Anatomy Module 2B - Muscles and Nerves of the Upper Limb PDF

ANATOMY MUSCLES AND NERVES OF THE MODULE 2B UPPER LIMB...

ANATOMY MUSCLES AND NERVES OF THE MODULE 2B UPPER LIMB Name of Doctor 9A, 10B, 7E, 8F PECTORAL MUSCLES OUTLINE Includes the: I. Muscles ○ Pectoralis major A. Pectoral Muscles ○ Pectoralis minor ○ Subscapularis 1. Pectoralis Major ○ Serratus anterior 2. Pectoralis Minor 3. Subclavius PECTORALIS MAJOR 4. Serratus Anterior Connected to the sternum and clavicle B. Back Muscles Fibers converge to a common point on the humerus 1. Trapezius ○ Connected to the lateral lip of the greater tuberosity 2. Latissimus Dorsi During muscle contraction, insertion always approaches the 3. Levator Scapulae origin, not the other way around 4. Rhomboid Major and Minor During pectoralis major contraction, it moves the upper limb C. Scapular & Shoulder Muscles by: 1. Deltoid ○ Adduction 2. Rotator Cuff Muscles ○ Internal (medial) rotation a) Supraspinatus b) Infraspinatus c) Teres Minor 3. Teres Major D. Fascial Compartment of the Arm 1. Anterior Fascial Compartment 2. Posterior Fascial Compartment E. Fascial Compartment of the Forearm 1. Anterior Fascial Compartment (4 Layers) 2. Posterior Fascial Compartment (2 Layers) F. Hand Muscles 1. Thenar Compartment 2. Hypothenar Compartment 3. Adductor Compartment 4. Central Compartment 5. Interosseous Compartment II. Nerves A. The Brachial Plexus Pectoralis Major B. Branches of the Brachial Plexus (MAMRU) 1. Musculocutaneous Nerve PECTORALIS MAJOR 2. Axillary Nerve Clavicle, sternum, and upper six costal Origin 3. Median Nerve: Anterior Interosseous Nerve cartilages 4. Radial Nerve: Posterior Interosseous Nerve Insertion Lateral lip of bicipital groove of humerus 5. Ulnar Nerve Medial and lateral pectoral nerves from C. Non-MAMRU Nerves Innervating Upper Limb Muscles Nerve Supply brachial plexus 1. Lateral & Medial Pectoral Nerves Nerve Roots* C5, 6, 7, 8, T1 2. Long Thoracic Nerve Serratus Anterior Action Adducts arm and rotates it medially; 3. Cranial Nerve clavicular fibers also flex arm 4. Thoracodorsal Nerve Reference for OINA in this muscle and the following: Snell’s 5. Dorsal Scapular Nerve Anatomy by Regions 10th Ed. Note that the predominant nerve 6. Suprascapular Nerve root supply is indicated by boldface type. 7. Subscapular Nerve PECTORALIS MINOR REFERENCES: When the pectoralis major is removed, the small triangular Dr. — PPT & Recorded Lecture muscle can be observed— the pectoralis minor Snell’s Anatomy by Regions 10th Ed. Muscle attachment to the rib Fibers converge to the coracoid process of the scapula NUMBER OF PAGES: 22 Movement of muscles will depress the scapula ○ The pectoralis minor cannot move the shoulder joint MUSCLES OF THE UPPER LIMB ○ Contraction of the pectoralis minor will pull the scapula Muscles have bony insertions: down ○ Origin Behind the pectoralis minor creates a space— part of the ○ Insertion axillary cavity They are attached to the bones via tendons ○ Any structure that passes behind the clavicle will also ○ Bone to bone - ligament pass behind the pectoralis minor ○ Muscle to bone - tendon When ligament tears: sPrain When muscle tears: sTrain Module 2B Muscles and Nerves of the Upper Limb 1  ○ Kumbaga, luluwag ang kapit because its purpose is to keep the scapula close to the chest wall–kaya lolobo like wings. Pectoralis Minor PECTORALIS MINOR Origin Third, fourth, and fifth ribs Serratus Anterior Insertion Coracoid process of scapula Nerve Supply Medial pectoral nerve from brachial plexus SERRATUS ANTERIOR Nerve Roots* C6, 7, 8 Origin Upper eight ribs Action Depresses point of shoulder; if the scapula is fixed, it elevates the ribs of origin Medial border and inferior angle of Insertion scapula SUBCLAVIUS Nerve Supply Long thoracic nerve From the 1st rib and inserts on the undersurface of the Nerve Roots* C5, C6, C7 clavicle Action Draws the forward anterior around More of a respiratory muscle than an upper limb muscle the thoracic wall; rotates scapula Since it is connected to the clavicle, if this contracts, this elevates the 1st rib BACK MUSCLES Used during labored breathing Trapezius Latissimus Dorsi * Levator Scapulae * Rhomboid Major * Rhomboid Minor * = Deep Muscles DELTOID TRAPEZIUS Subclavius Muscle SUBCLAVIUS Origin 1st costal cartilage Insertion Clavicle Nerve to subclavius from upper Nerve Supply trunk of brachial plexus Nerve Roots* C5, C6 Trapezius Muscle Action Depresses the clavicle and steadies this bone during movements of the shoulder Diamond shaped muscle girdle From skull, vertebral spine Fibers connect to the scapular processes: SERRATUS ANTERIOR ○ Scapular spine Found at the side of the chest ○ Acromion Serrated muscle ○ Lateral half of the clavicle Saw-shaped or like a shark’s teeth 3 groups of fibers The fibers will be coming from the upper eight ribs and it will ○ Descending group attach to the vertebral border of the scapula ○ Transverse group Our scapula is attached to the rib cage via serratus anterior ○ Ascending group If it contracts, it will keep the scapula closer to the chest wall In reality, it is hard to isolate the individual fibers of the or rib cage trapezius. Once it contracts, everything will contract. The serratus anterior will bring the vertebral border (of the Summation of all forces: upward and downward movement scapula) close to the chest wall will cancel out each other → resulting in scapular retraction Injury or paralysis on the serratus anterior will result in the bulging of the vertebral border of the scapula: “Winged scapula” Note: Trapezius is connected to the spine, acromion process, and to the lateral half of the clavicle. ○ Due to a weak serratus anterior Module 2B Muscles and Nerves of the Upper Limb 2  