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