# 8.2: Classification of Joints (2023)

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By the end of this section, you will be able to:

• Distinguish between the functional and structural classifications for joints
• Describe the three functional types of joints and give an example of each
• List the three types of diarthrodial joints

A joint, also called an articulation, is any place where adjacent bones or bone and cartilage come together (articulate with each other) to form a connection. Joints are classified both structurally and functionally. Structural classifications of joints take into account whether the adjacent bones are strongly anchored to each other by fibrous connective tissue or cartilage, or whether the adjacent bones articulate with each other within a fluid-filled space called a joint cavity. Functional classifications describe the degree of movement available between the bones, ranging from immobile, to slightly mobile, to freely moveable joints. The amount of movement available at a particular joint of the body is related to the functional requirements for that joint. Thus immobile or slightly moveable joints serve to protect internal organs, give stability to the body, and allow for limited body movement. In contrast, freely moveable joints allow for much more extensive movements of the body and limbs.

## Structural Classification of Joints

The structural classification of joints is based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage, or whether the articulating surfaces contact each other within a fluid-filled joint cavity. These differences serve to divide the joints of the body into three structural classifications. A fibrous joint is where the adjacent bones are united by fibrous connective tissue. At a cartilaginous joint, the bones are joined by hyaline cartilage or fibrocartilage. At a synovial joint, the articulating surfaces of the bones are not directly connected, but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid. Synovial joints allow for free movement between the bones and are the most common joints of the body. These three structural classifications will be discussed in further detail in the following sections of this chapter.

## Functional Classification of Joints

The functional classification of joints is determined by the amount of mobility found between the adjacent bones. Joints are thus functionally classified as a synarthrosis or immobile joint, an amphiarthrosis or slightly moveable joint, or as a diarthrosis, which is a freely moveable joint (arthroun = “to fasten by a joint”). Depending on their location, fibrous joints may be functionally classified as a synarthrosis or an amphiarthrosis. Cartilaginous joints are also functionally classified as either a synarthrosis or an amphiarthrosis joint. All synovial joints are functionally classified as a diarthrosis joint.

### Synarthrosis

An immobile or nearly immobile joint is called a synarthrosis. The immobile nature of these joints provides for a strong union between the articulating bones. This is important at locations where the bones provide protection for internal organs. Examples include sutures, such as the coronal, squamous, and lamdoid sutures, which are the fibrous joints between the bones of the skull (Figure $$\PageIndex{1}$$) , and the manubriosternal joint, the cartilaginous joint that unites the manubrium and body of the sternum for protection of the heart.

(Video) Chapter 8.2 Fibrous Joints BIO201

### Amphiarthrosis

An amphiarthrosis is a joint that has limited mobility but slight movement is available in many directions. An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae. Filling the gap between the vertebrae is a thick pad of fibrocartilage called an intervertebral disc (Figure $$\PageIndex{2}$$) . Each intervertebral disc strongly unites the vertebrae but still allows for a limited amount of movement between them. However, the small movements available between adjacent vertebrae can sum together along the length of the vertebral column to provide for large ranges of body movements.

Another example of an amphiarthrosis is the pubic symphysis of the pelvis. This is a cartilaginous joint in which the pubic regions of the right and left hip bones are strongly anchored to each other by fibrocartilage. This joint normally has very little mobility. The strength of the pubic symphysis is important in conferring weight-bearing stability to the pelvis.

### Diarthrosis

A freely mobile joint is classified as a diarthrosis. These types of joints include all synovial joints (structural classification) of the body, which provide the majority of body movements. Most diarthrotic joints are found in the appendicular skeleton and thus give the limbs a wide range of motion. These joints are divided into three categories, based on the number of axes of motion provided by each. An axis in anatomy is described as the movements in reference to the three anatomical planes: transverse, frontal, and sagittal. Thus, diarthroses are classified as uniaxial (for movement in one plane), biaxial (for movement in two planes), or multiaxial joints (for movement in all three anatomical planes).

A uniaxial joint only allows for a motion in a single plane (around a single axis). The elbow joint, which only allows for bending or straightening, is an example of a uniaxial joint. A biaxial joint allows for motions within two planes. An example of a biaxial joint is a metacarpophalangeal joint (knuckle joint) of the hand. The joint allows for movement along one axis to produce bending or straightening of the finger, and movement along a second axis, which allows for spreading of the fingers away from each other and bringing them together. A joint that allows for several directions of movement is called a multiaxial joint (polyaxial or triaxial joint). This type of diarthrotic joint allows for movement along three axes (Figure $$\PageIndex{3}$$) . The hip joint, where the head of the femur articulates with the acetabulum of the hip bone, is a multiaxial joint. They allow the upper or lower limb to move in an anterior-posterior direction and a medial-lateral direction. In addition, the limb can also be rotated around its long axis. This third movement results in rotation of the limb so that its anterior surface is moved either toward or away from the midline of the body.

