Human Muscles
Comprehensive guides to 23 major muscles covering origin, insertion, action, innervation, and clinical relevance. Perfect for medical students, physical therapists, and fitness professionals.
Upper Limb
Biceps Brachii
Flexion of the elbow joint
Triceps Brachii
Extension of the elbow joint (all three heads)
Deltoid
Abduction of the arm (middle fibers - main abductor after first 15°)
Rotator Cuff
Supraspinatus: Initiates abduction (first 15°), stabilizes shoulder
Rhomboids
Retraction of the scapula (pulling shoulder blades together)
Trunk & Core
Pectoralis Major
Adduction of the arm
Latissimus Dorsi
Extension of the arm
Rectus Abdominis
Flexion of the trunk (against gravity)
Trapezius
Elevation of the scapula (upper fibers)
Diaphragm
Primary muscle of inspiration (contraction flattens the dome)
External Obliques
Flexion of the trunk (bilateral contraction)
Erector Spinae
Extension of the vertebral column (bilateral contraction)
Lower Limb
Gluteus Maximus
Extension of the hip (most powerful hip extensor)
Quadriceps Femoris
Extension of the knee (all four muscles)
Hamstrings
Flexion of the knee (all three muscles)
Gastrocnemius
Plantarflexion of the ankle (strongest plantarflexor)
Iliopsoas
Flexion of the hip (strongest hip flexor)
Soleus
Plantarflexion of the ankle
Tibialis Anterior
Dorsiflexion of the ankle
Sartorius
Flexion of the hip
Adductor Group
Adduction of the hip (all muscles)
Head & Neck
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