What do the biceps and triceps to move an arm upwards?

To lift your arm upwards, your biceps brachii and triceps brachii work together in a coordinated manner. Here's how these muscles contract and cooperate during arm elevation:

1. Biceps Brachii (Agonist):

- The biceps brachii is the primary agonist muscle for elbow flexion.

- When you want to raise your arm, the biceps contracts to flex the elbow joint.

- It originates from the scapula (shoulder blade) and inserts onto the radius (one of the forearm bones).

- The contraction of the biceps pulls the forearm and hand towards the shoulder, causing the elbow to bend and the arm to move upwards.

2. Triceps Brachii (Antagonist):

- The triceps brachii, while often thought of as an elbow extensor, also plays an important role during arm elevation.

- It acts as an antagonist to the biceps brachii in this movement.

- Although its main function is to extend the elbow joint, the triceps also contributes to arm elevation.

- It consists of three heads: the long head, medial head, and lateral head.

- During arm elevation, the triceps long head assists the biceps brachii in bending the elbow and raising the arm.

The other two heads, the lateral and medial heads, become active later in the movement to provide stability to the elbow and prevent it from over-extending.

Summary:

The biceps brachii is the main muscle responsible for pulling the forearm and hand upwards by bending the elbow. At the same time, the triceps long head assists in elbow flexion, while the lateral and medial heads provide stability to the elbow during arm elevation. The coordinated action of the biceps and triceps allows for smooth and efficient upward arm movement.