Human Body Joints and Movements
What enables movement in human beings?
The human body is a complex system of various types of cells, tissues and organs.
It is made of 206 bones and this skeletal structure helps in giving it protection, support, shape and movement which is aided by attached muscles.
Living bone cells are found on the edges of bones and in small cavities inside the bone matrix. Although these cells make up very little of the total bone mass, they have several very important roles in the functions of the skeletal system. The bone cells allow bones to:
- Grow and develop
- Be repaired following an injury or daily wear
- Be broken down to release their stored minerals
What are bones made of?
The skeleton makes up about 30-40% of an adult’s body mass. The skeleton’s mass is made up of non-living bone matrix and many tiny bone cells. Roughly half of the bone matrix’s mass is water, while the other half is collagen protein and solid crystals of calcium carbonate and calcium phosphate. The point where two bones meet is known as a joint.
What are the types of joints in a human body?
The human body has three main types of joints; Fibrous (immovable), Cartilaginous (partially movable) and the Synovial (freely movable) joint.
What is Fibrous Joints?
These type of joints are held by ligaments and are immoveable. They are found at :
a. teeth to their bony sockets
b. bones of the skull (sutures)
c. radioulna joints at the elbow and tibiofibula joints at the knee
What is Cartilaginous Joints?
These are partially movable. There are two types of cartilaginous joints : Primary and Secondary
a. Primary : They are found in babies and small children as epiphyseal plates and tend to ossify on adulthood.
b. Secondary : These are permanent joints and made of fibriocartilage. They allow small movements and are found at skeletal midline:
c. ribcage to sternum and manubrium
d. intervertebral discs
e. between the pubic bones
What is Synovial Joints?
These are the most movable joints of the three types. And also more susceptible to damage. There is a synovial cavity filled with synovial fluid between the adjoining bones of this joint to allow movement. The synovial fluid and cartilage tissue prevents wear and tear that these types of joints are more prone to.
There are six types of Synovial Joints.
1. Hinge Joints :
These are found at elbows and knees. They allow movement only in one direction.
Hinge Joint Movement – Flexion and Extension
a. Flexion : This movement is the bending of a body part, or decreasing the angle between two parts. You flex your elbow when you bring your forearm up toward your upper arm, and you flex your spine when you bend your body forward.
b. Extension : The opposite of flexion is extension, the straightening of a part, or increasing the angle between two parts. You extend your elbow when you move your forearm away from your arm to straighten your elbow, and you extend your back when you move from being in a flexed position back upright.
2. Pivot Joints :
These are at the top of the spine.
Pivot Joint Movement – Rotation
Rotation : It is the turning movement of a bone around its own axis. Rotation may occur toward the body midline or away from it. Like the rotation of the neck.
3. Ball and socket Joints :
These are found where the arm joins the shoulder and where the leg joins the hip.
Ball and socket Joint Movements – Adduction and Abduction
a. Adduction : It is the body part’s movement towards the body’s midline. Lowering your raised hand is known as adduction.
b. Abduction : It is the body part’s movement away from the body’s midline. If you raise your arms to your shoulder or above your shoulder or swing your hands to the side.
3. Saddle Joints :
These are found between the trapezium carpel and metacarpel of a finger. They provide support to small bones.
4. Condyloid Joints :
These are found between the radius bone and the carpel bones at the wrist. These provides multiple movements in small spaces.
5. Gliding Joints :
These are found between the tarsal bones of the feet. They provide movement along the plane of the joint ; up – down and left – right.
Combination of movements for different body parts
- Elevation is the upward movement of structures of the body. If you raise your shoulder joint, it raises the corresponding arm as well.
- Depression is the downward movement of the structures of the body. If you lower your shoulder joint, it lowers the corresponding arm as well.
- Circumduction movement is found at the saddle and condyloid joints and ball and socket joints. It is the movement of limb, hand or fingers where the part that is attached to the torso is stationary and the part away from the torso is in a circular movement.