Human Anatomy & Physiology I PDF

BIOL243 – HUMAN ANATOMY & PHYSIOLOGY I Charles Smith, PhD CSCS HUMAN ANATOMY & PHYSIOLOGY Ch. 8 – Joints & Articulations JOINT CLASSIFICATION Classified based on Structure and Function Like anything else in anatomy… Structural Classifications: Functional Cla...

BIOL243 – HUMAN ANATOMY & PHYSIOLOGY I Charles Smith, PhD CSCS HUMAN ANATOMY & PHYSIOLOGY Ch. 8 – Joints & Articulations JOINT CLASSIFICATION Classified based on Structure and Function Like anything else in anatomy… Structural Classifications: Functional Classifications: What binds the joint together? Is a How much movement is allowed? joint cavity present? Synarthroses = immovable Fibrous Amphiarthroses = slightly movable Cartilaginous Diarthroses = freely movable Synovial Note: synarthroses & amphiarthroses mostly Only one with joint cavity found in axial skeleton; most appendicular joints are diarthroses FIBROUS & CARTILAGINOUS JOINTS Fibrous Joints: joined by dense, fibrous connective tissue 3 Types: Sutures: “seams”, seen only in bones of skull Synarthrotic (immovable) joints for protection of brain Syndesmoses: connected by ligaments & fibrous tissues (i.e., b/w tibia & fibula OR radius & ulna) Can be amphiarthrotic (slightly movable) depending on ligament length Gomphoses: “peg-in-socket”; only seen for teeth Cartilaginous Joints: bones united by cartilage 2 Types: Synchondroses: plate of hyaline cartilage connects bones i.e., synarthrotic epiphyseal plate connecting bone shaft to ends Symphyses: fibrocartilage in joint; strong Often act as shock absorber & permit limited movement (amphiarthrotic) i.e., intervertebral joints & pubic symphysis (between ischium) SYNOVIAL JOINTS Bones separated by fluid-filled joint cavity 6 General Features: Articular cartilage: hyaline cartilage covering ends of bones Joint (Synovial) Cavity: fluid-filled space separating articulating bones Articular (Joint) Capsule: two-layers thick (fibrous layer & synovial membrane) Synovial Fluid: viscous, plasma filtrate with hyaluronic acid lubricating & nourishing articular cartilage Reinforcing Ligaments: provide stability Nerves & Blood Vessels: detect pain, monitor stretch; supply filtrate for synovial fluid May also contain: Articular Discs (menisci & labra) : fibrocartilage separating & improving “fit” of articulating bone surfaces; stabilize joint; mitigate wear & tear; shock absorption Bursae: bags of synovial fluid surrounding joint; reduce friction between ligaments, muscles, skin, tendons, or bone HOW STABLE ARE SYNOVIAL JOINTS? 3 Factors: 1. Shape of Articular Surface (minor) Shallow contact surface = less stable; deeper surface = more stable Shallow surface less stable than ball-and-socket Better fit = more stable 2. Number and Location of Ligaments (limited) More ligaments = stronger joint 3. Muscle Tone as they cross Joint (MAJOR) Keep tendons taut Extremely important for stability of shoulder, knee, and foot arches  MOVEMENTS ALLOWED BY SYNOVIAL JOINTS Flexion: bending movement decreasing joint angle Moves articulating segments closer together Ankle “flexes” in two directions: Dorsiflexion moves toes toward shank Plantar flexion moves toes away from shank Extension: reverse of flexion increasing joint angle Straightens flexed limb/joint Hyperextension: extension movement beyond return to anatomical position  MOVEMENTS ALLOWED BY SYNOVIAL JOINTS Abduction: movement away from midline For fingers & toes = spreading them apart The ankle joint performs foot eversion turning sole of foot laterally Adduction: reverse of abduction moving back toward midline For fingers & toes = return to anatomical position The ankle joint performs foot inversion turning sole of foot medially Circumduction: circular movement involving flexion, abduction, extension & adduction of limb  MOVEMENTS ALLOWED BY SYNOVIAL JOINTS Rotation: turning of bone around