexes the thumb Median nerve Innervates radial 2 lumbricals of hand Flexes at MCP joints & extends at IP joints Innervates skin of radial ½ of palm, palmar aspect of radial 3½ digits, dorsal aspect of radial 2½ fingertips Innervates skin of posterior arm, forearm, & dorsum of radial 2½ digits (excluding fingertips) Radial nerve Innervates posterior compartment of arm Innervates posterior compartment of forearm Extends at elbow Extends, abducts & adducts at wrist, extends digits 2-5, & supinates at radioulnar joint Ulnar nerve Innervates skin of ulnar ½ of palm & dorsum of hand, ulnar 1½ digits Innervates hypothenar compartment of hand Innervates ulnar 2 lumbricals of hand Innervates some of anterior compartment of forearm Abducts & flexes 5th digit Flexes at metacarpophalangeal (MCP) joints & extends at interphalangeal (IP) joints Flexes & adducts at wrist, flexes 4th & 5th digit Published Nov 2, 2025 on www.thecalgaryguide.com