Muscles of Upper Limb PDF

**Muscles of Upper Limb** **e: Muscles of Scapular Region** - The two most superficial muscles of the shoulder: 1. **Trapezius** 2. **Deltoid** - Function: 1. Characteristic contour of the shoulder: - Trapezius: Attaches scapula and clavicle to the trunk....

**Muscles of Upper Limb** **e: Muscles of Scapular Region** - The two most superficial muscles of the shoulder: 1. **Trapezius** 2. **Deltoid** - Function: 1. Characteristic contour of the shoulder: - Trapezius: Attaches scapula and clavicle to the trunk. - Deltoid: Attaches scapula and clavicle to the humerus. **Deltoid** - **Origin:** - Inferior edge of the spine of the scapula, lateral margin of acromion, anterior border of lateral one-third of clavicle. - **Insertion:** - Deltoid tuberosity of humerus. - **Innervation:** - Axillary nerve (C5, C6). - **Actions:** - \- Major abductor of the arm; assists in flexion (clavicular fibers) and extension (posterior fibers) of the arm. **Posterior Scapular Region** - Location: - Occupies the posterior aspect of the scapula, deep to the trapezius and deltoid. - Contains four muscles b - etween the scapula and proximal humerus: - - **Muscles of Posterior Scapular Region** **Supraspinatus** - **Origin:** - Medial two-thirds of supraspinous fossa of scapula. - **Insertion:** - Most superior facet on greater tubercle of the humerus. - **Innervation:** - Suprascapular nerve (C5, C6). - **Actions:** - Rotator cuff muscle, participates in glenohumeral joint abduction, stabilizes joint. **Infraspinatus** - **Origin:** - Medial two-thirds of infraspinous fossa of scapula. - **Insertion:** - Middle facet on posterior surface of greater tubercle of humerus. - **Innervation:** - Suprascapular nerve (C5, C6). - **Actions:** - Rotator cuff muscle, lateral rotation of arm, stabilization. **Teres Minor** - **Origin:** - Upper two-thirds of flattened strip of bone on posterior surface of scapula, adjacent to lateral border. - **Insertion:** - Inferior facet on posterior surface of greater tubercle of humerus. - **Innervation:** - Axillary nerve (C5, C6). - **Actions:** - Rotator cuff muscle, lateral rotation of arm, stabilization. **Teres Major** - **Origin:** - Oval area on posterior surface of the inferior angle of the scapula. - **Insertion:** - Medial lip of the intertubercular sulcus on anterior surface of humerus. - **Innervation:** - Inferior subscapular nerve (C5, C6, C7). - **Actions:** - Medial rotation and extension of the arm, stabilization. **Subscapularis** - **Origin:** - Medial two-thirds of subscapular fossa. - **Insertion:** - Lesser tubercle of humerus. - **Innervation:** - Upper and lower subscapular nerves (C5, C6, C7). - **Actions:** - Rotator cuff muscle, medial rotation of the arm. **Rotator Cuff Muscles** - **Function:** - Group of muscles that connect scapula to humerus, keeping shoulder stable during movement. - **Components:** - - - - - **Mnemonic:** SITS muscle. **Pectoral Region** - Location: - Anterior chest wall. - Contains four muscles that exert force on the upper limb: - - - - **Pectoral Muscles** **Pectoralis Major** - **Origin:** - Anterior surface of medial half of clavicle; sternum; first seven costal cartilages; aponeurosis of external oblique. - **Insertion:** - Lateral lip of intertubercular sulcus of humerus. - **Innervation:** - Medial and lateral pectoral nerves (C5,T1). - **Actions:** - Flexion, adduction, and medial rotation at glenohumeral joint. **Pectoralis Minor** - **Origin:** - Anterior surfaces of ribs III to V. - **Insertion:** - Coracoid process of scapula. - **Innervation:** - Medial pectoral nerve (C5, C6). - **Actions:** - Pulls tip of shoulder down, protracts scapula. **Subclavius** - **Origin:** - First rib at junction of rib and costal cartilage. - **Insertion:** - Groove on inferior surface of middle one-third of clavicle. - **Innervation:** - Nerve to subclavius (C5, C6). - **Actions:** - Pulls tip of shoulder down, stabilizes sternoclavicular joint. **Serratus Anterior** - **Origin:** - Lateral surfaces of upper 8-9 ribs. - **Insertion:** - Costal surface of medial border of scapula. - **Innervation:** - Long thoracic nerve (C5, C6, C7). - **Actions:** - Protraction and rotation of the scapula, stabilization against thoracic wall. **Winging of Scapula** - **Cause:** - Damage to long thoracic nerve, causing loss of function in serratus anterior. - **Effect:** - Medial border and inferior angle of scapula elevate. - Impairs normal arm elevation. **Compartments of Arm** - **Location:** - Between shoulder joint and elbow joint. - **Muscles:** - 3 in anterior compartment: 1. **Biceps Brachii** 2. **Brachialis** 3. **A n:** - Anterior aspect of humerus and adjacent intermuscular septae. - **Insertion:** - Tuberosity of the ulna. - **Innervation:** - Musculocutaneous nerve (C5, C6); small contribution by radial nerve (C7). - **Actions:** - Powerful flexor of forearm at elbow joint. **Muscles in the Posterior Compartment of Arm** **Triceps Brachii** - **Origin:** - Long head: Infraglenoid tubercle of scapula; medial head: posterior surface of humerus; lateral head: posterior surface of humerus. - **Insertion:** - Olecranon