1. Throwing a baseball overhead
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Subscapularis
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Action: Medially rotates arm at shoulder joint.
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Innervation: Upper and lower subscapular nerve.
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Latissimus dorsi
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Action: Extends, adducts, and medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly. RMA: Elevates vertebral column and torso.
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Innervation: Thoracodorsal nerve
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2. Kicking a ball
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Quadriceps
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Action: All four heads extend leg at knee joint; rectus femoris muscle acting alone also flexes thigh at hip joint.
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Innervation: Femoral nerve.
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Iliopsoas
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Action: Psoas major and iliacus muscles acting together flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip as in sitting up from supine position.
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Innervation: Lumbar spinal nerves L2–L3.
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3. Doing sit-ups
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Rectus abdominis
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Action: Flexes vertebral column, especially lumbar portion, and compresses abdomen to aid in defecation, urination, forced exhalation, and childbirth. RMA: Flexes pelvis on the vertebral column.
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Innervation: Thoracic spinal nerves T7–T12.
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Transverus abdominis
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Action: Compresses abdomen.
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Innervation: Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve.
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4. Breathing
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Diaphragm
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Action: Contraction of diaphragm causes it to flatten and increases vertical dimension of thoracic cavity, resulting in inhalation; relaxation of diaphragm causes it to move superiorly and decreases vertical dimension of thoracic cavity, resulting in exhalation.
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Innervation: Phrenic nerve, which contains axons
from cervical spinal nerves (C3–C5).
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Exterior intercostals
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Action: Contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity, resulting in inhalation; relaxation depresses ribs and decreases anteroposterior and lateral dimensions of thoracic cavity, resulting in exhalation.
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Innervation: Thoracic spinal nerves T2–T12.
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Reference
Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy & physiology. Fifteenth edition; Wiley Loose-Leaf Print Companion. Hoboken, New Jersey, John Wiley & Sons, Inc.