The major muscle groups and what they do

What is a primary action of the deltoid muscle?

Abducting the arm at the shoulder

Which muscle is chiefly responsible for flexing the elbow and also helps turn the palm upward?

Biceps brachii

The triceps brachii performs which main movement?

Elbow extension

What does the pectoralis major do when it contracts?

Pulls the arm toward and across the chest

Which action is associated with the latissimus dorsi?

Pulling the arm downward and backward

The trapezius mainly helps move and stabilize which structure?

Scapula

What is the main role of the rectus abdominis?

Flexing the trunk

Which movement is produced by the external and internal oblique muscles?

Rotation and side-bending of the trunk

The erector spinae muscle group primarily performs which function?

Extends and helps stabilize the spine

What is a major action of the gluteus maximus?

Hip extension

The gluteus medius is especially important for which function?

Abducting the hip and stabilizing the pelvis during walking

Which muscle group straightens the leg at the knee?

Quadriceps

What are the main actions of the hamstrings?

Knee flexion and hip extension

The hip adductor muscles primarily move the thigh in which direction?

Toward the body's midline

Which action is performed by the gastrocnemius and soleus muscles of the calf?

Plantar-flexing the ankle

What is the main action of the tibialis anterior?

Pulling the foot upward at the ankle

The iliopsoas, a major hip flexor, produces which movement?

Bringing the thigh toward the trunk

What happens when the diaphragm contracts during breathing?

The chest cavity expands and air is drawn into the lungs