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Synovial Joint Types, Movements & Structure | What are Synovial Joints?

Christina Keathley, Dominic Corsini, Christianlly Cena
  • Author
    Christina Keathley

    Christina graduated with a Master's in biology from the University of Louisiana at Lafayette. She is a current PhD student in biology at Wake Forest University, and has been teaching undergraduate students anatomy and physiology for the last two years.

  • Instructor
    Dominic Corsini

    Dominic Corsini has an extensive educational background with a B.S. in Secondary Biology and General Science with a Minor in Environmental Education, an M.Ed. in Educational Leadership, an M.S. in Biology, and a K-12 Principal Certification Program. Corsini has experience as a high school Life, Earth, Biology, Ecology, and Physical Science teacher.

  • Expert Contributor
    Christianlly Cena

    Christianlly has taught college physics and facilitated laboratory courses. He has a master's degree in Physics and is pursuing his doctorate study.

Learn what a synovial joint is and see the structure, characteristics and types of synovial joints. Also see examples and learn about synovial joint movements. Updated: 05/18/2021

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What is a Synovial Joint?

Imagine sitting at home watching a movie. When the movie ends and the credits start rolling, you reach for the remote to change the channel. There are few tasks as easy as picking up the remote, but this simple action requires the coordination of multiple structures of the human body working in unison. Muscles must contract to generate force to move the arm, energy must be generated to fuel those contractions, bones must be rigid enough to hold the arm out straight and provide support, and joints must be able to bend and move to provide mobility. Let's take a moment to discuss joints.

When classified by joint material, there are three types of joints:

  • Fibrous joints are where bones are fused and there is no movement.
  • Cartilaginous joints are where bones are connected by cartilage and provide some movement.
  • Synovial joints are where there is a synovial cavity.

Of these three joint types, synovial joints are the most abundant in the body and allow the range of motion needed to move about our environments. They are identified from the other joints because of the presence of a cavity between the bones that contains synovial fluid. Let's look at this in more detail.

Characteristics of Synovial Joints

Synovial joints are characterized by the presence of an articular capsule. This capsule fills with fluid and allows bones to move without rubbing against each other. When observing a joint, it can be classified as synovial if the presence of this capsule is observed. Oftentimes, however, the inside of a joint cannot be seen. Fortunately, joints can also be classified by their function. The body contains three types of functional joints:

  • Synarthrosis joints are immobile.
  • Amphiarthrosis joints are partially mobile.
  • Diarthrosis joints are completely mobile.

All fibrous joints are synarthrosis joints, and cartilaginous joints can be either synarthrosis joints or amphiarthrosis joints. All synovial joints are classified as diarthrosis joints because, by definition, these joints are mobile. This means if a joint is completely moveable, then it is a synovial joint. Amphiarthrosis joints are much less mobile in comparison as the bones are connected by a sturdier layer of cartilage. An example of this is found in the pelvic bone, which is mobile to allow women to give birth but isn't freely movable.

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Types of Synovial Joints

Synovial joints can be further classified by how they move. Traditionally, there are six types of synovial joints:

  • pivot
  • gliding
  • ball and socket
  • hinge
  • condyloid
  • saddle

Examples of the six synovial joint types on the human body.

An illustration of a skeleton with examples of each of the six synovial joints labeled by type.

Pivot Joints

Pivot joints allow for a joint to rotate around a single axis. Joints that pivot are seen in the hand and neck, and allow us to rotate our hands about our wrist or our head so we can look from side to side.

Gliding Joints

Gliding joints are also often referred to as planar joints, as two planes are gliding on top of one another. Typically these joint types are found in areas of the body where flat bones glide against each other but a great amount of mobility isn't necessarily needed.

Ball and Socket Joints

Ball and socket joints provide an excellent range of motion. These types of joints can be found at the shoulder and hip, which allow humans to swing our arms and walk freely. Ball and socket joints typically involve a bone with a large, rounded head feeding into a deep groove of another bone. These joints are also commonly subject to arthritis and degradation with age.

Hinge Joints

Hinge joints work like a door, opening and closing in one direction. These joints are identified by a rounded end of a bone that sits within a notch of another joint. These notches are similar to the grooves seen in ball and socket joints, but don't allow for the same level of mobility and aren't typically as deep.

Condyloid Joints

Condyloid joints allow for a moderate range of motion. They are typically able to move in two perpendicular axes. Condyloid joints are seen in the fingers where the finger connects to the palm. These joints are also sometimes referred to as ellipsoid joints because two rounded bones come together to form this joint.

