1. Throwing a baseball overhead
a. Teres Major
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Action:
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Extends arm at shoulder joint
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Assist in adduction and medial rotation of arm at shoulder joint
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Internally rotates the arm
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Innervation: Supplied by the lower subscapular nerve (C5-C7) a branch of the brachial plexus
b. Subscapularis
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Action:
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Internally rotates the arm
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Stabilizes shoulder joint
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- Innervation: Subscapularis is innervated by the upper and lower subscapular nerves (C5-C6), that stem from the superior and posterior cords of the brachial plexus, respectively.
2. Kicking a ball
a. Quadriceps femoris
- Action:
- Extension of the knee joint
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- Contributes to flexion at the hip joint through the action of the rectus femoris
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Innervation: Femoral nerve
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The entire quadriceps femoris muscle is innervated by the femoral nerve (L2-L4).
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b. Iliopsoas muscles
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Action: powerful flexion of the thigh and hip joint
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Innervation:
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Iliacus: femoral nerve (L2-L4)
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Psoas major: anterior rami of spinal nerves (L1-L3); Its blood supply is derived mainly from the iliolumbar branch of the internal iliac artery, with contributions from the obturator and lumbar arteries, as well as branches of the external iliac of femoral arteries.
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3. Doing sit-ups
a. Rectus abdominis
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Action:
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Assist the flat muscles in compressing the abdominal viscera
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Stabilizes pelvis during walking
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Depresses the ribs
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Innervation: Thoracoabdominal nerves (T7-T11)
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The rectus abdominis muscle is innervated by the thoracoabdominal nerves, which enter the rectus sheath by piercing its anterior surface.
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b. Transversus abdominis
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Action:
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Maintain abdominal tension and support abdominal viscera
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Increase intraabdominal pressure that is helpful in forceful expiration, coughing, defecation
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Support the lumbopelvic during our movement, in concert with other core muscles.
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- Innervation:
- Intercostal nerves (T7-T11)
- Subcostal nerve (T12)
- Iliohypogastric nerve (L1)
- Ilioinguinal nerve (L1)
4. Breathing
a. Diaphragm
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Action:
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Depresses costal cartilages, primary muscle of breathing (Inspiration)
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Contracts and flattens and the chest cavity enlarges
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Innervation: Phrenic nerves (C3-C5) (sensory innervation of peripheries via 6th-11th intercostal nerves)
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Mnemonic: C3, 4, 5 keeps the diaphragm alive!
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b. Intercostals (Internal & External)
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Action:
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Internal: depresses ribs
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External: elevates ribs
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Innervation: Intercostal muscles are innervated by the intercostal nerves.
Reference:
Tortora, G. J., & Derrickson, B. H. (2017). Tortora’s Principles of Anatomy & Physiology. Wiley.