its own long axis Internal (medial) rotation: rotation towards midline External (lateral) rotation: rotation away from midline Radial & Ulnar rotation named based upon palm positioning Supination Supination: palms face anteriorly Pronation (radius rotates P (radius and ulna are parallel) (anatomical position) over ulna) Pronation: palms face posteriorly S TYPES OF SYNOVIAL JOINTS TYPES OF SYNOVIAL JOINTS TYPES OF SYNOVIAL JOINTS SELECT SYNOVIAL JOINTS There are a lot of synovial joints in the body All serve different purposes which are important for day-to-day function Let’s cut it down to 5 (for now) 1. Temporomandibular Joint (Jaw) 2. Glenohumeral Joint (Shoulder) 3. Humeroulnar Joint (Elbow) 4. Coxal Joint (Hip) 5. Tibiofemoral Joint (Knee) 1. TEMPOROMANDIBULAR JOINT (TMJ) Mandibular condyle articulates with temporal bone forming a modified hinge joint Does more than “hinge” to elevate & depress mandible Also glides creating lateral movement Helps with chewing/grinding of foods Protracts & Retracts pushing chin outward or inward, respectively 2. GLENOHUMERAL (SHOULDER) JOINT Large humeral head (ball) fits in shallow glenoid cavity of scapula (socket) Allows for high degree of movement, but relatively low stability Fibrocartilaginous glenoid labrum helps to add depth Prone to tearing in sports where frequent overhead shoulder movements are required (i.e., baseball, volleyball, & tennis) Stability reinforced by: Coracohumeral & Glenohumeral ligaments (anteriorly) Muscle Tendons (majority of stability) Biceps & Deltoid Tendons (anteriorly) Rotator Cuff Tendons encircle shoulder Subscapularis Supraspinatus Infraspinatus Teres Minor 3. HUMEROULNAR (ELBOW) JOINT Humerus articulates distally with radius & ulna forming hinge joint allowing only flexion & extension movements Lateral movement still possible but restricted by Ulnar Collateral Ligament (UCL) If torn/ruptured, repaired via Tommy John surgery Common in throwing sports Radial Collateral Ligament (RCL) Radial articulation with ulna allows for pronation & supination movements Radial head held in place by anular ligament 4. COXAL (HIP) JOINT Large, spherical head of femur (ball) articulates with deep acetabulum on pubis (socket) Provides most of joint’s stability, but limits range of motion (compared to shoulder) Stability also provided by: Iliofemoral ligament Pubofemoral ligament Ischiofemoral ligament Ligament head of femur Large muscle masses surrounding (i.e., glute max, quadriceps) Like shoulder, has an acetabular labrum deepening socket making dislocations rare However, tearing common in dancers, gymnastics, and other activities where high ROM movements necessary and common 5. TIBIOFEMORAL (KNEE) JOINT Largest most complex joint of body Really a combo of 2 joints: Femoropatellar joint: plane joint allowing patella to glide during knee flexion Tibiofemoral joint: actual articulation of femoral condyles to medial/lateral menisci on tibial plateau creating hinge joint Anteriorly, quadriceps tendon gives rise to 3 ligaments attaching patella to tibia at tibial tuberosity 12 bursae associated with knee joint Assist in smooth, free movement Numerous ligaments stabilize joint, but most crucially are: Medial & Lateral Collateral Ligaments (MCL/LCL) Prevent medial & lateral collapse of knee Minimize lateral translation of femur on tibia Anterior & Posterior Cruciate Ligaments (ACL/PCL) Prevent hyperextension & hyperflexion of knee Minimize sagittal translation of femur on tibia CLINICAL CONNECTION –KNEE INJURIES Knee absorbs a lot of vertical forces (and is very good at this) However, is very susceptible to horizontal & torsional forces Most common injuries involve the 3 C’s: Collateral Ligaments Cruciate Ligaments Cartilages (menisci) Lateral blows to extended knee can result in Unhappy Triad injury Damage to MCL, ACL, and medial meniscus ACL can be damaged