TRAPEZIUS MUSCLE Descending group: External occipital protuberance Transverse group: Spinous processes of Origin C7-T4 Ascending group: Spinous processes of T5-T12 Descending group: lateral third of the clavicle, acromion of scapula Transverse group: acromion of scapula, Insertion lateral end of spine of scapula Ascending group: medial end of spine of scapula Spinal accessory nerve: Accessory nerve Nerve Supply Anterior rami of 3rd and 4th cervical nerves Levator Scapulae (Posterior View) C7-74 Nerve Roots Levator scapulae is from the cervical spine inserting in the T5-T12 superior angle of the scapula Action Descending group: Scapular elevation Transverse group: Retraction Levator Scapulae Ascending group: Scapular depression Origin Transverse processes of the first four cervical vertebra LATISSIMUS DORSI Insertion Medial border of scapula Nerve Supply C3 and C4 and dorsal scapular nerve Nerve Roots C3, C4, C5 Action Raises medial border of scapula RHOMBOID MAJOR DEEP MUSCLE, can only be seen when trapezius is Latissimus Dorsi removed Located at the distal part of the vertebral border White structure: lumbosacral fascia (from the pelvic bone) Bigger than rhomboid MINOR ○ Forms the fibers of latissimus dorsi from the lumbar spine to the humerus Action: adduction and shoulder extension Primary adductor of the arm LATISSIMUS DORSI 9th - 12th ribs Origin Posterior half of iliac arrest Insertion Intertubercular groove of the humerus Nerve Supply Thoracodorsal nerve Nerve Roots C6-C8 Action Extension Adduction Internal rotation (humerus) DEEPER BACK MUSCLES Rhomboid Major You remove the trapezius, and it will expose the three muscles: Rhomboid Major 1. Attached to the superior angle of the scapula 2. Adjacent to the spine of the scapula Origin 2nd - 5th thoracic spines 3. Adjacent to the infrascapular fossa These are the levator scapulae, rhomboid minor, and Insertion Medial border of scapula rhomboid major Nerve Supply Dorsal scapular nerve Role: If this three muscles will contract, it will pull the scapula towards the midline → scapular retraction Nerve Roots C4, C5 Isolating the levator scapulae → scapular elevation Action Raise medial border of scapula upward and medially LEVATOR SCAPULAE Elevates the scapula RHOMBOID MINOR DEEP MUSCLE, can only be seen when trapezius is DEEP MUSCLE, can only be seen when trapezius is removed removed Scapular retraction Smaller than the rhomboid MAJOR Attached at the base of the scapular spine Module 2B Muscles and Nerves of the Upper Limb 3  Anterior Fiber of Deltoid Rhomboid Minor It is adjacent to the scapular spine Rhomboid Minor Origin Ligamentum nuchae and spine of 7th cervical vertebrae and 1st thoracic vertebrae Insertion Medial border of scapula Nerve Supply Dorsal scapular nerve Nerve Roots C4, C5 Middle Fiber of Deltoid Action Raises medial border of scapula upward and medially SCAPULAR AND SHOULDER MUSCLES Deltoid Rotator Cuff Muscles ○ Supraspinatus ○ Infraspinatus ○ Teres Minor ○ Subscapularis Teres Major DELTOID Posterior Fiber of Deltoid Prominent shoulder muscle Contraction of three fiber would cause: ROTATOR CUFF MUSCLES ○ Anterior fiber → shoulder flexion “SITS” Muscles that originates from the scapula ○ Middle fiber → shoulder abduction (considered to be the ○ Common insertion: the greater tuberosity of the prime abductor of the shoulder) humerus ○ Posterior fiber → shoulder extension ○ Fused to the underlying capsule of the shoulder joint All fibers will converge into the deltoid tuberosity ○ if these muscles contract, the humerus will rotate Origin: lateral half of the clavicle, acromion, spine of scapula externally, making the group of muscles the external rotator of the shoulder DELTOID MUSCLE “ROTATOR” → considered the major rotators of the shoulder Origin Lateral third of the clavicle “CUFF” → because of the configuration of the glenohumeral Acromion joint composed of a spherical humeral head and a flat glenoid Spine of scapula cavity Insertion Middle of lateral surface of shaft of Helps in improving stability of the shoulder joint humerus They are slightly contracted even when not in use Nerve Supply Axillary nerve; lower half is supplied by the upper and lateral cutaneous nerve of arm Nerve Roots C5, C6 Action Abducts arm Anterior fiber: flex and medially rotates Posterior fiber: extend and laterally rotates Module 2B Muscles and Nerves of the Upper Limb 4  Supraspinatus Rotator Cuff Muscles INFRASPINATUS Occupies the whole infraspinous fossa of the scapula Lateral rotator of the shoulder along with teres minor Has a common insertion with the teres minor and supraspinatus which is the greater tuberosity of the humerus, hence will rotate the shoulder externally INFRASPINATUS MUSCLE Origin Infraspinous fossa of scapula Insertion Greater tuberosity of humerus; Shoulder joint capsule Nerve Supply Suprascapular nerve Nerve Roots C4, C5, C6 Action Laterally rotates arm and stabilizes shoulder joint Rotator Cuff muscles and Humerus (a) Subscapularis; (b) Supraspinatus; (c) Infraspinatus; (d) Teres Minor SUPRASPINATUS Located in the supraspinous fossa Has a common insertion with teres minor and infraspinatus: greater tuberosity of humerus ○ will rotate the shoulder externally If it contracts, it has the capacity to abduct the shoulder ○ Initiator of Shoulder Abduction (first 45 degrees) SUPRASPINATUS MUSCLE Infraspinatus Origin Supraspinous fossa of scapula Insertion Greater tuberosity of humerus; TERES MINOR Shoulder joint capsule Arises on the axillary border of the infraspinatus fossa Nerve Supply Suprascapular nerve Lateral rotator of the shoulder along with infraspinatus Nerve Roots C4, C5, C6 muscle Action Abducts arm and stabilizes shoulder joint Has a common insertion with the