Anatomy Exam 1 Study Guide PDF

**Please review myotomes and dermatomes** The C5 myotome is a group of muscles in the upper arm that are controlled by the C5 spinal nerve. These muscles include the deltoids, infraspinatus, biceps brachii, and brachioradialis. The C5 myotome is responsible for shoulder abduction and external rotat...

**Please review myotomes and dermatomes** The C5 myotome is a group of muscles in the upper arm that are controlled by the C5 spinal nerve. These muscles include the deltoids, infraspinatus, biceps brachii, and brachioradialis. The C5 myotome is responsible for shoulder abduction and external rotation, as well as elbow flexion.  2. Please review isometric and isotonic contractions, you should be able to determine from the description of an action , which muscle are undergoing concentric and eccentric contractions isometric and isotonic contraction of muscles.png 3. Review the boundaries of the intervertebral foramina The boundaries of an intervertebral foramen (clockwise) include the following: the superior margin (roof) is formed by the inferior vertebral notch of the vertebra above, the anterior margin by the interverte-bral disc between the vertebral bodies of the adjacent vertebrae, the inferior margin (floor) by the superior vertebral notch of the vertebra below, and the posterior margin by the zygapophysial (facet) joint of the adjacent vertebrae. **Each pedicle contains superior and inferior vertebral notches.**  4. Please review the planes of the body 5. List different types of joints and then know the six different types of synovial joints , their movements and examples 6. IV disc protrusions-which direction , remember the rule "one below" for nerve impingements 7. Know the difference between IV disc protrusions and tumors or calcifications in the intervertebral foramina- the spinal nerves that will be affected will follow the table below 8. Ligaments of the vertebral column and what they limit 9.  10. Characteristic features of vertebrae 11. Please MEMEORIZE the origins , insertions, actions and nerve supply to Muscles of the Back, Pectoral region, Brachium, extensor and flexor compartment muscles 12. Regarding the spinal cord know the following: a. Where it ends, number of spinal nerves, difference between roots and rami, their function, filum terminale, denticulate ligament, where do you perform a spinal tap, what are the landmarks for the spinal tap 13. Quadrangular space -boundaries contents and what happens if the space is compressed 14. Shoulder: Which muscles belong to the rotator cuff, their origins ACTIONS, INNERVATIONS NERVE SUPPLY Which rotator cuff muscle does not do rotation at the shoulder joint 15. Axilla- boundaries, and contents 16. Brachial plexus- everything about brachial plexus Roots, trunks, divisions, cords and their branches , upper brachial plexus and lower brachial plexus injuries The main function of each of the nerves -chief nerve of extension, chief nerve of elbow function , why is musculocutaneous called Musculo cutaneous 17. Axillary artery, define the three parts, and their branches 18. Cubital fossa boundaries and contents. 19. At which joint do you see pronation and supination: radioulnar joint, articulation create pronation and supination. 20. Anterior interosseous nerve is a branch of the median nerve , what muscles does it supply? 21. Posterior interosseous nerve aka deep branch of the radial nerve is a branch of the radial nerve, what does it supply? 22. Where are the anterior and posterior interosseous arteries coming from? 23. List the muscles that do pronation and supination and which compartment they are found 24. List all the muscles that do flexion at the elbow and where they are found, there is a muscle that is located in the extensor compartment that does elbow flexion, what is it, which nerve supplies this muscle? 25. Please make a table of exceptions to the rules : b. Radial nerve supplies all of the extensors of the upper arm and forearm-exception is Brachioradialis -which is an elbow flexor that supplied by Radial nerve c. All the muscles of the flexor compartment of the forearm are supplied by median nerve with exception of FCU, medial half of FDP d. FDP receive innervation from what two nerves e. All the muscle s in the thenar eminence are supplied by recurrent branch of the median nerve : except Adductor pollicis f. Innervation of lumbricals 26. Actions of interossei and their nerve supply 27. Cutaneous innervation of the hand sensory innervation to hand.png 28. Most commonly dislocated carpal bone I the body 29. Nursemaids elbow , subluxation of the radial head: partial dislocation of elbow, manipulate the elbow and put elbow back in place. 