Ch 6 Elbow Forearm Anatomy PDF

Elbow and Forearm Chapter 6 PTH516 Pathokinesiology Letrisha Stallard, DPT  Introduction Three bones and four articulations- elbow and forearm complex Designed to serve the hand. ○ Mobility ○ Stability  Osteology Humerus ○ Coron...

Elbow and Forearm Chapter 6 PTH516 Pathokinesiology Letrisha Stallard, DPT  Introduction Three bones and four articulations- elbow and forearm complex Designed to serve the hand. ○ Mobility ○ Stability  Osteology Humerus ○ Coronoid fossa ○ Medial epicondyle – more prominent  Osteology Ulna o Coronoid process o Ulnar head covered with articular cartilage Radius o Head disk-like o Radial tuberosity — biceps brachii muscle  Arthrology of Elbow Humero-ulnar joint Humeroradial joint Classification: modified hinge Humero-ulnar Joint of Elbow Very stable Valgus = angled outward Varus = angled inward M-L axis Valgus angle 13⁰ (SD 6⁰) Female > male (~2⁰) Dominant arm greater valgus angle Pathokinesiology (H-U Joint) Excessive cubitus valgus ~20-25⁰ beyond normal Overstretch and damage ulnar nerve Pathokinesiology (H-U Joint) Humeroradial Joint of Elbow Counters valgus-producing force at elbow ~50% Less congruent: capsuloligamentous connection improves it. Periarticular C.T. Articular capsule ○ Encloses humero-ulnar, humeroradial, and proximal radio-ulnar joints Medial Collateral ligament Lateral Collateral ligament Medial Collateral ligament Anterior fiber bundle Posterior fiber bundle– less defined than anterior fibers Transverse fibers– both insertions on ulna Stabilizing Muscles Dynamic medial stabilizers Wrist flexor group (especially FCU) Pronator teres Pathokinesiology of MCL Valgus force Lateral Collateral Ligament Complex Lateral (ulnar) collateral ligament Radial collateral ligament Pathokinesiology of LCL Relatively uncommon Rupture will lead to: Excess varus Subluxation of humero-ulnar & humeroradial joints Kinematics of Humero-ulnar Joint Degree of freedom: 1 Functional arc: 30-130 degrees Medial View Lateral View Kinematics of Humero-ulnar Joint Flexion 145⁰-150⁰ Ulna rolls and slides palmarly Motion-limiting periarticular C.T. at end range Posterior capsule MCL LCL Kinematics of Humero-ulnar Joint Extension 5⁰ hyperextension Ulnar rolls & slides dorsally Extension = close-packed position Motion-limiting periarticular C.T. at end range Anterior capsule MCL (anterior bundle only) Kinematics of Humeroradial Joint Flexion/Extension Fovea of radius rolling & sliding same direction Radial fovea pulled firmly against capitulum during concentric flexion or eccentric extension Interosseous Membrane Central fibers distal and medial from radius to ulna about 20⁰ Primary functions: Bind radius to ulna Stable attachment site Interosseous Membrane Force transmission proximally through upper limb o Hand → radius → IO membrane → ulna → humerus → scapula Interosseous Membrane Proximal Radio-ulnar Joint Classification: Pivot joints Oblique axis from radial head through the ulnar head Supination/Pronation (proximal R/U) Stand up and put your forearm in neutral position! Supination/Pronation (proximal R/U) Supination = 85⁰ Functional Range = 50⁰ Radial head rotates Pronation = 75⁰ Functional = 50⁰ (100⁰ functional rotation arc)  Supination (proximal R/U) Motion-limiting C.T. Palmar capsular ligament Interosseous membrane  Pronation (proximal R/U) Motion-limiting C.T. Dorsal capsular ligament Distal Radio-ulnar Joint Supination (distal R/U) Supination Rolls and slides dorsally Motion-limiting C.T. Palmar capsular ligament Interosseous membrane Pronation (distal R/U) Pronation Rolls and slides palmarly Motion-limiting C.T. Dorsal capsular ligament Muscle