1. Throwing a Baseball Overhead
Muscle 1: Deltoid
Action: Abducts, flexes, and extends the arm at the shoulder joint.
Innervation: Axillary nerve (C5, C6)
Muscle 2: Supraspinatus
Action: Initiates abduction of the arm.
Innervation: Suprascapular nerve (C5, C6)
Muscle 3: Pectoralis Major
Action: Adducts and medially rotates the arm; assists in shoulder flexion.
Innervation: Medial and lateral pectoral nerves (C5-T1)
2. Kicking a Ball
Muscle 1: Quadriceps Femoris
Action: Extends the leg at the knee joint.
Innervation: Femoral nerve (L2-L4)
Muscle 2: Iliopsoas (Iliacus and Psoas Major)Action: Flexes the thigh at the hip joint.
Innervation: Iliacus: Femoral nerve (L2-L3); Psoas Major: Lumbar plexus (L1-L3)
Muscle 3: Gluteus Maximus
Action: Extends and laterally rotates the thigh at the hip joint.
Innervation: Inferior gluteal nerve (L5-S2)
3. Doing Sit-Ups
Muscle 1: Rectus Abdominis
Action: Flexes the trunk (bends forward).
Innervation: Lower six thoracoabdominal nerves (T7-T11) and subcostal nerve (T12)
Muscle 2: External Oblique
Action: Flexes and rotates the trunk; compresses abdominal contents.
Innervation: Lower six thoracoabdominal nerves (T7-T11) and subcostal nerve (T12)
Muscle 3: Internal Oblique
Action: Flexes and rotates the trunk; compresses abdominal contents.
Innervation: Lower six thoracoabdominal nerves (T7-T11), subcostal nerve (T12), and iliohypogastric and ilioinguinal nerves (L1)
4. Breathing
Muscle 1: Diaphragm
Action: Contracts to increase thoracic cavity volume and draw air into the lungs.
Innervation: Phrenic nerve (C3-C5)
Muscle 2: External Intercostals
Action: Elevates the ribs, expanding the thoracic cavity and aiding in inhalation.
Innervation: Intercostal nerves (T1-T11)
Muscle 3: Internal Intercostals
Action: Depresses the ribs, aiding in forced exhalation.
Innervation: Intercostal nerves (T1-T11)