Human Anatomy Lecture 6 2024 PDF

Class 6 ARTICULATIONS (AKA JOINTS)  Lecture Outline Joints  Structure and Function Classification  Fibrous Joints  Cartilaginous Joints  Synovial Joints Body Movements  Definition  An articulation, or joint, is the place wher...

Class 6 ARTICULATIONS (AKA JOINTS)  Lecture Outline Joints  Structure and Function Classification  Fibrous Joints  Cartilaginous Joints  Synovial Joints Body Movements  Definition  An articulation, or joint, is the place where a bone meets another bone, cartilage, or teeth  The study of joints is called Arthrology  Joints vary in stability and mobility  Determined by joint structure  More mobility = less stability  More stability = less mobility  Relationship Between Mobility and Stability in Joints Copyright © McGraw-Hill Education. Permission required for reproduction or display. Mobility Most mobile Immobile Glenohumeral joint Hip joint Elbow joint Intervertebral joints Suture (shoulder) Stability Very unstable Most stable Fig. 9.1  Classification of Joints Classification by structure:  Fibrous: Bones held together by dense fibrous connective tissue  Cartilaginous: Bones joined by cartilage  Synovial: Bones separated by small fluid-filled cavity  Classification of Joints Classification by function (movement):  Synarthrosis: is an immobile joint  Amphiarthrosis: is a slightly movable joint  Diarthrosis: is a freely moveable joint  Fibrous Joints  Bones joined by dense fibrous connective tissue  Little to no space between bones (no joint cavity)  Specific types:  Suture: Joint between skull bones  Synarthrosis joint  Syndesmosis: Joint between parallel bones in the forearm and leg (radius and ulna, tibia and fibula)  Amphiarthrosis joint  Gomphosis: Joint between the tooth root and alveolar bone (alveolar socket) of the jaw. The tooth and alveolar bone are joined by the periodontal ligament  Synarthrosis joint  Fibrous Joints SUTURES SYNDESMOSIS GOMPHOSIS  Cartilaginous Joints  Bones attached by cartilage  Specific types:  Synchondrosis: Bones joined by hyaline cartilage (e.g., costochondral junction, spheno-occipital joint, epiphyseal growth plates during development)  Synarthrosis joint  Symphysis: Bones joined by pad of fibrocartilage (e.g., pubic symphysis, intervertebral discs)  Amphiathrosis joint  Cartilaginous Joints SYNCHONDROSIS SYMPHYSIS  Copyright © McGraw-Hill Education. Permission required for reproduction or display. Synchondroses (contain hyaline cartilage) Costochondral joints Epiphyseal plate (immobile joints between the rib and its costal cartilage) Joint between first rib and sternum Cartilaginous Joints - Articulating bones are joined by (a) cartilage Symphyses (contain fibrocartilage) Intervertebral Intervertebral disc joint Body of vertebra Pubic symphysis Fig. 9.3 (b)  Synovial Joints  Freely mobile (diathrosis)  Articulating bones separated by a joint cavity  Anatomy:  Articular capsule  Joint cavity  Synovial fluid  Articular cartilage  Ligaments  Nerves& blood vessels  Anatomy of Synovial Joints  Articular capsule Two layers:  Outer fibrous layer made of connective tissue; strengthens joint  Inner synovial membrane; secretes synovial fluid  Anatomy of Synovial Joints  Articular cartilage  Articular surfaces in synovial joints are covered by hyaline cartilage  Reduces friction and acts as shock absorber  Joint cavity  Space between articulating bones  Contains small amount of synovial fluid  Lubricates and nourishes articular cartilages  Nourishes chondrocytes of articular cartilage  Absorbs shock during compression of the joint  Anatomy of Synovial Joints Ligaments: Connect bone to bone; dense fibrous connective tissue  Strengthen and reinforce capsule Sensory nerves: Detect pain and amount of stretch in a joint Blood vessels: Nourish tissues in the joint  