Throwing a baseball overhead
1. Pectoralis major
Action: As a whole, adducts and medially rotates arm at shoulder joint; clavicular head flexes arm, and sternocostal head extends flexed arm to side of trunk
Innervation: Medial and lateral pectoral nerves
2. Latissimus dorsi
Action: Extends, adducts, and medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly. RMA: Elevates vertebral column and torso
Innervation: Thoracodorsal nerve
Kicking a ball
1. Biceps femoris
Action: Flexes leg at knee joint and extends thigh at hip joint.
Innervation: Tibial and fibular nerves from sciatic nerve.
2. Semitendinosus
Action: Flexes leg at knee joint and extends thigh at hip joint.
Innervation: Tibial nerve from sciatic nerve
Doing sit-ups
1. Transversus Abdominis
Action: Compresses abdomen
Innervation:Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve
2. 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
Breathing
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 spinal nerves (C3–C5)
2. Internal Intercostals
Action: Contraction draws adjacent ribs together to further decrease anteroposterior and lateral dimensions of thoracic cavity during forced exhalation.
Innervation: Thoracic spinal nerves T2–T12.
References:
Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy & physiology. Fifteenth edition; Wiley Loose-Leaf Print Companion. Hoboken, New Jersey, John Wiley & Sons, Inc.