N3 Anatomy and Physiology AY 2023-2024

1. Throwing a baseball overhead

• Teres Major

  • Action: Extends arm at shoulder joint; assists in adduction and medial rotation of arm at shoulder joint

  • Innervation: Lower subscapular nerve

• Subscapularis

  • Action: Medially rotates arm at shoulder joint

  • Innervation: Upper and lower subscapular nerve

2. Kicking a ball 

• Quadriceps femoris

  • Action: All four heads extend leg at knee joint; rectus femoris muscle acting alone also flexes thigh at hip joint

  • Innervation: Femoral nerve

• Tibialis anterior

  • Action: Dorsiflexes foot at ankle joint and inverts (supinates) foot at intertarsal joints

  • Innervation: Deep fibular (peroneal) nerve

3. Doing sit-ups

• Rectus abdominis 

  • Action: Flexes vertebral column, especially lumbar portion; compresses abdomen to aid in defecation, urination, forced exhalation, and childbirth

  • Innervation: Thoracic spinal nerves (T7–T12)

• Internal Obliques

  • Action: when acting together = compresses abdomen and flexes vertebral column; when acting singly = laterally flex vertebral column, especially lumbar portion, and rotate vertebral column

  • Innervation: Thoracic spinal nerves (T8–T12), the iliohypogastric nerve,  ilioinguinal nerve

4. Breathing

• Diaphragm

  • Action: inhalation caused by the contraction of the diaphragm as it flattens and increases vertical dimension of thoracic cavity; relaxation of diaphragm moves superiorly and decreases vertical dimension of thoracic cavity = exhalation

  • Innervation:  Phrenic nerve (C3-C5)

• External Intercostals

  • Action: Inhalation = Contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity; Exhalation = relaxation depresses ribs and decreases anteroposterior and lateral dimensions of thoracic cavity

  • Innervation: Thoracic spinal nerves (T2-T12)

Reference:

Tortora, G. J., & Derrickson, B. (2015). Principles of Anatomy & Physiology (15th ed.) [E-book]. John Wiley & Sons, Inc.