30. Dislocation of the glenohumeral joint 31. Colles fracture 32. Where do you feel the radial pulse , next to what tendon 33. Golfers and tennis elbow median : thumb, half of ring finger, numbness tingling created by lunate **Myotomes and Dermatomes** **Myotome**: A myotome is a group of muscles innervated by the motor fibers of a single spinal nerve root. **C5 Myotome**: **Muscles**: Deltoid, infraspinatus, biceps brachii, and brachioradialis. **Actions**: Shoulder abduction, external rotation, and elbow flexion. **Dermatome**: A dermatome is an area of skin supplied by sensory fibers from a single spinal nerve root. ** Isometric and Isotonic Contractions** **Isometric Contraction**: Muscle length remains constant while tension increases; no movement occurs. **Isotonic Contraction**: Muscle changes length to produce movement and includes: **Concentric Contraction**: Muscle shortens during contraction (e.g., lifting a weight). **Eccentric Contraction**: Muscle lengthens under tension (e.g., lowering a weight) **Boundaries of the Intervertebral Foramina** Foramina is important because its where spinal nerves exit. Ligaments run across the spine. Ligaments are spine support system. anterior longitudinal(prevents you to bend too far backwards). prevent hyperextension posterior longitudinal (prevents you to move forward)/prevent hyperflexion The intervertebral foramina are openings between adjacent vertebrae that allow spinal nerves to exit the spinal column. Their boundaries are: **Superior**: Inferior vertebral notch of the vertebra above. **Inferior**: Superior vertebral notch of the vertebra below. **Anterior**: Intervertebral disc and adjacent vertebral bodies. **Planes of the Body** The body is divided into sections using anatomical planes: **Sagittal Plane**: Divides the body into right and left parts. **Midsagittal (Median) Plane**: Divides the body into equal right and left halves. **Frontal (Coronal) Plane**: Divides the body into anterior (front) and posterior (back) parts. **Transverse (Horizontal) Plane**: Divides the body into superior (upper) and inferior (lower) parts **Posterior**: Zygapophysial (facet) joint between the articular processes of the vertebrae. **Types of Joints** **Fibrous Joints**: Bones connected by dense connective tissue; little to no movement (e.g., sutures of the skull). **Cartilaginous Joints**: Bones connected by cartilage; limited movement. **Synchondroses**: Hyaline cartilage unites bones (e.g., epiphyseal plates). **Symphyses**: Fibrocartilage unites bones (e.g., pubic symphysis). **Synovial Joints**: Freely movable joints with a synovial cavity. **Six Types of Synovial Joints**: 1\. **Plane (Gliding) Joints**: Allow sliding movements (e.g., intercarpal joints). Allows sliding or gliding movements; Example: Joints between ankle bones  2\. **Hinge Joints**: Permit flexion and extension (e.g., elbow joint). Allows flexion and extension only; Example: Elbow, Knee  3\. **Pivot Joints**: Allow rotational movement (e.g., atlantoaxial joint). Allows rotation around a central axis; Example: Neck (atlas and axis vertebrae)  4\. **Condyloid (Ellipsoid) Joints**: Permit movement in two planes (e.g., wrist joint). Allows up-and-down and side-to-side movements, but not full rotation; Example: Wrist joint  5\. **Saddle Joints**: Allow movement in two planes with greater freedom (e.g., carpometacarpal joint of the thumb). Allows back-and-forth and side-to-side movements; Example: Base of the thumb  6\. **Ball-and-Socket Joints**: Permit movement in multiple planes (e.g., shoulder and hip joints). Allows movement in all planes (flexion, extension, abduction, adduction, rotation); Example: Shoulder, Hip  ** Intervertebral Disc Protrusions** **Direction**: Most commonly occur posterolaterally due to the posterior longitudinal ligament's relative thinness. **"One Below" Rule**: A herniation at a specific