Bodybuilding muscles
Each region and each muscle has its own page: anatomy, function, and the lifts that train it.
Chest
The chest is the main pressing surface of the torso. Pectoralis major has clavicular, sternocostal, and abdominal fibers; pectoralis minor and serratus anterior sit deeper and help the scapula protract and rotate during presses and flyes.
Shoulders
The deltoid has anterior, lateral, and posterior heads that raise, abduct, and horizontally pull the arm. The rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) centers the humeral head so heavy pressing stays stable.
Arms
Elbow flexors (biceps, brachialis, brachioradialis) and the triceps control the elbow. Forearm flexors and extensors grip the bar and stabilize the wrist. Curl grip (supinated, hammer, pronated) changes which flexor takes more load; elbow position changes which triceps head is biased.
Back
The back is both a width muscle (latissimus dorsi, teres major) and a posture muscle (traps, rhomboids). Erectors stabilize the lumbar spine in hinges. Vertical pulls emphasize adduction and width; rows emphasize retraction and thickness; shrugs load upper traps.
Core
Rectus abdominis flexes the spine; obliques rotate and resist rotation; transversus abdominis cinches the waist and raises intra-abdominal pressure. Neck muscles support posture and should be loaded lightly. A useful core is anti-extension and anti-rotation as much as it is crunching.
Legs
The lower body is a set of hip extensors (glutes, hamstrings), knee extensors (quadriceps), hip abductors and adductors, and lower-leg muscles that plantarflex, dorsiflex, and stabilize the ankle. Compound squats, hinges, and lunges train several of these at once; isolation work fills gaps.