1.2 Types of Body Movements
Learning Objectives
By the end of this section, you will be able to:
- Define the different types of body movements
- Identify the joints that allow for these motions
The body has a tremendous range of movement. Each movement at a joint results from the contraction or relaxation of the muscles that are attached to the bones on either side of the articulation. Movement types are generally paired, with one being the opposite of the other. Body movements are always described in relation to the anatomical position of the body: upright stance, with upper limbs to the side of body and palms facing forward. Refer to Figure 1.6 as you go through this section.
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Flexion and Extension
Flexion and extension are typically movements that take place within the sagittal plane and involve anterior or posterior movements of the neck, trunk, or limbs. For the vertebral column, flexion is an anterior (forward) bending of the neck or trunk, while extension involves a posterior-directed motion (bending backward). Lateral flexion of the vertebral column occurs in the coronal plane and is defined as the bending of the neck or trunk toward the right or left side.
In the limbs, flexion decreases the angle between the bones (bending of the joint), while extension increases the angle and straightens the joint. For the upper limb, all anterior-going motions are flexion and all posterior-going motions are extension. These include anterior-posterior movements of the arm at the shoulder, the forearm at the elbow, the hand at the wrist, and the fingers at the metacarpophalangeal and interphalangeal joints. In the lower limb, bringing the thigh forward and upward is flexion at the hip joint, while posterior-going motion of the thigh is extension. Knee flexion is the bending of the knee to bring the foot toward the posterior thigh, and extension is the straightening of the knee.
Hyperextension is the abnormal or excessive extension of a joint beyond its normal range of motion, thus resulting in injury. Similarly, hyperflexion is excessive flexion at a joint. Hyperextension injuries are common at hinge joints such as the knee or elbow.
Abduction and Adduction
Abduction and adduction motions occur within the coronal plane and involve medial-lateral motions of the limbs, fingers, toes, or thumb. Abduction moves the limb laterally away from the midline of the body, while adduction is the opposing movement that brings the limb toward the body or across the midline. For example, abduction is raising the arm at the shoulder joint, moving it laterally away from the body, while adduction brings the arm down to the side of the body. Similarly, abduction and adduction at the wrist moves the hand away from or toward the midline of the body. Spreading the fingers or toes apart is also abduction, while bringing the fingers or toes together is adduction.
Circumduction
Circumduction is the movement of a body region in a circular manner, in which one end of the body re