Muscles of Breathing

Question 1

Diaphragm

Answer 1

Origin: Cartilage of ribs 7-12, xiphoid process, lumbar vertebrae
Insertion: Anterior longitudinal ligament (vertebral column)
Action: Expands thoracic cavity, compresses abdominal cavity
Innervation: phrenic nerve (C3-5)

Question 2

Internal Intercostals

Answer 2

Origin: Superior border of ribs 2-12
Insertion: Inferior or ribs above 1-11
Action: Depresses ribs in forced expiration
Innervation: Intercostal nerves

Question 3

External Intercostals

Answer 3

Origin: Lower border of ribs 1-11
Insertion: Upper border of ribs below 1-12
Action: Elevates ribs in normal inspiration
Innervation: Intercostal nerves