Activity #2
1. Throwing a baseball overhead
- Muscle: 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
- Muscle: Latissimus dorsi
- Action: Extends, adducts, and medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly
- Innervation: Thoracodorsal nerve
2. Kicking a ball
- Muscle: Quadriceps femoris muscle group, specifically the 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
- Muscle: 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
3. Doing sit-ups
- Muscle: 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
- Muscle: Transversus abdominis
- Action: Compresses abdomen
- Innervation: Thoracic spinal nerves T8–T12, iliohypogastric nerve, and ilioinguinal nerve
4. Breathing
- Muscle: 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)
- Muscle: 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
Reference:
Tortora, G. J., & Derrickson, B. H. (2017). Tortora’s Principles of Anatomy & Physiology. Wiley.