ACTIVITY 2
1. 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.
- Subscapularis
- Action: Medially rotates arm at shoulder joint.
- Innervation: Upper and lower subscapular nerve.
2. Kicking a ball
- Rectus femoris
- Action: All four heads extend leg at knee joint; rectus femoris muscle acting alone also flexes thigh at hip joint.
- Innervation: Femoral nerve.
- Gluteus maximus
- Action: Extends thigh at hip joint and laterally rotates thigh; helps lock knee in extension. RMA: Extends torso.
- Innervation: Inferior gluteal nerve.
3. Doing sit-ups
- 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.
- Transversus abdominis
- Action: Compresses abdomen.
- Innervation: Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve.
4. Breathing
- 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).
- 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(S):
Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy and physiology (15th ed.). Wiley Custom Learning Solutions. https://handoutset.com/wp-content/uploads/2022/05/Principles-of-anatomy-and-physiology-Wiley-2017-Derrickson-Bryan-H._-Tortora-Gerard-J..pdf