supraspinatus and infraspinatus which is the greater tuberosity of the humerus, hence will rotate the shoulder externally TERES MINOR MUSCLE Upper two thirds of lateral border of the Origin scapula Greater tuberosity of the humerus; Insertion shoulder joint capsule Nerve Supply Axillary nerve Nerve Roots C4, C5, C6 Action Laterally rotates arm and stabilizes shoulder joint Module 2B Muscles and Nerves of the Upper Limb 5  Teres Major FASCIAL COMPARTMENT OF THE ARM Organized in 2 osseofascial compartments ○ Anterior compartment: mainly flexors Biceps brachii Coracobrachialis Teres Minor Brachialis ○ Posterior compartment: mainly extensors SUBSCAPULARIS Triceps brachii Located anteriorly in the subscapular fossa and inserts into Musculocutaneous nerve supplies anterior compartment the lesser tuberosity causing the internal rotation of the Radial nerve supplies posterior compartment shoulder Attached to the lesser tuberosity of the humerus ANTERIOR FASCIAL COMPARTMENT Internal rotator of the shoulder BICEPS BRACHII SUBSCAPULARIS MUSCLE PRIME SUPINATOR of the forearm Origin Subscapular fossa Powerful supinator Insertion Lesser tuberosity of humerus ○ Supination against resistance Nerve Supply Upper and lower subscapular nerves Powerful flexor of elbow joint Nerve Roots C5, C6, C7 Weak flexor of shoulder joint Action Medially rotates arm and stabilizes Tendons of biceps brachii (upper part) covered by pectoralis shoulder joint major and deltoids ○ Portion of long head tendon (proximal) is hiding inside the shoulder capsule of glenohumeral joint then occupies intertubercular groove (bicipital groove) Intertubercular groove is covered by transverse humeral ligament (intertubercular/bicipital ligament) Called “biceps” due to its 2 heads ○ Lateral head: long ○ Medial head: short Distal tendon inserts to radial tuberosity (bicipital tuberosity) BICEPS BRACHII Supraglenoid tubercle of Long Head Subscapularis Origin scapula Short Head Coracoid process of scapula TERES MAJOR Tuberosity of radius and bicipital aponeurosis Insertion Connected just below the surgical neck of the humerus into deep fascia of forearm ○ Attaches to the shaft of the humerus Nerve Action: shoulder adduction Musculocutaneous nerve Supply Not part of the rotator cuff muscle group Nerve Roots C5,C6 Supination of forearm TERES MAJOR MUSCLE Action Flexor of elbow joint Origin Lower third of lateral border of scapula Weak flexor of shoulder joint Insertion Medial lip of bicipital groove of humerus * Recall: Muscles connected with coracoid process: Nerve Supply Lower subscapular nerve Short head of biceps brachii (O) Nerve Roots C6, C7 Coracobrachialis (O) Pectoralis minor (I) Action Medially rotates and adducts arm and * O = origin; I = insertion stabilizes shoulder joint Module 2B Muscles and Nerves of the Upper Limb 6  Heads of Biceps brachii Brachialis POSTERIOR FASCIAL COMPARTMENT TRICEPS BRACHII 3 heads: ○ Long Head ○ Lateral Head ○ Medial Head The 3 heads will converge to form the tendon that will insert in the olecranon process Transverse Humeral Ligament It can perform slight extension of the shoulder but it is primarily the: ○ PRIME EXTENSOR of the elbow CORACOBRACHIALIS Located deep to biceps brachii TRICEPS BRACHII Attached to coracoid process alongside with short of biceps brachii and pectoralis minor lnfraglenoid tubercle of Long Head scapula CORACOBRACHIALIS Upper half of posterior Origin Lateral Head surface of shaft of humerus Origin Coracoid process of scapula Lower half of posterior Insertion Medial aspect of humerus shaft Medial Head surface of shaft of humerus Nerve Supply Musculocutaneous nerve Insertion Olecranon process of ulna Nerve Roots C5, C6, C7 Nerve Supply Radial nerve Action Flexes arm & weak adductor Nerve Roots C6, C7, C8 Action Extensor of elbow joint Coracobrachialis Lateral and Long Head of the Triceps Brachii (Left Arm) BRACHIALIS Located deep to biceps brachii PRIME FLEXOR of elbow BRACHIALIS Origin Front of lower half of humerus Insertion Coronoid process of ulna Nerve Supply Musculocutaneous nerve Nerve Roots C5, C6 Action Flexor of elbow joint Module 2B Muscles and Nerves of the Upper Limb 7  Upper four or five ribs Lateral Border Biceps Brachii Coracobrachialis Anterior and Posterior Borders of the Axilla Medial Head of the Triceps Brachii (Left Arm) Medial and Lateral Borders of the Axilla Summary of points (Fascial Compartment of the Arm): Biceps brachii: PRIMARY SUPINATOR of the forearm Brachialis: PRIMARY FLEXOR of the elbow Triceps brachii: PRIMARY EXTENSOR of the elbow Triceps Brachii Tendon FASCIAL COMPARTMENT OF THE FOREARM Divided into two compartments AXILLA Compartments can be distinguished by looking at their AKA armpit Common Tendon Origin: Pyramid-shaped space between the upper part of the arm ○ Anterior Fascial Compartment and the side of the chest Muscles coming from the MEDIAL EPICONDYLE Forms a space/cavity/opening for neurovascular structures ○ Posterior Fascial Compartment (such as nerves, blood vessels, and lymph channels) to Muscles coming from the LATERAL EPICONDYLE travel between the root of the neck to supply the upper limb Axilla Region of the Upper Limb The axillary region consists of four walls/borders: Axillary border Muscles Common Tendon Origin Anterior Border Pectoralis major Subclavius FLEXOR & EXTENSOR RETINACULUM Pectoralis minor muscles Connective tissue that serves as a wristband covering both Posterior Border Latissimus dorsi anterior and posterior sides Subscapularis Prevents bowstringing effect of the tendons Teres major muscles ○ Flex without the retinaculum→tendons will pop out Medial Border Serratus Anterior Holds tendons in place Module 2B Muscles and Nerves of the Upper Limb 8  Flexor retinaculum (Anterior) Pronator teres PRONATOR TERES Origin Humeral head Medial epicondyle of the humerus Ulnar head Medial border of the Extensor retinaculum (Posterior) coronoid process of the ulna ANTERIOR FASCIAL COMPARTMENT Insertion Lateral aspect of shaft of the radius Nerve Supply Median Nerve LAYER 1 (SUPERFICIAL) Nerve Roots C6, C7 Pronator teres Action Pronation and flexion of forearm Palmaris longus Flexor carpi ulnaris FLEXOR CARPI RADIALIS Flexor carpi radialis LAYER 2 Flexor digitorum superficialis LAYER 3 Flexor digitorum profundus Flexor pollicis longus LAYER 4 (DEEP) Pronator quadratus LAYER 1 (SUPERFICIAL) Flexor carpi radialis FLEXOR CARPI RADIALIS Origin Medial epicondyle of humerus Insertion Bases of 2nd and 3rd metacarpal bones Nerve Supply Median nerve Nerve Roots C6, C7 Action Flexes and abducts hand at wrist joint FLEXOR CARPI ULNARIS There is a groove at the origin of the flexor carpi ulnaris called the cubital tunnel where the ulnar nerve courses through to reach the forearm Muscles of the Anterior Fascial Compartment PRONATOR TERES Role: pronate the forearm Has two (2) heads ○ Humeral head ○ Ulnar head There is a space underneath where neurovascular structures pass Flexor carpi ulnaris Module 2B Muscles and Nerves of the Upper Limb 9  ○ Supply the individual fingers except the thumb If you observe closely, there is a hole in the middle of the tendon before it reaches the intermediate phalanx ○ Where the tendons of flexor digitorum profundus pass through If the muscle contracts, it will perform flexion of the proximal interphalangeal joint Cubital tunnel FLEXOR CARPI ULNARIS Origin Humeral head Medial epicondyle of humerus Ulnar head Medial aspect of olecranon process Flexor digitorum superficialis (highlighted yellow) and posterior border of ulnaj Insertion Pisiform bone, hook of the hamate, base at 5th metacarpal bone Nerve Supply Ulnar nerve Nerve Roots C8, T1 Action Flexes and adducts hand at wrist joint PALMARIS LONGUS Absent in 20% of the population Does not pass under the flexor retinaculum Determined by observing a prominent tendon vis approximating the thumb and little finger while simultaneously Tendinous arch of flexor digitorum superficialis flexing the wrist Point of attachment for flexor digitorum superficialis FLEXOR DIGITORUM SUPERFICIALIS Origin Humeroulnar head Medial epicondyle of humerus, medial Palmaris longus border of coronoid process of ulna PALMARIS LONGUS Radial head Oblique line on Origin Medial epicondyle of humerus anterior surface of Insertion Flexor retinaculum and palmar aponeurosis shaft of radius Nerve Supply Median nerve Insertion Middle phalanx of medial four fingers Nerve Roots C7, C8 Nerve Supply Median nerve Action Flexes hand Nerve Roots C7, C8, T1 Action Flexes middle phalanx of fingers and assists LAYER 2 (FLEXOR DIGITORUM SUPERFICIALIS) in flexing proximal phalanx and hand LAYER 3 FLEXOR DIGITORUM SUPERFICIALIS Moves the fingers FLEXOR DIGITORUM PROFUNDUS Although it is a forearm muscle, the extension of the tendon is attached to the fingers except for the thumb Four individual tendons that pass through the openings at the As the muscles form its tendons, it will start to form 4 different base of the flexor digitorum superficialis in order to insert at tendons that will pass under the flexor retinaculum and attach the base of the distal phalanges. to the bases of the intermediate phalanx Module 2B Muscles and Nerves of the Upper Limb 10  Stronger muscles than lumbricals, allowing people who wall LAYER 4 (DEEP; PRONATOR QUADRATUS) climb to carry the whole body through this muscle only PRONATOR QUADRATUS ”Wristband-like” muscle connecting the radius and ulna Pronator Quadratus Isolated Flexor Digitorum Profundus Isolated PRONATOR QUADRATUS Origin Anterior surface of ulna shaft Insertion Anterior surface of radius shaft Nerve Supply Anterior interosseus branch of median nerve Nerve Roots C8, T1 Action Pronates the forearm at the radioulnar joint Deep fibers of the muscle also stabilizes the connection of the radius and ulna POSTERIOR FASCIAL COMPARTMENT Extensor Retinaculum Flexor Digitorum Profundus and Flexor Digitorum ○ Important ligament which holds the tendons of the Superficialis posterior fascial compartment FLEXOR DIGITORUM PROFUNDUS Origin Anteromedial surface of ulna shaft Insertion Distal phalanges of medial four fingers Nerve Supply Ulnar nerve for medial half; and median nerve for lateral half Nerve Roots C8, T1 Action Flexes distal phalanx of fingers, assists in flexion of midde and proximal phalanges and wrist FLEXOR POLLICIS LONGUS Serves as the only flexor of the first digit Extensor retinaculum (highlighted in green) Medical term for the thumb is Pollex Common Tendon of Origin: Lateral epicondyle of the humerus Layers Muscles Brachioradialis Extensor carpi radialis longus (ECRL) Extensor carpi radialis brevis (ECRB) Layer 1 Extensor digitorum (Superficial) Extensor digiti minimi Extensor carpi ulnaris Anconeus Supinator Extensor indicis Anatomical Snuffbox Layer 2 (Deep) ○ Abductor pollicis longus Flexor Pollicis Longus Isolated ○ Extensor pollicis brevis ○ Extensor pollicis longus FLEXOR POLLICIS LONGUS Origin Anterior surface of radius shaft LAYER 1 (SUPERFICIAL) Insertion Distal phalanx of thumb Common Nerve Supply: Radial Nerve Nerve Supply Anterior interosseus branch of median nerve Common Nerve Roots: C5-T1 Nerve Roots C8, T1 Action Flexes distal phalanx of thumb BRACHIORADIALIS Lateral Trio: Close proximity of the brachioradialis, ECRL, & ECBL in the posterior fascial compartment of the forearm ○ Lateral trio position: Most anterior to extensor carpi radialis brevis and extensor carpi radialis brevis muscles Module 2B Muscles and Nerves of the Upper Limb 11  Crosses