Activity 2
Throwing a baseball overhead
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 at shoulder joint.
Innervation: Axillary nerve
Biceps brachii
Action: Flexes forearm at elbow joint, supinates forearm at radioulnar joints, and flexes arm at shoulder joint.
Innervation: Musculocutaneous nerve.
Kicking a ball
Popliteus
Action: Flexes leg at knee joint and medially rotates tibia to unlock the extended knee
Innervation: Tibial nerve
Gastrocnemius
Action: Plantar flexes foot at ankle joint and flexes leg at knee joint.
Innervation: Tibial nerve
Doing sit-ups
Iliopsoas
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.
Innervation: Lumbar spinal nerves L2–L3.
Gluteus Maximus
Action: Extends thigh at hip joint and laterally rotates thigh; helps lock knee in extension. RMA: Extends torso.
Innervation: Inferior gluteal nerve.
Breathing
Anterior Scalene
Action: Acting together, right and left anterior scalene and middle scalene muscles elevate first ribs during deep inhalation.
Innervation: Cervical spinal nerves
Posterior Scalene
Action: Acting together, right and left posterior scalene elevate second ribs during deep inhalation.
Innervation: Cervical spinal nerves.
References:
Tortora, G. J., & Derrickson, B. H. (2017). Principles of Anatomy & Physiology. Wiley.