ARTICULATIONS JOINTS ARTICULATIONS

Classifications of Joints Joints can be classified by function or structure Functional classification is based on amount of movement Synarthroses —immovable; common in axial skeleton Amphiarthroses —slightly movable; common in axial skeleton Diarthroses —freely movable; common in appendicular skeleton (all synovial joints)

Classifications of Joints Structural classification is based on: Material that binds bones together Presence or absence of a joint cavity Structural classifications include: Fibrous Cartilaginous Synovial

Fibrous Joints Bones are connected by fibrous connective tissue Do not have a joint cavity Most are immovable or slightly movable 3 TYPES

FIBROUS JOINT: Sutures Bones are tightly bound by a minimal amount of fibrous tissue Occur only between the bones of the skull Allow bone growth so the skull can expand with brain during childhood Fibrous tissue ossifies in middle age Synostoses —closed sutures

FIBROUS JOINT: Syndesmoses Bones are connected exclusively by ligaments Amount of movement depends on length of fibers Tibiofibular joint —immovable synarthrosis Interosseous membrane between radius and ulna Freely movable diarthrosis

FIBROUS JOINT: Gomphoses Tooth in a socket Connecting ligament—the periodontal ligament

Cartilaginous Joints Bones are united by cartilage Lack a joint cavity Two types

Synchondroses Hyaline cartilage unites bones Epiphyseal plates Joint between first rib and manubrium Synarthrotic Cartilaginous Joints

Symphyses Fibrocartilage unites bones; resists tension and compression Slightly movable joints that provide strength with flexibility Intervertebral discs Pubic symphysis Hyaline cartilage —present as articular cartilage Cartilaginous Joints

Synovial Joints: each contains a fluid-filled joint cavity.

General Structure of Synovial Joints Articular cartilage (hyaline) Covers ends of opposing bones Absorbs compression Joint (articular) cavity Holds synovial fluid Articular capsule —joint cavity is enclosed in a two-layered capsule Fibrous layer —dense irregular connective tissue, which strengthens joint Synovial membrane —loose connective tissue Lines joint cavity Makes synovial fluid Periosteum Synovial membrane Fibrous layer Articular (hyaline) cartilage Joint cavity (contains synovial fluid) Ligament Articular capsule A typical synovial joint #1 of 4

General Structure of Synovial Joints Periosteum Synovial membrane Fibrous layer Articular (hyaline) cartilage Joint cavity (contains synovial fluid) Ligament Articular capsule A typical synovial joint Synovial fluid A viscous fluid similar to raw egg white A filtrate of blood Arises from capillaries in synovial membrane Contains glycoprotein molecules secreted by fibroblasts Weeping lubrication —Pressure on joints squeezes synovial fluid into and out of articular cartilage #2 of 4

General Structure of Synovial Joints Periosteum Synovial membrane Fibrous layer Articular (hyaline) cartilage Joint cavity (contains synovial fluid) Ligament Articular capsule A typical synovial joint Reinforcing ligaments Often are thickened parts of the fibrous layer Sometimes are extracapsular ligaments —located outside the capsule Sometimes are intracapsular ligaments —located internal to the capsule #3 of 4

General Structure of Synovial Joints Periosteum Synovial membrane Fibrous layer Articular (hyaline) cartilage Joint cavity (contains synovial fluid) Ligament Articular capsule A typical synovial joint Richly supplied with sensory nerves Detect pain Most monitor how much the capsule is being stretched #4 of 4

Synovial Joints with Articular Discs Some synovial joints contain an articular disc; meniscus (if it only partially subdivides the cavity). Occur in the TMJ and at the knee joint Occur in joints whose articulating bones have somewhat different shapes Improves the fit Articular disc Also, note bursa. “Bursa” is Latin for “Purse.” It is a fluid-filled fibrous sac, which protects.

3 Types of Movements Allowed by Synovial Joints

3 Types of Movements: GLIDING 1) Gliding —one bone across the surface of another Gliding movements at the wrist Gliding occurs between: Carpals Articular processes of vertebrae Tarsals

3 Types of Movements - ANGULAR 2 ) Angular movement — movements change the angle between bones Movements involve: Flexion and extension Abduction and adduction Circumduction EXTENSION AND FLEXION ABDUCTION/ ADDUCTION CIRCUMDUCTION

3 Types of Movements - ROTATION 3 ) Rotation —movement around a bone's long axis Involves turning movement of a bone around its long axis The only movement allowed between atlas and axis vertebrae Occurs at the hip and shoulder joints Rotation of the head, neck, and lower limb

Special Movements SOME MOVEMENTS DO NOT FIT INTO ANY OF THE PREVIOUS CATEGORIES AND ONLY OCCUR AT A FEW JOINTS

Elevation Lifting a body part superiorly Depression Moving a body part inferiorly Elevation of mandible Depression of mandible DURING CHEWING, THE MANDIBLE IS ALTERNATELY ELEVATED AND DEPRESSED