and Joint Interaction Muscles of the Elbow Elbow Flexors Biceps brachii o Combined flexion and supination Brachioradialis o Primarily elbow flexion  Elbow Flexors Pronator teres o Least work o High-power elbow flexion demands Brachialis o Largest physiologic cross-section o Sole function to flex elbow o Workhorse of elbow flexors ( greatest force and is active in any forearm position)  Elbow Flexion Torque 70% greater than extension Maximum torque [80⁰ best for mm length, 100⁰ for MA] Elbow Extensors Triceps brachii o Long head ▪ Greatest volume o Lateral & long heads ▪ Moderate to high demands o Medial head ▪ Workhorse of extensors ▪ Recruited after anconeus Anconeus o Small moment arm o Longitudinal and M-L stability o Initiate (and maintain) low-level extension force Elbow Extensors  Elbow Extension Torque 80⁰ best for mm length Medial Epicondylitis Lateral Epicondylitis Supinators of the Forearm Supinator o Low-power tasks Biceps brachii o Medium and high-power tasks when elbow flexion is also needed o Most effective at 90⁰ Supinator Biceps brachii Supination Torque Pronators Pronator teres o High-power pronation Pronator quadratus o Always active with any pronation  EMG of Forearm Muscles Resisted Pronation Resisted Supination  EMG - Forearm Any Triceps or Biceps activity? Supination:Resisted Isometric Pronation: Resisted Isometric Maximum Grip: Isometric  The Wrist Chapter 7 PTH516 Pathokinesiology Letrisha Stallard, DPT Introduction Radiocarpal, midcarpal, and intercarpal joints. Osteology axis of wrist is in capitate  Dorsal Tubercle of Radius Dorsal tubercle– stabilize/guide tendons, palpable landmark ○ Separates tendons ECRB & EPL ECRL ECRB Dorsal Tubercle EPL  Tilt of Radius ulnar tilt is greater because Scaphoid contacts distally radial styloid process Ulnar tilt 25º – Scaphoid contacts radial styloid process Palmar tilt 10 º palmar tilt helps with flexion  Ulna Styloid process 8 Volunteers needed. Please put your hand up! Carpals Scaphoid (“boat-like”) Contacts 4 ○ Radiocarpal & midcarpal joints Proximal pole –radius Distal pole – trapezium & trapezoid Lunate Most unstable Frequently dislocated Carpals cont. Triquetrum Most ulnarly-Radial deviation to palpate Pisiform Articulates Triquetrum Attachment for muscles and ligaments Trapezium Saddle-shaped Carpals cont. Trapezoid Capitate Articulates 7 bones Axis: M-L for flex/ext; A-P for r/u deviation Hamate Hook-like projection Hook provides attachment site Carpal Tunnel Median nerve and (FDS, FDP, FPL) [not FCU] Wrist Joints Radiocarpal and Midcarpal Radiocarpal Joint – Ellipsoid joint 2 degrees of freedom flexion/ extension ulnar/ radial deviation Radiocarpal- articular disc Midcarpal Joint – Ellipsoid joint Medial compartment Larger Dorsal Radiocarpal Ligaments Restraint against lunate dislocation Taut full flexion Radial Collateral Ligaments Moderate lateral stability Stability from abductor pollicis longus and extensor pollicis brevis Palmar Radiocarpal Ligaments Stronger and thicker Taut in full extension and extension with ulnar deviation Triangular Fibrocartilage Complex 1. Articular disc 2. Distal Radio-ulnar 3. Palmar ulnocarpal 4. Ulnar collateral 5. Fascial sheath  Intrinsic Wrist Ligaments Short ligaments Dorsal, Palmar, Interosseous Intermediate ligaments – 4 Lunotriquetral, Scapholunate, Scaphotrapezial Scaphotrapezoidal Long ligaments –2 Palmar intercarpal - lateral and medial legs and Dorsal intercarpal Kinematics Degrees of Freedom: 2 plus circumduction 2 degrees: flexion/ extension and ulnar/ radial deviation + circumduction (combination of the 2 degrees) Wrist Extension Extension Sagittal plane M-L axis through capitate (head) 60-75 ROM Full extension = close-packed position Central Column of the Wrist Central column: 3rd MC Capitate Lunate Radius Humerus Scapula Radiocarpal and Midcarpal Joint Radiocarpal Joint Lunate rolls dorsally & slides palmarly on concave radius Midcarpal Joint Capitate head rolls dorsally & slides palmarly Motion-limiting periarticular C.T. Palmar radiocarpal ligament Wrist/finger flexors passively Wrist Flexion Flexion Sagittal plane M-L axis through capitate (head) 70-85⁰ ROM Radiocarpal Lunate rolls palmarly & glides dorsally Midcarpal Joint Capitate rolls palmarly & glides dorsally Motion-limiting periarticular C.T. Dorsal radiocarpal ligament Wrist/finger extensors passively Ulnar Deviation Ulnar Deviation Frontal plane convex-concave A-P axis through capitate (head) 35-40⁰ ROM Radiocarpal Joint Scaphoid rolls ulnarly and slide radially Midcarpal Joint Capitate head rolls ulnarly and glides radially Motion-limiting periarticular C.T. Palmar intercarpal ligament Palmar ulnocarpal ligament Radial collateral ligament Abductor pollicis longus Extensor pollicis brevis Radial Deviation Frontal plane A-P axis through capitate (head) 15-20⁰ ROM Radial Deviation Radiocarpal Joint Scaphoid roll radially and glide ulnarly Midcarpal Joint Capitate rolls radially and glides ulnarly Endfeel: Hard/bony Motion-limiting periarticular C.T. Palmar intercarpal ligament Palmar radiocarpal ligament Ulnar collateral ligament FCU and ECU Rotational Collapse of Wrist  Rotational Collapse of Wrist Most often dislocated = lunate  Ulnar Translocation of the Carpals Arthrodesis (fusion) fusion = type of surgery where they put pins to stabalize joints o Often fused at 10-15 degrees Extension and 10 degrees ulnar deviation. Muscle and Joint Interaction  Wrist Extensors Attaches to lateral epicondyle Extensor carpi radialis longus Extensor carpi ulnaris o Inserts 2nd MC o Radial deviate o Inserts 5th MC Extensor carpi radialis brevis o Ulna deviate o Inserts 3rd MC o Radial deviate Wrist Extensors Secondary Set Extensor digitorum Extensor indicis Extensor digiti minimi Extensor pollicis longus  Functional Considerations of Wrist Extensors 30-35⁰ extension; 5-15⁰ ulnar deviation  Wrist Flexors Attach to the medial epicondyle 2X cross-sectional area & 70% > torque of extensors Wrist Flexors Flexor carpi radialis 2nd MC Ulnar/radial deviation cancel Flexor carpi ulnaris 5th MC Greatest wrist flexion torque Palmaris longus 15% don’t have Secondary Set Flexor digitorum profundus Flexor digitorum superficialis Flexor pollicis longus Abductor pollicis longus Extensor pollicis brevis  Radial Deviators Extensor carpi radialis longus o APL greatest torque Extensor carpi radialis brevis o 3rd greatest torque Extensor pollicis longus Extensor pollicis brevis Flexor carpi radialis Abductor pollicis longus o With ECRL greatest torque potential Flexor pollicis longus Ulnar Deviators Extensor carpi ulnaris With FCU Most torque production Rheumatoid arthritis ECU weaker FCU stronger Flexor carpi ulnaris Cancel unwanted flexion and extension Flexor carpi ulnaris Cancel unwanted flexion and extension “Now we see things imperfectly, like puzzling reflections in a mirror, but then we will see everything with perfect clarity. All that I know now is partial and incomplete, but then I will know everything completely, just as God now knows me completely.” 