intervertebral disc typically impinges the nerve root of the vertebra below. For example, an L4-L5 disc herniation affects the L5 nerve root. **Differences Between Disc Protrusions and Tumors/Calcifications in the Intervertebral Foramina** **Disc Protrusions**: Often compress the nerve root corresponding to the lower vertebra of the affected disc space. **Tumors/Calcifications**: Can compress any nerve root passing through the intervertebral foramen, depending on their location and size. ** Ligaments of the Vertebral Column and Their Functions** **Anterior Longitudinal Ligament**: Prevents hyperextension. **Posterior Longitudinal Ligament**: Prevents hyperflexion. **Ligamenta Flava**: Connects laminae; maintains upright posture. **Interspinous Ligaments**: Connect spinous processes; limit flexion. **Supraspinous Ligament**: Connects tips of spinous processes; limits flexion. **Intertransverse Ligaments**: Connect transverse processes; limit lateral flexion. **Characteristic Features of Vertebrae** The vertebral column consists of 33 vertebrae, categorized into five regions: **Cervical (7)**: Smallest, with transverse foramina and bifid spinous processes. vertebral artery and vein run through vertebral foramen, **Thoracic (12)**: Heart-shaped bodies vertebrae connect to chest, long spinous processes, and costal facets for rib articulation. **Lumbar (5)**: Large, kidney-shaped bodies, short and sturdy spinous processes, largest and strongest desined tto keep the weight of the upper body. **Sacral (5, fused)**: Form the sacrum; articulate with the pelvis. **Coccygeal (4, fused)**: Form the coccyx; vestigial tailbone **Origins, Insertions, Actions, and Nerve Supply of Key Muscles** **A. Back Muscles** 1\. **Trapezius** **Origin**: External occipital protuberance in skull, nuchal ligament neck, spinous processes of C7-T12( vertebrae) **Insertion**: Lateral third of clavicle, acromion, spine of scapula. **Action**: Elevates, retracts, and rotates scapula; lower fibers depress scapul( every movement) **Nerve Supply**: Accessory nerve (CN XI). 2\. **Latissimus Dorsi** **Origin**: Spinous processes of T7-T12, thoracolumbar fascia, iliac crest, inferior ribs. **Insertion**: Intertubercular groove of humerus. **Action**: Extends, adducts, and medially rotates humerus. **Nerve Supply**: Thoracodorsal nerve (C6-C8). 3\. **Rhomboid Major** **Origin**: Spinous processes of T2-T5. **Insertion**: Medial border of scapula below spine. **Action**: Retracts and rotates scapula to depress glenoid cavity. **Nerve Supply**: Dorsal scapular nerve (C4-C5). 4\. **Rhomboid Minor** **Origin**: Nuchal ligament, spinous processes of C7-T1. **Insertion**: Medial border of scapula at spine. **Action**: Retracts and rotates scapula to depress glenoid cavity. **Nerve Supply**: Dorsal scapular nerve (C4-C5). 5\. **Levator Scapulae** **Origin**: Transverse processes of C1-C4. **Insertion**: Medial border of scapula above spine. **Action**: Elevates scapula and tilts glenoid cavity inferiorly. **Nerve Supply**: Dorsal scapular nerve (C5) and cervical nerves (C3-C4). **B. Pectoral Region Muscles** 1\. **Pectoralis Major** **Origin**: Clavicular head: medial half of clavicle; Sternocostal head: sternum, upper six costal cartilages. **Insertion**: Lateral lip of intertubercular groove of humerus. **Action**: Adducts and medially rotates humerus; flexes humerus (clavicular head). **Nerve Supply**: Lateral and medial pectoral nerves (C5-T1). 2\. **Pectoralis Minor** **Origin**: Ribs 3-5 near costal cartilages. **Insertion**: Coracoid process of scapula. **Action**: Stabilizes scapula by drawing it inferiorly and anteriorly. **Nerve Supply**: Medial pectoral nerve (C8-T1). **C. Brachium (Arm) Muscles** 1\. **Biceps Brachii** **Origin**: Short head: coracoid process; Long head: supraglenoid tubercle. **Insertion**: Radial tuberosity and bicipital aponeurosis. **Action**: Flexes elbow and supinates forearm.: (flexion: bends the arm) and turns it up **Nerve Supply**: Musculocutaneous nerve (C5-C6). 