The alveolus is the basic unit of gas exchange
in the lung

The fibrous pericardium is attached to the
posterior surface of the sternum by the sternopericardial ligaments

The interior of the left ventricle includes
anterior and posterior papillary muscles

The pulmonary veins, two on each side,
carry well-oxygenated (“arterial”) blood from
the lungs to the left atrium of the heart

The right main bronchus is wider and
shorter, running more vertically than the left
main bronchus as it passes directly to the hilum
of the lung. The left main bronchus passes inferolaterally, inferior to the arch of the aorta and
anterior to the esophagus and thoracic aorta, to
reach the hilum of the lung

The tubercle has a smooth articular part for
articulating with the corresponding transverse
process of the vertebra and a rough nonarticular part for attachment of the costotransverse
ligament

The tricuspid valve guards the right AV
orifice. The bases of the valve cusps are attached
to the fibrous ring around the orifice. Chordae
tendineae attach to the free edges and ventricular surfaces of the anterior, posterior, and septal
cusps

The parietal pleura includes costal, mediastinal, diaphragmatic, and cervical parts

A bronchopulmonary segment is a pyramid shaped segment of the lung with its apex facing
the lung root and its base at the pleural surface.
It is the largest subdivision of a lobe and is separated from adjacent segments by connective tissue. It is surgically resectable

The middle mediastinum contains the heart

After descending past the 2nd costal cartilage, the internal thoracic artery runs anterior to
the transversus thoracis muscle. It ends in the
6th intercostal space, where it divides into the
superior epigastric and musculophrenic arteries

The interior of the left atrium has a largewalled part and a smaller muscular auricle containing pectinate muscles

Typically, the right coronary artery supplies
the right atrium, most of the right ventricle, part
of the left ventricle, part of the AV septum, and
the SA node in approximately 60% of people and
the AV node in approximately 80% of people

The dorsal and ventral rami are both motor
and sensory. The cutaneous branches include
anterior, lateral, and posterior branches. The dorsal root is sensory and the ventral root is motor.
The spinal nerves supply a band-like skin area
known as a dermatome

The surface of the 1st rib has two transversely directed shallow grooves, anterior and
posterior to the scalene tubercle, for the subclavian vein and the subclavian artery respectively

The coronary sinus receives the great and
small cardiac veins, middle cardiac vein, left posterior ventricular vein, and left marginal vein.
The anterior cardiac veins begin over the anterior surface of the right ventricle and cross over
the coronary groove to end directly in the right
atrium

The SA node is located anterolaterally just
deep to the epicardium at the junction of the SVC
and right atrium, near the superior end of the
sulcus terminalis. The SA node, a small collection of nodal tissue and specialized cardiac muscle fibers, is the pacemaker of the heart. The SA
node is supplied by a branch of the right coronary artery in about 60% of individuals

The right lung has three lobes, the left two.
The right lung is larger and heavier than the left,
but it is shorter and wider, because the right
dome of the diaphragm is higher and the heart
and pericardium bulge more to the left. The anterior margin of the right lung is relatively straight,
whereas the margin of the left lung has a deep
cardiac notch. The cardiac notch primarily indents the anteroinferior aspect of the superior
lobe of the left lung. This often creates a thin,
tongue-like process of the superior lobe, called
the lingula

The posterior mediastinum contains the thoracic aorta, thoracic duct, azygos and hemiazygos veins, esophagus, and thoracic sympathetic
trunks

Between the breast and deep pectoral fascia is a loose connective tissue plane or potential space known as the retromammary space

Because the axillary lymph nodes are the
most common site of metastases from a breast
cancer, enlargement of the palpable nodes in a
woman suggests the possibility of breast cancer
and may be key to early detection. However, the
absence of enlarged axillary nodes is no guarantee that metastasis from a breast cancer has not
occurred, because the malignant cells may have
passed to other nodes, such as the infraclavicular and supraclavicular lymph nodes

The pleural cavity, the potential space between the layers of pleura, contains a capillary
layer of serous pleural fluid. It provides the lubrication and cohesion that keep the lung surface in
contact with the thoracic wall

The interventricular septum is composed
of membranous and muscular parts. The conus
arteriosus leads into the pulmonary trunk. A
thick muscular ridge, the supraventricular crest,
separates the ridged muscular wall of the inflow
part of the right ventricle from the smooth wall
of the conus arteriosus or outflow part

The sternal angle is located opposite the
2nd pair of costal cartilages at the level of the 4th
intervertebral disc between T4 and T5 vertebrae