Thorax Anatomy
Terms
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- Sternum
- Long flat bone; composed of the manubrium, body and xiphoid process
- True ribs
- Ribs 1-7; articulate with sternum directly
- False ribs
- Ribs 8-10; articulate to costal cartilages of the ribs above
- Floating ribs
- Ribs 11 and 12; articulate with vertebrae only
- Capsule (ligament)
- Clavicle and manubrium; allows elevation, depression, protraction, retraction, and circumduction
- Sternoclavicular (ligament)
- Clavicle and manubrium; Consists of anterior and posterior ligaments
- Interclavicular (ligament)
- Between both clavicles; Connects two sternoclavicular joints
- Costoclavicular (ligament)
- Clavicle to first rib; Anchors clavicle to first rib
- First sternocostal (joint)
- First rib to manubrium; Allows no movement at this joint
- Radiate sternocostal (joint)
- Ribs 2-7 with sternum; Permit some gliding or sliding movement at these synovial plane joints
- Costochondral cartilage joints
- Costal cartilage to rib; Allow no movement at these joints
- Interchondral joints
- Between costal cartilages; Allow some gliding movement
- External intercostal muscles
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Origin-Inferior border of rib
Insertion-Superior border of rib below
Innervation-Intercostal nerve
Actions-Elevate ribs - Internal intercostal muscles
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Origin-Inferior border of rib
Insertion-Superior border of rib below
Innervation-Intercostal nerve
Actions-Elevate ribs (upper four and five); other depress ribs - Innermost intercostal muscles
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Origin-Inferior border of rib
Insertion-Superior border of rib below
Innervation-Intercostal nerve
Actions-Probably elevate ribs - Transversus thoracis muscle
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Origin-Posterior surface of lower sternum
Insertion-Internal surface of costal cartilages 2-6
Innervation-Intercostal nerve
Actions-Depress ribs - Subcostal muscles
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Origin-Internal surface of lower rib near their angles
Insertion-Superior borders of second or third ribs below
Innervation-Intercostal nerve
Actions-Elevate ribs - Levator costarum muscle
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Origin-Transverse processes of C7 and T1-11
Insertion-Subjacent rubs between tubercle and angle
Innervation-Dorsal primary rami of C8-T11
Actions-Elevate ribs - Internal thoracic artery
- Arises from subclavian and terminates by dividing into superior epigastric and musculophrenic arteries
- Intercostal arteries
- Anterior and posterior segments that arise from internal thoracic and aorta, respectively, and anastomose