ACTIVITY 2. Name at least two muscles that actively contracts during the following activities and name its action and innervation.
- Throwing a baseball overhead
- Triceps brachii
- Action. Extends forearm at elbow joint and extends arm at shoulder joint.
- Innervation. Radial nerve
- Biceps brachii
- Action. Flexes forearm at elbow joint, supinates forearm at radioulnar joints, and flexes arm at shoulder joint.
- Innervation. Musculocutaneous nerve.
- Triceps brachii
- Kicking a ball
- Obturator externus
- Action. Laterally rotates and abducts thigh at hip joint.
- Innervation. Obturator nerve.
- Tensor fasciae latae
- Action. Flexes and abducts thigh at hip joint.
- Innervation. Superior gluteal nerve.
- Obturator externus
- Doing sit-ups
- External oblique
- Action. Compress abdomen and flex vertebral column; Laterally flex vertebral column, especially lumbar portion, and rotate vertebral column.
- Innervation. Thoracic spinal nerves T7–T12 and the iliohypogastric nerve.
- Transversus abdominis
- Action. Compresses abdomen.
- Innervation. Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve.
- External oblique
- Breathing
- Diaphragm
- Action: Contracts and flattens when inhaling and relaxes and returns to its original dome shape when exhaling.
- Innervation. Phrenic nerve, which contains axons from cervical spinal nerves (C3–C5).
- 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.
- Diaphragm
Reference
Tortora, G., & Derrickson B. (2017). Principles of Anatomy and Physiology (15th ed.). Wiley.