The chest wall is composed of the thoracic skin, fat, muscles, and skeleton (rib cage).
- Protection of thoracic organs
- Stabilization of
- Dynamic expansion and recoil during respiration ( )
- Reference lines
|Anterior chest|| |
|Posterior chest|| |
- Surface anatomy: see
Vasculature and innervation: neurovascular bundles
- Each bundle is composed of an intercostal vein (most superior), artery , and nerve (most inferior).
- They course along the costal groove at the inferior border of each rib.
Below each rib parks a VAN: Vein, Artery, Nerve (intercostal bundles from superior to inferior).
rib to prevent injury of the intercostal nerves and vessels, which run along the lower margin. are placed along the upper margin of a
- Composed of 3 flat bones
- Suprasternal notch: visible and palpable U-shaped depression above the manubrium between the two clavicles
- Sternal angle
There are 12 pairs of ribs separated by intercostal spaces (ICSs).
- Parts of a typical rib
- True ribs (ribs 1–7): Connect directly to the sternum via costal cartilage.
- False ribs (ribs 8–10): Connect indirectly to the sternum via the costal arch.
- Floating ribs (ribs 11–12): Do not connect to the sternum.
- Accessory ribs: Anatomical variant in up to 0.5% of the population that usually arises from the seventh cervical vertebra ( ).
- Costovertebral joints: Connect the rib heads to the vertebral bodies.
- Costotransverse joints: Connect the rib tubercle to the transverse processes of the vertebral bodies.
- Nipples in men: ∼ 5th ICS, can be lower in women
- Dome of the diaphragm and liver: right 5th ICS at the midclavicular line
- Lung: see
- Right margin: extends from right 3rd costal cartilage to right 6th costal cartilage
- Left margin: extends from left 2nd ICS to the apex at the midclavicular line of the 5th ICS
- Anterior interventricular sulcus: 2.5 cm lateral of the midline at 3rd left ICS
- For the projection of the heart valves and the auscultation of the heart sounds, see .
A lower trunk of the brachial plexus, and/or the subclavian artery ( ). is usually asymptomatic but can cause compression of the C8/T1 roots, the
The chest wall is comprised of 5 muscles, which are all innervated by the intercostal nerves:
|Intercostal muscles (found between the ribs)||External intercostal muscles||Run anteroinferiorly||Elevate the ribs during inspiration (widens ICSs → ↑ thoracic volume)|
|Internal intercostal muscles||Run posteroinferiorly||Lower the ribs during expiration (narrows ICSs → ↓ thoracic volume)|
|Innermost intercostal muscles||Run posteroinferiorly||Lower the ribs during expiration (narrows ICSs → ↓ thoracic volume)|
|Subcostal muscles||Run posteroinferiorly|
|Transversus thoracis muscle||Runs craniolaterally from posterior surface of lower sternum to cartilage of 2nd–6th ribs|
Other muscles that attach to the thoracic wall include:
|Pectoralis major||Medial clavicle, anterior sternum, and six upper costal cartilages||Proximal humerus||Medial and lateral pectoral nerves|| |
|Pectoralis minor||Ribs 3–5 near costal cartilages||Medial border of the scapula's coracoid process||Medial pectoral nerve|| |
|Serratus anterior||Upper borders of ribs 1–8||Medial scapula||Long thoracic nerve|| |
|Subclavius||Rib 1 near costal cartilage||Deep surface of clavicle||Subclavian nerve|| |
|Latissimus dorsi||Posterior ilium, sacrum, spinous processes of T6–L5, thoracolumbar fascia, posterior ribs 8–12, and inferior angle of scapula||Intertubercular groove of the humerus||Thoracodorsal nerve|| |
|Serratus posterior superior||Spinous processes of C7–T3||Ribs 2–5||Intercostal nerves|| |
|Serratus posterior inferior||Spinous processes of T11–L2||Ribs 9–12||Intercostal nerves|| |
- Trunk develops from paraxial and lateral plate mesoderm
- Failure of the fusion of the sternal bars results in a cleft sternum
- Xiphoid process does not ossify until after birth, unlike the rest of the sternum
- Excessive depression and rotation of the sternum can result in pectus excavatum, the most common congenital chest wall deformity.