2\. **Triceps Brachii** **Origin**: Long head: infraglenoid tubercle; Lateral head: posterior humerus above radial groove; Medial head: posterior humerus below radial groove. **Insertion**: Olecranon process of ulna. **Action**: Extends elbow; long head extends and adducts shoulder. (extension= straightening the arm) **Nerve Supply**: Radial nerve (C6-C8). **D. Forearm Muscles** 1\. **Flexor Compartment** **Flexor Carpi Radialis**: **Origin**: Medial epicondyle of humerus. **Insertion**: Base of 2nd and 3rd metacarpals. **Action**: Flexes and abducts wrist. spinal cord ends at L1 and L2, and then cauda equida will continue, because as we grew, we didn't need it at that time. dorsal( for back and sensory) ventral(anterior front and supplies limbs) denticulate ligament: anchors stabilize it laterally. CSF from subarachnoid space Brachial plexus follows the path as spinal nerves branch out: **Randy Travis Drinks Cold Beer. Roots, Trunks(upper, middle, lower), Divisions(nerves), Cords, Branches.** Brachial plexus injury can happen in upper(Erbs Plasy shoulder): falls, or childbirth, and lower (clumky ) fine motor skills(C8-T1, hamate,droopy eye, decreased swelling ) super star nerve: musculocutaneous nerve(elbow flexion such as bend the elbow, bicept brachii, brachialis, coracobracialis provides sensation to lateral portion of skin. Radial nerve : strengthen your arm, sensation to back of hand, extension. supplies externsor muscles in the arm, reach out and grab nerve. one muscle it controls called brachioradialis, is in the extensor compartment but it flexes the arm. axillary artery is continuation of subclavian artery. axilarry artery uses pectoralis muscle as a key. axillary artery: main artery supplies to arm. divides into 3 braches: 1. superior thoracic artery 2. thoracoacromial and lateral thoracic 3. subscapular artery(biggest one and supplies to posterior one), anterior/posterior circumflex humeral artery(wrap around humerus joint and deltoid muscle) median nerve innervates parts in forearm. flexor carpu ulnaris and digitorum profundus will switch nerves. digitorum profundus gets supply from ulnar nerve and anterior interosseous nerve. Ulnar nerves for the interosseous arm. **28. Most Commonly Dislocated Carpal Bone in the Body** **Answer**: The **lunate** is the most commonly dislocated carpal bone. Lunate dislocations typically result from high-energy trauma, such as a fall on an outstretched hand, causing the lunate to displace from its normal position in the wrist. This injury can lead to wrist pain, swelling, and limited motion. Prompt medical attention is essential to realign the bone and prevent complications.   **28. Most Commonly Dislocated Carpal Bone** **Answer**: **Lunate** The lunate dislocates most commonly due to its central position in the wrist. **Clinical Significance**: Can compress the median nerve, causing carpal tunnel-like symptoms ** Nursemaid's Elbow (Subluxation of the Radial Head)** **Explanation**: Nursemaid's elbow, also known as "pulled elbow," occurs when the radius bone in a child's forearm slips out of its normal position at the elbow joint. This injury often happens in children under 5 years old when a sudden pull is applied to an extended arm, such as when lifting or swinging a child by the hands. Symptoms include immediate pain in the affected arm, refusal to use the arm, and holding the elbow slightly bent with the forearm turned inward. Treatment involves a healthcare professional performing a gentle maneuver to relocate the radius into its proper position, providing immediate relief.  ** Dislocation of the Glenohumeral Joint** **Explanation**: The glenohumeral joint, commonly known as the shoulder joint, is particularly susceptible to dislocation due to its wide range of motion and relatively shallow socket. Anterior dislocations are the most common, often resulting from a fall onto an outstretched arm or a direct blow to the shoulder. Symptoms include severe shoulder pain, visible deformity, and an inability to move the joint. Immediate medical attention is required to reposition the humeral head into the glenoid cavity, followed by rehabilitation to restore function and prevent recurrence. ** Colles' Fracture** **Explanation**: A Colles' fracture is a break in the distal radius bone of the forearm, occurring near the wrist. It typically results from a fall onto an outstretched hand with the wrist extended. This fracture is characterized by a dorsal (upward) displacement of the broken fragment, leading to a visible deformity often described as a "dinner fork" appearance. Symptoms