How Many Joints in Human Body - Movable and Immovable Joints
- Do all the individuals have an equal number of joints?
- Are all the joints movable?
- What makes synovial joints freely movable?
- What is the difference between an anatomist and an orthopaedist?
A joint can be defined as a point of intersection where two or more bones meet. While the skeleton renders stature, support and shape to your body, the joints give it mobility and agility. There are animals which don’t have bones and move through the coordinated movements of differently oriented muscles. They lack the speed and briskness as enjoyed by humans. Read on to discover truth about how many joints in human body.
A person specializing in the structuring and functioning of joints needs to learn a whole new terminology of several thousand words. Most of these terms have been derived from the root word “arthron” which comes from the Greek, meaning joint.
Some common terminology derived from “arthron” include arthrosis, arthritis, arthropathy, and arthralgia. The term “arthrosis” (plural: arthroses) simply means a joint. Just like appendicitis which refers to the inflammation of appendix, arthritis means the inflammation of a joint. Arthropathy is the disease of a joint, just like pathology which means the study of a disease. Like neuralgia which is nerve pain, arthralgia means a joint pain.
Point to Ponder: Did you know why many anatomical terms have been derived either from Latin or Greek? The subject like Greek and Latin, which are seldom taught in school today, once used to be the universal language of philosophers and researchers who categorized and classified the human body.
How Many Joints in Human Body?
You may logically assume that all the persons must have an equal number of joints but that is not the case! Different sources put the number of joints between 300 and 400.
Martin Ferrier Young, in his book “Essential Physics for Manual Medicine”, argues that the number of joints is not fixed at 360 in the human body but varies from individual to individual. According to him, both an anatomist and a structuralist need to know that one patient in twenty is likely to have been born with fewer or extra joints than normal. This is especially true around and in the vertebral column.
Therefore, the spinal manipulative therapists need to be aware of the biomechanical implications and consequences of a varying number of joints in the vertebral column across individuals.
Types of Joints in Your Body:
There are two ways to categorize (classify) joints, i.e. by their structure and by their function. In reality, the two systems for the classification of joints considerably overlap with each other. An orthopaedist or functionalist is a clinician who specializes in the mechanism of working or functioning of joints. On the other hand, an anatomist or structuralist studies the structure of joints.
Fibrous, cartilaginous and synovial are the three main types of joints in the human body. Among them, the fibrous joints are immovable and cartilaginous ones allow for partial movability. The third type, the synovial, is of those which are freely movable.
When a strong connective tissue holds tightly together two adjacent bones, it results in the formation of a fibrous joint. Functionally called a synarthrosis (“syn” meaning “together” and “arthron” meaning “joint” in the Greek), a fibrous joint does not allow for any significant movement.
The presence of cartilaginous elements in a joint allows a degree of flexibility within it but restricts free movement. A Greek term for this type of joint is amphiarthrosis, where “amphi” means “on both sides” and “arthron” means “joint”.
Characterized by a synovial capsule, a synovial joint is freely movable. Here the free movement is restricted only by the joint anatomy and the soft tissue that holds the elements together. The joints falling in this category have all the elements required for free movement.
It is the fluid-filled membrane between the bones that renders free movability to a synovial joint. There are six different types of freely movable joints in your body, namely, hinged, pivot, plane, saddle, condyloid, and ball-and-socket. Some of these types have been briefly described with examples below.
- Hinged: Working like a hinge, these joints are found at the knee and the elbow.
- Pivot: Found at the level of atlas and axis bones in the spine, the pivot joint allows for the rotational movement of your neck.
- Ball-and-Socket: A spheroidal or ball-and-socket joint consists of an almost round ball sitting in a hollow surface, as found in the shoulder and the hip.
- Plane: Also called a gliding joint, a plane joint is formed by a simple apposition of two flat surfaces, whereby the articular surfaces slide over each other to allow a small amount of movement. The examples include the intratarsal and intracarpal joints.