## Concept Review

Structural classifications of the body joints are based on how the bones are held together and articulate with each other. At fibrous joints, the adjacent bones are directly united to each other by fibrous connective tissue. Similarly, at a cartilaginous joint, the adjacent bones are united by cartilage. In contrast, at a synovial joint, the articulating bone surfaces are not directly united to each other, but come together within a fluid-filled joint cavity.

The functional classification of body joints is based on the degree of movement found at each joint. A synarthrosis is a joint that is essentially immobile. This type of joint provides for a strong connection between the adjacent bones, which serves to protect internal structures such as the brain or heart. Examples include the fibrous joints of the skull sutures and the cartilaginous manubriosternal joint. A joint that allows for limited movement is an amphiarthrosis. An example is the pubic symphysis of the pelvis, the cartilaginous joint that strongly unites the right and left hip bones of the pelvis. The cartilaginous joints in which vertebrae are united by intervertebral discs provide for small movements between the adjacent vertebrae and are also an amphiarthrosis type of joint. Thus, based on their movement ability, both fibrous and cartilaginous joints are functionally classified as a synarthrosis or amphiarthrosis.

The most common type of joint is the diarthrosis, which is a freely moveable joint. All synovial joints are functionally classified as diarthroses. A uniaxial diarthrosis, such as the elbow, is a joint that only allows for movement within a single anatomical plane. Joints that allow for movements in two planes are biaxial joints, such as the metacarpophalangeal joints of the fingers. A multiaxial joint, such as the shoulder or hip joint, allows for three planes of motions.

(Video) Chapter 8.2 Joints: Structural Classification

## Review Questions

Q. The joint between adjacent vertebrae that includes an invertebral disc is classified as which type of joint?

A. diarthrosis

B. multiaxial

C. amphiarthrosis

D. synarthrosis

Q. Which of these joints is classified as a synarthrosis?

A. the pubic symphysis

B. the manubriosternal joint

(Video) Joint Classification

C. an invertebral disc

D. the shoulder joint

Q. Which of these joints is classified as a biaxial diarthrosis?

A. the metacarpophalangeal joint

B. the hip joint

C. the elbow joint

D. the pubic symphysis

Q. Synovial joints ________.

(Video) Fall 2015 Chapter 8.2 Joints: Structural Classification

A. may be functionally classified as a synarthrosis

B. are joints where the bones are connected to each other by hyaline cartilage

C. may be functionally classified as a amphiarthrosis

D. are joints where the bones articulate with each other within a fluid-filled joint cavity

## Critical Thinking Questions

Q. Define how joints are classified based on function. Describe and give an example for each functional type of joint.

A. Functional classification of joints is based on the degree of mobility exhibited by the joint. A synarthrosis is an immobile or nearly immobile joint. An example is the manubriosternal joint or the joints between the skull bones surrounding the brain. An amphiarthrosis is a slightly moveable joint, such as the pubic symphysis or an intervertebral cartilaginous joint. A diarthrosis is a freely moveable joint. These are subdivided into three categories. A uniaxial diarthrosis allows movement within a single anatomical plane or axis of motion. The elbow joint is an example. A biaxial diarthrosis, such as the metacarpophalangeal joint, allows for movement along two planes or axes. The hip and shoulder joints are examples of a multiaxial diarthrosis. These allow movements along three planes or axes.

Q. Explain the reasons for why joints differ in their degree of mobility.

A. The functional needs of joints vary and thus joints differ in their degree of mobility. A synarthrosis, which is an immobile joint, serves to strongly connect bones thus protecting internal organs such as the heart or brain. A slightly moveable amphiarthrosis provides for small movements, which in the vertebral column can add together to yield a much larger overall movement. The freedom of movement provided by a diarthrosis can allow for large movements, such as is seen with most joints of the limbs.

