Antagonistic Muscle: Definition, Types, and Examples

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Antagonistic Muscle Definition

The word antagonistic means working opposite or the primary doer. Thus, antagonism is defined as an action or substance that can prevent the physiological process. In anatomy, generally, those muscles are described by the word antagonistic that works opposite to the primary muscle. The primary muscles carrying movement are known as agonist muscles.

Let’s discuss antagonistic muscles. The muscles acting in the opposite direction of the agonist muscles are called antagonistic muscles. They resist the movement of the agonist muscle at the joint and balance the tension.

Antagonistic Muscle vs Agonist Muscles

Agonist MusclesAntagonistic Muscle
It is the doer of an actionIt is the opposer to the action or action in opposite direction
It is also called primary muscle. It carry out the movementIt oppose the movement or works in the opposite direction of primary muscles
They are important for movement of bonesImportant for returning bones to their original position
Examples of agonist muscles include Biceps brachii; located in the anterior part of the arm, Muscle Hamstrings found in the posterior part of the thigh, and muscle combination of flexor digitorum superficialis and flexor digitorum profundusThe antagonistic muscles have some examples such as Triceps brachii; located in the posterior part of the arm, Quadriceps femoris found in anterior of the thigh, and muscle Extensor digitorum

Function of Antagonistic Muscle

Antagonistic muscles play two important roles in our body:

• Uphold the body or limb position

• Regulating the hasty movement and keeping a check on the limb motion.

The coordination of action between agonist and antagonist muscles results in the movement of the body. Co-activation is the critical condition for the movement. The co-activation also provides resistance to the action that is also called the stiffness of the joints in simple words. This stiffness resists the movement of muscles that is essential to maintain stability under varying load conditions.

Antagonistic Muscle Examples

The movement of the body parts needs the co-activation and coordination between agonist and antagonist muscles. Some common pairs of antagonistic muscles in our body include-

• Biceps and triceps

• Gluteus maximum and hip flexors

• Hamstrings and quadriceps

• Pectoralis major and latissimus dorsi

• Gastrocnemius and tibialis anterior

• Abductor and adductor

The quadriceps femoris is the combination of four muscles present in the anterior of the thigh. It is the agonist muscle or primary muscle that coordinates with the hamstring muscle of the posterior part of the thigh and results in the extension of the legs at the knee. Now it is understood that all the muscles have an opposing muscle that coordinates with it and acts in the opposite direction, this phenomenon leads to the movement of the body part.

Some other pairs of agonist and antagonist muscles include-

• Deltoids and Latissimus Dorsi (shoulder)

• Pectoralis Major and Trapezius (chest and upper back)

• Abdominals and Erector Spinae (stomach and lower back)

• Lliopsoas and gluteus Maximus in hips

• Tibialis Anterior and Gastrocnemius in the lower leg

• Some other pairs of muscles are also present in the wrist, ankles, and neck that include extensors and flexors and move the neck forward and backward. They are also responsible for the movement of the wrist and ankle.

Muscle Contraction

The transformation of the body parts, which results in the movement is called muscle action. It occurs due to the contraction of muscles, also called muscle contraction. The muscles can have different types of contraction movements that generate tension in the muscle and sometimes shortening of muscles. The contraction in muscles can occur in the following ways-

• Isometric Contraction: the movement does not occur in this type of contraction. It includes pushing or pulling any immobile object. Here, less tension is generated as compared to the load on the muscle.

• Isotonic Contraction: the movement takes place in this type of movement. An example is pulling an object successfully. In this type of contraction, more tension is created by the contracting muscle.

Isotonic contraction is further divided into different types-

• Concentric Contraction– it decreases the length of the muscle against an opposing load. Example- lifting a heavyweight in an upward direction.

• Eccentric Contraction– the length of the muscle increase while resting a load. The example includes keeping weight down in a slow way.

Our body carries out efficient movements that need the coordination of multiple levers. The transmission of forces to the bones via tendons takes place by muscles that result in the movement of a required body part. The whole process is called muscle contraction that brings two bones closer to each other. It results in the movement of bones and is called flexing of the bones.

The bones are placed in their original position by another group of muscles. These muscles are called antagonistic muscles that act in the opposite way of agonistic muscles. Usually, the agonistic muscle contracts and antagonistic muscles relax them. Both the muscles are complementary to each other that work in the prerequisite manner for any action to be carried out efficiently.

The complementary movements are described by some common examples-

• Flexion vs extension

• Abduction vs adduction

• Protraction vs retraction

The support and stabilization to the joints are provided by the fixators or synergists. The synergist muscles are also called neutralizers that reduce or neutralize the extra movement. For example- the trapezius muscle act as a fixator for flexing the elbow joint, the abdominals act as fixators for the hip and knee movement. The complementary muscle of the agonistic muscle act as an antagonistic muscle.

Antagonistic Muscle Citations
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