1. Throwing a baseball overhead
Deltoid
Innervation: Axillary nerve (C5, C6)
Action: Anterior part: flexion and medial rotation of arm; middle part: abduction of arm; posterior part: extension and lateral rotation of arm
Pectoralis major
Innervation: Medial pectoral nerve (C8, T1) lateral pectoral nerve (C5, C6, C7) of brachial plexus
Action: Flexion, adduction, medial rotation of the humerus
2. Kicking a ball
Quadriceps femoris
Innervation: Femoral nerve
Action: Extends the knee; rectus femoris flexes the thigh
Gluteus maximus
Innervation: Inferior gluteal nerve
Action: Extends the thigh; laterally rotates the femur
3. Doing sit-ups
Rectus abdominis
Innervation: Intercostal nerves 7-11 and subcostal nerve
Action: Flexes the trunk
Abdominal obliques
Innervation: Intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves
Action: Flexes and laterally bends the trunk
4. Breathing
Diaphragm
Innervation: Phrenic nerve (C3-C5)
Action: Pushes the abdominal viscera inferiorly, increasing the volume of the thoracic cavity (inspiration)
External intercostals
Innervation: Intercostal nerves (T1-T11)
Action: Keeps the intercostal space from blowing out or sucking in during respiration
References
Javed, O., Maldonado, K. A., & Ashmyan, R. (2023, July 24). Anatomy, shoulder and upper limb, muscles. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK482410/
Univ of Michigan - Gross Anatomy - Muscles Tables. (n.d.). Copyright 2000 the University of Michigan. https://www.med.umich.edu/lrc/anatomy-tables/muscles_alpha.html