Thorachumeral muscles:
① Pectoralis major
- I: Humerus - intratubercle
- N: Pectoralis n. (lateral & medial)
- F: adduction, flexion & internal rotation of the arm
- B.S: thoracoacromial art
- ↳ branch of axillary art.
② Pectoralis minor
- O: 3rd - 5th ribs
- I: Scapula - coracoid process
- N: medial pectoral n.
- F: Protraction + depression of the scapula.
- B.S: Thoracoacromial art.
③ Serratus anterior m.
- O: Outer surface of the upper 8 ribs
- I: → super. angle of the scapula
- → medial border " "
- → infer. angle " "
- N: long thoracic n.
- B.S: Sup. & lateral thoracic alt.s
- ↳ branches of the axillary art.
④ Subclavian
- O: 1st rib
- I: clavicle
- N: Subclavian n.
Proper muscles:
① External intercostal m. → for exhalation.
- O: ribs - caudal margin of rib
- I: ribs - cranial " " "
- N: Intercostal n.
- F: Elevates the ribs
- Fibers direction: hands to pocket.
- absent in the region of the costal cartilage
② Internal intercostal m. → for inhalation
- O: ribs - caudal "
- I: ribs - cranial "
- N: intercostal n.
- F: Depression of the ribs
- F.D = Hands to chest
- absent from the vertebral column.
③ Innermost intercostal m.
- O: " "
- I: " "
- N: Intercostal n.
- F: Depression
- F.D = Hands to chest
- absent " vertebral column.
B.S. : Ant. + Post. intercostal art.
④ Transverse thoracis
- O: → Sternum
- → cartilage of the 4th - 7th ribs
- I: cartilage of 2nd - 6th ribs
- N: intercostal n.
- F: Depression of the ribs
- B.S: Sternal branches of internal thoracic (branch of the subclavian).
⑤ Levatores costarum
- N: Spinal n.
- F: Elevates
- B.S: Posterior intercostal art.