1 Corinthians 13:12 NLT  The Hand Chapter 8 PTH516 Pathokinesiology Letrisha Stallard, DPT Dovison Kereri, PhD, MHS, OTR/L Course Objectives Apply principles of kinematics, kinetics, and biomechanics to normal and pathological human movement for both the appendicular and axial joints. (SLO – 2, 7) Differentiate between the basic characteristics of connective tissue, compare the composition of tendons, ligaments, bones and cartilage, and apply to normal and compromised joint motion. (SLO – 2, 7) Describe anatomy, attachments, functions of, motions limited by, and pathophysiology of ligaments and other connective tissue presented in this course. (SLO – 2, 7) Introduction Osteology 8 carpal bones 5 metacarpals 5 proximal phalanges 4 middle phalanges 5 distal phalanges  Arches of Hand Proximal transverse arch Keystone of arch = Capitate provides central stability. Distal transverse arch 2nd and 3rd are the more stable central metacarpals Longitudinal arch Mobile distal end allows for finger mobility Wrist creases (distal/palmar) These creases can be used as landmarks when making splints/orthoses Carpometacarpal Joints of Fingers CMC- Allow for mobility, especially 1st, 4th and 5th Articulation: 2nd: trapezoid, capitate, and trapezium 3rd: capitate 4th: hamate, capitate 5th: hamate Intermetacarpal joints between 2nd-5th CMCs = aid in stabilizing base CMC Periarticular Connective Tissue Joint capsules Dorsal carpometacarpal ligaments Dorsal intermetacarpal ligaments Palmar carpometacarpal ligaments Palmar intermetacarpal ligaments CMC Finger Kinematics 4th and 5th CMC mobile to fit obj in palm. “Cupping” motion – flexion and IR towards middle digit CMC Joint of Thumb Classification: Saddle joint Degrees of Freedom: 2 Periarticular C.T. of Thumb CMC Role of the Ligaments of CMC joint The 5 ligaments of CMC joint play vital role Control the extent and direction of the joint movement Joint alignment Joint stability Dissipate forces produced by activated muscles Thumb CMC Abduction/Adduction Plane: Sagittal Axis: M-L Convex 1st MC on Concave Trapezium Abd: palmar roll and dorsal slide Abduction motion-limiting periarticular C.T. and muscles Anterior oblique ligament and intermetacarpal ligament Adductor pollicis muscle Thumb CMC Flexion/Extension Concave 1st MC on Convex trapezium Thumb CMC Opposition/Reposition Opposition Phase one: Abduction Phase two: flexion and medial rotation Closed pack: full opposition MCPs of Fingers Classification: Condyloid Degrees of Freedom: 2 Periarticular Connective Tissue of Finger MCPs FDP runs through fibrous digital sheaths  Kinematics of MCP Finger Flexion ~90⁰ (2nd) to ~110-115⁰ (5th) Concave phalanx rolls and slides palmarly  Kinematics of MCP Finger Extension 30 - 45⁰ beyond neutral  Kinematics of MCP Finger Abduction ~20⁰ (either side from 3rd MC midline reference) MCP Joint Accessory Motions MCP Joint of Thumb Degree of freedom: 1 Similar to MCP of fingers except: Osteokinematics limited to flexion/extension in the frontal plane Extension = few degrees Flexion = ~60 degrees across the palm toward middle digit IP Joints of Fingers Classification: Hinge Degrees of Freedom: 1 Note: distal phalanx has 2 concave surfaces (separated by a shallow ridge) and the proximal has 2 convex surfaces (separated by a shallow groove). ❖ This restricts axial rotation IP Joints of Fingers Motion-limiting periarticular C.T. and muscles ❖ Capsule ❖ Collateral ligaments ❖ Palmar plate ❖ Fibrous digital sheath Kinematics of IP Finger Flexion/Extension Flexion Concave surface rolls and slides palmarly on convex mate same direction  IP Joint of Thumb 20⁰ extension passively beyond neutral, applied usually by a force between pad of thumb and object. Functionally useful: scraping with a putty knife. Position of Function of Wrist and Hand Wrist: 20 – 30 degrees of extension with slight ulnar deviation MCP: 35-45 degrees of flexion PIPs/DIPs: 15-30 degrees of flexion Thumb – CMC