Hand: Extrinsic Muscles PDF

Nomenclature: The Hand Phalanges/Digits Thumb D1 Metacarpals Index (Pointer)- D2 Phalanges Long (Middle) - D3 A “Ray”= metacarpal and a phalange Ring-...

Nomenclature: The Hand Phalanges/Digits Thumb D1 Metacarpals Index (Pointer)- D2 Phalanges Long (Middle) - D3 A “Ray”= metacarpal and a phalange Ring- D4 i.e.- the index ray Small – D5 Bones of the Hand: Bones of the Hand: Ray Bony Landmarks: Base is the more proximal aspect of the metacarpal Head is the more distal aspect Neck is below the head Joint Structures Carpometacarpal Joint (CMC) Articulation between proximal end of a metacarpal and distal row of carpal bones Metacarpophalangeal Joint (MCP or MP) Articulation between the distal ends of the metacarpals and the proximal phalanges Interphalangeal Joint (IP) Proximal IP Distal IP Articulation between the phalanges CMC Joints Type of Joint: Non-axial plane (irregular) synovial joint Articulation Between: Thumb: trapezium & 1st metacarpal Index: Trapezoid & base of 2nd metacarpal Long: Capitate & base of 3rd metacarpal Ring: Hamate & base of the 4th metacarpal Small: Hamate & base of the 5th metacarpal Mobility versus Stability: Thumb CMC: High Mobility, Low Stability 2nd and 3rd CMC: Low Mobility, High Stability 4th CMC: Slight Mobility, High Stability 5th CMC: Slight Mobility, High Stability The 5th CMC joint is the most mobile of the fingers and allows for a small amount of finger opposition, but not as much as the thumb. CMC Joints: Interactive Activity 1. Start with the forearm supinated and elbow flexed. 2. Form a relaxed fist. 3. Note that with a relaxed fist, the MCP joints are essentially in a straight line. 4. Now make a tight fist. 5. What do you notice about the movements at the MCP joints? 6. When you make a tight fist, the 5th MCP moves a great deal, 4th MCP moves slightly and 2nd and 3rd MCP remains stationary. 1. That movement is initiated at the CMC.  “Knuckles” Type of Joint: Biaxial Condyloid Joints Rounded heads of metacarpals articulate with base of concave phalanges Motions: Flexion & Extension Hyperextension Abduction & Adduction Volar plate on volar surface prevents hyperextension MCP Joints: Motions The middle finger is the point of reference for abduction and adduction Abduction: Occurs when the 2nd, 4th and 5th fingers move away from the 3rd finger. Also occurs when the 3rd finger moves in either direction Adduction: Occurs when the 2nd, 4th, and 5th fingers return from abduction and move toward the 3rd finger. There is no adduction of the middle (3rd) finger, only abduction occurring in either direction Interphalangeal Joint (IP) Type of Joint: Uniaxial Hinge Joints Joint Motions: Flexion & Extension Digit 1 (Thumb): 1 IP Joint Digits 2-5: 2 IP Joints PIP  Proximal DIP  Distal Joint Motion: Digits 2-5 Flexion Extension ABduction ADduction Thumb CMC Joint: Review Trapezium articulates with the base of the 1st metacarpal Type of Joint Saddle Joint Concave & Convex Surfaces Note: This joint is sometimes described as a modified ball and socket joint, which implies that it has motion in all three planes. There is rotation at the CMC joint with opposition, which is involuntary and occurs as a result of the joint’s shape. Considered: Accessary Motion Thumb CMC Joint: Motions Flexion / Extension Occur in a plane parallel to the palm (frontal plane) Palmar Abduction / Adduction Occur in a plan perpendicular to the palm (sagittal plane) Opposition / Reposition Opposition is a combination of flexion and abduction, with accessory rotation Reposition is the return to anatomical position Bones and Landmarks: Review 5 MCPs 5 Proximal Phalanges 4 Middle Phalanges 5 Distal Phalanges Proximal end of the metacarpal and phalanges is called the base Distal end of the metacarpal and phalanges is called the head Ligaments and Other Structures Flexor retinaculum: A fibrous