elbow joint ○ Movement: Elbow flexion Extensor carpi radialis brevis (more posterior) EXTENSOR CARPI RADIALIS BREVIS Origin Lateral epicondyle of humerus Insertion Posterior surface of the base of the 3rd Brachioradialis (isolated) metacarpal bone Nerve Supply Deep branch of radial nerve A part of brachioradialis can be seen in an anterior view of the Nerve Roots C7, C8 arm, yet the muscle is still part of the posterior fascial Action Hand extension and abduction at wrist joint compartment, since its common tendon of origin is in the lateral supracondylar ridge. Due to close proximity of the brachioradialis, ECRL, and ECRB, Dr. JC often call these the “lateral trio” BRACHIORADIALIS Origin Lateral supracondylar ridge of humerus Insertion Base of radial styloid process Nerve Supply Radial nerve Nerve Roots C5, C6, C7 Action Forearm flexion at elbow joint; forearm rotation to the mid-prone position EXTENSOR CARPI RADIALIS LONGUS (ECRL) Anatomical difference: Runs along the radial side compared to extensor carpi ulnaris Lateral trio position: Anterior to extensor carpi radialis brevis muscle but posterior to brachioradialis muscle Lateral Trio of the posterior fascial compartment of forearm Brachioradialis at most anterior portion while ECRL & ECRB at the more posterior regions EXTENSOR DIGITORUM Distal tendons are interconnected Movement: Assume knuckle formation ○ Notice how the other digits follow the extension of the ring finger ○ Reason: Interconnected tendons Extensor Carpi Radialis Longus (more anterior) EXTENSOR CARPI RADIALIS LONGUS Origin Lateral supracondylar ridge of humerus Insertion Posterior surface of the base of the 2nd metacarpal bone Nerve Supply Radial nerve Nerve Roots C5, C7 Action Hand extension and abduction at wrist joint Extensor digitorum EXTENSOR CARPI RADIALIS BREVIS (ECRB) Anatomical difference: Runs along the radial side EXTENSOR DIGITORUM compared to extensor carpi ulnaris Origin Lateral epicondyle of humerus Lateral trio position: Most posterior to brachioradialis and Insertion Middle & distal phalanges of four medial extensor carpi radialis longus muscles fingers (thumb is excluded) Nerve Supply Deep branch of radial nerve Nerve Roots C7, C8 Action Hand & fingers (excluding thumb) extension Module 2B Muscles and Nerves of the Upper Limb 12  Triceps brachii are still the primary extensor of the Movement elbow ○ Allows movement of little finger relative to other medial Last muscle that forms the superficial layer of the posterior digits (except the thumb) compartment Extensor digiti minimi Anconeus EXTENSOR DIGITI MINIMI ANCONEUS Origin Lateral epicondyle of humerus Origin Lateral epicondyle of humerus Insertion Extensor expansion of little finger Insertion Lateral surface of olecranon process of ulna Nerve Supply Deep branch of radial nerve Nerve Supply Radial nerve Nerve Roots C7, C8 Nerve Roots C7, C8, T1 Action Little finger metacarpophalangeal joint Action Elbow joint extension extension (and helps extend the wrist) *used for drinking wine LAYER 2 (DEEP) Common Nerve Supply: Radial Nerve EXTENSOR CARPI ULNARIS Common Nerve Roots: C5-C8 Anatomical difference: Runs along the ulnar side compared to ECRL & ECRB Layer 2 (Deep) Muscles SUPINATOR Movement Extensor carpi ulnaris ○ Rotates the forearm so the palm faces anteriorly EXTENSOR CARPI ULNARIS Origin Lateral epicondyle of humerus Insertion Base of 5th metacarpal bone Nerve Supply Deep branch of radial nerve Nerve Roots C7, C8 Action Hand extension and adduction at wrist joint Supinator SUPINATOR Origin Lateral epicondyle of humerus, anular ligament of proximal radioulnar joint, and ulna Insertion Neck and shaft of radius Nerve Supply Deep branch of radial nerve Extensor carpi ulnaris (isolated) Nerve Roots C5, C6 Action Supination of forearm ANCONEUS Movement EXTENSOR INDICIS ○ Aids in elbow extension Supplies the index finger Movement Module 2B Muscles and Nerves of the Upper Limb 13  ○ Extension of index finger Extensor Pollicis Brevis (EPB) muscle Extensor Indicis EXTENSOR POLLICIS BREVIS EXTENSOR INDICIS Origin Posterior surface of shaft of radius Origin Posterior surface of ulna shaft Insertion Base of proximal phalanx of thumb Insertion Extensor expansion of index finger Nerve Supply Deep branch of radial nerve Nerve Supply Deep branch of radial nerve Nerve Roots C7, C8 Nerve Roots C7, C8 Action Extends metacarpophalangeal joints of Action Extends metacarpophalangeal joint of index thumb finger EXTENSOR POLLICIS LONGUS ANATOMICAL SNUFFBOX Separated tendon from other 2 muscles in anatomical Triangular depression formed due to Lister’s tubercle snuffbox Movement: ○ Fully extends the thumb Anatomical Snuffbox Extensor Pollicis Longus (EPL) ABDUCTOR POLLICIS LONGUS Most lateral muscle in the anatomical snuffbox EXTENSOR POLLICIS LONGUS Movement: ○ Lateral movement of the thumb Origin Posterior surface of ulna shaft Insertion Base of distal phalanx of thumb Nerve Supply Deep branch of radial nerve Nerve Roots C7, C8 Action Extends distal phalanx of thumb HAND MUSCLES THENAR COMPARTMENT Located at the thumb Thumb = thenar “Pollex (Plural form: Pollices)” = thumb muscle Short muscle = brevis Abductor Pollicis Longus (APL) ABDUCTOR POLLICIS LONGUS Origin Posterior surface of shafts of radius and ulna Insertion Base of first metacarpal bone Nerve Supply Deep branch of radial nerve Nerve Roots C7, C8 Action Abducts and extends thumb EXTENSOR POLLICIS BREVIS Tendon is beside APL Muscle found between APL and EPL Movement: ○ Straightens the thumb away from palm Module 2B Muscles and Nerves of the Upper Limb 14  Nerve Roots C8, T1 Action Flexes metacarpophalangeal joint of thumb OPPONENS POLLICIS BREVIS Thenar Compartment / Thenar Eminence Memory Aid: AFO A → Abductor pollicis brevis Opponens Pollicis Brevis F → Flexor pollicis brevis O → Opponens pollicis brevis OPPONENS POLLICIS BREVIS Origin Flexor retinaculum ABDUCTOR POLLICIS BREVIS Insertion Shaft of metacarpal bone of thumb Nerve Supply Median nerve Nerve Roots C8, T1 Action Pulls thumb medially and forward across palm HYPOTHENAR COMPARTMENT Located at the ulnar side of hand Digiti minimi = little finger Abductor Pollicis Brevis (Isolated view) ABDUCTOR POLLICIS BREVIS Origin Scaphoid, trapezium, flexor retinaculum Insertion Base of proximal phalanx of thumb Nerve Supply Median nerve Nerve Roots C8, T1 Action Abduction of thumb Hypothenar Compartment FLEXOR POLLICIS BREVIS Memory Aid: AFO A → Abductor digiti minimi F → Flexor digiti minimi O → Opponens digiti minimi ABDUCTOR DIGITI MINIMI Flexor Pollicis Brevis FLEXOR POLLICIS BREVIS Origin Flexor retinaculum Insertion Base of proximal phalanx of thumb Nerve Supply Median nerve Abductor Digiti Minimi Module 2B Muscles and Nerves of the Upper Limb 15  ABDUCTOR DIGITI MINIMI Origin Pisiform bone Insertion Base of proximal phalanx of little finger Nerve Supply Deep branch of ulnar nerve Nerve Roots C8, T1 Action Abducts little finger FLEXOR DIGITI MINIMI Adductor Pollicis ADDUCTOR POLLICIS Oblique head; 2nd and 3rd metacarpal Origin bones; transverse head; 3rd metacarpal bones Insertion Base of proximal phalanx of thumb Nerve Supply Deep branch of ulnar nerve Nerve Roots C8, T1 Action Adduction of thumb Flexor Digiti Minimi CENTRAL COMPARTMENT Contains the lumbricals FLEXOR DIGITI MINIMI LUMBRICAL MUSCLES Origin Flexor retinaculum There are 4 lumbrical muscles Insertion Base of proximal phalanx of little finger ○ Lumbrical 1, 2, 3, 4 Nerve Supply Deep branch of ulnar nerve Lumbrical 1 inserts into Digit 2 (Index Finger) Nerve Roots C8, T1 Lumbrical 2 inserts into Digit 3 (Middle Finger) Action Flexes little finger Lumbrical 3 inserts into Digit 4 (Ring Finger) Lumbrical 4 inserts into Digit 5 (Little Finger) ○ Comes from the tendons of the flexor digitorum OPPONENS DIGITI MINIMI profundus Only muscle that originates from a tendon ○ Inserts at the base of the proximal phalanx ○ Flexor digitorum superficialis, flexor digitorum profundus and lumbricals allow the closing of hand and forming of fist Contracts together to flex joints Opponens Digiti Minimi OPPONENS DIGITI MINIMI Origin Flexor retinaculum Insertion Medial border of 5th metacarpal bone Nerve Supply Deep branch of ulnar nerve Nerve Roots C8, T1 Action Pulls 5th metacarpal forward as in cupping Lumbricals the palm LUMBRICALS (4) ADDUCTOR COMPARTMENT Origin Tendons of flexor digitorum profundus Formed by the adductor pollicis Insertion Extensor expansion of medial four fingers ADDUCTOR POLLICIS 1st and 2nd (lateral two): Medial nerve Muscle of the thumb that is found in the web between the Nerve Supply 3rd and 4th: Deep branch of ulnar nerve thumb and the index finger Nerve Roots C8, T1 ○ Sensed by pressing the meaty portion in this area Flex metacarpophalangeal joints and extend Action interphalangeal joints of fingers except thumb Module 2B Muscles and Nerves of the Upper Limb 16  INTEROSSEOUS COMPARTMENT DORSAL INTEROSSEI Formed by the palmar and dorsal interosseous muscles Abductors ○ Responsible for finger adduction and abduction ○ Fingers (index finger and ring finger) move away from the Midline is the middle finger midline (middle finger) Adduction: Moving towards the middle finger ○ Two dorsal interossei in the middle finger → Can move Putting fingers together side-to-side Abduction: Moving away from the middle finger There is no dorsal interosseous muscle in the little finger and Spreading fingers apart thumb as they have their own abductor muscles ○ Little Finger: Abductor digiti minimi ○ Thumb: Abductor pollicis brevis Memory Aid: DAb Dorsal Interosseous Muscle → Abduction Palmar and Dorsal Interossei PALMAR INTEROSSEI Adductors ○ Index finger, ring finger, and little finger moves towards the middle finger Dorsal Interossei There is none in the middle finger and thumb ○ Middle Finger: Cannot adduct something that is already DORSAL INTEROSSEI (4) in the middle Contiguous sides of shafts of metacarpal Origin ○ Thumb: Has its own adductor muscle, the adductor bones pollicis Proximal phalanges of index, middle, and Insertion ring fingers and dorsal extensor expansion Memory Aid: PAd Nerve Supply Deep branch of ulnar nerve Palmar Interosseous Muscle → Adduction Nerve Roots C8, T1 Abduct fingers from the center of third finger; Both dorsal and palmar interossei flex Action metacarpophalangeal joints and extend interphalangeal joints NERVES OF THE UPPER LIMB Serve as our electrical wires to power up the muscles, directing electrical impulses generated by skin receptors ○ Allows movement to occur Converts sensory stimulus → electrical impulse ○ e.g: pain, temperature, light touch Focused on Peripheral Nerves & it always has: ○ Motor → Muscles ○ Sensory → Skin Palmar Interossei Hypoesthesia: Affectation of a particular nerve will make the PALMAR INTEROSSEI (4) muscle paralyzed and the skin being supplied by the nerve to First arises from the base of first metacarpal; have no sensation at all remaining three from anterior surface of Origin shafts of second, fourth, and fifth THE BRACHIAL PLEXUS metacarpals Supplies the nerves of the upper limbs Proximal phalanges of thumb and index, ○ Each segment of the spinal cord has a pair of spinal Insertion ring, and little fingers and dorsal extensor nerves that exit the intervertebral foramen expansion of each finger Location: Posteriorly to the clavicle Nerve Supply Deep branch of ulnar nerve ○ Clavicular fracture can affect brachial plexus Nerve Roots C8, T1 Spinal cord – Has 31 pairs of nerves