in running with sudden directional changes Or landings where knee shifts forwards and collapses inwards COMMON JOINT INJURIES Cartilage Tears Usually caused by compression or shear (rotational) stress Fragments may cause joint to lock or bind Repaired with surgery as cartilage will not repair itself With meniscal removal, joint movement is restored but is less stable Sprains Reinforcing ligaments get overly stretched or torn i.e., ankle, knee, lumbar region Partial tears will repair but slowly (8 – 12 wks) Poor vascularization If completely torn, surgical repair needed (either sewing back together or grafting) Dislocations (Luxations) Bones forced out of alignment (usually with accompanying sprain and/or tear) Usually caused by serious fall or collision Must be reduced (pushed back in place) to treat All conditions require rest & immobilization for healing TENDONITIS & BURSITIS Inflammatory conditions involving either joint tendons or bursa Tendonitis usually due to overuse inflaming tendon sheath Bursitis usually caused by a direct blow or friction on the tendon Rest up, ice down, and talk NSAIDs (if really bad) ARTHRITIS Umbrella of >100 inflammatory or degenerative conditions which damage joints Most widespread crippling disease in US Characterized by pain, stiffness (esp. in morning), and swelling in joint Most acute forms caused by bacteria (antibiotics treatment) 4 Chronic Forms: 1. Osteoarthritis (OA) 2. Rheumatoid Arthritis (RA) 3. Gouty Arthritis 4. Lyme Disease CHRONIC ARTHRITIS 1. Osteoarthritis (OA) 3. Gouty Arthritis Most common, but irreversible “wear & tear” Excess uric acid crystals get deposited in joint Cartilage broken down faster than it can be replaced & soft tissue (esp. around big toe) Friction creates bone spurs (osteophytes) Ends of bones thicken restricting movement If untreated, can actually fuse joint & “Crunching” noise (crepitus) can at times be heard immobilize it Can only moderate activity & take pain relievers (as More common in men necessary) Some joints may be surgically replaced (i.e., knee, hip, 4. Lyme Disease shoulder) Autoimmune condition acquired from 2. Rheumatoid Arthritis (RA) spirochete bacteria in deer tick bites Chronic, inflammatory, autoimmune disease Along with acute rash & flu-like symptoms, Causes joint pain, swelling, weakness, can cause joint pain & arthritis cardiovascular problems Usually abate with antibiotic treatment, but some Especially affects hands & feet symptoms may persist Usually arises between ages 40 – 50 yrs; affects If untreated, may cause neurological symptoms women 3x more frequently JOINTS SUMMARY Joints are characterized both by their structure and function What holds it together? Is there a joint cavity? How much can it move? While many of these types are immovable (or have limited movement), most joints in our extremities are movable, synovial joints Synovial Joints can be subclassed based upon how the articulating structures interact & how they move Each movement has its own characteristics Synovial joints get stabilized in part by the joint structure itself and ligaments but largely by the surrounding musculature Due to use and life, these joints are prone to injury and disorders Some of which are traumatic, some are part of life/aging, others are due to outside circumstances SAMPLE QUESTIONS 1. What is the term used for a joint which is immovable? 2. What kind of movement is described as the lateral translation of a body part away from midline? 3. Which type of synovial joint is characterized by a rounded head sitting with a cup-like groove allowing high degrees of movement (i.e., the shoulder)? 4. Tearing of which elbow ligament is repaired by Tommy John surgery? 5. Which form of chronic arthritis is characterized as simply general wear and tear on the cartilage of the joint?  COPYRIGHT © Pearson Edited by Charles Smith, PhD CSCS 2024