include immediate pain, swelling, bruising, and difficulty moving the wrist or hand. Treatment may involve immobilization with a cast or surgical intervention, depending on the severity and alignment of the fracture. **. Where to Feel the Radial Pulse** **Answer**: The radial pulse can be palpated on the lateral aspect of the wrist, just proximal to the base of the thumb. To locate it, place your index and middle fingers on the anterior surface of the wrist, lateral to the tendon of the **flexor carpi radialis** muscle. Applying gentle pressure in this area allows you to feel the pulsation of the radial artery. **32. Where to Feel the Radial Pulse** **Answer**: The radial pulse can be palpated on the lateral aspect of the wrist, just proximal to the base of the thumb. To locate it, place your index and middle fingers on the anterior surface of the wrist, lateral to the tendon of the **flexor carpi radialis** muscle. Applying gentle pressure in this area allows you to feel the pulsation of the radial artery. **33. Golfer's and Tennis Elbow** **Explanation**: **Golfer's Elbow**: **Medical Term**: Medial epicondylitis. **Cause**: Overuse or repetitive stress leading to inflammation of the tendons attached to the medial epicondyle of the humerus. **Symptoms**: Pain and tenderness on the inner (medial) side of the elbow, which may radiate down the inner forearm. **Activities Associated**: Swinging a golf club, throwing, or any repetitive wrist flexion and forearm pronation movements. **Tennis Elbow**: **Medical Term**: Lateral epicondylitis. **Cause**: Overuse or repetitive stress causing inflammation of the tendons attached to the lateral epicondyle of the humerus. **Symptoms**: Pain and tenderness on the outer (lateral) side of the elbow, which may radiate down the back of the forearm. **Activities Associated**: Playing tennis, painting, or any repetitive wrist extension and forearm supination movements.  **Randy Travis Drinks Cold Beer** (Roots, Trunks, Divisions, Cords, Branches). "A patient presents with weakness in wrist extension and numbness over the dorsum of the hand following a midshaft humerus fracture. Which nerve is most likely injured?" **Step 1: Identify the Injury**: Midshaft humerus → Likely affects the **radial nerve** (travels in the radial groove). **Step 2: Recognize Symptoms**: Weak wrist extension → Innervation to extensor muscles (posterior compartment). Numbness on dorsum of hand → Sensory distribution of radial nerve. **Answer**: **Radial nerve**. **Nursemaid's Elbow (Radial Head Subluxation)** **Answer**: Subluxation of the radial head due to pulling on an extended arm in young children. **Clinical Presentation**: Child refuses to use the arm, holding it slightly flexed and pronated. **Treatment**: Gentle supination and flexion of the forearm relocates the radial head. ** Dislocation of the Glenohumeral Joint** **Answer**: **Anterior dislocation** is the most common type. **Cause**: Trauma (e.g., fall on an outstretched arm). **Clinical Significance**: Can injure the **axillary nerve**, leading to deltoid paralysis and loss of sensation over the lateral shoulder. **Colles' Fracture** **Answer**: Fracture of the distal radius with **dorsal displacement** of the fractured fragment. **Cause**: Fall on an outstretched hand with the wrist extended. **Clinical Significance**: Creates a "dinner fork" deformity. **Complications**: Median nerve injury, carpal tunnel syndrome. **Where Do You Feel the Radial Pulse?** **Answer**: The radial pulse is felt lateral to the tendon of the **flexor carpi radialis** at the wrist. **Golfer's Elbow and Tennis Elbow** 1\. **Golfer's Elbow (Medial Epicondylitis)**: **Cause**: Overuse of wrist flexors originating from the medial epicondyle. **Symptoms**: Pain on the medial elbow and worsens with wrist flexion. 2\. **Tennis Elbow (Lateral Epicondylitis)**: **Cause**: Overuse of wrist extensors originating from the lateral epicondyle. **Symptoms**: Pain on the lateral elbow and worsens with wrist extension. **Target High-Yield Topics** Here's a prioritized list of areas likely emphasized on tests: 1\. **Brachial Plexus**: Roots, trunks, divisions, cords, branches. Injuries: Erb's palsy, Klumpke's palsy. 2\. **Rotator Cuff**: Muscles, actions, and which one doesn't rotate (supraspinatus). 