Brachial Plexus

 ### **Brachial Plexus Made Easy!** The **Brachial Plexus** is a **network of nerves (C5-T1)** that supplies the **upper limb**. It is crucial for movements and sensations of the arm. --- ## **1. Structure of the Brachial Plexus (Mnemonic: Randy Travis Drinks Cold Beer)** | **Part** | **Mnemonic** | **Components** | |----------|------------|--------------| | **Roots** | **R**andy | C5, C6, C7, C8, T1 | | **Trunks** | **T**ravis | Upper (C5-C6), Middle (C7), Lower (C8-T1) | | **Divisions** | **D**rinks | Each trunk has an **Anterior & Posterior Division** | | **Cords** | **C**old | Lateral, Medial, Posterior (named based on axillary artery) | | **Branches** | **B**eer | 5 Major Terminal Branches | --- ## **2. Major Branches & Their Functions** ### **1️⃣ Musculocutaneous Nerve (C5-C7)** ✔ **Motor:** Biceps Brachii, Brachialis, Coracobrachialis (**flexion of elbow**) ✔ **Sensory:** Lateral forearm ✔ **Injury:** Weak elbow flexion (e.g., stabbing injury) ### **2️⃣ Axillary Nerve (C5-C6)** ✔ **Motor:** Deltoid & Teres Minor (**shoulder abduction**) ✔ **Sensory:** Upper lateral arm ✔ **Injury:** **Fracture of Surgical Neck of Humerus** → Weak **abduction** (>15°) ### **3️⃣ Radial Nerve (C5-T1)** ✔ **Motor:** Triceps, Extensors of wrist & fingers (**extension of elbow, wrist, and fingers**) ✔ **Sensory:** Posterior arm & forearm, dorsum of the hand ✔ **Injury:** **Midshaft Humerus Fracture** → **Wrist Drop** ### **4️⃣ Median Nerve (C5-T1)** ✔ **Motor:** Forearm flexors, Thenar muscles (**thumb movements**) ✔ **Sensory:** Lateral palm, first 3.5 fingers ✔ **Injury:** - **Carpal Tunnel Syndrome** → Weak **thumb opposition** - **Hand of Benediction** (proximal lesion) ### **5️⃣ Ulnar Nerve (C8-T1)** ✔ **Motor:** Most intrinsic hand muscles (**fine finger movements**) ✔ **Sensory:** Medial palm, last 1.5 fingers ✔ **Injury:** - **Fracture of Medial Epicondyle of Humerus** → **Claw Hand** - **Guyon’s Canal Syndrome** (cyclists) --- ## **3. Common Brachial Plexus Injuries & Clinical Signs** ### **Erb’s Palsy (C5-C6 Injury) – "Waiter’s Tip"** ✔ Cause: Birth trauma, fall on shoulder ✔ **Muscles Affected:** Deltoid, Biceps, Supraspinatus ✔ **Sign:** Arm adducted, medially rotated, elbow extended ### **Klumpke’s Palsy (C8-T1 Injury) – "Claw Hand"** ✔ Cause: Birth trauma (excess arm pull), hanging injury ✔ **Muscles Affected:** Intrinsic hand muscles ✔ **Sign:** Hyperextension of MCP, flexion of IP joints ### **Radial Nerve Injury – "Wrist Drop"** ✔ Cause: Midshaft humerus fracture, crutches compression ✔ **Sign:** Loss of wrist & finger extension ### **Median Nerve Injury – "Hand of Benediction"** ✔ Cause: Supracondylar fracture of humerus ✔ **Sign:** Cannot flex first 3 fingers ### **Ulnar Nerve Injury – "Claw Hand"** ✔ Cause: Medial epicondyle fracture ✔ **Sign:** Hyperextended MCP, flexed IP joints in last 2 fingers --- ## **4. Study Tips to Master Brachial Plexus** ✔ **Use Mnemonics** (Randy Travis Drinks Cold Beer) ✔ **Draw & Label** the plexus diagram ✔ **Watch Dissection Videos** (Kenhub, YouTube) ✔ **

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