that is divided into 5 Adduct fingers toward the center of third parts: finger; Both dorsal and palmar interossei flex 1. Cervical – 8 segments (C1 to C8) Action metacarpophalangeal joints and extend C8 has no corresponding vertebra interphalangeal joints C8 emerges between C7 and T1 C5, C6, C7, C8, & T1 supply the upper limb 2. Thoracic - 12 segments (T1 to T12) Module 2B Muscles and Nerves of the Upper Limb 17  3. Lumbar - 5 segments NON-MAMRU NERVES INNERVATING UL MUSCLES 4. Sacral - 5 segments 5. Coccyx - 1 segment NERVES (Non-MAMRU) SUPPLIED MUSCLES Vertebral column – Encased within the spinal cord Lateral Pectoral Nerve Pectoralis Major ○ Cervical Vertebra: C1-C7 Pectoralis Major ○ Thoracic: T1 - T12 Medial Pectoral Nerve Pectoralis Minor Roots – Peripheral nerves exiting from the vertebral column Long Thoracic Nerve Serratus Anterior ○ 5 roots: C5, C6, C7, C8, T1 Cranial Nerve XI or Spinal Trunks & Divisions Trapezius Accessory Nerve ○ Each trunk has a posterior division and an anterior Thoracodorsal Nerve Latissimus Dorsi division Levator Scapulae ○ Upper trunk - C5 and C6 joined together Dorsal Scapular Nerve Rhomboid Minor Divisions: Rhomboid Major Anterior Supraspinatus Posterior Suprascapular Nerve Infraspinatus ○ Lower trunk - C8 and T1 joined together Upper Subscapular Nerve Subscapularis Divisions: Anterior Subscapularis Lower Subscapular Nerve Posterior Teres Major ○ Middle trunk - formed by C7 Divisions: LATERAL AND MEDIAL PECTORAL NERVES Anterior Muscles Supplied: Pectoralis Major and Pectoralis Minor Posterior ○ Pectoralis Major: Dually innervated by the Lateral and Cords Medial Pectoral Nerves ○ Medial cord - Formed by the anterior of lower trunk (C8 Larger, thus it receives 2 nerves & T1) ○ Pectoralis Minor: Innervated by Medial Pectoral Nerves ○ Lateral cord - Formed by the interior of the middle trunk only (C7) and upper trunk (C5 and C6) ○ Posterior cord - Formed by all posterior uniting at the Memory Aid: Less Lateral, More Medial back More Medial → 2 muscles (more) are innervated by the Medial Branches Pectoral Nerve ○ Musculocutaneous Nerve - Formed by the lateral cord Less Lateral → Only one muscle (less) innervated by the (split into two) Lateral Pectoral Nerve ○ Ulnar Nerve - Formed from half of the medial cord Lateral and Medial Pectoral Nerve are sub-branches of the ○ Median Nerve - Formed from the other half of the medial brachial plexus cord and the other half of the lateral cord ○ Coming from the lateral and medial cord of the brachial ○ Axillary Nerve - Formed by the smaller posterior cord plexus, respectively ○ Radial Nerve - Formed by the bigger posterior cord ○ Named after their origins from the cords of the brachial plexus Memory Aid: YIY (roots) XZ with an inverted Z (divisions to cords) Lateral Pectoral Nerve (Supplying the Pectoralis Major) Branching from the Lateral Cord of the Brachial Plexus VVV with M – cords to branches MAMRU - branches *must know RoTonDa sa CuBao - to remember the classification of divisions under brachial plexus (from roots to branches) Medial Pectoral Nerve (Supplying the Pectoralis Major) Branching from the Medial Cord of the Brachial Plexus Module 2B Muscles and Nerves of the Upper Limb 18  Medial and Lateral Pectoral Nerve Relative to the Pectoralis Minor Trapezius Muscle LONG THORACIC NERVE Muscle Supplied: Serratus Anterior Damage to the Long Thoracic Nerve → Paralyzed Serratus Anterior → Winged Scapula Deformity ○ Usually the long thoracic nerve may be affected during breast surgery Spinal Accessory Nerve Supplying the Trapezius Muscle Cranial Nerve: Supplies the sternocleidomastoid muscle THORACODORSAL NERVE Muscle Supplied: Latissimus dorsi Long Thoracic Nerve Supplying the Serratus Anterior Comes from the brachial plexus specifically C6, C7, C8 of the posterior cord Chest Tube Thoracostomy: Surgical operations involving the chest tube to collect or drain fluid, wherein the long thoracic nerve can be damaged in the procedure Where in the brachial plexus does the long thoracic nerve come from? [Snell’s Clinical Anatomy by Regions, 10th Edition] Long thoracic nerve (C5 to C7) arises from the roots of the brachial plexus in the neck and enters the axilla by passing down over the lateral border of the first rib deep to the axillary vessels and brachial plexus. It descends over the superficial surface of the serratus anterior muscle, which it supplies. CRANIAL NERVE Muscle Supplied: Trapezius ○ Supplied by Cranial Nerve XI (11) or the Spinal Posterolateral view of the back Accessory Nerve From the brain, it goes down along the neck to supply the trapezius Among the muscles that move the upper limb, it is the only one supplied by a cranial nerve ○ Cranial nerve comes from the brainstem Damage to the Cranial Nerve → Paralyzed Trapezius → Patient would not be able to shrug the shoulder ○ Patients stabbed in the neck may have cut spinal accessory nerve Module 2B Muscles and Nerves of the Upper Limb 19  Anterior View of the Thoracodorsal Nerve DORSAL SCAPULAR NERVE Anterosuperior of the Right Scapula Muscle Supplied: Rhomboid minor, rhomboid major, Levator scapulae Comes from the brachial plexus specifically the root of C5 Muscles Innervated by the Suprascapular Nerve Muscles Innervated by Dorsal Scapular Nerve Posterior View of Suprascapular Nerve Innervating the Dorsal Scapular Nerve Innervating the Right Rhomboid Infraspinatus Major SUBSCAPULAR NERVE Dorsal Scapular Nerve: Runs parallel to the vertebral border of Divided into two: Upper and Lower Subscapular Nerve the scapula ○ Muscle Supplied (Lower): Teres Major ○ Muscle Supplied (Both or Dual Innervation): SUPRASCAPULAR NERVE Subscapularis Muscle Supplied: Supraspinatus and Infraspinatus Both subscapular nerves come