band that spans the anterior surface of the wrist in a mediolateral (horizontal) direction Function # 1: Hold tendons close to the wrist (preventing the tendons from puling away during wrist flexion). Function # 2: Prevents the two sides of the carpal bones from separating. Split into the palmar carpal ligament & transverse carpal ligament Ligaments and Other Structures Palmar Carpal Ligament Transverse Carpal Ligament More proximal and superficial Lies deeper and more distal Distal fibers blend with the Attaches to the pisiform and transverse carpal ligament hook of the hamate on the Attaches to the styloid medial side and to the scaphoid processes of the radius and ulna and trapezium laterally and crosses over the flexor Arch over the carpal bones muscles forming a tunnel through which the median nerve and 9 extrinsic flexor tendons pass Ligaments and Other Structures Ligaments and Other Structures: Carpal Tunnel Median FDS (4) Nerve FDP (4) FPL (1) Ligaments of the Hand and Other Structures Extensor Retinaculum Fibrous band crossing on dorsal side Attaches medially to the ulnar styloid and laterally to the triquetrum, pisiform and radius Function: Holds extensor tendons close to wrist during wrist extension Divided into six sections (tunnels) called dorsal compartments Ligaments of the Hand and Other Structures: Dorsal Compartments 1st: Abductor Pollicis Longus (APL) Apple (APL) in 1st Extensor Pollicis Brevis (EPB) 2 muscles in 1st *2nd: Extensor Carpi Radialis Longus (ECRL) 2 muscles in 2nd Extensor Carpi Radialis Brevis (ECRB) 3rd: Extensor Pollicis Longus (EPL) 1 muscle in 3rd 4th: Extensor Digitorum Communis (EDC) Extensor Indicis Proprius (EIP) 2 muscles in 4th 5th: Extensor Digiti Minimi (EDM) 1 muscle in 5th 5th compartment to 5th finger *6th: Extensor Carpi Ulnaris (ECU) 1 muscle in 6th *  Ligaments of the Hand and Other Structures Extensor Expansion Ligament ”Extensor Hood” A small, triangular, flat aponeurosis covering the dorsum and sides of the proximal phalanx of the fingers * This will be discussed in- depth in a separate lecture *  Arches of the Hand Longitudinal Transverse Starts at wrist and goes to tip Distal – Metacarpal Heads Proximal – CMC Joints When the hand is relaxed, the palm assumes a cupped position. This palmar concavity is due to the arrangement of the bony skeleton reinforced by ligaments. Function: Arches of hand allow for high level of function with various grasp patterns  Creases 1 Distal palmar crease 2 Proximal palmar crease 3 Thenar crease 4 Distal wrist crease 5 Proximal wrist crease Thenar eminence Extrinsics Muscles of Thumb & Fingers Extrinsic muscles have an origin above the wrist and have an insertion inside of the hand. Cross the wrist and the joints in the hand Primary Function: Finger motion Secondary Function: Wrist motion (Weak)  Extrinsic Muscles Anterior: Flexor Digitorum Superficialis (FDS) Flexor Digitorum Profundus (FDP) Flexor Pollicis Longus (FPL) Posterior: Abductor Pollicis Longus (APL) Extensor Pollicis Brevis (EPB) Anatomical Snuff Box Extensor Pollicis Longus (EPL) Extensor Digitorum Communis (EDC) Extensor Indicis (EI) Extensor Digiti Minimi (EDM)  Flexor Digitorum Superficialis O. Medial Epicondyle of Humerus (common flexor origin), coronoid process & medial collateral ligament I. Anterior margin of the base of 2nd – 5th middle phalanx A. Flexion of PIP; Secondary MCP Flexion (2nd-5th Digits) N. Median nerve  Flexor Digitorum Profundus O. Medial olecranon, anterior and medial ulna & interossseous membrane I. Base of the 2nd - 5th distal phalanges A. Flexion of DIP, Secondary MCP and PIP Flexion (2nd – 5th Digits) N. Median N. (2nd and 3rd) & Ulnar N. (4th & 5th) Relationship of the Profundus and Superficialis Insertions Profundus Superficialis Flexor Pollicis Longus O. Radius, anterior surface and interosseous membrane I. Distal phalanx of thumb