Joints_2024_with_slide_29_corrected.pptx

Arthrology=the study of Joints. Session Goals 1. Gain an understanding of the structure of the 3 major classes of joints found in the human body. 2. Understand the difference between anatomy (structure) and morphology (shape or form) and how shape/form relate to the potential for movement at a jo...

Arthrology=the study of Joints. Session Goals 1. Gain an understanding of the structure of the 3 major classes of joints found in the human body. 2. Understand the difference between anatomy (structure) and morphology (shape or form) and how shape/form relate to the potential for movement at a joint. 3. Appreciate the importance of changes in joints during the human life span, in particular: the development of cranial sutures and synovial joints. Learning Objectives 1. Describe the basic structural characteristics and functions of each of the three major classes of joints (fibrous, cartilaginous, and synovial) and name examples of each.  Definitions hat, exactly, is meant by the terms “joint” nd “articulation”? Joint: a meeting place between two or more skeletal elements Articulation: where two or more skeletal elements are related to one an at their region of contact NOTE: joints do not always allow movement (more about that later …)  Types of Joints, Classified by Structure 1. Fibrous 2. Cartilaginous symphyses 3. Synovial 1. Fibrous Joints anterior a) Sutures type of fibrous joint limited to the skull formed by a zone of dense connective tissue in young adults -infants and young children, resembles a surviving strip of residual mesenchyme (embryonic connective tissue) from which the intramembranous bones of the skull form Function as strong, durable connectors, shock absorbers, and regions of growth example: coronal suture b) Gomphosis fibrous joint tooth socket/tooth articulation with periodontal ligaments (dense regular connective tissue) anchoring tooth to bone of the jaw bind elements together while and responsible for translating compressive to tensile stress example: articulation between all teeth and the upper & c) Schindylesis fibrous joint articulation where a ridged bone fits into a groove of another bone or rigid structure, bound together by dense, regular connective tissue bind elements together and responsible for translating compressive to tensile stress example: spheno- vomer Williams, et al., 1995 articulation d) Syndesmosis fibrous joint closely apposed bone surfaces bound together by a strong ligament (dense connective tissue) creates strong, flexible connection but limits excursion between bones example: distal tibio-fibular joint  2. Cartilaginous Joints a) Symphysis (plural: symphyses) any midline, fibrocartilage joint, eg: a) joints formed between intervertebral discs and vertebrae b) joint between left and right pubic bones in example: pelvis mandibular symphysis c) joint between left and right halves of immature mandible b) Synchondrosis (pl. synchrondroses) type of cartilaginous joint temporary joints - also known as growth plates Lengthwise section through a developing longbone - found between components of immature endochondrally example: growth forming bones (bones formed plate between the shaft (diaphysis) from cartilaginous precursors) and extremity (epiphysis) of a long bone 3. Synovial (diarthroidal or moveable) unique to vertebrates structurally characterized by bony articulations in contact but not continuity with one another -bones covered by a thin layer of hyaline cartilage, but note: this hyaline cartilage also contains collagen type I fibers which enhance its durability -areas of contact characterized by very low coefficient of friction (µ=0.02 or less); this made possible by the presence of synovial fluid https://radiopaedia.org/cases/normal-mr i-hip?lang=us example: hip joint Learning Objectives: Application 1. Describe the basic structural characteristics and functions of each of the three major classes of joints (fibrous, cartilaginous, and synovial) and name examples of each. Ask yourself: What is the general design (tissue constituents and actual pattern of articulation) of each class of joints? What functional capabilities characterize each class of joints? How are the constituent tissues of each joint class ideally suited to meet the functional demands placed on those joints? What are 2 specific examples (name, type of joint, and location in the body) of each of the 3 major classes of joints? Learning Objectives 2. Diagram and describe the basic anatomy of a synovial joint (including accessory structures) and explain what each of its components contributes to the structural and functional integrity of the joint.  Basic Parts of a Synovial Joint Synovial membrane Articular surfaces Synovial cavity (containing synovial fluid) Fibrous joint capsule Section through a generic synovial joint, Williams, et al., 1975) Synovial joints may also include: articular disc or meniscus fat pads or labra internal (i.e., intracapsular) Williams, et al., 1985 ligaments  KEY DESIGN OF A SYNOVIAL JOINT a fibrous joint capsule b synovial membrane (lining joint capsule) b1 parietal layer, synovial tendon sheath b2 visceral layer, synovial tendon sheath 3 b3 synovial membrane line of reflection c synovial space, containing synovial fluid d articular cartilage e ligament (local thickening of fibrous joint capsule) f articular surfaces (covered by articular cartilage) g synovial membrane (covering intracapsular portion of bone) h periosteum i meniscus Cross-section of j bursa (outer membrane) tendon k tendon surrounded by l fibrous tendon sheath Vascular supply, synovial tendon m mesotendon conveyed by mesotendon sheath  Fibrous Capsule forms a cuff around the articular ends of the bones participating in the joint perforated by articular vessels and nerves Reinforced by surrounding ligaments; often blends into those ligaments shoulder, anterior aspect Williams, et al., 1985 shoulder, posterior aspect Synovial Membrane lines non-articular parts of synovial joints as well as synovial bursae and synovial tendon sheaths delicate membrane highly innervated with autonomic and with sensory (including pain) fibers in joints, membrane lines fibrous capsule, but absent from surfaces engaged in weight-bearing produces synovial fluid filters/cleanses synovial fluid Section through a synovial joint  Synovial Membrane Histology ose, fibroelastic CT ontains numerous blood vessels onsists of two layers cell populations: on-resident’ (so-called even though hey are a fairly permanent feature of he membrane): Type A synoviocytes (not hown) are macrophages that filter the novial fluid; these are phagocytic nd derived from blood monocytes esident: Type B synoviocytes modified fibroblasts that help aintain the synovial membrane http://www2.indstate.edu/thcme/mmmoga/histology/slide35.html produce synovial fluid (SC in image Light micrograph of synovial membrane a fibroblastic synoviocyte). Communicate a meshwork via dendritic processes that meet at gap junctions.  Synovial membrane Luminal surface of projecting villi, covered with rounded phagocytic synoviocytes interspersed with tall, projecting processes of type B (fibroblastic) synoviocytes. Preparation illustrating interlacing processes of Type B synoviocytes. These are in constant communication with each other, via gap junctions, which permits them to to quickly change synovial fluid production in response to SEMS of synovial membrane SEM of type B mechanical and other signals. synoviocyte SEMS from Shikichi, M, et al. 1  Synovial Fluid ypocellular, avascular connective tissue; ECM produced by type B synoviocytes clear, pale yellow, viscous flairy fluid ECM; slightly alkaline in pH at rest - this diminishes with exercise carries a small mixed cell population joint volume of synovial fluid low in humans (