1. Throwing a baseball overhead
- Muscle: Triceps brachii
- Action: Extends forearm at elbow joint and extends arm at shoulder joint
- Innervation: Radial nerve
- Muscle: Deltoid
- Action: Lateral fibers abduct arm at shoulder joint
- Innervation: Axillary nerve
2. Kicking a ball
- Muscle: Gluteus Maximus
- Action: Extends thigh at hip joint and laterally rotates thigh; helps lock knee in extension
- Innervation: Inferior gluteal nerve
- Muscle: Adductor longus
- Action: Adducts thigh at hip joint, medially rotates thigh, and flexes leg at knee joint
- Innervation: Obturator nerve
3. Doing sit-ups
- Muscle: Rectus abdominus
- Action: Flexes vertebral column, especially the lumbar portion; compresses the abdomen
- Innervation: Thoracic spinal nerves T7-T12
- Muscle: External oblique
- Action: Compresses the abdomen and flexes the vertebral column
- Innervation:
4. Breathing
- Muscle: Diaphragm
- Action: Contraction causes it to flatten and increase vertical dimension of thoracic cavity (inhalation); Relaxation causes it to move superiorly and decreases the vertical dimension of the thoracic cavity (exhalation)
- Innervation: Phrenic nerve containing axons from cervical spinal nerves (C3-C5)
- Muscle: External intercostals
- Action: Contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity (inhalation); Relaxation depresses ribs and decreases anteroposterior lateral dimensions of thoracic cavity (exhalation)
- Innervation: Thoracic spinal nerves T2-T12