A. Flexes all joints of the thumb N. Anterior Interosseous (Median)  Abductor Pollicis Longus O. Posterior radius, interosseous membrane, middle ulna I. Base of the thumb metacarpal A. Radial abduction of thumb N. Radial nerve Note: It effectively abducts the thumb at the CMC even though it is attached only to the metacarpal because the MCP and IP only allow flexion and extension; therefore the thumb moves as one unit in the direction of abduction Extensor Pollicis Brevis O. Posterior distal radius I. Base of the proximal phalanx of thumb A. Extends MCP joint of thumb N. Radial nerve  Extensor Pollicis Longus O. Middle posterior ulna and interosseous membrane I. Base of distal phalanx of thumb A. Extension of thumb IP N. Radial nerve Anatomical Snuff Box Deep depression on dorsal base of thumb Formed by 3 tendons: Radial (Lateral) Side 1- Abductor Pollicis Longus 2- Extensor Pollicis Longus Ulnar (Medial) Side: 3- Extensor Pollicis Brevis Extend your thumb and you will notice a depression formed between the tendons What bone is found in this depression? Extensor Digitorum O. Lateral epicondyle of humerus I. Base of middle and distal phalanx of 4 fingers (extensor mechanism) A. Extension all three joints of fingers N. Radial nerve Note: The only common extensor muscle of the digits  Extensor Indicis O. Distal Ulna I. Base of distal phalanx of 2nd finger and dorsal expansion A. Extension of MCP joint of 2nd (Index) Finger N. Radial nerve Extensor Digiti Minimi O.Lateral epicondyle of humerus I. Base of proximal phalanx of small finger and dorsal expansion A. Extension MP joints of 5th finger N. Radial nerve Sensory Innervations Review Questions: 1. Which finger and thumb motions occur in the frontal plane? 2. Which finger and thumb motions occur in the sagittal plane? 3. Which finger and thumb motions occur in the transverse plane? 4. How many bones comprise one thumb? 5. How many bones comprise one finger? 6. How many joints comprise the thumb? What are the names of these joints? 7. How many joints comprise the finger? What are the names of these joints? 8. Which thumb opposition motion is considered an accessory motion? 9. Which tendons and nerve runs through the carpal tunnel? 10. What is an extrinsic muscle? 11. What is the ”anatomical snuffbox”? Which muscles act as the borders of this area?  Name – Flexor Digitorum Superficialis O. Medial epicondyle of humerus, coronoid process of ulna, and radial tuberosity medial collateral ligament I. Base of middle phalanx of digits 2-5 A. Flexion of PIP joints N. Median  Name – Flexor Digitorum Profundus O. Medial and anterior ulna, coronoid process Medial olecranon, and interosseous membrane I. Base of distal phalanxes 2-5 A. Flexion of DIP joints N. Median (2 and 3) and ulnar (4 and 5) Name – Flexor Pollicis Longus O. Interosseous membrane, anterior surface of radius I. Base of distal phalanx of thumb A. Flexion of thumb at all joints N. Median  Name Abductor Pollicis Longus O. Posterior surface of ulna, interosseous membrane, and distal posterior surface of radius I. Base of 1st metacarpal A. Radial Abduction of thumb N. Radial Name Extensor Pollicis Longus O. Posterior ulna and interosseous membrane I. Base of distal phalanx of thumb A. Extension of thumb at all joints IP joint N. Radial  Name Extensor Pollicis Brevis O. Interosseous membrane, and distal posterior radius I. Base of proximal phalanx of thub A. Extension of the MCP joint N. Radial Name Extensor Digitorum Communis O. Lateral Epicondyle of humerus I. Base of middle and distal phalanx of digits 2-5, dorsal expansion A. Extension of all joints for digits 2-5 N. Radial  Name Extensor Indicis O. Distal medial surface of ulna, interosseous membrane I. Base of distal phalanx of digit 2 and dorsal expansion A. Extension of MCP joint of 2nd digit N. Radial Name Extensor Digiti Minimi O. Lateral epicondyle of