(Video) 2. Functional Classification of Joints

## Glossary

amphiarthrosis
slightly mobile joint
articulation
joint of the body
biaxial joint
type of diarthrosis; a joint that allows for movements within two planes (two axes)
cartilaginous joint
joint at which the bones are united by hyaline cartilage (synchondrosis) or fibrocartilage (symphysis)
diarthrosis
freely mobile joint
fibrous joint
joint where the articulating areas of the adjacent bones are connected by fibrous connective tissue
joint
site at which two or more bones or bone and cartilage come together (articulate)
joint cavity
space enclosed by the articular capsule of a synovial joint that is filled with synovial fluid and contains the articulating surfaces of the adjacent bones
multiaxial joint
type of diarthrosis; a joint that allows for movements within three planes (three axes)
synarthrosis
immobile or nearly immobile joint
synovial joint
joint at which the articulating surfaces of the bones are located within a joint cavity formed by an articular capsule
uniaxial joint
type of diarthrosis; joint that allows for motion within only one plane (one axis)

## FAQs

### What is the correct classification of joints? ›

The structural classification divides joints into fibrous, cartilaginous, and synovial joints depending on the material composing the joint and the presence or absence of a cavity in the joint. The functional classification divides joints into three categories: synarthroses, amphiarthroses, and diarthroses.

How many classifications of joints are there? ›

Functionally the three types of joints are synarthrosis (immovable), amphiarthrosis (slightly moveable), and diarthrosis (freely moveable).

What is the classification of joints based on quizlet? ›

Functional classification of joints is based on: the amount of movement allowed by the joint.

What is the maximum number of joints? ›

As we know, there are 360 joints in the human body. The human body is an amazing machine with 270 bones at birth, which decreases to 206 as we age as parts of our bones fuse together. Thus, there are 360 joints in our body, connecting one bone to another.

What are the classification of synovial joints with example? ›

Synovial joints are often further classified by the type of movements they permit. There are six such classifications: hinge (elbow), saddle (carpometacarpal joint), planar (acromioclavicular joint), pivot (atlantoaxial joint), condyloid (metacarpophalangeal joint), and ball and socket (hip joint).

Where are all the joints in your body? ›

Key synovial joints of the body
Common Joint NameBones of the Joint
SacroiliacSacrum and ilium
HipFemur and pelvis
KneeFemur, patella, tibia and fibula
3 more rows

What are freely movable joints called? ›

Diarthroses. Most joints in the adult body are diarthroses, or freely movable joints. The singular form is diarthrosis. In this type of joint, the ends of the opposing bones are covered with hyaline cartilage, the articular cartilage, and they are separated by a space called the joint cavity.

Is the wrist a pivot joint? ›

Pivot Joints

The joint of the wrist that allows the palm of the hand to be turned up and down is also a pivot joint.

How would you classify the shoulder and hip joints? ›

Ball and socket joint – the rounded head of one bone sits within the cup of another, such as the hip joint or shoulder joint. Movement in all directions is allowed. Saddle joint – this permits movement back and forth and from side to side, but does not allow rotation, such as the joint at the base of the thumb.

What are the 28 joints? ›

The 28-joint count consists of the finger joints excluding the DIP joints, the wrists, elbows, shoulders, and knees.

### What are the 3 types of joints? ›

What are the different types of joints?
• Ball-and-socket joints. Ball-and-socket joints, such as the shoulder and hip joints, allow backward, forward, sideways, and rotating movements.
• Hinge joints. ...
• Pivot joints. ...
• Ellipsoidal joints.

How do you calculate the number of joints? ›

For a perfect frame, the number of joints (j) and the number of members (n) are given by
1. n = 2j - 3.
2. j = 2n - 3.
3. n = j - 3.
4. j = n - 3.
Apr 10, 2023

What are the 9 types of joints? ›

Types of freely movable joints
• Ball and socket joint. Permitting movement in all directions, the ball and socket joint features the rounded head of one bone sitting in the cup of another bone. ...
• Hinge joint. ...
• Condyloid joint. ...
• Pivot joint. ...
• Gliding joint. ...
May 17, 2019

What are the 3 main functions of joints? ›

Some of the functions of joints include providing flexibility to the skeleton, making different types of movements possible, providing stability to specific structures such as the skull and pelvis, and directing the motion of a specific bone or set of bones.

What is an example of a joint? ›

Examples include the elbow, knee, ankle, and interphalangeal joints. A condyloid joint, or an ellipsoid joint, is an articulation between the shallow depression of one bone and the rounded structure of one or more other bones.

Which type of joints move the most? ›

Synovial joints are capable of the greatest movement of the three structural joint types; however, the more mobile a joint, the weaker the joint. Knees, elbows, and shoulders are examples of synovial joints.

