Chapter 9 Part 1

Synchondroses

-An articulation in which bones are joined by hyaline cartilage -All synchondroses are immobile and thus classified as synarthroses -Epiphyseal plates in growing children -Costochondral joints between each rib and the costal cartilage

Articulations (Joints)

-An articulation, or joint, is the place where a bone meets another bone, cartilage, or teeth -Study of joints=arthrology -Articulations vary in stability and mobility, and are classified into categories based on these qualities -Determined by joint structure -More mobility = less stability, and vice versa

General Anatomy of Synovial Joints: Articular Joints

-Articular surfaces in synovial joints are covered by a thin layer of hyaline cartilage -Reduces friction during movement and acts as shock absorber to absorb compression placed on joint, prevents damage to articulating ends of bones

Cartilaginous Joints

-Bones attached by cartilage -Two specific types: -Synchondroses: Bones joined by hyaline cartilage (synarthrotic or immobile) -Epiphyseal plates in growing bones -Costochondral joints of ribs connecting to costal cartilage -Symphyses: Bones joined by pad of fibrocartilage (amphiarthrotic or slightly mobile) -Pubic symphysis of os coxae -Intervertebral discs

Fibrous Joints

-Bones joined by dense regular CT -Three specific types: -Gomphoses: Joints between teeth and maxilla and mandible (synarthrotic or immobile) -Sutures: Joints between skull bones; (synarthrotic or immobile) -Syndesmoses: Joints between parallel bones in the forearm and leg (amphiarthrotic or slightly mobile) -radius and ulna -tibia and fibula

Amphiarthrotic Joints Cont'd

-Cartilaginous types: -Pubic symphysis -symphysis between right and left os coxae -formed from fibrocartilage, thus is cartilaginous -Intervertebral discs -symphysis formed from fibrocartilage pad, thus is cartilaginous -Symphysis: Has a pad of fibrocartilage between the articulating bones -Helps to resist compression and tension/stress applied to the joint -All symphyses are amphiarthroses

Classification of Joints by Structure

-Classification by structure: -Fibrous: Bones held together by dense regular connective tissue -Cartilaginous: Bones joined by cartilage -Synovial: Bones separated by fluid-filled cavity that separates the cartilage-covered articulating surfaces of the bones. The articulating surfaces are enclosed in a capsule.

General Anatomy of Synovial Joints

-Each synovial joint is composed of a double-layered Articular capsule or joint capsule -Two layers: 1. Outer fibrous layer made of dense regular connective tissue; strengthens joint so bones don't get pulled apart 2. Inner synovial membrane; secretes synovial fluid. Synovial membrane is composed primarily of areolar connective tissue covering all the internal joint surfaces and lining the articular capsule.

Synovial Joints

-Freely mobile diarthroses -Articulating bones separated by a joint cavity -General anatomy: -Articular capsule -Joint cavity -Synovial fluid -Articular cartilage (hyaline) -Ligaments -Nerves and blood vessels

Diarthrotic Joints

-Freely mobile joints -All Synovial joints are diarthroses -Examples: -Intercarpal and intertarsal joints -Metacarpophalangeal and metatarsophalangeal -Interphalangeal joints (fingers and toes) -Elbow joint -Knee joint -Glenohumeral -Hip joint

Synarthrotic Joints

-Immobile joints -Gomphosis -Consists of periodontal membranes which hold the tooth in the bony jaw -Resembles 'peg in socket' -ONLY Gomphoses in human body in mandible and maxillae

Synarthrotic Joints (Sutures)

-Immobile joints -Sutures -Immobile fibrous joints -Interlocking irregular edges which increase strength of joint and decrease the number of fractures -Held together by dense regular connective tissue which later becomes ossified

Synarthrotic Joints (Cont'd)

-Immobile joints -(Synchondroses) -Epiphyseal plates -Hyaline cartilage between bones -Epiphyseal plates in growing bones in children -When hyaline cartilage stops growing, bone replaces cartilage and synchondrosis no long exists -Costochondral joints -Hyaline cartilage between bones -Costochondral joints of ribs to costal cartilage

General Anatomy of Synovial Joints

-Ligaments: Connect bone to bone; dense regular connective tissue -Strengthen and reinforce most synovial joints -Sensory nerves: Detect pain and amount of stretch in a joint (found in all synovial joints) -By monitoring stretch at the joint, the nervous system can detect changes in our posture and adjust body movements -Blood vessels: Nourish tissues in the joint

General Anatomy of Synovial Joints: Joint Cavity

-Space between articulating bones; permits separation of articulating bones -Contains small amount of synovial fluid -Lubricates and nourishes articular cartilage -Nourishes chondrocytes of articular cartilage (provides nutrients, removes wastes) -Absorbs shock during compression of the joint distributing stresses evenly across articular surface when pressure increases

Classification of Joints by Function

-Synarthrosis: Immobile joint -Amphiarthrosis: Slightly mobile joint -Diarthrosis: Freely moveable joint

Amphiarthrotic Joints

-slightly mobile -structurally these joints can be either fibrous or cartilaginous -Fibrous types: -Articulation between the radius and ulna -Syndesmosis -Fibrous -Articulation between the tibia and fibula -Syndesmosis -Fibrous -Syndesmosis=fibrous joint in which bones are joined by dense regular connective tissue only -A ligament like sheet or interosseous membrane provides a pivot bone for the two bones to move against

General Anatomy of Synovial Joints Cont'd

-Accessory structures surround the joint; function in reducing friction and filling spaces -Ligaments: Dense regular connective tissue connecting bone to bone and strengthening and reinforcing synovial joints. -Tendons: Not part of joint itself, but helps stabilize joints because they pass across or around joint providing mechanical support. [Attaches muscle to bone] -Bursae: Fibrous sac-like structure containing synovial fluid. Occur around most synovial joints. Found where bones, ligaments, muscles, tendons rub together. Designed to alleviate friction.

General Anatomy of Synovial Joints Cont'd 2

-Accessory structures surround the joint; function in reducing friction and filling spaces -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 for the joint