humerus I. Base of distal proximal phalanx of 5th finger and dorsal expansion A. Extension of 5th finger at all joints MP joints N. Radial Intrinsics (Intrinsic Muscles of Hand)  Muscle originates and inserts within the hand  Proximal attachment at or distal to the carpal bones  Intrinsic “in the hand”  Function:  Motion of thumb and fingers  Responsible for precision and fine motor control Intrinsic Muscles of Hand Thenar Muscles  Form thenar eminence  Act to move the thumb Hypothenar Muscles  Form hypothenar eminence  Act primarily on little finger Deep Palm Muscles  Act to move the lumbricals and interossei as well as one thumb muscle  The muscles located between the thenar and hypothenar  Intrinsic Muscles of the Hand: Thenar Flexor Pollicis Brevis (FPB) Abductor Pollicis Brevis (APB) Opponens Pollicis (OP)  Thenar - Flexor Pollicis Brevis O. Trapezium & Flexor Retinaculum I. Proximal phalanx A. Flexion MCP joint of thumb N. Median nerve Thenar - Abductor Pollicis Brevis O. Scaphoid, trapezium & flexor retinaculum I. Proximal phalanx A. Abducts the thumb N. Median nerve ** Note: APB is first muscle innervated by the median nerve after the carpal tunnel therefore its health and function is measured for carpal tunnel syndrome  Thenar- Opponens Pollicis O. Trapezium & flexor retinaculum A. First metacarpal I. Opposes the thumb N. Median nerve **Note: OP is innervated by the median nerve after the carpal tunnel so therefore its health and function is measured when carpal tunnel syndrome is suspected Intrinsic Muscles of the Hand: Hypothenar Flexor Digit Minimi (FDM) Abductor Digiti Minimi (ADM) Opponens Digiti Minimi (ODM) Hypothenar - Flexor Digiti Minimi O. Hamate and flexor retinaculum I. Base of proximal phalanx of the 5th finger A. Flexes CMC & MCP of 5th finger N. Ulnar nerve  Hypothenar - Abductor Digiti Minimi O. Pisiform & tendon of flexor carpi ulnaris I. Proximal phalanx of small (5th ) finger A. Abducts MP of 5th finger N. Ulnar nerve Hypothenar - Opponens Digiti Minimi O. Hamate & flexor retinaculum I. 5th metacarpal A. Opposition of small (5th) finger N. Ulnar nerve Note: Deep to the other hypothenar muscles Instrinsic Muscles of Hand: Deep Palm  Adductor Pollicis (AP)  Dorsal Interossei (DAB)  Palmar Interossei (PAD)  Lumbricals Adductor Pollicis (Deep) O. Capitate, base of 2nd metacarpal, palmar surface of 3rd metacarpal I. Base of proximal phalanx of thumb A. Adducts thumb N. Ulnar nerve Note: Not considered part of the thenar group as it is located deep and does not make up the bulk of the thenar eminence  Dorsal Interossei - Deep O. 2 metacarpal bases – adjacent (bipennate muscle) I. Base of proximal phalanx & dorsal apparatus and EDC A. Abduct fingers at MCP, flex MP joint, extend PIP (DAB) N. Ulnar nerve Palmar Interossei - Deep O. Base and Shaft of metacarpal I. Base of proximal phalanx, dorsal expansion and EDC A. Adduct fingers at MCP (PAD) N. Ulnar nerve Note: The palmar interossei do not attach or have function on the middle finger Palmar interossei (PAD): Palmar-ADducts Dorsal interossei (DAB): Dorsal-ABducts  Lumbricals O. Tendon of flexor digitorum profundus I. Tendon of extensor digitorum muscle A. Flex the MCP, extend IP N. Median nerve (1st & 2nd), Ulnar nerve (3rd & 4th) Lumbricals: Flex MP’s, Extend IP’s Review Questions: 1. What is an intrinsic muscle? 2. Explain the difference between the thenar muscles and hypothenar muscles. Provide an example of each. 3. What hand muscle does not have a bony attachment? To what two tendons does it attach? Flexor Ligamentous Structures Collateral Ligaments Pulleys Cruciate Ligaments Collateral Ligaments Located on the lateral aspect of the DIP, PIP and MCP joints Radial Collateral Ligaments Stabilizes Laterally Ulnar Collateral Ligaments Stabilizes Medially Pulley System - There are 5 flexor tendon pulleys in the fingers that are named A1 to A5. - The thumb only has 2 pulleys that are named A1 and A2. - The flexor pulley system consists of: - Palmar Aponeurosis Pulley - (5) Annular Pulleys - (3) Cruciform Pulley - Together they form a fibro-osseous tunnel on the palmar aspect of the hand through which the deep and superficial flexor tendons pass. - Function: The flexor tendon pully system maintains flexor tendons close to the joint’s axis of motion and prevents bowstringing.  