Note: Good day, class! My apologies for posting my answers in this forum discussion so late. I was setback last week by an illness that lasted for six days. I had informed our professors about this health condition and provided them with a medical clearance. I kindly ask for your consideration and understanding. Thank you.
1. Throwing a baseball overhead
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Muscle: Deltoid
Action: Abducts arm; anterior fibers flex and medially rotate arm; posterior fibers extend and laterally rotate arm.
Innervation: Nerve Supply - Axillary nerve (Roots - C5, 6)
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Muscle: Pectoralis major
Action: Adducts arm and rotates it medially, clavicular fibers also flex am
Innervation: Nerve Supply - Medial and lateral pectoral nerves from brachial plexus (Roots - C5, 6, 7, 8; T1)
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Muscle: Latissimus dorsi
Action: Extends, adducts, and medially rotates the arm
Innervation: Nerve Supply - Thoracodorsal nerve (Roots - C6, 7, 8)
2. Kicking a ball
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Muscle: Biceps femoris
Action: Flexes and laterally rotates leg at knee joint; long head also extends thigh at hip joint
Innervation: Long head: tibial portion of sciatic nerve, Short head: common peroneal portion of sciatic nerve (Nerve Roots - L5; S1, 2)
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Muscle: Gastrocnemius
Action: Plantar flexes foot at ankle joint; flexes knee joint
Innervation: Tibial nerve (Nerve Roots - S1, 2)
3. Doing sit-ups
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Muscles: External and Internal Oblique
Action: Supports abdominal contents; compresses abdominal contents; assists in flex-ing and rotation of trunk; assists in forced expiration, micturition, defecation, parturition and vomiting
Innervation: Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves (LI)
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Muscle: Transversus Abdominis
Action: Compresses abdominal contents
Innervation: Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves (LI)
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Muscle: Rectus Abdominis
Action: Compresses abdominal contents and flexes vertebral column; accessory muscle of expiration
Innervation: Lower six thoracic nerves
4. Breathing
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Muscle: Diaphragm (most important muscle of respiration)
Action: Very important muscle of inspiration; increases vertical diameter of thorax by pulling central tendon downward; assists in raising lower ribs. Also used in abdominal straining and weight lifting
Innervation: Phrenic Nerve, which contains axons from cervical spinal nerves (C3-C5)
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Muscle: Levatores costarum (12)
Action: Raises ribs and therefore inspiratory muscles
Innervation: Posterior rami of thoracic spinal nerves
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Muscle: Innermost intercostal muscle (incomplete layer)
Action: Assists external and internal intercostal muscles
Innervation: Intercostal nerves
References:
Moore, Keith Leon, Dalley, Arthur F, Agur, Anne M. R. (2014). Clinically oriented anatomy (7th). Philadelphia: Wolters Kluwer, Lippincott Williams & Wilkins.
Snell, Richard S. (2012). Clinical anatomy by regions (9th). Baltimore, MD: Wolters Kluwer/Lippincott Williams & Wilkins.
Tortora, G., & Derrickson, B. (2012). Principles of ANATOMY & PHYSIOLOGY (13th ed.). John Wiley & Sons, Inc.