topic 5: The muscles and layers of the thoracic wall. The intercostal space.

Question 1

muscles

Answer 1

External Intercostal Muscles
-Location: Found between adjacent ribs.
-Orientation: Fibers run inferoanteriorly from rib above to rib below.
-Function: Elevate the ribs during inspiration, aiding in increasing the thoracic cavity volume.

Internal Intercostal Muscles
-Location: Deep to the external intercostals.
-Orientation: Fibers run inferoposteriorly from rib above to rib below.
-Function: Aid in forced expiration by depressing the ribs and decreasing thoracic cavity volume.

Innermost Intercostal Muscles
-Location: Deepest layer of intercostal muscles.
-Orientation: Similar to internal intercostals.
-Function: Assist in expiration, especially during forced expiration.

Question 2

layers of thoracic wall

Answer 2

Skin: Outermost layer providing protection and sensation.

Superficial Fascia: Contains variable amounts of adipose tissue.

Deep Fascia: Tough connective tissue layer providing additional support.

Muscles: External, internal, and innermost intercostal muscles.

Endothoracic Fascia: Thin layer covering the inner surface of the thoracic wall muscles.

Parietal Pleura: Serous membrane lining the inner surface of the thoracic cavity.

Question 3

intercostal space

Answer 3

The intercostal spaces are the anatomical regions between adjacent ribs, separated by intercostal muscles and neurovascular structures. Each intercostal space contains the following structures, from superior to inferior:

Intercostal Vein, Artery, and Nerve (VAN):
-Found in the costal groove on the inferior border of each rib.
-VAN runs along the inferior margin of the rib, with vein superior to artery and nerve.
-supplies thoracic wall & overlying structures

** Muscles**:
- occupy the intercostal space.
-External and internal intercostals are involved in respiration, while innermost intercostals aid in forced expiration.

Intercostal Neurovascular Bundle:
Consists of the intercostal vein, artery, and nerve, along with associated lymphatics.
Positioned between the internal intercostal and innermost intercostal muscles.

Collateral Branches:
Small arteries and veins that provide collateral circulation between adjacent intercostal spaces.
Important in cases of arterial or venous obstruction.