1. Throwing a baseball overhead
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- Muscle 1: Deltoid (anterior fibers)
- Action: Flexes and medially rotates the arm.
- Innervation: Axillary nerve.
- Muscle 2: Triceps brachii (long head)
- Action: Extends the elbow and aids in shoulder extension.
- Innervation: Radial nerve.
- Muscle 1: Deltoid (anterior fibers)
2. Kicking a ball
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- Muscle 1: Quadriceps (Rectus femoris)
- Action: Extends the knee and flexes the hip.
- Innervation: Femoral nerve.
- Muscle 2: Gluteus maximus
- Action: Extends and laterally rotates the hip.
- Innervation: Inferior gluteal nerve.
- Muscle 1: Quadriceps (Rectus femoris)
3. Doing sit-ups
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- Muscle 1: Rectus abdominis
- Action: Flexes the vertebral column.
- Innervation: Lower six thoracic nerves (T7-T12).
- Muscle 2: External oblique
- Action: Flexes and rotates the trunk.
- Innervation: Lower six thoracic nerves (T7-T12).
- Muscle 1: Rectus abdominis
4. Breathing
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- Muscle 1: Diaphragm
- Action: Contracts to increase thoracic volume during inhalation.
- Innervation: Phrenic nerve (C3, C4, C5).
- Muscle 2: External intercostals
- Action: Elevates ribs to expand the thoracic cavity during inhalation.
- Innervation: Intercostal nerves (T1-T11).
- Muscle 1: Diaphragm