The straightening and contraction of muscles perform the motion of the joints. Flexion and extension are two anatomical terms used to describe angular motion. The direction of the movement or the change in the angle between the two bones determines the type of motion as a flexion or extension.
The main difference between flexion and extension is that flexion is the action that brings the two bones together, decreasing the angle between the bones whereas extension is the action that increases the angle between the two bones.
What is Flexion — Definition, Angle, Examples 2. What is Extension — Definition, Angle, Examples 3. Flexion refers to a movement that decreases the angle between two body parts. The opposite movement of flexion is the extension. Flexion of the elbow, which decreases the angle between ulnar and the humerus, is a general example of flexion. Dorsiflexion, plantar flexion, and lateral flexion are special movements in flexion.
Dorsiflexion is the backward bending. Bending of hand or foot are examples of dorsiflexion. Plantar flexion is the forward bending of hand or foot. These are the only movements available at the ankle joint see Figure 4. Figure 4. Supination and pronation. Inversion and eversion are complex movements that involve the multiple plane joints among the tarsal bones of the posterior foot intertarsal joints and thus are not motions that take place at the ankle joint.
Inversion is the turning of the foot to angle the bottom of the foot toward the midline, while eversion turns the bottom of the foot away from the midline. The foot has a greater range of inversion than eversion motion.
These are important motions that help to stabilize the foot when walking or running on an uneven surface and aid in the quick side-to-side changes in direction used during active sports such as basketball, racquetball, or soccer see Figure 5.
Protraction and retraction are anterior-posterior movements of the scapula or mandible. Protraction of the scapula occurs when the shoulder is moved forward, as when pushing against something or throwing a ball. Retraction is the opposite motion, with the scapula being pulled posteriorly and medially, toward the vertebral column. For the mandible, protraction occurs when the lower jaw is pushed forward, to stick out the chin, while retraction pulls the lower jaw backward.
See Figure 5. Figure 5. Inversion, eversion, protraction, and retraction. Depression and elevation are downward and upward movements of the scapula or mandible. The upward movement of the scapula and shoulder is elevation, while a downward movement is depression.
These movements are used to shrug your shoulders. Similarly, elevation of the mandible is the upward movement of the lower jaw used to close the mouth or bite on something, and depression is the downward movement that produces opening of the mouth see Figure 6. Figure 6. Depression, elevation, and opposition. Excursion is the side to side movement of the mandible.
Lateral excursion moves the mandible away from the midline, toward either the right or left side. Medial excursion returns the mandible to its resting position at the midline. Superior and inferior rotation are movements of the scapula and are defined by the direction of movement of the glenoid cavity. These motions involve rotation of the scapula around a point inferior to the scapular spine and are produced by combinations of muscles acting on the scapula.
During superior rotation , the glenoid cavity moves upward as the medial end of the scapular spine moves downward. This is a very important motion that contributes to upper limb abduction. Without superior rotation of the scapula, the greater tubercle of the humerus would hit the acromion of the scapula, thus preventing any abduction of the arm above shoulder height.
Superior rotation of the scapula is thus required for full abduction of the upper limb. Superior rotation is also used without arm abduction when carrying a heavy load with your hand or on your shoulder. You can feel this rotation when you pick up a load, such as a heavy book bag and carry it on only one shoulder.
To increase its weight-bearing support for the bag, the shoulder lifts as the scapula superiorly rotates. Inferior rotation occurs during limb adduction and involves the downward motion of the glenoid cavity with upward movement of the medial end of the scapular spine. Opposition is the thumb movement that brings the tip of the thumb in contact with the tip of a finger.
This movement is produced at the first carpometacarpal joint, which is a saddle joint formed between the trapezium carpal bone and the first metacarpal bone. Thumb opposition is produced by a combination of flexion and abduction of the thumb at this joint. Returning the thumb to its anatomical position next to the index finger is called reposition see Figure 6.
Skip to main content. Module Joints. Search for:. Flexion at the elbow is decreasing the angle between the ulna and the humerus. Where does flexion and extension occur? What are the 12 types of body movement? Flexion and Extension. Flexion and extension are movements that take place within the sagittal plane and involve anterior or posterior movements of the body or limbs.
Abduction and Adduction. Supination and Pronation. Dorsiflexion and Plantar Flexion. Inversion and Eversion. Protraction and Retraction. Where does flexion occur? Flexion occurs when the angle between two adjacent segments in the body decreases as the ventral surfaces of the segments approximate each other and occurs in a sagittal plane about a frontal axis.
An exception is flexion of the thumb, which takes place in a frontal plane about a sagittal axis. How does flexion occur? Flexion and Your Joints. Flexion typically occurs when muscles contract and the bones thus move the nearby joint into a curved or bent position. Flexion is a physical position that decreases the angle between the bones of the limb at a joint.
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