Name at least two muscles that actively contracts during the following activities and name its action and innervation
Throwing a baseball overhead
Muscle 1: Deltoid
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 and shoulder joint.
Innervation: Axillary nerve
Muscle 2: Latissimus Dorsi
Action: Extends, adducts, and medially rotates arm at shoulder joint; draw arms inferiorly and posteriorly.
Innervation: Thoracodorsal nerve
Kicking a ball
Muscle 1: Quadriceps femoris (Rectus femoris)
Action: All four heads extend leg at knee joint; rectus femoris muscle acting alone also flexes thigh and hip joint.
Innervation: Femoral nerve
Muscle 2: Gastrocnemius
Action: Plantar flexes foot at ankle joint and flexes leg at knee joint
Innervation: Tibial nerve
Doing Sit-ups
Muscle 1: Rectus abdominis
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.
Innervation: Thoracic spinal nerves T7-T12
Muscle 2: Transversus abdominis
Action: Compresses abdomen
Innervation: Thoracic spinal nerves T8-T12, iliohypogastric nerve, and ilioinguinal nerve
Breathing
Muscle 1: Diaphragm
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.
Innervation: Phrenic nerve, which contains axons from cervical spinals nerves (C3-C5).
Muscle 2: External intercostals
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
Innervation: Thoracic spinal nerves T2-T12
Reference: Tortora, G. J., & Derrickson, B. (2017). Chapter 11: The Muscular System. Principles of Anatomy & Physiology (15th ed). John Wiley & Sons, Inc.