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Introduction to Joints

Introduction to Joints

The adult human body usually has 206 bones, and except for the hyoid bone in the neck, each bone is connected to at least one other bone. Joints are the location where bones come together. Many joints allow for movement between the bones. At these joints, the articulating surfaces of the adjacent bones can move smoothly against each other. However, the bones of other joints may be joined by connective tissue or cartilage. These joints are designed for stability and provide little or no movement.

Joints

Joints

Joints, also called articulations or articular surfaces, are points at which ligaments or other tissues connect adjacent bones. Joints permit movement and stability, and can be classified based on their structure or function.
Structural joint classifications are based on the material that makes up the joint as well as whether or not the joint contains a space between the bones. Joints are structurally classified as fibrous, cartilaginous, or synovial.
Fibrous Joints Are Immovable
The bones of a...

Method of Joints: Problem Solving II

Method of Joints: Problem Solving II

Consider a truss structure with frictionless joints fixed to a wall and roller support. If a force of 150 N is applied to joint A, the forces in each member of the truss can be determined using the method of joints.

Method of Joints: Problem Solving I

Method of Joints: Problem Solving I

The method of joints is a commonly used technique to analyze the forces in structural trusses. The method is based on the principle of equilibrium, which assumes that the truss members are connected by frictionless pins. The forces at each joint can be determined by considering the equilibrium of the forces acting on that joint. Consider a truss structure with two forces of 20 N and 10 N acting at joints C and D, respectively. The method of joints can be used to determine the forces FCB, FDC,...

Structural Joints: Cartilaginous Joints

Structural Joints: Cartilaginous Joints

As the name indicates, at a cartilaginous joint, the adjacent bones are united by cartilage, a tough but flexible type of connective tissue. Unlike synovial joints, these types of joints lack a joint cavity and involve bones joined together by either hyaline cartilage or fibrocartilage.
There are two types of cartilaginous joints:
Synchondrosis
A synchondrosis ("joined by cartilage") is a cartilaginous joint where bones are connected by hyaline cartilage. Synchondrosis may be temporary or...

Development of the Limb Synovial Joints

Development of the Limb Synovial Joints

Joints form during embryonic development in conjunction with the formation and growth of the associated bones. The embryonic tissue that gives rise to all bones, cartilage, and connective tissues of the body is called mesenchyme.
The mesenchymal stem cells differentiate into chondrocytes that form the hyaline cartilage, and later the cartilaginous model of the bone. This model further transforms into a bone. This process is known as endochondral ossification.
During development, the limbs...

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Related Experiment Video

Updated: Jun 20, 2026

Quantifying Learning in Young Infants: Tracking Leg Actions During a Discovery-learning Task

Quantifying Learning in Young Infants: Tracking Leg Actions During a Discovery-learning Task

Published on: June 1, 2015

Young children's understanding of joint commitments.

Maria Gräfenhain¹, Tanya Behne, Malinda Carpenter

¹Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany. graefenhain@uni-goettingen.d

Developmental Psychology

|August 26, 2009

Summary

Young children understand joint commitments. Three-year-olds recognize obligations in shared activities, reacting when a partner breaks commitment, unlike two-year-olds.

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Area of Science:

Developmental Psychology
Social Cognition
Moral Development

Background:

Adults form joint commitments, creating mutual obligations.
Understanding of joint commitments in early childhood is not well-established.

Purpose of the Study:

To investigate if young children understand joint commitments.
To determine the developmental onset of recognizing joint commitments.

Main Methods:

Two studies examined children's reactions to joint activity disruptions.
Participants included 2- and 3-year-olds in Study 1, and 3- and 4-year-olds in Study 2.

Main Results:

Three-year-olds reacted to joint commitment breaches, unlike two-year-olds.
Children acknowledged leaving joint activities more when a commitment was made.

Conclusions:

By age three, children recognize their own and others' commitments to joint activities.
This indicates an early understanding of social obligations in shared endeavors.