Pulley System: Annular Ligaments Annular ligaments A2 and A4 are critical to prevent bowstringing most biomechanically important A1, A3, and A5 overlie the MP, PIP and DIP joints respectively originate from palmar plate  Pulley System: Cruciform Pulleys Cruciform Pulleys Three pulleys that function to prevent sheath collapse and expansion during digital movement C1 Pulley: Just Distal to A2 Pulley C2 Pulley: Between A3 and A4 Pulleys C3 Pulley: Distal to A4 Pulley Pulley System: A1, A2, A3, A4, A5 Pulley System: Dysfunction  Pulley System: Dysfunction Inflammation causes swelling and nodules (bumps) on tendon which can get stuck on pulley  Trigger Finger Stages Stage 1: Stage 2: Stage 3: Tenderness Clicking & Stuck Catching Extensor Mechanism Extensor Mechanism  The extensor mechanism is an elaboration of the EDC tendon on the dorsum of each phalanx.  The EI and EDM insert into the extensor mechanism of the second and fifth digits, respectively.  Several tendinous structures comprise the extensor mechanism, including:  EDC Tendon  Central Tendon  Lateral Bands  Extensor Hood  Oblique Retinacular Ligament  Extensor Mechanism 1. The EDC tendon attaches by a tendinous slip to the proximal phalanx, through which it extends the MP joint. 2. The central tendon (slip) proceeds dorsally to attach to the base of the middle phalanx 1. Tension in the central tendon (slip) can extend the PIP joint  Extensor Mechanism 3. The lateral bands proceed on either side of the dorsal midline and rejoin before attaching to the distal phalanx. Tension in the lateral bands extends the DIP joint. Extensor Mechanism 4. The extensor hood surrounds the MP joint laterally, medially and dorsally and receives tendinous fibers from the lumbricals and interossei.  Extensor Mechanism 5. Fibers of the oblique retinacular ligament (ORL) attach at the sides of the proximal phalanx and digital tendon sheaths and proceed to distal portion of the lateral bands. Extensor Mechanism Dysfunctions 1- Mallet Finger 2-Boutenierre Deformity 3-Swan Neck Deformity 4- Intrinsic Minus Hand Extensor Mechanism Dysfunction: Mallet Finger A finger joint deformity caused by disruption of the terminal extensor tendon distal to the DIP joint Extensor Mechanism Dysfunction: Boutonneire Deformity The finger is flexed at the PIP joint and hyperextended at the DIP joint caused by injury to the central slip Extensor Mechanism Dysfunction: Swan Neck Deformity The finger is hyperextended at the PIP and flexed at the DIP caused by a laxity of the volar plate or imbalance of muscle forces at the PIP (extension > flexion force)  Name – Flexor Pollicis Brevis O Flexor retinaculum and trapezium I proximal phalanx of thumb A Flexes thumb at MCP N Median Name – Abductor Pollicis Brevis O Trapezium, Scaphoid and Flexor retinaculum I Proximal phalanx of thumb A abducts the thumb N Median  Name – Opponens Pollicis O Flexor Retinaculum, trapezium, scaphoid I Lateral surface of proximal phalanx first metacarpal A Opposes the thumb N Median Name Flexor Digiti Minimi O Hamate and flexor retinaculum I Base of distal proxima phalanx of 5th finger A Flexes 5th finger at all joints Flexes CMC and MCP of 5th finger N Ulnar  Name – Abductor Digiti Minimi O Ligament tendon of flexor carpi ulnaris, Hamate, lunate Pisiform I Base of proximal phalanx of 5th finger A Abducts the MP of 5th finger N ulnar Name Opponens Digiti Minimi O Lunate, Hamate, and Flexor