Muscle Groups

Understanding muscle groups is essential in Honors Anatomy and Physiology. Each muscle plays a unique role in movement, stability, and overall function. From the deltoids to the tibialis anterior, these muscles work together to support daily activities and athletic performance.

1. Deltoids

   • Located on the shoulder, responsible for arm abduction, flexion, and extension.
   • Comprised of three distinct heads: anterior, lateral, and posterior.
   • Essential for overhead movements and stabilizing the shoulder joint.

2. Pectoralis major

   • A large chest muscle that aids in arm flexion, adduction, and internal rotation.
   • Divided into two parts: clavicular (upper) and sternal (lower).
   • Plays a key role in pushing movements, such as push-ups and bench presses.

3. Biceps brachii

   • Located in the upper arm, primarily responsible for elbow flexion and forearm supination.
   • Consists of two heads: long head and short head.
   • Important for lifting and pulling movements.

4. Triceps brachii

   • Situated at the back of the upper arm, responsible for elbow extension.
   • Composed of three heads: long, lateral, and medial.
   • Crucial for pushing movements and stabilizing the shoulder.

5. Latissimus dorsi

   • A large back muscle that aids in arm extension, adduction, and internal rotation.
   • Extends from the lower back to the upper arm, contributing to a V-shaped torso.
   • Important for pulling movements, such as pull-ups and rowing.

6. Rectus abdominis

   • A long muscle in the front of the abdomen, known as the "six-pack."
   • Responsible for trunk flexion and stabilization of the pelvis.
   • Plays a key role in maintaining posture and core stability.

7. Quadriceps femoris

   • A group of four muscles located at the front of the thigh, responsible for knee extension.
   • Includes the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.
   • Essential for activities like walking, running, and jumping.

8. Hamstrings

   • A group of three muscles located at the back of the thigh, responsible for knee flexion and hip extension.
   • Comprises the biceps femoris, semitendinosus, and semimembranosus.
   • Important for running, cycling, and activities requiring leg movement.

9. Gastrocnemius

   • The prominent calf muscle that aids in plantar flexion of the foot and knee flexion.
   • Composed of two heads: medial and lateral.
   • Plays a crucial role in walking, running, and jumping.

10. Trapezius

    • A large muscle in the upper back that stabilizes and moves the shoulder blades.
    • Divided into upper, middle, and lower fibers, each with distinct functions.
    • Important for posture and movements involving the shoulders and neck.

11. Gluteus maximus

    • The largest muscle in the body, located in the buttocks, responsible for hip extension and external rotation.
    • Plays a key role in activities like climbing, running, and maintaining an upright posture.
    • Important for overall lower body strength and stability.

12. Soleus

    • A muscle located beneath the gastrocnemius in the calf, primarily responsible for plantar flexion.
    • Works with the gastrocnemius during activities like walking and running.
    • Important for maintaining balance and posture.

13. Erector spinae

    • A group of muscles that run along the spine, responsible for extending and stabilizing the back.
    • Comprises three columns: iliocostalis, longissimus, and spinalis.
    • Essential for maintaining an upright posture and supporting spinal movements.

14. Obliques

    • Located on the sides of the abdomen, responsible for trunk rotation and lateral flexion.
    • Includes the external and internal obliques.
    • Important for core stability and movements involving twisting.

15. Tibialis anterior

    • A muscle located in the front of the lower leg, responsible for dorsiflexion of the foot.
    • Plays a key role in walking, running, and maintaining balance.
    • Important for preventing foot drop and stabilizing the ankle.