abduction: 35-45 degrees Special Focus 8-3, page 268 Muscle and Joint Interaction Course Objectives Apply principles of kinematics, kinetics, and biomechanics to normal and pathological human movement for both the appendicular and axial joints. (SLO – 2, 7) Differentiate between the basic characteristics of connective tissue, compare the composition of tendons, ligaments, bones and cartilage, and apply to normal and compromised joint motion. (SLO – 2, 7) Describe anatomy, attachments, functions of, motions limited by, and pathophysiology of ligaments and other connective tissue presented in this course. (SLO – 2, 7)  Introduction Primary effector organ for our most complex motor behaviors and expresses our emotions through gesture, touch, music and art. 29 muscles drive 19 bones and 19 articulations within the hand Biomechanically these structures interact with superb proficiency The hand has an enormous biomechanical complexity and has such it involves disproportionately large region on the brain cortex It is worth noting that any disease or injury that involves the hand creates a disproportionate loss of function  Extrinsic Flexors of Digits (As a Group, FDS, FDP, FPL) By flexing digits, assist with opposition, and once activated together they assist in gripping  Fibrous Digital Sheaths Flexor pulleys Hold tendons close to joints preventing bowstringing Digital Synovial Sheaths  Synovial Sheath The flexor tendons of the hand are enclosed in a double-layered synovial sheath composed of an inner visceral layer and an outer parietal layer, which creates a closed system. There are seven synovial sheaths, including a digital synovial sheath for each of the five digits and a radial and an ulnar bursa extending from the neck of the thumb metacarpal and small finger metacarpal, respectively Common Flexor Sheath of Hand  Trigger Finger Nodule develops on tendon becoming wedged in narrowed sheath causing trigger finger  Tenodesis Grip Tenodesis grip with paralyzed digital flexors/extensors (Fig. 8-38) Spinal cord injury around C6 Flexor Digitorum Superficialis Primary action = flexes the PIPs Assists flexing wrist and MCPs, counter extension torque is needed at these joints FDP and FPL Flexor digitorum profundus Sole flexor of DIPs Assists flexing wrist, MCPs, and PIPs; counter extension torque is needed at these joints Flexor pollicis longus Sole flexor of thumb IP Substantial flexion torque at thumb CMC and MCP joints Extrinsic Extensors of the Digits Extensor digitorum interconnected by juncturae tendinae Extend IP with help of intrinsics Active during hand closing o With normal hand closing, ED counters MCP flexion torque of FDS/FDP so digital flexors can concentrate on IP flexion Active insufficiency with MCP and wrist flexion if ED was not activated Extensor indicis Extensor digiti minimi Extensor Mechanism Extensor Mechanism Extensor Mechanism Extensor tendons become integrated into a fibrous expansion of C.T. Primary distal attachment for ○ ED, EI, EDM, and most intrinsics acting on fingers Slip from ED attaches to dorsal base of proximal phalanx Remaining tendon flattens into central band ○ Runs distally along shaft of prox. phalanx & attaches to base of middle phalanx Before crossing PIP, central band splits into 2 lateral bands Lateral bands fuse together into a single terminal tendon, then attach to base of distal phalanx Oblique retinacular ligament attaching to terminal tendon, If ruptured, no DIP active extension Extensor Mechanism  Extensor Mechanism Multiple attachments of EM allow extensor digitorum to transfer extensor force distally  Oblique Retinacular Ligament Oblique retinacular