retinaculum I 5th metacarpal A Opposes the 5th finger Note: Deep to the N Ulnar other hypothenar muscles Name – Adductor Pollicis O Capitate, base of 2nd metacarpal, and lateral surface of 3rd metacarpal I Proximal phalanx of thumb A Adducts the thumb N Median  Name – Dorsal Interossei O Adjacent bases between metacarpals I Proximal bases of phalanx, dorsal expansion, EDC A Abduct the metacarpals of digits 2-5 N Radial Ulnar Name – Palmar Interossei O Lateral surface of metacarpals 4 and 5 and medial surface of 1st metacarpal Base and shaft of metacarpal I Base of Proximal phalanx of digits 2, 4, and 5, Dorsal apparatus and EDC A Adduct the metacarpals for digits 2, 4, and 5 N Median Ulnar  Name - Lumbricals O – tendon of the flexor digitorum profundus I tendon of the extensor digitorum A flexes the MCP and extends the PIP IP joints of digits 2-5 N Median (2 and 3 digits) and ulnar (4 and 5 digits) Hand Function OT 505 Module 4.4 Functional 0-25 Position ´ Defined as MCP in 50-70 deg flexion and slight flexion of IP’s to allow for optimal position for the wrist and hand ´ Most effective position for hand use including strength and precision  Hand Performs many Functions ´ Grasp- is the primary function of the hand. ´ Hand is designed to hold and manipulate objects ´ Proximal muscles give stability ´ Prehension - grasping and manipulating an object ´ Power Grip- forceful grasp using and isometric contraction (i.e. hammer, doorknob) ´ Prehension grip - object is being manipulated by finger movement (holding a pin, threading a needle)  Grasp Patterns Spherical Grasp Cylindrical Grasp Develops between 18 months and 3 years Power Grip - Spherical All fingers and thumb abduct around an object. Palm of hand not involved - Mostly finger tips Examples: apple doorknob Power Grip - Cylindrical Fingers flexed around the object with thumb wrapped around the object. Fingers adducted, object pressed against palm i.e. hammer Variation would be holding a screwdriver Power – Hook Fist 2nd - 5th digits flexed around object Flexor digitorum profundus and superficialis contracting. Holding a handle i.e. suitcase, bucket  Which muscle is activated primarily for a straight fist? TENDON GLIDES Precision grips (pinch) ´ Tripod ´ Involves thumb and 1st 2 digits ´ Pincer/tip to tip ´ Pick up small objects i.e. toothpick ´ Lateral prehension (key) ´ Thumb on lateral side of index finger ´ Most powerful  Pinch Patterns: Application What muscles are involved with this pinch? Identify 2 occupations that one may use a 3-point pinch/tripod grasp for. 3 Point Pinch Aka Tripod “grasp” Aka three draw chuck  Pinch Patterns: Application What muscles are involved with this pinch? What activities in a child require a pincer /2 point pinch? What occupations in an adult require a 2 point or pincer pinch? Pincer Grasp aka Two Point Pinch  Pinch Patterns: Application What muscles are involved with this pinch? What activities require a lateral pinch? “ Key “ Pinch aka Lateral Pinch Lumbrical Plus pinch ´ Strong pinch using lumbrical muscles ´ i.e. hold a plate Progression of grip Writing Grasp Patterns Pediatric Development of Grasp http://media-cache-ak0.pinimg.com/originals/ 18/30/c5/1830c59d9e3467ed8e359f9424c53bb0.jpg https://s-media-cache-ak0.pinimg.com/ 564x/72/9c/c8/729cc8abca6b6af830d277bfafae354d.jpg Grasp Pattern Dysfunction COMMON WRIST AND HAND PATHOLOGIES OT 505 Module 4.3  COLLES’ FRACTURE A common injury of elderly people, resulting from a fall on the outstretched hand This transverse fracture of the distal radius includes a posterior displacement of the distal fragment  SMITH’S FRACTURE An injury caused by a fall on the back of the hand This transverse fracture of the distal radius includes an anterior displacement of the distal fragment  GREENSTICK FRACTURE Refers to an incomplete fracture, usually of the radius and more proximal than a