Thoracic Walls Flashcards
What elements make up the thoracic walls?
The thoracic cage, muscles between the ribs, subcutaneous tissues, fascia, muscles and skin are all components within the thoracic walls.
What tissues are involved in the breast?
-consists of glandular tissue (mammary gland proper) but also contains fibrous and adipose tissues as well as blood vessels nerves and lymphatics.
Where is the breast situated with respect to external landmarks?
The horizontal base of the breast is from the lateral border of the sternum to the mid axillary line. The vertical aspect is from the 2nd to the 6th rib.
The breast has a superiolateral extension towards the axilla, this means that there is more glandular tissue in the upper outer quadrant, which is where the highest incidence of carcinoma is found.
The deep aspect of the breast is slightly concave and is related to pectoralis major underneath it. The glandular tissue is separated by a retromammary/submammary space (allow the breast some degree of movement and is used for breast implants) from the fascia and underlying muscles.
What is the arterial supply of the breast?
The breast shares arterial supply and venous drainage with the thoracic walls medially and the upper limb laterally.
What is the lymphatic system supplying the breast?
Lymphatics are shared with upper limb (axillary node) and the chest wall (parasternal lymph nodes). This means that lumps in the axilla can be associated with breast cancer and that cancer is easily able to metastasise.
What is included in the thoracic cage?
12 thoracic vertebrae & IV discs
sternal complexes
12 pairs of ribs
Where do the ribs articulate?
The ribs articulate anteriorly with costal cartilage
- upper 7 articulate with the sternal complex directly
- costal cartilages 8, 9, 10 turn up and articulate with the costal cartilage above. These form the costal margin and act as attachments for the abdominal muscles.
- 11 and 12 costal cartilages do not articulate anteriorly - floating ribs
Posteriorly, the ribs articulate with the thoracic vertebrae.
Explain the different aspects of the ribs?
- ribs have a vertebral end which has a head, neck and a tubercle:
Head: has two articular facets (sup. and inf.)
Neck: head narrows to neck
Tubercle: has two facets (medial -closest to the head; very smooth and is an articular facet where a joint occurs & lateral which is rougher and acts as an attachment for a ligament) - The shaft or body of the rib is vertically oriented so it has a superior and inferior edge. The internal aspect of the inferior aspect is grooved called the costal groove. This is where the neurovascular structures run.
- The anterior/sternal end has a pit that the costal cartilage plugs into.
Explain atypical ribs.
Not all ribs are typical. The top and bottom of the series have some abnormalities. 11 and 12 have short costal cartilage as well as no neck or tubercles.
The first rib is short, broad and almost horizontal in its body. it is also far more curved. It bears very distinct curves for the subclavian vessels. It only articulates with T1 and so it only has a singular facet on the head.
What are the features of thoracic vertebrae?
Thoracic vertebrae: (Giraffe)
- Costal facets on the body: for articulation with the ribs (Head)
- Facets on the transverse process: for articulation with the ribs (tubercle) [no other vertebrae have these facets but thoracic vertebrae]
- long almost vertically oriented spinous process
What are the features of Costovertebral joints?
Costovertebral joints: the head of the rib articulates with the vertebral demifacets on the posterolateral aspect of the body of the vertebrae.
- The head of the rib sits between the two vertebrae and lies on the joining IV disc.
- There is also an incredibly strong radiate ligament of the head of the rib which reinforces the joint
What are the features of Costotransverse joints?
Costotransverse joints: between the medial facet of the tubercle of the rib and the facet on the transverse process of the vertebrae. Has a 3 part reinforcement of the joint in the form of costotransverse ligaments. These joints never dislocate and the ribs fracture before the joints are disrupted.
-Blunt trauma to the chest wall can cause multiple rib fractures that can cause a flail check segment that begins to function independently. This can have a large impact on respiration.
Explain the shape of the thoracic cage and the significance of the suprapleural membrane.
The rib cage gives a cylinder where the top is narrower. It is made more narrow by Sibsen’s fascia/suprapleaural membrane which runs on the internal aspect of the first rib, and attaches to the transverse process of C7. There is a gap in the centre of this membrane.
Where is the diaphragm situated?
The inferior aperture of the thoracic cage is closed off completely by the diaphragm, separating the thorax and the abdomen.
What are the attachments and insertions of the diaphragm?
Unlike muscles in the upper/lower limb, it has a circumferential origin from the inferior aperture of the thorax and a central insertion called the central tendon. It attaches to xiphoid process, costal margins, tips of 11 and 12th ribs. Posteriorly, there are a pair of arcuate ligaments (med/lat) which are thickenings of the posterior abdominal walls. It has a lateral arcuate ligament overlying quadratus lumborum (thickening of the fascia of quadratus lumborum) and the medial arcuate ligament overlying psoas major muscle. Beyond that the diaphragm attached to the lumbar vertebral column by a pair of ligaments called crura. The left crus (L1,2) right crus (L1, 2,3) The diaphragm then creates two domes, the right side is higher for the liver and then attaches into the central tendon. The central tendon is club-shaped.