from the C5 and C6 of the Passes through the suprascapular notch to supply the posterior cord supraspinatus and infraspinatus Comes from the upper trunk of C5 and C6 Module 2B Muscles and Nerves of the Upper Limb 20  Musculocutaneous Nerve from Complete Anatomy Muscles being Innervated by the Subscapular Nerve Upper and Lower Subscapular Nerve Innervating the Subscapularis BRANCHES OF THE BRACHIAL PLEXUS Isolated image of the Musculocutaenous Nerve MAMRU IMPORTANT: Know the course, location, muscles being Scenario 1: A patient with superficial lacerated wound in the supplied, and skin territory of each nerve interior arm Sensory innervation: Skin Findings: NOT a musculocutaneous injury Motor innervation: Group of muscles being supplied Reason: The nerve is located deep under the biceps brachii Scenario 2: Gunshot wound that traversed the arm & went through the posterior compartment Findings: A musculocutaneous injury Reason: A deep hacking wound that you can view the humerus Affectations: Elbow & shoulder flexion, weak forearm supination, loss of sensation on the lateral side of the forearm AXILLARY NERVE Origin: Posterior cord Location: Surgical neck of the humerus ○ Circumflex humeral artery is also found on the surgical neck of the humerus Summary map of the primary location of MAMRU nerves Fracture involving the surgical neck will affect the axillary nerve or the circumflex humeral artery MUSCULOCUTANEOUS NERVE Sensory innervation: Skin near the deltoid area Origin: lateral cord Muscle innervation: Deltoid, Teres minor Supplies the anterior fascial compartment of the arm ○ Muscles: Biceps brachii, brachialis, & coracobrachialis Movement ○ Extends beyond the elbow and will go further into the forearm Supplies sensation on the lateral side of the forearm Location: Just beneath the biceps brachii ○ Sandwiched between the biceps brachii and the deeper muscles (e.g. coracobrachialis and brachialis muscles) Module 2B Muscles and Nerves of the Upper Limb 21  Axillary Nerve from Complete Anatomy ○ Anterior fascial compartment of the forearm ○ Thenar eminence Axillary nerve injury: Loss of sensation on the skin near the ○ Lumbricals 1 - index finger deltoid area; Difficulty in shoulder abduction (up to 20°) = ○ Lumbrical 2 - middle finger Impacted supraspinatus; In addition, rupture involving the ○ EXCEPTIONS surgical neck of the humerus can also affect the axillary nerve. Flexor carpi ulnaris → ulnar nerve Medial half of flexor digitorum profundus → ulnar nerve MEDIAN NERVE Skin innervation: More on the palmar surface of the hand ○ 3 ½ skin of the fingers (½ of ring finger) RADIAL NERVE Origin: Posterior cord Skin innervation: Posterior compartment of the arm and forearm, including the posterior dorsum of the hand Muscle innervation: entirety of posterior fascial compartment of the arm and forearm; no exception to the rule Course: Through the spiral groove of the humerus ○ Profunda brachii artery: Also passes through the spiral groove; supplies the posterior compartment of the arm Spiral fracture involving the humeral shaft will affect both profunda brachii and radial nerve. – Memory Aid: Triceps brachii: Only muscle found in the posterior fascial 3 ½ fingers forms the letter “M” when inverted (posterior) - compartment of the arm originates from the Median nerve ○ Damaged radial nerve in the brachium will lead to paralyzation Other 1 ½ formed the letter “U” - originates from the Ulnar nerve ○ Movement affected: Extension of the elbow, wrist drop Wrist drop deformity Ring finger is shared by the media and ulnar nerve ULNAR NERVE Location: Medial to the biceps brachii Does not have any role as far as the arm is concerned ○ Also positioned to the medial side of the brachial artery (similar to medial nerve) - passes through only Arrangement: TAN - tendon, artery, nerve Accompanies brachial artery Tendon of Biceps Brachii → Brachial Artery → Skin innervation: Medial side of the hand and ½ medial side Median Nerve of the ring finger Accompanies the brachial artery until it reaches the cubital At the elbow, the medial nerve will course anteriorly entering fossa the cubital fossa but the ulnar nerve will course posteriorly to the medial epicondyle Question: Does it supply all the muscles in the arm region? ○ Stimulated when elbow hits a surface Answer: No, it only passes through the arm & only innervates Muscle: the forearm ○ Flexor carpi ulnaris (forearm) ○ Medial half of flexor digitorum profundus(forearm) Course: Disappears as it enters the cubital fossa and ○ Wrist and hand - territory of the ulnar nerve courses under the pronator teres ○ EXCEPTIONS ○ Occupation that utilizes the pronator teres Thenar Eminence → Median Nerve Carpenter, mechanics: Those who use screwdrivers Lumbrical 1 and 2 → Median Nerve ○ Hypertrophy: increase the diameter of the muscle due to being used often Hypertrophy of pronator teres - since the median nerve will pass under the pronator teres it can now compress on the nerve → Pronator teres syndrome ○ Atrophy: Muscle is not used; shrinkage of muscle Together with the ulnar artery, passing in between the FDS (flexor digitorum superficialis) and FDP (flexor digitorum profundus) continue to descend until reaches the wrist area where it will pass under the flexor retinaculum ○ Flexor retinaculum – connective tissue that converts the concave shape of the carpal into a tunnel Median nerve - primary nerve that will enter the carpal tunnel 10 structures that will cross the carpal tunnel: ○ Tendons of the FDS (4) ○ Tendons of the FDP (4) ○ Flexor pollicis longus (1) ○ Median nerve (1) - only nerve passing through the carpal tunnel Hypertrophy can compress the median nerve Muscles Module 2B Muscles and Nerves of the Upper Limb 22