ligament attaching to terminal tendon allows DIP active extension Extrinsic Extensors of the Thumb Extensor pollicis longus ○ Adducts CMC and assist with reposition ○ RD and extend wrist Extensor pollicis brevis ○ Extends MCP & CMC ○ Flex wrist Abductor pollicis longus ○ Extends and abd CMC. ○ RD and flexes  Intrinsic Thenar Muscles Main function for position thumb in varying amounts of opposition Pathokinesiology Carpal tunnel syndrome median nerve impingement/damage; loss of precision grip and fine manipulation Opponens pollicis medially rotates thumb Abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis  Intrinsic Hypothenar Muscles Main function = raise and “cup” ulnar border, deepens distal transverse arch (grasp) Palmaris brevis Raises height of hypothenar eminence, deepens concavity of palm Ulnar nerve injury Complete paralysis of hypothenar muscles possible with ulnar nerve injury Abductor digiti minimi, Flexor digiti minimi, Opponens digiti minimi, Palmaris brevis  Adductor pollicis (Two heads) Greatest combination of flexion/adduction torque at CMC joint  Lumbricals Flexion at MCPs Passes MCP on palmar side. Extension at IPs Passes IP on dorsal side.  Interossei 1. Palmar- adduction (PAD) MCP 2. Dorsal- abduction (DAB) MCP Intrinsic-plus vs. Extrinsic-plus Opening the Hand: Finger Extension Early phase ED extends at MCP joint-overcome passive tension of FDS and FDP Lumbricals and Interosseous counter MCP extension torque of ED Opening the Hand: Finger Extension Middle phase ED extends PIP and DIP Lumbricals and Interosseous via dorsal hood of extensor mechanism. Opening the Hand: Finger Extension Late phase Wrist flexors (FCR) flex wrist slightly; adds back to length of ED ORL and Lumbrical Contribution Late phase Lumbricals decrease FDP passive tension by proximal pull placed on extensor mechanism, flexion torque at MCP joint  Ulnar Nerve Injury “Claw” position Also known as ‘intrinsic-minus’ posture because of the lack of intrinsic-innervated muscles; lacking flexion torque at MCP, extension torque of IP  Closing the Hand Early and Late Phase FDS and FDP flex IP’s, Interosseous mm flex MCP as needed ED stabilization function; preventing active insufficiency Prehension: Grip and Pinch  Prehension: Grip and Pinch Power grip: Stability and large forces, without need for precision Precision grip: Control and/or delicate action Power (key) pinch: Large forces stabilize object between thumb and lateral border of index finger Precision pinch: Fine control to objects held between thumb and index finger, without high power. ○ Tip to tip method: tiny objects, skill and precision. ○ Pad to pad method: greater surface area, increases prehensile security, used for larger objects Hook grip: Prehension without thumb, partially flexed PIP and DIP Joint Deformities caused by R.A. Zigzag Deformity of the Thumb Due to advanced RA Ruptured CMC ligaments → MC dislocation off trapezium→adductors and short flexors spasm Normally provide dynamic stability Palmar Dislocation of MCP From RA, patient education is key to protect joint from further palmar dislocation Palmar Dislocation of MCP Ulnar Drift of MCPs  Ulnar Drift of MCPs ↑ ulnar deflection of ED as it crosses the dorsal side of the joint; deflection creates a potentially destabilizing bowstringing force on the tendon Swan-neck Deformity  Boutonniere Deformity ↑ passive tension of taut lateral band causes hyperextension of DIP ; hard to pick small objects, PIP joint loses all sources of extension  Other Hand Deformities Mallet Finger Dupuytren’s Contracture Volkmann’s Contracture Mallet Finger Dupuytren’s Contracture Volkmann’s Contracture Toe Transfer