Colles’ fracture More common in children than adults This fracture is similar to the breaking of a young or new tree limb: If you try to break the limb, you will find that it does not break completely in half  GANGLION CYST A benign tumor mass commonly seen as a bump on the dorsal surface of the wrist They commonly develop along the tendons or joints of the wrist and hand They are typically round or oval and are filled with a jelly like fluid They can be painful if they press on a nearby nerve Their location can sometimes interfere with joint movement  C ARPAL TUNNEL SYNDROME An extremely common condition caused by compression of the median nerve within the carpal tunnel Symptoms Include: Numbness, tingling and weakness of the thumb, index and middle fingers  DE QUERVAIN’S DISEASE Caused by inflammation and thickening of the sheath containing the EPB and APL Because it is an inflammation of tendons and their surrounding sheaths it is called a tenosynovitis Symptoms Include: Pain on the radial side of the wrist  TRI G G E R F I N G E R: STE N O SI N G TE N O SYN OVITIS A disorder with the sliding mechanism of a tenon in its sheath When a nodule or swelling of the sheath lining or the tendon develops, the tendon can no longer slide in and out smoothly It may pass into the sheath when the finger flexes, but it becomes stuck as the finger attempts to extend The flexor tendons of the middle and ring fingers are the most commonly involved  DUPUTYREN’S CONTRACTURE Occurs when the palmar aponeurosis undergoes a nodular thickening It is most common in the area of the palm in line with the ring and little fingers These fingers will typically develop flexion contractures  SKIER’S THUMB Also known as “Gamekeeper’s Thumb” A common hand injury among athletes Involves an acute tear of the ulnar collateral ligament of the thumb  RE VI E W: E X TE N SO R M E C H A NISM DYSF U N C TI ON S 1) What is a swan neck deformity characterized by? 2) What is a boutonniere deformity characterized by? 3) What is a mallet finger? REVIEW OF BRACHIAL PLEXUS: HAND  RADIAL NERVE: PATHWAY The posterior interosseus nerve is a continuation of the deep branch of the radial nerve, which begins at the supinator.  The radial nerve becomes compressed as it RADIAL NERVE spirals around the humerus The name is derived from the nature of the INJURY: SATURDAY injury (a person, often intoxicated, falls asleep NIGHT PALSY with his arm over the back of a chair) There will be a loss of wrist extensors  RADIAL NERVE INJURY: WRIST DROP There is a loss of wrist extension and a weakened ability to release objects (finger extension) This will result from a high radial nerve injury This is often a complication of a mid- humeral fracture  MEDIAN NERVE: PATHWAY The median nerve gives rise to the Anterior Interosseous Nerve (AIN) at the radiohumeral joint line This motor nerve supplies the deep muscles in the anterior forearm: FPL Pronator Quadratus FDP (II and III)  ME DIAN NE RVE INJURY: APE HAND DE FORMITY The thumb demonstrates a loss of opposition and atrophy of the thenar eminence muscles  MEDIAN NERVE INJURY: SIGN OF BENEDICTINE Will be present when making a fist: - The MCP and PIP joints of the 2nd and 3rd finger will be in extended position due to the loss of action of their flexor muscles. The MCP joints of the 4th and 5th fingers will appear flexed due to the normal medial two lumbricals  AIN DYSFUNCTION Compression or dysfunction of the AIN will result in the inability to form an “OK” sign Inability to perform Thumb IP Joint Flexion & IF DIP Joint Flexion ULNAR NERVE: PATHWAY  ULNAR NERVE INJURY: ULNAR CLAW The ulnar claw will be present when extending all digits: Due to the loss of the medial two lumbricals, the RF and SF’s proximal phalanges are in hyperextension and the middle and distal phalanges are in extreme flexion ULNAR & MEDIAN NERVE INJURY: CLAW HAND