1. Throwing a baseball overhead
> Muscle 1: Deltoids
- Action: Shoulder flexion; medial rotation
- Innervation: Axillary nerve (C5, C6)
> Muscle 2: Triceps Brachii
- Action: Elbow extension
- Innervation: Radial nerve (C6-C8)
2. Kicking a ball
> Muscle 1: Rectus Femoris
- Action: Knee extension; hip flexion
- Innervation: Femoral nerve (L2-L4)
> Muscle 2: Gluteus Maximus
- Action: Hip extension; external rotation
- Innervation: Inferior gluteal nerve (L5-S2)
3. Doing sit-ups
> Muscle 1: Rectus Abdominis
- Action: Trunk flexion
- Innervation: Thoracoabdominal nerves (T7-T11)
> Muscle 2: External Oblique
- Action: Flexion of the trunk; rotation to opposite sides
- Innervation: Thoracoabdominal nerves (T7-T11)
4. Breathing
> Muscle 1: Diaphragm
- Action: Primary muscle of respiration; expansion of thoracic cavity
- Innervation: Phrenic nerve (C3-C5)
> Muscle 2: Intercostal muscles (External Intercostals)
- Action: Elevation of ribs during inspiration
- Innervation: Intercostal nerves (T1-T11)