. Bone

**Chest Wall Anatomy**

* Skin, subcutaneous fat
* Blood vessels, lymphatics, nerves
* Bone, cartilage
* Muscles
* Endothoracic fascia, fibroelastic connective tissue between inner aspect of chest wall and costal pleura

FUNCTION

* Musculoskeletal cage: Surrounds cardiorespiratory system; effects respiration by expanding and contracting during ventilation

SURFACE LANDMARKS

* Suprasternal (jugular) notch: At superior manubrium of sternum; between sternal ends of clavicles
* Sternal angle: Landmark for internal thoracic anatomy;anterior projection at level of costal cartilage of 2nd rib
* Costal margin: Inferior margins of lowest ribs and costal cartilages

SKELETAL STRUCTURE

* Thoracic Vertebrae
	+ Twelve vertebrae (T1-T12)
* Shoulder Girdle
	+ Clavicle, scapula and proximal humerus
* Sternum
	+ Flat, broad bone forms anterior thoracic wall; three parts (manubrium, body, xiphoid process)
* Scapula
	+ Large, triangular flat bone; parallel to upper posterior thorax; extends from 2nd-7th ribs bilaterally
	+ Glenoid fossa at glenohumeral joint
* Ribs
	+ 12 pairs, symmetrically arrayed; numbered in accordance with attached vertebral body

MUSCLES

* Pectoral
	+ Pectoralis major
	+ Pectoralis minor
* Intercostal
	+ External
	+ Internal
	+ Innermost
* Serratus Anterior
* Back Muscles
	+ Superficial extrinsic muscles: trapezius, latissimus dorsi, levator scapulae, rhomboids
	+ Intermediate extrinsic muscles (superficial respiratory muscles): serratus posterior
	+ Deep intrinsic muscles: splenius muscle, erector spinae muscles, deep transversospinales muscles

VESSELS

* Arteries
	+ Internal thoracic (internal mammary): Branch of subclavian artery; descends posterior to first six costal cartilages; supplies upper anterior chest wall
		- Supplies anterior intercostal arteries to first six intercostal spaces
* Veins
	+ Azygos vein receives drainage from posterior intercostal veins, hemi-azygos and accessory hemi-azygos veins
* Lymphatics
	+ Chest wall drainage through thoracic duct (right upper limb, right face and neck drained by right lymphatic duct)

NERVE:

* Anterior rami of thoracic spinal nerves (T1-T11) supply skin, tissues of chest wall; form intercostal nerves
* Intercostal nerves run in costal groove, between internal and innermost intercostal muscles
* Brachial plexus: Branching network of nerve roots, trunks, divisions, cords and branches
	+ Spinal roots form three trunks; behind clavicle, each dividing into anterior and posterior divisions

ANATOMIC REGIONS

* Thoracic Inlet
	+ Opening at superior end of thoracic rib cage; conduit for cervical structures to enter thorax
	+ Bounded by T1 vertebral body, right and left 1st ribs and their costal cartilages, and manubrium of sternum
* Thoracic Outlet
	+ Opening at inferior end of thoracic rib cage; conduit for thoracic structures to exit thorax
	+ Bounded by T12 vertebral body, right and left 12th ribs, costal cartilages of 7th-12th ribs, xiphisternal joint
* Breast and Pectoral Region
	+ Anterior and superior part of chest; muscles and fascia assist movement of upper limb; mammary glands

Congenital and Developmental Abnormalities

* Pectus excavatum (syn. funnel chest): Abnormal growth of costal cartilages; sternal depression/rotation; compression/obscuration of right heart border on PA radiograph
* Pectus carinatum (syn. pigeon breast): Abnormal growth of costal cartilage; sternal protrusion
* Cervical rib: Supernumerary rib, usually arising from seventh cervical vertebra
* Poland syndrome: Uncommon; partial or total absence of pectoralis major muscle; associated malformations of ipsilateral ribs (2-5) and clavicle; congenital absence of ipsilateral breast tissue