of ulna. - **Innervation:** - Radial nerve (C6, C7, C8). - **Actions:** - Extension of forearm at elbow joint; long head can extend and adduct arm at shoulder joint. **Compartments of Forearm** - **Location:** - Between elbow joint and wrist joint. - Divided into anterior and posterior compartments. **Muscles in the Anterior Compartment of Forearm** **Superficial Layer** - **Flexor Carpi Ulnaris** - **Origin:** Humeral head: medial epicondyle; ulnar head: olecranon. - **Insertion:** Pisiform bone, into hamate, metacarpal V. - **Innervation:** Ulnar nerve. - **Actions:** Flexes and adducts wrist joint. - **Palmaris Longus** - **Origin:** Medial epicondyle of humerus. - **Insertion:** Palmar aponeurosis of hand. - **Innervation:** Median nerve. - **Actions:** Flexes wrist joint. - **Flexor Carpi Radialis** - **Origin:** Medial epicondyle. - **Insertion:** Bases of metacarpals II and III. - **Innervation:** Median nerve. - **Actions:** Flexes and abducts wrist. - **Pronator Teres** - **Origin:** Humeral head: medial epicondyle; ulnar head: medial side of coronoid process. - **Insertion:** Midshaft of radius. - **Innervation:** Median nerve. - **Actions:** Pronation. **Intermediate Layer** - **Flexor Digitorum Superficialis** - **Origin:** Medial epicondyle and adjacent margin of coronoid process; radial head: oblique line of radius. - **Insertion:** Palmar surfaces of middle phalanges of fingers II, III, IV, V. - **Innervation:** Median nerve. - **Actions:** Flexes proximal interphalangeal joints and can flex metacarpophalangeal joints and wrist. **Deep Layer** - **Flexor Digitorum Profundus** - **Origin:** Anterior and medial surfaces of ulna; anterior medial half of interosseous membrane. - **Insertion:** Palmar surfaces of distal phalanges of fingers II, III, IV, V. - **Innervation:** Lateral half by median nerve; medial half by ulnar nerve. - **Actions:** Flexes distal interphalangeal joints and can flex metacarpophalangeal and wrist joints. - **Flexor Pollicis Longus** - **Origin:** Anterior surface of radius and radial half of interosseous membrane. - **Insertion:** Base of distal phalanx of thumb. - **Innervation:** Median nerve (anterior interosseous). - **Actions:** Flexes interphalangeal joint of thumb. - **Pronator Quadratus** - **Origin:** Distal anterior surface of ulna. - **Insertion:** Distal anterior surface of radius. - **Innervation:** Median nerve (anterior interosseous). - **Actions:** Pronation. **General Features of Muscles in the Anterior Compartment of Forearm** - All muscles are flexors. - Responsible for pronation: Pronator Quadratus & Pronator Teres. - Innervation: - Most muscles innervated by Median Nerve. - **Exceptions:** Flexor Carpi Ulnaris & medial head of Flexor Digitorum Profundus (innervated by Ulnar Nerve). **Posterior Compartment of Forearm** - **Layers:** - Superficial and deep layers. - **Functions:** - Movement of wrist joint, extension of fingers and thumb, supination. **Muscles in the Posterior Compartment of Forearm** **Superficial Layer** - **Brachioradialis** - **Origin:** Proximal part of lateral supraepicondylar ridge. - **Insertion:** Lateral surface of distal end of radius. - **Innervation:** Radial nerve. - **Actions:** Accessory flexor of elbow when forearm midpronated. - **Extensor Muscles:** - **Extensor Carpi Radialis Longus & Brevis**: Extend and abduct the wrist. - **Extensor Digitorum**: Extends fingers. - **Extensor Carpi Ulnaris**: Extends and adducts wrist. **Deep Layer** - **Supinator** - **Origin:** Lateral epicondyle of humerus, radial collateral ligaments, supinator ridge of ulna. - **Insertion:** Lateral surface of radius. - **Innervation:** Radial nerve. - **Actions:** Supination. - **Pollicis Extensions:** - Abductor Pollicis Longus, Extensor Pollicis Brevis, Extensor Pollicis Longus, Extensor Indicis. **General Features of Muscles in Posterior Compartment of Forearm** - All muscles are extensors of wrist and fingers. - Innervation: All are innervated by Radial Nerve, except Supinator and Brachioradialis. **Muscles of Hand** - **Extrinsic Muscles:** - Located in anterior & posterior compartments of forearm, controlling crude movements (grip). - **Intrinsic Muscles:** - Located within hand, responsible for fine motor functions. **Intrinsic Muscles of Hand** **Thenar Muscles** - **Muscles:** 1. Opponens Pollicis 2. Abductor Pollicis Brevis 3. Flexor Pollicis Brevis - **Function:** Control movements of the thumb. - **Innervation:** Median nerve. **Hypothenar Muscles** - **Function:** Similar to thenar muscles; located at base of little finger. - **Innervation:** Ulnar nerve. **Lumbricals** - **Functions:** Important for finger movement; link extensor & flexor tendons. - **Innervation:** - Lateral two (index, middle): Median Nerve. - Medial two (little, ring): Ulnar Nerve. **Important Muscles to Learn** - **Must Know:** - Origin, insertion, action & innervation of: Pectoralis Major, Pectoralis Minor, Biceps Brachii, Coracobrachialis, Triceps Brachii. - **Know Actions & Innervation for:** - Rotator cuff muscles, serratus anterior, deltoid, lumbricals. - **Identifying Only:** - Muscles of forearm & wrist.