ACTIVITY 2
Name at least two muscles that actively contract during the following activities and name their action and innervation:
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Throwing a baseball overhead uses muscles like the Subscapularis, Deltoid, and such.
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Subscapularis
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ACTION: Medially rotates the arm and stabilizes the shoulder joint
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NERVE: Upper and lower subscapular nerve.
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Deltoid
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ACTION: Lateral fibers abduct arm at shoulder joint; anterior fibers flex and medially rotate arm at shoulder joint; posterior fibers extend and laterally rotate arm at shoulder joint.
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NERVE: Axillary nerve.
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Kicking a ball uses muscles like Quadriceps, Rectus femoris and such.
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Biceps femoris
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ACTION: Flexes leg at knee joint and extends thigh at hip joint.
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NERVE: Tibial and fibular nerves from sciatic nerve.
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Rectus femoris
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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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NERVE: Femoral nerve.
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Doing sit-ups uses muscles like Rectus abdominis, Transversus abdominis, and such.
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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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NERVE: Thoracic spinal nerves T7–T12.
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Transversus abdominis
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ACTION: Compresses abdomen.
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NERVE: Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve
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Breathing uses muscles like Diaphragm , External intercostals, and such.
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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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NERVE: Phrenic nerve, which contains axons from cervical spinal nerves (C3–C5).
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External 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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NERVE: Thoracic spinal nerves T2–T12.
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Reference:
Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy and physiology. Wiley Custom Learning Solutions.