3\. **Spinal Cord**: End point (L1-L2), roots vs. rami, spinal taps (L3-L4 landmark). 4\. **Ligaments**: Vertebral column ligaments and their functions. 5\. **Clinical Conditions**: Colles' fracture, nursemaid's elbow, dislocations (e.g., glenohumeral joint). **2. Rotator Cuff** **Muscles and Actions**: **Supraspinatus**: **Action**: Initiates arm abduction (first 15 degrees). **Note**: Does not rotate the arm. **Infraspinatus**: **Action**: External (lateral) rotation of the arm. **Teres Minor**: **Action**: External rotation and adduction of the arm. **Subscapularis**: **Action**: Internal (medial) rotation of the arm **Function**: Stabilize the glenohumeral joint by keeping the humeral head centered in the glenoid cavity. **3. Spinal Cord** **End Point**: Terminates at the level of L1-L2 vertebrae in adults. **Roots vs. Rami**: **Roots**: **Ventral (anterior)**: Motor fibers. **Dorsal (posterior)**: Sensory fibers. **Rami**: **Dorsal Rami**: Innervate deep back muscles and skin over the back. **Ventral Rami**: Form plexuses (e.g., brachial, lumbar) and innervate limbs and anterior trunk. **Spinal Tap (Lumbar Puncture)**: **Site**: Between L3-L4 or L4-L5 vertebrae. **Landmark**: Iliac crests align with L4 vertebra. **4. Vertebral Column Ligaments** **Key Ligaments and Functions**: **Anterior Longitudinal Ligament**: **Location**: Anterior surface of vertebral bodies. **Function**: Prevents hyperextension. **Posterior Longitudinal Ligament**: **Location**: Posterior surface of vertebral bodies within the vertebral canal. **Function**: Prevents hyperflexion. **Ligamentum Flavum**: **Location**: Connects laminae of adjacent vertebrae. **Function**: Maintains upright posture and assists in returning to neutral position after flexion. **Interspinous Ligaments**: **Location**: Between spinous processes. **Function**: Limit flexion. **Supraspinous Ligament**: **Location**: Runs along the tips of spinous processes. **Function**: Limits flexion.  Axilla: ✔ **Passageway for nerves and blood vessels** to the upper limb. ✔ **Lymphatic drainage** of the breast and upper limb. ✔ **Protected by muscles and fascia**. **Boundary** **Structures Forming It** **Apex (Inlet)** Clavicle (anterior), 1st rib (medial), Scapula (posterior) **Base (Floor)** Skin, axillary fascia **Anterior Wall** Pectoralis major, pectoralis minor, clavipectoral fascia **Posterior Wall** Subscapularis, teres major, latissimus dorsi **Medial Wall** Serratus anterior, ribs 1-4, intercostal muscles **Lateral Wall** Intertubercular groove of the humerus Boundary Structures Forming It ---------------- ------------------------------------------------------------ Apex (Inlet) Clavicle (anterior), 1st rib (medial), Scapula (posterior) Base (Floor) Skin, axillary fascia Anterior Wall Pectoralis major, pectoralis minor, clavipectoral fascia Posterior Wall Subscapularis, teres major, latissimus dorsi Medial Wall Serratus anterior, ribs 1-4, intercostal muscles Lateral Wall Intertubercular groove of the humerus **Brachial Plexus is divided into** Roots → Trunks → Divisions → Cords → Branches. **Mnemonic to Remember**: **"Randy Travis Drinks Cold Beer"** (Roots → Trunks → Divisions → Cords → Branches) **A. Roots (C5-T1)** **Five roots**: C5, C6, C7, C8, T1. These combine to form **trunks**. **B. Trunks** **Upper trunk**: C5 + C6. **Middle trunk**: C7. **Lower trunk**: C8 + T1. **C. Divisions** Each trunk splits into: **Anterior divisions** (supply flexors). **Posterior divisions** (supply extensors). **D. Cords** Named based on their position relative to the **axillary artery**: **Lateral cord** (from anterior divisions of C5-C7). **Posterior cord** (from posterior divisions of all trunks, C5-T1). **Medial cord** (from anterior division of the lower trunk, C8-T1). Mnemonic Roots Trunks Divisions Cords ------------------------------- ------- -------------------------------------------- ------------------------------------------- ---------------------------------------------------- Randy Travis Drinks Cold Beer C5-T1 Upper: C5 + C6, Middle: C7, Lower: C8 + T1 Anterior (flexors), Posterior (extensors) Lateral (C5-C7), Posterior (C5-T1), Medial (C8-T1) ✔ **Major nerves:** **Musculocutaneous, Axillary, Radial, Median, Ulnar**. ✔ **Upper plexus injury (Erb's Palsy)**: "Waiter's Tip." ✔ **Lower plexus injury (Klumpke's Palsy)**: "Claw Hand." **Cord** **Major Branches** **Lateral Cord** **Musculocutaneous nerve (C5-C7)** -- Arm flexors (biceps, brachialis) **Medial Cord** **Ulnar nerve (C8-T1)** -- Intrinsic hand muscles **Posterior Cord** **Axillary nerve (C5-C6)** -- Deltoid & teres minor **Radial nerve (C5-T1)** -- Extensors of arm & forearm **Lateral + Medial Cord** **Median nerve (C5-T1)** -- Forearm flexors, thenar muscles Cord Major Branches Innervation ----------------------- -------------------------------- ---------------------------------- Lateral Cord Musculocutaneous nerve (C5-C7) Arm flexors (biceps, brachialis) Medial Cord Ulnar nerve (C8-T1) Intrinsic hand muscles Posterior Cord Axillary nerve (C5-C6) Deltoid & teres minor Posterior Cord Radial nerve (C5-T1) Extensors of arm & forearm Lateral + Medial Cord Median nerve (C5-T1) Forearm flexors, thenar muscles **Brachial Plexus Injuries** 💡 **Mnemonic**: "Upper roots control **shoulder & elbow**, lower roots control **hand**." **A. Upper Brachial Plexus Injury (C5-C6) → Erb-Duchenne Palsy** **Cause**: Shoulder dystocia (birth injury), fall on shoulder. **Nerves Affected**: **Musculocutaneous, Axillary, Suprascapular**. **Symptoms**: **"Waiter's tip position"**: Arm **adducted & medially rotated** (deltoid & supraspinatus lost). Elbow **extended** (biceps lost). Forearm **pronated** (biceps & supinator lost). **B. Lower Brachial Plexus Injury (C8-T1) → Klumpke's Palsy** **Cause**: Excessive arm traction during birth or hanging injury. **Nerves Affected**: **Ulnar & Median Nerves**. **Symptoms**: **"Claw hand"**: **Hyperextended MCP joints**, **flexed IP joints** (intrinsic hand muscles lost). **Horner's Syndrome** (if T1 sympathetic fibers affected). **Mnemonic to Remember**: **"Screw The Lawyer, Save A Patient"** (Superior Thoracic, Thoracoacromial, Lateral Thoracic, Subscapular, Anterior Circumflex, Posterior Circumflex) **Part** **Location** **Branches** **Function** **1st Part** **From 1st rib to medial border of pectoralis minor** **Superior thoracic artery** Supplies 1st & 2nd intercostal spaces **2nd Part** **Behind pectoralis minor** **Thoracoacromial artery** (4 branches: clavicular, acromial, deltoid, pectoral) Supplies pectoral muscles, deltoid, acromion **Lateral thoracic artery** Supplies serratus anterior & lateral breast **3rd Part** **From lateral border of pectoralis minor to inferior border of teres major** **Subscapular artery** (largest branch, gives circumflex scapular & thoracodorsal) Supplies scapular anastomosis & latissimus dorsi **Anterior circumflex humeral artery** Supplies humeral head & shoulder **Posterior circumflex humeral artery** Passes through quadrangular space, supplies deltoid & shoulder joint Part Location Branches Function ---------- --------------------------------------------------------------------------- -------------------------------------------------------------------------------- ---------------------------------------------------------------------- 1st Part From 1st rib to medial border of pectoralis minor Superior thoracic artery Supplies 1st & 2nd intercostal spaces 2nd Part Behind pectoralis minor Thoracoacromial artery (4 branches: clavicular, acromial, deltoid, pectoral) Supplies pectoral muscles, deltoid, acromion 2nd Part Behind pectoralis minor Lateral thoracic artery Supplies serratus anterior & lateral breast 3rd Part From lateral border of pectoralis minor to inferior border of teres major Subscapular artery (largest branch, gives circumflex scapular & thoracodorsal) Supplies scapular anastomosis & latissimus dorsi 3rd Part From lateral border of pectoralis minor to inferior border of teres major Anterior circumflex humeral artery Supplies humeral head & shoulder 3rd Part From lateral border of pectoralis minor to inferior border of teres major Posterior circumflex humeral artery Passes through quadrangular space, supplies deltoid & shoulder joint Cubital Fossa **Structure** **Description** **Radial nerve** Runs laterally, dividing into **deep (motor) and superficial (sensory) branches** **Median nerve** Runs medially, passing between the two heads of **pronator teres** **Biceps brachii tendon** Centrally located, attaches to the **radial tuberosity** **Brachial artery** Divides into **radial