#separator:tab #html:false #tags column:4 Frontalis Forehead; raises the eyebrows tp-anat-muscles Orbicularis oculi Around the eye; closes the eyelid tp-anat-muscles Orbicularis oris Around the mouth; closes and purses the lips tp-anat-muscles Zygomaticus major Cheek; lifts the corner of the mouth to smile tp-anat-muscles Masseter Cheek; closes the jaw to chew tp-anat-muscles Temporalis Side of head; closes the jaw tp-anat-muscles Buccinator Cheek; presses the cheek against the teeth tp-anat-muscles Platysma Neck; pulls the lower lip and jaw down tp-anat-muscles Sternocleidomastoid Side of the neck; turns and flexes the head tp-anat-muscles Trapezius Upper back and neck; raises and pulls back the shoulder blades tp-anat-muscles Latissimus dorsi Wide back muscle; pulls the arm down and back tp-anat-muscles Rhomboids Between shoulder blades; pull the scapula toward the spine tp-anat-muscles Erector spinae Along the spine; extends the back tp-anat-muscles Deltoid Shoulder cap; raises the arm tp-anat-muscles Pectoralis major Chest; moves the arm across the body tp-anat-muscles Serratus anterior Side of the ribs; moves the shoulder blade forward tp-anat-muscles Rotator cuff Four small muscles that stabilize the shoulder tp-anat-muscles Supraspinatus Rotator cuff muscle that starts raising the arm tp-anat-muscles Biceps brachii Front of the upper arm; flexes the elbow tp-anat-muscles Triceps brachii Back of the upper arm; extends the elbow tp-anat-muscles Brachialis Deep upper-arm muscle that flexes the elbow tp-anat-muscles Brachioradialis Forearm muscle that flexes the elbow tp-anat-muscles Flexor carpi Front of forearm; bends the wrist tp-anat-muscles Extensor carpi Back of forearm; straightens the wrist tp-anat-muscles Rectus abdominis Front of the abdomen; flexes the trunk tp-anat-muscles External oblique Side of the abdomen; twists and bends the trunk tp-anat-muscles Internal oblique Beneath the external oblique; twists the trunk tp-anat-muscles Transversus abdominis Deepest abdominal muscle; compresses the abdomen tp-anat-muscles Diaphragm Under the lungs; main muscle of breathing tp-anat-muscles Intercostals Between the ribs; help breathing tp-anat-muscles Gluteus maximus Buttock; extends the hip tp-anat-muscles Gluteus medius Side of hip; moves the leg out and steadies the pelvis tp-anat-muscles Iliopsoas Deep hip flexor tp-anat-muscles Tensor fasciae latae Upper outer thigh; flexes and abducts the hip tp-anat-muscles Quadriceps femoris Front of the thigh; extends the knee tp-anat-muscles Rectus femoris Quadriceps part that also flexes the hip tp-anat-muscles Vastus lateralis Outer quadriceps tp-anat-muscles Sartorius Longest muscle; crosses the thigh and flexes the hip and knee tp-anat-muscles Hamstrings Back of the thigh; flex the knee tp-anat-muscles Biceps femoris Outer hamstring tp-anat-muscles Adductors Inner thigh; pull the leg toward the midline tp-anat-muscles Gracilis Inner thigh muscle that adducts the leg tp-anat-muscles Gastrocnemius Calf; points the foot and flexes the knee tp-anat-muscles Soleus Deep calf muscle; points the foot tp-anat-muscles Tibialis anterior Front of the shin; lifts the foot tp-anat-muscles Peroneus longus Outer lower leg; turns the foot outward tp-anat-muscles Achilles tendon Joins calf muscles to the heel bone tp-anat-muscles Flexor A muscle that decreases a joint angle tp-anat-muscles Extensor A muscle that increases a joint angle tp-anat-muscles Abductor Moves a limb away from the midline tp-anat-muscles Adductor Moves a limb toward the midline tp-anat-muscles Agonist The prime mover in a movement tp-anat-muscles Antagonist A muscle that opposes the prime mover tp-anat-muscles Synergist A muscle that helps the prime mover tp-anat-muscles Origin The attachment that stays fixed tp-anat-muscles Insertion The attachment that moves tp-anat-muscles Isotonic contraction Muscle changes length while producing force tp-anat-muscles Isometric contraction Muscle produces force without changing length tp-anat-muscles Concentric contraction Muscle shortens under tension tp-anat-muscles Eccentric contraction Muscle lengthens under tension tp-anat-muscles Muscle tone Slight constant tension in resting muscles tp-anat-muscles Fascia Connective tissue wrapping muscles tp-anat-muscles Motor unit One motor neuron and the fibers it controls tp-anat-muscles Neuromuscular junction Synapse between a motor neuron and a muscle fiber tp-anat-muscles Acetylcholine Neurotransmitter that triggers muscle contraction tp-anat-muscles Creatine phosphate Quick energy store in muscle tp-anat-muscles Fast-twitch fibers Muscle fibers for quick, powerful action that tire quickly tp-anat-muscles Slow-twitch fibers Muscle fibers for endurance tp-anat-muscles Rigor mortis Stiffening of muscles after death tp-anat-muscles Tetany Sustained, involuntary muscle contraction tp-anat-muscles Atrophy Wasting of muscle from disuse tp-anat-muscles Hypertrophy Enlargement of muscle fibers tp-anat-muscles Strain Overstretching or tearing of a muscle or tendon tp-anat-muscles Sprain Overstretching or tearing of a ligament tp-anat-muscles Spasm Sudden involuntary contraction tp-anat-muscles Myoglobin Oxygen-storing pigment in muscle tp-anat-muscles Lactic acid Product of anaerobic energy production in muscles tp-anat-muscles Pectoralis minor Beneath the pectoralis major; pulls the shoulder blade forward tp-anat-muscles Teres major Back of the shoulder; rotates the arm inward tp-anat-muscles Psoas major Deep muscle linking the spine to the thigh tp-anat-muscles Piriformis Deep buttock muscle that rotates the hip outward tp-anat-muscles Popliteus Behind the knee; unlocks the knee for bending tp-anat-muscles Pronator teres Forearm; turns the palm down tp-anat-muscles Supinator Forearm; turns the palm up tp-anat-muscles