Muscles of the Rib Cage Joints

Question 1

What are the muscles of the Rib Cage Joints?

Answer 1

1. External Intercostals
2. Internal Intercostals
3. Transversus Thoracis
4. Diaphragm
5. Serratus Posterior Superior
6. Serratus Posterior Inferior
7. Subcostales

Question 2

What is the origin, insertion and actions of External Intercostals?

Answer 2

O : In the intercostal spaces of ribs 1-12
I : Superior border of the rib directly inferior
A :
1. Elevate ribs 2-12 at the sternocostal and costospinal joints
2. Rotate contralaterally the trunk at the spinal joints

Question 3

What is the origin, insertion and action of Internal Intercostals?

Answer 3

O : In the intercostal spaces of ribs 1-12 from the superior border of one rib and its costal cartilage
I : Inferior border of the rib and its costal cartilage
A :
1. Depresses ribs 1-11 at the sternocostal and costospinal joints
2. Rotate ipsilaterally the trunk at the spinal joints

Question 4

What is the action of Transversus Thoracis?

Answer 4

Depresses ribs 2-6 at the sternocostal and costospinal joints

Question 5

What is the origin, insertion and action of Diaphragm?

Answer 5

O : Internal surfaces of rib cage, sternum and spine
I : Central Tendon of Diaphragm
A : Increases the volume of (expands) the thoracic cavity via abdominal breathing

Question 6

What is the origin, insertion and actions of Serratus Posterior Superior?

Answer 6

O : Spinous Processes of C7-T3 and Lower nuchal ligament
I : Ribs 2-5 at the superior borders and external surfaces
A : Elevates ribs 2-5 at the sternocostal and costospinal joints

Question 7

What is the origin, insertion and actions of Serratus Posterior Inferior?

Answer 7

O : Spinous Processes of T11-L2
I : Ribs 9-12
A : Depresses ribs 9-12 at the sternocostal and costospinal joints

Question 7

What is the action of Levatores Costarum?

Answer 7

Elevates the ribs at the sternocostal and costospinal joints