Saddle Joints

Saddle joints are called that because it appears that one bone covers the next bone like a saddle. A convex bone sits nestled in the concave portion of another bone. These joints allow for an intermediate range of motion between a ball and socket joint and a condyloid joint. An example of this is the thumb, which has a great range of motion but isn't as movable as the shoulder.

Synovial Joint Examples

See the list below on specific examples of each joint type.

Pivot joints:

  • Between the axis and atlas vertebrae at the base of the skull
  • Junction of the radius and ulna to the humerus

Gliding joints:

  • Between the metacarpals of the hand
  • Between the metatarsals of the feet

Ball and socket joints:

  • Where the femoral head articulates with the acetabulum of the pelvis
  • The site where the top of the humerus meets with the scapula and clavicle

Hinge joints:

  • Between the distal and middle phalanges of the hand
  • Where the tibia and fibula meet with the tarsals

Condyloid joints:

  • The articulation between the radius and carpals of the hand
  • The site where the proximal phalanges articulate with the metacarpals of the hand

Saddle joints:

  • The articulation of the proximal phalanx of the thumb to the metacarpals
  • Where the clavicle meets with the sternum

Structure of Synovial Joint

When two bones articulate, or meet, they need to have a joint that connects them together. A synovial joint connects two bones with the use of an articular capsule. The articular capsule is surrounded on all sides by the synovial membrane and an outer layer of cartilage. The bone caps that make up the roof and floor of the articular capsule are lined by articular cartilage to prevent the ends of bones from rubbing together and creating painful inflammation. The articular capsule is filled with synovial fluid. The main purpose of this fluid is to reduce friction at the joint and further prevent damage to the bones. This synovial fluid is thick and composed of nutrients, plasma, and hyaluronic acid, an ingredient in many anti-aging beauty products because of the benefits it provides to tissues.

Outside of this articular capsule, the joint has several ligaments that connect the bones together. These strengthen the joints and keep them secured in place to prevent the bones from separating.

Synovial joints may (but don't always) contain the following structures:

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  • Activities
  • FAQs

Types of Synovial Joints: Fill-in-the-Blank Activity

This activity will help you assess your knowledge of the six types of synovial joints in the human body.

Guidelines

For this activity, print or copy this page on a blank piece of paper. Use the words presented in the word bank to complete the sentence. Neatly write them on the appropriate blank space provided.

Word Bank

Sentences

  1. The __________ has three joints, one of which is the __________ joint, which allows it to move from side to side.
  2. A __________ is a connection made between __________ in the body, which allows bending and rotation.
  3. __________ joints permit movement in two planes but do not allow rotation inside the joint.
  4. A hinge joint is a common class of __________ that allows bone motion along one axis to flex or extend.
  5. The __________ motion of the hips and shoulders is attributed to the ball-and-socket joint.
  6. The large rotational bone structure at the base of the spine that supports the legs is called the __________.
  7. A __________ is a freely moveable joint that allows only rotational movement around a single axis.
  8. Our ankle is a __________ that connects the foot with the leg.
  9. The complex joint that connects the small bones of the wrist is called a __________.
  10. An __________ may result from the twisting or overextending of the joint.


Answer Key

  1. Thumb, Saddle
  2. Joint, Bones
  3. Condyloid
  4. Synovial joint
  5. Rotational
  6. Pelvis
  7. Rotary joint
  8. Hinge joint
  9. Gliding joint
  10. Injury

What is the function of the synovial joint?

All joints have different purposes. Fibrous joints provide strength and fuse two bones together. Cartilaginous joints provide structure and support and allow for slight mobility. Synovial joints function to provide movement. They're what allow us to turn our head, pick up our pencil, and walk across a room.

What are the 6 characteristics of synovial joints?

Synovial joints must meet the following criteria:

  • They must be where two or more bones meet and the bones must have cartilaginous ends
  • They must contain an articular cavity
  • The articular capsule must be reinforced on the sides with articular cartilage
  • They must contain synovial fluid
  • They must be reinforced with tendons and/or ligaments
  • They must have a nutrient supply, such as those provided by nearby capillaries

Which joints are synovial joints?

All mobile (diarthrosis) joints are synovial joints. Synovial joints are classified by the fact that they are mobile when compared to fibrous joints (which are immobile) and cartilaginous joints (which are only minimally mobile). Synovial joints are also classified as those which have an articular capsule filled with synovial fluid between two articulating bones.

What are the 6 types of synovial joints?

Synovial joints are described based on how they move and the anatomy of the joint. The six joint types are saddle, pivot, hinge, ball and socket, condyloid, and gliding. Ball and socket is the most mobile, while gliding is the least mobile.

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