and ulnar arteries** within the fossa **Median cubital vein** (superficial) Used for **venipuncture** (blood draws) Structure Description ----------------------------------- ------------------------------------------------------------------------------- Radial nerve Runs laterally, dividing into deep (motor) and superficial (sensory) branches Median nerve Runs medially, passing between the two heads of pronator teres Biceps brachii tendon Centrally located, attaches to the radial tuberosity Brachial artery Divides into radial and ulnar arteries within the fossa Median cubital vein (superficial) Used for venipuncture (blood draws) **Cubital fossa is a triangular space in front of the elbow.** ✔ **Boundaries mnemonic**: "My Brother Ruins Drinks" (Medial, Base, Roof, Lateral). ✔ **Contents mnemonic**: "Really Need Beer To Be Cool" (Radial Nerve, Median Nerve, Biceps Tendon, Brachial Artery, Median Cubital Vein). Muscles involved in pronation and supination: **Muscles Involved: Pronation** (palm down): **Pronator teres and** **Pronator quadratus** **Supination** (palm up): **Supinator and** **Biceps brachii** Condition Description ----------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Golfer's Elbow Medial epicondylitis (Flexor muscle overuse) Tennis Elbow Lateral epicondylitis (Extensor muscle overuse) Anterior interosseous nerve (AIN) - Branch of the Median Nerve: Muscles Supplied Flexor pollicis longus (FPL), Pronator quadratus (PQ), Lateral half of Flexor digitorum profundus (FDP to index & middle fingers) Posterior interosseous nerve (PIN) - Branch of the Radial Nerve: Muscles Supplied Extensor digitorum, Extensor digiti minimi, Extensor carpi ulnaris, Abductor pollicis longus, Extensor pollicis longus, Extensor pollicis brevis, Extensor indicis Origin of Anterior & Posterior Interosseous Arteries Both arise from the Common Interosseous Artery (a branch of the Ulnar Artery) Muscles Involved in Pronation & Supination Pronation: Pronator teres & Pronator quadratus (anterior compartment) Supination: Supinator (posterior compartment) & Biceps brachii (anterior compartment) Elbow Flexors & Exception in Extensor Compartment Flexors: Biceps brachii, Brachialis (anterior compartment). Exception: Brachioradialis (found in posterior compartment but acts as a flexor, supplied by Radial nerve) Exceptions to Nerve Supply Rules a\. Radial nerve supplies extensors, but Brachioradialis (a flexor) is supplied by Radial nerve b. Median nerve supplies most flexors, except Flexor carpi ulnaris & medial half of FDP (supplied by Ulnar nerve) c. FDP receives dual innervation from Median (lateral half) & Ulnar (medial half) d. Thenar muscles are supplied by the Recurrent branch of Median nerve except Adductor pollicis (Ulnar nerve) e. Lumbricals: Lateral two (Median nerve), Medial two (Ulnar nerve) Actions & Innervation of Interossei Palmar interossei (Ulnar nerve): Adduction of fingers (PAD) Dorsal interossei (Ulnar nerve): Abduction of fingers (DAB) Cutaneous Innervation of the Hand Median nerve: Palmar lateral 3.5 fingers & fingertips dorsally Ulnar nerve: Palmar & dorsal medial 1.5 fingers Radial nerve: Dorsal lateral 3.5 fingers (except fingertips) Most Commonly Dislocated Carpal Bone Lunate Nursemaid's Elbow (Radial Head Subluxation) Partial dislocation of radial head. Fixed by supination & elbow flexion Glenohumeral Joint Dislocation Most commonly dislocated anteriorly due to trauma or external rotation & abduction Colles\' Fracture Distal radius fracture with dorsal displacement (FOOSH injury) Location of Radial Pulse Lateral to the Flexor carpi radialis tendon at the wrist **5. Clinical Conditions** **Colles' Fracture**: **Description**: Fracture of the distal radius with dorsal displacement. **Cause**: Fall on an outstretched hand. **Presentation**: "Dinner fork" deformity. **Nursemaid's Elbow**: **Description**: Subluxation of the radial head. **Cause**: Sudden pull on a child's extended and pronated arm. **Presentation**: Child holds arm slightly flexed and pronated, refusing to use it. **Glenohumeral Joint Dislocation**: **Common Type**: Anterior dislocation. **Cause**: Abduction and external rotation injury. **Complications**: Injury to the axillary nerve, leading to deltoid muscle weakness and sensory loss over the lateral shoulder.