The Thoracic Cage, Pleura, Lungs, Mediastinum, and Heart

Comprehensive vocabulary flashcards covering the anatomy of the thoracic wall, lungs, pleura, mediastinum, and the heart's internal structures and conduction system.

True (vertebrosternal) ribs

The $1^{st}$ to $7^{th}$ ribs that attach directly to the sternum via their own costal cartilages.

False (vertebrochondral) ribs

The $8^{th}$, $9^{th}$, and usually $10^{th}$ ribs whose cartilages connect to the cartilage of the rib above them, providing an indirect connection to the sternum.

Floating (free vertebral) ribs

The $11^{th}$, $12^{th}$, and sometimes $10^{th}$ ribs which have no connection to the sternum and end in the posterior abdominal musculature.

Typical ribs ($3^{rd}$ to $9^{th}$)

Ribs characterized by a wedge-shaped head with two facets, a neck, a tubercle with articular and non-articular parts, and a body with a costal angle and costal groove.

First rib

The broadest, shortest, and most sharply curved true rib, possessing a single facet on its head for $T1$ and two grooves for the subclavian vessels separated by the scalene tubercle.

Costal margin

A continuous boundary formed by the articulation of the $8^{th}$ to $10^{th}$ costal cartilages with the cartilage superior to them.

Subcostal space

The space immediately below the $12^{th}$ rib, containing the subcostal nerve, which is the anterior ramus of spinal nerve $T12$.

Sternal angle of Louis

The junction of the manubrium and the body of the sternum located at the level of $T4$; it is the most common site of sternal fracture in the elderly.

Xiphoid process

The smallest part of the sternum, lying at level $T10$; it serves as a midline marker for the superior limit of the liver, the central tendon of the diaphragm, and the inferior border of the heart.

Superior thoracic aperture

The opening bounded by the $T1$ vertebra posteriorly, the $1^{st}$ pair of ribs and their costal cartilages laterally, and the superior border of the manubrium anteriorly.

Costotransverse joint

A synovial plane joint articulating the tubercle of a rib with the transverse process of the vertebra of the same number.

Serratus posterior superior

A muscle of the thoracic wall involved in proprioception and the elevation of the ribs.

Intercostal nerve components

Primary anterior rami of spinal thoracic nerves $T1$-$T11$ which include rami communicantes, collateral branches, lateral cutaneous branches, and muscular branches.

Intercostobrachial nerve

A large lateral cutaneous branch arising from the second intercostal nerve.

Visceral pleura

The serous membrane that closely covers the lungs and adheres to all its surfaces, including fissures, and is continuous with the parietal pleura at the hilum.

Costodiaphragmatic recesses

Potential pleural spaces surrounding the upward convexity of the diaphragm into which the inferior borders of the lungs descend during inspiration.

Pulmonary ligament

A fold of pleura hanging inferiorly from the root of the lung that allows for movement of the lung root and expansion of the pulmonary veins.

Lingula

A thin, tongue-like process on the most inferior anterior part of the superior lobe of the left lung, located below the cardiac notch.

Hilum of the lung

The concave area on the mediastinal surface of the lung where the structures forming the root of the lung enter and leave.

Bronchial circulation

The systemic blood supply to the lung tissues, where two left bronchial arteries arise from the thoracic aorta and one right bronchial artery arises from the $3^{rd}$ posterior intercostal artery.

Superior mediastinum contents

A compartment containing the thymus gland remnant, brachiocephalic veins, SVC, arch of aorta, trachea, esophagus, phrenic and vagus nerves, and the thoracic duct.

Thoracic duct

The largest lymphatic vessel, originating from the chyle cistern at $T12$, ascending between the esophagus and azygos vein, and entering the union of the left internal jugular and subclavian veins.

Transverse pericardial sinus

A passage located between the aorta/pulmonary trunk anteriorly and the left atrium/SVC posteriorly, connecting the two sides of the pericardial cavity.

Base of the heart

The posterior surface formed mainly by the left atrium (and slightly by the right), facing towards vertebrae $T6$-$T9$, receiving pulmonary veins and the venae cavae.

Fossa ovalis

A thumb-shaped depression on the interatrial septum of the right atrium, representing the remnant of the fetal foramen ovale.

Septomarginal trabecula (moderator band)

A muscular bundle traversing the right ventricle from the IV septum to the base of the anterior papillary muscle, facilitating conduction time for ventricular contraction.

Mitral valve

The valve guarding the left atrioventricular (AV) orifice, preventing backflow from the left ventricle to the left atrium.

Sinoatrial (SA) node

Known as the pacemaker of the heart, located at the junction of the SVC and right atrium near the superior end of the sulcus terminalis.

Angina pectoris

Chest pain resulting from myocardial ischemia, where pain is often referred to the $T1$-$T5$ dermatomes and the medial border of the left upper limb.

T4 landmark significances

The anatomical plane marking the sternal angle, the tracheal bifurcation, the beginning and end of the aortic arch, and the level where the thoracic duct deviates to the left.