N3 AY 2023-2024: Loquias, Hanna Kae F.

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
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.

2. Kicking a ball

Quadriceps femoris (Rectus femoris, Vastus lateralis, Vastus medialis, Vastus intermedius)
- Action: All four heads extend leg at knee joint; rectus femoris muscle acting alone also flexes thigh at hip joint.
- Innervation: femoral nerve (L2-L4).
Biceps femoris of Hamstrings muscle group
- Action: Flexes leg at knee joint and extends thigh at hip joint.
- Innervation: Tibial and fibular nerves from sciatic nerve.

3. Doing sit-ups

Internal-External Obliques
- Action: The external obliques cause ipsilateral lateral flexion of the trunk and contralateral rotation of the trunk when it contracts unilaterally. While internal obliques flexes and bends the trunk, assists forced expiration by depressing the lower ribs, and helps to maintain intra-abdominal pressure in defecation.
- Innervation: Internal obliques: Intercostal nerves (T7-T11), subcostal nerve (T12), iliohypogastric nerve (L1), ilioinguinal nerve (L1); External Obliques: Intercostal nerves (T7- T11), Subcostal nerve (T12)
Transversus abdominis
- Action: (1) Bilateral contraction - Compresses abdominal viscera, expiration (2) Unilateral contraction - Trunk rotation (ipsilateral)
- Innervation: Intercostal nerves (T7-T11), subcostal nerve (T12), iliohypogastric nerve (L1), ilioinguinal nerve (L1)

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.

References:

Tortora, G. J., & Derrickson, B. H. (2017). Principles of Anatomy and Physiology. (15th Ed.). John Wiley & Sons Inc.