Pectoral Fascia (fascia pectoralis)
This fascial system covers the anterior chest wall. It plays a crucial role in biomechanics by creating continuous transitions to the fascial sheaths of the anterior abdominal wall, axillary fossa, and shoulder girdle. Traditionally, it is divided into two lamina.
Superficial layer (lamina superficialis) Located superficial to the pectoralis major muscle, covering it tightly. It features extensive attachments to adjacent structures:
- Superiorly, it securely attaches to the clavicle.
- Medially (closer to the midline), it fixes to the sternum.
- Laterally, it thins out and smoothly continues into the fascia of the serratus anterior muscle.
- Inferiorly, it transitions into the fascia covering the anterior abdominal wall.
Feature: In the region of the infraclavicular fossa, this layer becomes noticeably thicker. Here, it firmly fuses with the major blood vessels passing deep to it (from the subclavian artery and vein, a. et v. subclavia).
Deep layer (lamina profunda) Located deep to the pectoralis major muscle. Its primary function is to form isolated fascial sheaths for the pectoralis minor and subclavius muscles. This layer attaches to the clavicle and the coracoid process of the scapula.
In the axillary region, the deep layer meets the lower borders of the pectoralis major and latissimus dorsi muscles. At this site, it thickens significantly and forms the axillary fascia (fascia axillaris), which constitutes the soft connective tissue floor of the axillary fossa.
Clavipectoral Fascia (fascia clavipectoralis)
This is a specialized part of the pectoral fascia. It is tightly stretched between the clavicle and the apex of the axilla.
It not only encloses the pectoralis minor and subclavius muscles but also performs an essential scaffolding function by strengthening the anterior wall of the axillary space. A major topographical feature of the clavipectoral fascia is that it is pierced by numerous openings (foramina) through which major vessels and nerve trunks pass.
Thoracic and Endothoracic Fasciae
In addition to the fasciae servicing the muscles of the shoulder girdle, the thorax features membranes directly associated with the ribs and intercostal spaces.
- Parietal thoracic fascia (fascia thoracica) is a relatively thin connective tissue plate. It lies on the outer surface of the thoracic wall, covering the ribs and external intercostal muscles throughout their extent.
- Endothoracic fascia (fascia endothoracica) lines the thoracic wall from the inside. It lies in the space between the osteomuscular framework of the thorax and the parietal pleura. This fascia forms a subpleural adipose layer. Superiorly, it is firmly attached to the suprapleural membrane (dome of the pleura), and medially it transitions into the connective tissue of the mediastinal pleura.