Chapter 7: Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Joints Classification of joints Fibrous joints Cartilaginous joints Synovial joints Types of movements at synovial joints Types of synovial joints Aging and joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Classification of Joints  A joint (articulation) is a point of contact between two bones, cartilage and bone, or teeth and bone.  A joint’s structure determines its combination of strength and flexibility.  Structural classification is based on the presence or absence of a synovial cavity and the type of connecting tissue. Structurally, joints are classified as fibrous, cartilaginous, or synovial.  Functional classification of joints is based on the degree of movement permitted. A joint may be a synarthrosis (immovable), amphiarthrosis (slightly movable), or diarthrosis (freely movable). © 2013 John Wiley & Sons, Inc. All rights reserved.

Classification of Joints The structural classification of joints is based on two criteria: (1) the presence or absence of a space between the articulating bones, called a synovial cavity, and (2) the type of connective tissue that holds the bones together. Structurally, joints are classified as one of the following types:  Fibrous joints (FĪ-brus). There is no synovial cavity and the bones are held together by dense irregular connective tissue that is rich in collagen fibers.  Cartilaginous joints (kar-ti-LAJ-i-nus). There is no synovial cavity and the bones are held together by cartilage.  Synovial joints (si-NŌ-vē-al). The bones forming the joint have a synovial cavity and are united by the dense irregular connective tissue of an articular capsule, and often by accessory ligaments. © 2013 John Wiley & Sons, Inc. All rights reserved.

Classification of Joints The functional classification of joints relates to the degree of movement they permit. Functionally, joints are classified as one of the following types:  Synarthrosis (sin-ar-THRŌ -sis; syn- = together). An immovable joint. The plural is synarthroses.  Amphiarthrosis (am-fē-ar-THRŌ-sis; amphi- = on both sides). A slightly movable joint. The plural is amphiarthroses.  Diarthrosis (dī-ar-THRŌ-sis = movable joint). A freely movable joint. The plural is diarthroses. All diarthroses are synovial joints. They have a variety of shapes and permit several different types of movements. © 2013 John Wiley & Sons, Inc. All rights reserved.

Anatomy Overview: You must be connected to the internet to run this animation. Joints

Fibrous Joints  In fibrous joints there is no joint cavity and the bones are held together by dense irregular connective tissue.  A fibrous joint may be a slightly movable or immovable suture (found between skull bones), a slightly movable syndesmosis (such as the distal joint between the tibia and fibula), an immovable gomphosis (such as the root of a tooth in an alveolus of the mandible and maxilla), or a slightly movable interosseous membrane (found between the radius and ulna and tibia and fibula). © 2013 John Wiley & Sons, Inc. All rights reserved.

Fibrous Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Fibrous Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Fibrous Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Cartilaginous Joints  There is no joint cavity and the bones are held together by cartilage in cartilaginous joints.  These joints can be an immovable synchondrosis united by hyaline cartilage (epiphyseal plates) or a slightly movable symphysis united by fibrocartilage (pubic symphysis). © 2013 John Wiley & Sons, Inc. All rights reserved.

Cartilaginous Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Synovial Joints  A synovial joint contains a synovial (joint) cavity. All synovial joints are diarthroses.  Other characteristics of a synovial joint are the presence of articular cartilage and an articular ( joint) capsule, made up of a fibrous membrane and a synovial membrane.  The synovial membrane secretes synovial fluid, which forms a thin, viscous film over the surfaces within the articular capsule.  Many synovial joints also contain accessory ligaments and articular discs.  Bursae are saclike structures, similar in structure to joint capsules, that reduce friction in joints such as the shoulder and knee joints. © 2013 John Wiley & Sons, Inc. All rights reserved.

Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Movements at Synovial Joints  In a gliding movement, the nearly flat surfaces of bones move back-and- forth and side-to-side.  In angular movements, there is a change in the angle between bones. Examples are flexion–extension, hyperextension, abduction– adduction, and circumduction.  In rotation, a bone moves around its own longitudinal axis.  Special movements occur at specific synovial joints in the body. Examples are as follows: elevation–depression, protraction–retraction, inversion– eversion, dorsiflexion–plantar flexion, and supination–pronation. © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Movements at Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Movements at Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Movements at Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Movements at Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Movements at Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Movements at Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Anatomy Overview: You must be connected to the internet to run this animation. Selected Muscles and Movements

Types of Synovial Joints Types of synovial joints are plane, hinge, pivot, condyloid, saddle, and ball- and-socket. In plane (planar) joints the articulating surfaces are flat, and the bones glide back-and-forth and side-to-side (many are biaxial); they may also permit rotation (triaxial). Examples of plane joints are the joints between carpals and the joints between tarsals. In hinge joints, the convex surface of one bone fits into the concave surface of another, and the motion is angular around one axis (uniaxial); examples are the elbow, knee (a modified hinge joint), and ankle joints. In pivot joints, a round or pointed surface of one bone fits into a ring formed by another bone and a ligament, and movement is rotational (uniaxial); examples are the atlanto-axial and radioulnar joints. © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Synovial Joints  In condyloid joints, an oval projection of one bone fits into an oval cavity of another, and motion is angular around two axes (biaxial); examples include the wrist joint and metacarpophalangeal joints of the second through fifth digits.  In saddle joints, the articular surface of one bone is shaped like a saddle and the other bone fits into the “saddle” like a sitting rider; motion is angular around two axes (biaxial). An example is the carpometacarpal joint between the trapezium and the metacarpal of the thumb.  In ball-and-socket joints, the ball-shaped surface of one bone fits into the cuplike depression of another; motion is around three axes (triaxial). Examples include the shoulder and hip joints.  The knee joint is a diarthrosis that illustrates the complexity of this type of joint (Exhibit 7.A). It contains an articular capsule, several ligaments within and around the outside of the joint, menisci, and bursae. Arthroplasty refers to the surgical replacement of severely damaged natural joints with artificial joints. © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Types of Synovial Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

Aging and Joints  With aging, a decrease in synovial fluid, thinning of articular cartilage, and decreased flexibility of ligaments occur.  Most individuals experience some degeneration in the knees, elbows, hips, and shoulders due to the aging process. © 2013 John Wiley & Sons, Inc. All rights reserved.

Aging and Joints © 2013 John Wiley & Sons, Inc. All rights reserved.

End of Chapter 7 Copyright 2013 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information herein. © 2013 John Wiley & Sons, Inc. All rights reserved.