Copyright © McGraw-Hill Education. Permission required for reproduction or display. Periosteum Yellow bone marrow Typical Synovial Joint Fibrous layer Articular Synovial capsule membrane Joint cavity (containing synovial fluid) Articular cartilage Ligament Fig. 9.4 Typical synovial joint Synovial Joint  Anatomy of Synovial Joints  Accessory structures surround the joint; function in reducing friction and filling spaces  Bursae: Sacs outside most synovial joints where ligaments, muscles, tendons, and/or bones rub; contain synovial fluid  Tendon sheaths: Elongated bursae around tendons, particularly in confined areas (wrist and ankle) where tendons rub each other  Fat pads: Packing material; also provide some protection  Bursae and Tendon Sheaths Knee joint Figure 9.5 Classification of Synovial Joints  Synovial joints are classified by the shapes of their articulating surfaces and the types of movements.  Movement of bone at synovial joints is described with respect to three intersecting planes/axes: 1. Uniaxial – the bone moves in one plane or axis 2. Biaxial – the bone moves in two planes or axes 3. Multiaxial – the bone moves in multiple planes or axes  Classification of Synovial Joints  In order of increasing movement, the six classes of synovial joint: 1. Plane joints 2. Hinge joints 3. Pivot joints 4. Condylar joints 5. Saddle joints 6. Ball-and-socket joints  Synovial: Plane Joint (uniaxial) Examples: intercarpal and intertarsal joints, zygapophyseal joints Movement: gliding/sliding  Synovial Hinge Joint (uniaxial) Examples: elbow joint, knee joint, interphalangeal joints Movements: Flexion and Extension  Synovial Pivot Joint (uniaxial) Examples: atlantoaxial joint, proximal radioulnar joint Movement: Rotation Synovial Condylar Joint (Biaxial) Examples: metacarpophalangeal joints and metatarsophalangeal joints Movements: flexion and extension, abduction and adduction  Synovial Saddle Joint (Biaxial) Examples: carpometacarpal joint of the thumb Movements: Flexion and Extension, Abduction and Adduction, circumduction Synovial Ball-&-Socket Joint (Multiaxial) Examples: Glenohumeral (shoulder) joint, hip joint Movements: Flexion and extension, Abduction and Adduction, circumduction, medial and lateral rotation. Synovial Joints  Movements at Synovial Joints  Four types of motion:  Gliding motion  Angular motion  Rotational motion  Special movements  Gliding Motion  Articular surfaces sliding back-and-forth or side-to-side  Angle between bones does not change  Occurs mainly in plane joints  Example: Between carpals (intercarpal joints)  Rotational Motion  A bone turns on its longitudinal axis  Examples:  Atlanto-axial joint turning back-and-forth in the “no” gesture  Limbs turning to and from median plane  Lateral rotation  Medial rotation  Pronation  Supination  Angular Motion  Increases or decreases the angle between bones  Flexion  Extension  Hyperextension  Lateral flexion  Abduction  Adduction  Circumduction  Flexion, Extension, Hyperextension, and Lateral Flexion Figure 9.7a,b Flexion, Extension, Hyperextension, and Lateral Flexion Figure 9.7c,d Flexion, Extension, Hyperextension, and Lateral Flexion Figure 9.7e  Abduction and Adduction Figure 9.8a,c  Abduction and Adduction Figure 9.8b,d  Circumduction Figure 9.9  Rotational Movements Figure 9.10  Special Movements  Occur only at specific joints  Depression vs. elevation  Dorsiflexion vs. plantar flexion  Inversion vs. eversion  Protraction vs. retraction  Opposition Special Movements Allowed at Synovial Joints Figure 9.11  Quick Summary Articulations aka Joints  more mobile = less stable  more stable = less mobile  Classification (fibrous, cartilaginous, synovial)  Anatomy of the synovial joints  Ligaments, nerves, BV’s, bursae, tendons  Types of synovial joints  Movements of synovial joints