Thoracic Cage Muscles Flashcards
What are the superficial muscles of the Thoracic Cage
- Pectoralis major
- Pectoralis minor
- Subclavius
- Serratus anterior
- Serratus posterior
Pectoralis Major OIAI
Origin:
1. Anterior surface of clavicle & sternum
2. Upper costal cartilage
3. External oblique aponeurosis
Insertion:
- Lateral lip of the Intertubercular groove
Actions:
At the glenohumeral joint
1. Adduction
2. Flexion
3. Medial rotation
Innervation:
1. Medial pectoral nerve
2. Lateral pectoral nerve
Pectoralis Minor OIAI
Original:
1. Ribs 3-5
Insertion:
1. Coracoid process of scapula
Actions:
1. Depresses scapula
2. Protracts scapula
Innervation
1. Medial pectoral nerve
Subclavius OIA (dwa I)
Origin:
1. First rib
Insertion:
1. Inferior surface of clavicle
Actions:
1. Depresses / Stabilizes clavicle
Serratus Anterior OIAI
Origin:
1. ribs 1-8
Insertion:
1. Medial border of scapula (costal surface)
Actions:
1. Protracts scapula
Innervation
1. Long thoracic nerve
Serratus posterior superior OIA (I?)
Origin:
1. C7-T3 spinous processes
Insertion:
1. Ribs 2-4 (superior border)
Actions:
1. Elevates upper ribs
Serratus posterior inferior OIA (I?)
Origin:
1. T11-L2 spinous processes
Insertion:
1. Ribs 9-12 (inferior border)
Actions:
1. Depresses lower ribs
What are the deep muscles of the thoracic cage?
- External intercostals
- Internal intercostals
- Innermost intercostals
- Transversus thoracis
- Diaphragm
Intercostals muscles
3 layers of muscles that run between the intercostal spaces of the ribs
- External
- Internal
- Innermost
External intercostal muscle (layer position, action & fibre direction)
- most superficial
Action:
1. Elevate ribs (for inspiration)
Fibre direction: hand in pockets
Internal intercostal muscles (layer position, action & fibre direction)
Layer: intermediate
Action: depress the ribs (expiration)
Fibre direction: hands in pits
Innermost intercostal muscles (layer position, action, fibre direction
Layer: deepest, incomplete (more posterior)
Action: Depress the ribs (expiration)
Fibre direction: hands in pits
Intercostal muscles blood supply & innervation
Intercostal vein, artery & nerve run the costal groove or the ribs between the internal and innermost intercostal muscles.
Transverse Thoracis OIAI
Origin: posterior surface of sternum
Insertion: ribs 2-6 & their costal cartilages
Actions: depress ribs (expiration)
Innervation: intercostal nerves
Diaphragm OIAI
Origin:
1. xiphoid process
2. L1-L4
3. Lower ribs & their costal cartilage
Insertion: central tendon of diaphragm
Actions:
- Contraction: inspirstion
Relaxed: expiration
Innervation: phrenic nerve (originates from C3-C5 spinal nerves - C3,C4,C5 keep diaphragm alive)
