Key Human Arm Muscles

• Deltoid: Shoulder muscle for lifting the arm.
• Biceps Brachii: Front of upper arm, flexes the elbow.
• Triceps Brachii: Back of upper arm, extends the elbow.
• Forearm Muscles: Extensor carpi radialis and brachioradialis control wrist and finger movement. 

Key Human Leg Muscles

• Quadriceps: Four muscles on the front of the thigh (vastus lateralis, medialis, intermedius, and rectus femoris) that straighten the knee.
• Hamstrings: Muscles on the back of the thigh that flex the knee.
• Calf Muscles: Gastrocnemius and soleus on the back of the lower leg.
• Glutes: Large buttock muscles, crucial for hip movement. 

Function and Structure

• Legs: Focus on stability, support, and locomotion (walking/running).
• Arms: Focus on range of motion, lifting, and manipulation.
• Types: Skeletal muscles are voluntary, while others include smooth and cardiac muscles.