Superficial muscles are those positioned close to the body’s surface, lying directly beneath the skin. They are often visible and contribute significantly to the body’s external shape and appearance. These muscles enable a wide range of movements and are frequently the focus of physical training.
What Superficial Muscles Are
Superficial muscles are located just beneath the skin and a layer of connective tissue called superficial fascia. This positioning gives the body its contours and makes them readily felt or seen, such as the trapezius in the back.
The term “superficial” in anatomy refers to a structure’s proximity to the body’s exterior. These muscles are large and play a role in broad movements and maintaining posture.
Key Superficial Muscles and Their Roles
Many common muscles are superficial, contributing to everyday movements. The trapezius muscle, a large, V-shaped muscle extending from the neck across the shoulders and down to the lower back, assists with shoulder and neck movements, including elevating, retracting, and depressing the scapula.
The latissimus dorsi, often called “lats,” are the largest muscles in the upper body, starting below the shoulder blades and extending to the lower back. These muscles facilitate arm movements such as extension, adduction, and medial rotation. Another prominent superficial muscle is the pectoralis major, located in the chest, which flexes, adducts, and medially rotates the arm at the shoulder joint.
The deltoid muscle, which gives the shoulder its rounded shape, is a superficial muscle. It has three distinct portions—anterior, middle, and posterior—each contributing to different arm movements like flexion, abduction, and extension. In the core, the rectus abdominis is the outermost abdominal muscle, contributing to trunk movement and stability.
How Superficial Muscles Differ from Deep Muscles
Superficial muscles are distinguished from deep muscles primarily by their anatomical layering. Superficial muscles lie closer to the skin’s surface, often directly underneath the superficial fascia. Deep muscles, in contrast, are located further inward, closer to bones or internal organs.
Functionally, superficial muscles contribute to large, gross movements and generate power, such as moving the limbs or maintaining posture. Deep muscles, while also contributing to movement, focus more on providing stability to joints and enabling fine motor control. For instance, superficial back muscles primarily assist with shoulder movements, whereas deep back muscles are associated with movements of the vertebral column itself. This distinction in depth also means superficial muscles are more visible and palpable than their deeper counterparts.