What type of joint is the hip? ›

The hip joint is a ball-and-socket joint that allows motion and gives stability needed to bear body weight. The socket area (acetabulum) is inside the pelvis. The ball part of this joint is the top of the thighbone (femur).

Is the skull a pivot joint? ›

The pivot joint situated at the base of the skull, connects the first vertebrae of the spine to the second vertebrae. Thereby, allowing the side-to-side rotation of the head. A pivot joint permits movement of the bones in one plane, such as rotation around a single axis.

What are 8 possible joint actions at the shoulder joint? ›

This mobility provides the upper extremity with tremendous range of motion such as adduction, abduction, flexion, extension, internal rotation, external rotation, and 360° circumduction in the sagittal plane. Furthermore, the shoulder allows for scapular protraction, retraction, elevation, and depression.

How many human joints are there? ›

The joints connect bone to bone, and there are 360 joints in our bodies. Bone mass reaches maximum density in our late 20's and early 30's. As we age, our bones may weaken causing them to be more prone to fractures, so taking care of our bone and joint health is vital.

### What is a joint made up of? ›

Joints are movable connections between two bones. Each joint is made up of the surfaces of the bones involved, a joint cavity and a joint capsule. The joint surfaces (articular surfaces) of the bones are covered with a layer of cartilage.

Which of the following is not a functional classification for joints? ›

Answer and Explanation: The following is not a functional classification of joints D. Arthrofibrosis.

Which joint is present in our finger? ›

Hinge joint is a movable joint that is like a door hinge where only back and forth movement is possible. These type of joints are found in fingers and toes, knees, elbow, etc.

What are fixed joints? ›

Synarthroses (immovable joints), also known as fixed or fibrous joints, are defined as two or more bones in close proximity that have no movement. An example of immovable joints are the plates of the skull.

What type of joint is a skull? ›

Most of the bones of the skull are held together by firm, immovable fibrous joints called sutures or synarthroses.

What type of joint is the neck? ›

It consists of three distinct, synovial joints: one medial joint and two lateral atlantoaxial joints. The median atlantoaxial joint's structure is formed by the dens of C1 vertebrae and two ligamentous structures anteriorly and posteriorly.

Which of these functions is not performed by the skeletal system? ›

Final answer: The production of body heat is not a function of the skeletal system.

Saddle joints are another type of synovial joint. The saddle joint gets its name because the bone forming one part of the joint is concave (turned inward) at one end and looks like a saddle. The other bone's end is convex (turned outward), and looks like a rider in a saddle.

What type of joint is a tooth socket? ›

The teeth are anchored into their sockets within the bony jaws by the periodontal ligaments. This is a gomphosis type of fibrous joint.

What type of joint is your knee? ›

The knee is a synovial joint, which means it is lined by synovium. The synovium produces fluid lubricating and nourishing the inside of the joint. Articular cartilage is the smooth surfaces at the end of the femur and tibia.

### What special joint is in your thumb? ›

The basal joint at the base of the thumb — or thumb CMC joint — is located near the wrist and at the fleshy part of the thumb. It enables the thumb to swivel, pivot, and pinch so that you can grip things in your hand. This joint is highly vulnerable to arthritis as people age.

What is arthritis score? ›

The DAS28 is a measure of disease activity in rheumatoid arthritis (RA). DAS stands for 'disease activity score', and the number 28 refers to the 28 joints that are examined in this assessment.

What is a rheumatoid arthritis score? ›

The DAS Scores indicate how active a patient's rheumatoid arthritis (RA) is currently, and can be trended over time. They were initially developed for comparing clinical trial results of RA drugs, but are now used as overall markers of disease activity.

What is the joint count for arthritis? ›

How Many Joints Are Counted? There are a few different methods for counting joints; they vary by how many joints are counted and how they are scored. The number of joints counted goes as high as 68 on some scales, but the standard system used for most patient care and research trials is the 28-joint count.

What connects muscle to muscle? ›

Because tendons connect every muscle in your body, a wide range of injuries and disorders can cause tendon problems. Tendon issues are more common with age.

What connects muscle to bone? ›

Listen to pronunciation. (TEN-dun) Tough, fibrous, cord-like tissue that connects muscle to bone or another structure, such as an eyeball. Tendons help the bone or structure to move.

Which type of bones forms the arms and legs? ›

Long bone – has a long, thin shape. Examples include the bones of the arms and legs (excluding the wrists, ankles and kneecaps). With the help of muscles, long bones work as levers to permit movement.