Figure 9.7b Some special body movements. Protraction of mandible Retraction of mandible Protraction Moving a body part in the anterior direction Retraction Moving a body part in the posterior direction PROTRACTION AND RETRACTION: NON-ANGULAR MOVEMENTS IN THE ANTERIOR AND POSTERIOR DIRECTION

Figure 9.7c Some special body movements. Pronation (P) Rotating the forearm so the palm faces posteriorly Supination (S) Rotating the forearm so the palm faces anteriorly Pronation (radius rotates over ulna) Supination (radius and ulna are parallel)) S P

Figure 9.7d Some special body movements. Opposition Opposition Moving the thumb to touch the tips of the other fingers MOVEMENT OF THE JOINT BETWEEN METACARPAL 1 AND THE TRAPEZIUM

Figure 9.7e Some special body movements. Inversion Eversion Inversion Turning the sole of the foot medially Eversion Turning the sole of the foot laterally

Figure 9.7f Some special body movements. Dorsiflexion Plantar flexion Dorsiflexion Lifting the foot so its superior surface approaches the shin Plantar flexion Depressing the foot elevating the heel

Classification of Synovial Joints by Shape 6 Types

6 Types of Synovial Joints Ball-and-Socket Joint hip shoulder Condyloid Joint between metacarpals and phalanges 8-9

6 Types of Synovial Joints Gliding Joint between carpals between tarsals Hinge Joint elbow between phalanges PLANE JOINT

6 Types of Synovial Joints Pivot Joint between proximal ends of radius and ulna Saddle Joint-between carpal (trapezium) and metacarpal of thumb

Selected Synovial Joints

Temporomandibular joint a modified hinge joint The head of the mandible articulates with the temporal bone Lateral excursion is a side-to-side movement Two surfaces of the articular disc allow both Hinge-like movement Gliding of superior surface anteriorly

Shoulder Joint – the most freely movable joint ball-and-socket head of humerus glenoid cavity of scapula loose joint capsule (lacks stability) bursae (cushioning) ligaments prevent displacement: Muscle tendons of the shoulder contribute strongly to this joint’s stability

Wrist Joint Composed of radiocarpal and intercarpal joint Radiocarpal joint —joint between the radius and proximal carpals (the scaphoid and lunate) Allows for flexion, extension, adduction, abduction, and circumduction Intercarpal joint —joint between the proximal and distal rows or carpals Allows for gliding movement Right wrist, anterior (palmar) view Radius Wrist joint Scaphoid Capitate Trapezoid Trapezium Thumb Ulna Lunate Triquetrum Pisiform Hamate I II III IV V

THE WRIST JOINT IS STABILIZED BY NUMEROUS LIGAMENTS: Ligaments of the wrist, anterior (palmar) view Palmar radiocarpal ligament Radial collateral ligament of wrist joint Ulnar collateral ligament of wrist joint I II III IV V Scaphoid Intercarpal ligaments Trapezium Capitate Radius Ulna Lunate Pisiform Hamate Carpo- metacarpal ligaments CARPAL TUNNEL SYNDROME

Hip joint A ball-and-socket structure Movements occur in all axes Limited by ligaments and acetabulum Head of femur articulates with acetabulum Stability comes chiefly from acetabulum and capsular ligaments Muscle tendons contribute somewhat to stability Frontal section through the right hip joint Articular cartilage Acetabular labrum Ligament of the head of the femur (ligamentum teres) Femur Coxal (hip) bone Synovial cavity Articular capsule

Knee joint The largest and most complex joint a hinge joint Has some capacity for rotation when leg is flexed Two fibrocartilage menisci occur within the joint cavity Femoropatellar joint —shares the joint cavity Allows patella to glide across the distal femur Sagittal section through the right knee joint Femur Lateral meniscus Tibia Tendon of quadriceps femoris Suprapatellar bursa Patella Synovial cavity Lateral meniscus Infrapatellar fat pad Deep infrapatellar bursa Patellar ligament Subcutaneous prepatellar bursa Articular capsule Posterior cruciate ligament Anterior cruciate ligament

Posterior cruciate ligament Medial meniscus Articular cartilage on medial tibial condyle Lateral meniscus Superior view of the right tibia in the knee joint, showing the menisci and cruciate ligaments Articular cartilage on lateral tibial condyle Anterior Intracapsular ligaments: Cruciate ligaments Cross each other like an “X” PREVENT SLIDING see next 2 slides. Each cruciate ligament runs from the proximal tibia to the distal femur Anterior cruciate ligament Posterior cruciate ligament

Figure 9.16a Stabilizing function of the cruciate ligaments. 1 Anterior cruciate ligament Posterior cruciate ligament Tibia Lateral meniscus Medial condyle Patella Femur Quadriceps muscle During movement of the knee, the anterior cruciate prevents anterior sliding of the tibia; the posterior cruciate prevents posterior sliding of the tibia.

Figure 9.16b Stabilizing function of the cruciate ligaments. 2 Anterior cruciate ligament Posterior cruciate ligament When the knee is fully extended, both cruciate ligaments are taut and the knee is locked.