Thoracic wall

Question 1

Identify 1. Origin & Insertion?

Answer 1

• *1. External intercostal muscles**
• *Origin (superior attachment):** Each muscle arises from the lower border of a rib.

Insertion (inferior attachment): Each muscle attaches to the upper border of the rib below its origin.

Question 2

How many external intercostal muscles on each side of thorax?

Answer 2

there are 11 external intercostal muscles on each side of the thorax.

Question 3

Identify 1. Action?

Answer 3

1. External intercostal muscles

Action:

• active during inspiration → elevate the ribs.

Question 4

Identify 1. Innervation?

Answer 4

1. External intercostal muscles

→ Innervation: intercostal nerves

(which are numbered sequentially according to the intercostal interspace; e.g, The 4th intercostal nerve supplies muscles that occupy the 4th intercostal space, between the 4th and 5th ribs.)

Question 5

Identify 1. O & I?

Answer 5

Internal intercostal muscles

• Origin (superior attachment):
  
  • from a ridge on the inner surface of the inferior aspect of each rib
  • from the corresponding costal cartilage.
• Insertion (inferior attachment): Each muscle attaches to the upper border of the rib below its origin.

Question 6

Identify 1. Action?

Answer 6

Internal intercostal muscles

Action:

• May elevate the ribs. (upper 4 or 5 muscles)
• Depress the ribs (lateral and posterior portions of muscles)
• active during expiration. (lateral and posterior portions of muscles)

Question 7

Identify 1. Innervation?

Answer 7

Internal intercostal muscles

Innervation: Intercostal nerves.

Question 8

The general role of intercostal muscles

All of the intercostal muscles keep the intercostal spaces (1)___, preventing them from (2)___ during expiration and being (3)___ during inspiration.

Answer 8

1. rigid
2. bulging out
3. drawn in

Question 9

Identify 2 & 3

Answer 9

2. Transversus thoracis muscle
3. Respiratory diaphragm

Question 10

Identify 1. O & I?

Answer 10

1. Innermost intercostal muscles

Origin: Each innermost intercostal arises from the lower border of a rib.

Insertion: Each innermost intercostal attaches to the upper border of the rib below its origin.

Question 11

Identify 1. Action?

Answer 11

1. Innermost intercostal muscles

→ depress the ribs

Question 12

Identify 1. Innervation?

Answer 12

1. Innermost intercostal muscles

→ Intercostal nerves.

Question 13

Identify 2. O & I?

Answer 13

2. Transversus thoracis muscle

Origin: arises from the posterior surface of the lower portion of the body of the sternum and the xiphoid process.

Insertion: attaches to the inner surfaces of costal cartilages 2-6.

Question 14

Identify 2. Action

Answer 14

2. Transversus thoracis muscle

→ depresses the ribs.

Question 15

Identify 2. Innervation?

Answer 15

2. Transversus thoracis muscle

Innervation: Intercostal nerves.

Question 16

Identify

Answer 16

1. Serratus anterior muscle
2. External intercostal muscle
3. Long thoracic nerve

Question 17

Identify 1. O & I?

Answer 17

1. Serratus anterior muscle

Origin: arises from the outer surfaces and superior borders of the first 8 to 9 ribs.

Insertion: insert on the ventral aspect of the vertebral (medial) border of the scapula.

Question 18

Identify 1. Action?

Answer 18

1. Serratus anterior muscle

Action:

• Protraction of scapula → Muscle pulls the medial border of the scapula anteriorly toward the thoracic wall
• preventing the bone from protruding (winging).
• Rotate the scapula upward by laterally rotating the inferior angle. → abduct the arm at the shoulder.

Question 19

Abduction above (above the horizontal) can be accomplished only by (1)___ rotation of the (2)___ angle of the scapula.

Answer 19

1. Lateral
2. inferior

Question 20

Identify 1. Innervation

Answer 20

1. Serratus anterior muscle

Long thoracic nerve (C5, C6, and C7). (3)

Question 21

Identify 3. its origin?

Answer 21

Long thoracic nerve (C5, C6, and C7).