How many joints are in a finger? ›

Each of the fingers has three joints: metacarpophalangeal joint (MCP) – the joint at the base of the finger. proximal interphalangeal joint (PIP) – the joint in the middle of the finger. distal interphalangeal joint (DIP) – the joint closest to the fingertip.

What are joints in math? ›

Joint variation describes a situation where one variable depends on two (or more) other variables, and varies directly as each of them when the others are held constant. We say z varies jointly as x and y if. z=kxy. for some constant k.

How many joints are in a half? ›

Weight. A half ounce of cannabis weighs around 14 grams, which is about the size of a grapefruit. You'll probably be able to get 30 joints out of this.

### What are the 3 functional classifications of joints? ›

Three Categories of Functional Joints
• Synarthrosis: These types of joints are immobile or allow limited mobility. ...
• Amphiarthrosis: These joints allow a small amount of mobility. ...
• Diarthrosis: These are the freely-movable synovial joints.
Jan 17, 2023

How are joints classified and what are the 6 types? ›

A joint is the part of the body where two or more bones meet to allow movement. Generally speaking, the greater the range of movement, the higher the risk of injury because the strength of the joint is reduced. The six types of freely movable joint include ball and socket, saddle, hinge, condyloid, pivot and gliding.

What are the three classifications of joints based on movement quizlet? ›

The functional classification joint is based on the degree of movement that they allow. The three functional classes are: 1) synarthroses, which are totally immovable, 2) amphiarthroses, which have slight movement, and 3) diarthroses, which are freely moveable joints.

What is the classification of the intervertebral joint? ›

The structural classification of the intervertebral disc joint is a fused, fibrocartilaginous symphysis. However, functionally, it is considered an amphiarthrosis which permits a limited amount of movement.

What is the definition and classification of joints? ›

Joints aka articular surface can be defined as a point where two or more bones are connected in a human skeletal system. Cartilage is a type of tissue which keeps two adjacent bones to come in contact (or articulate) with each other. 3 Types of joints are Synovial Joints, Fibrous Joints, and Cartilaginous Joints.

What are the 8 major joints of the body? ›

Classification of Joints
• Fibrous Joints. Fixed joints, also called immovable joints, are found where bones are not flexible. ...
• Cartilaginous Joints. ...
• Synovial Joints. ...
• Ball and Socket Joints. ...
• Pivotal Joints. ...
• Hinge Joints. ...
• Condyloid Joints.
Mar 10, 2020

What is the functional classification of joints based on? ›

Functional classification of joints is based on the degree of mobility exhibited by the joint. A synarthrosis is an immobile or nearly immobile joint. An example is the manubriosternal joint or the joints between the skull bones surrounding the brain.

What are the 3 types of joints and give 1 example of each as it occurs in your body? ›

Hinge joints, such as in the fingers, knees, elbows, and toes, allow only bending and straightening movements. Pivot joints. Pivot joints, such as the neck joints, allow limited rotating movements. Ellipsoidal joints.

Are all joints synovial? ›

Most joints are synovial joints, such as knees and knuckles. All synovial joints allow for movement and are susceptible to arthritis.

Which of the following is not a structural classification of joints? ›

Answer and Explanation: The following is not a functional classification of joints D. Arthrofibrosis.

### Which functional joint classification has free movement? ›

Functionally, based on the amount of movement permitted. ie synarthrosis (immovable), amphiarthrosis (slightly moveable), and diarthrosis (freely moveable).

What are the gliding joints? ›

Also known as the plane joint, gliding joints are composed of two smooth surfaces that slide over one another to produce limited movement. They are primarily found in the ankles, wrist, and spine.

What type of joint is the thumb? ›

The thumb basal joint, also known as the carpometacarpal (CMC) joint, is a specialized saddle-shaped joint that is formed by a small wrist bone (trapezium) and the first of the three bones in the thumb (metacarpal).

## Videos

1. 3. Structural Classification of Joints
(Dr. Lorena Canelon)
2. Joints: Structure Classification
3. Chapter 8 Lecture A Fibrous Cartilaginous Joints
(Colin Everhart)
4. Types of Joints: Synovial, Fibrous, Cartilaginous
(EmpoweRN)
5. INTRO TO JOINTS & FIBROUS JOINTS
(Megan Butler)
6. Dr. Benaduce: Introduction to joints & Fibrous Joints (Joints Lecture)
(Witty Anatomy - Dr. Ana Paula Benaduce)

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