One should have a clear understanding of anatomy of the respiratory system to
perform a proper physical exam. Some of the important anatomical details are outlined
below. For details review the link provided to Dr. McNulty's lesson on Thorax by clicking
on anatomic principles.
Pleura: Once the diaphragm has been outlined you can appreciate
that the pleural gutter is deep posteriorly. Fluid thus tends to
- Starts from cricoid cartilage to sternal angle anteriorly and T4 spinous process
posteriorly, where it divides into left and right main stem bronchi. This information is
important in understanding D'spine sign seen in patients with large Mediastinal mass.
- Trachea is slightly slanted to right. Bronchovesicular breathing
heard in right infraclavicular region is due to this phenomenon.
- Trachea has intra and extra thoracic components. This has
important bearing in the understanding of physiology of variable obstruction.
- The angle between the body and Manubrium. Many important land marks occur at this
level. It is called Louis Angle.
- 2nd rib articulates to Manubrium at this site. The ribs
are counted anteriorly starting from this point.
- Carina of trachea is at this level.
is divided into superior and inferior at this level.
In the surface anatomy exercise we arbitrarily divide the thorax into various
spaces and create lines. Localization of abnormal finding is achieved and described using
the ribs, interspaces, spaces, and lines.
- Anteriorly ribs are counted down starting from 2nd rib. There are 12 ribs and 11
interspaces. You can also count up from 12th rib. Inferior angle of scapula sits on 7th
- Anteriorly there are supra clavicular, infraclavicular, precardiac and Traube's
space. Posteriorly we have interscapular, supra, and infra scapular spaces.
- Infraclavicular: Space below clavicle
- Supraclavicular: Space above clavicle
- Precardiac: Space in front of heart
- Traube's: Space overlying stomach
- Interscapular: Space between scapula
- Suprascapular: Space above scapula
- Infrascapular: Space below the scapula
- There are following vertical lines around chest. Midsternal, parasternal,
midclavicular, anterior axillary, mid-axillary, posterior axillary, infrascapular
- Midsternal Line: A vertical line down the middle of sternum
- Parasternal Line: A vertical line along lateral edge of sternum
- Mid-Clavicular Line: A vertical line from middle of clavicle
- Anterior Axillary Line: A vertical line along anterior axillary
- Mid-Axillary Line: A vertical line at mid point between anterior
and posterior axillary line.
- Posterior Axillary Line: Along post axillary fold
- Scapular Line: Inferior angle of scapula
- Vertebral line: Over spinous processes in the midline
- Surface Anatomy of Lungs
- Right Lung: With a marking pen start 3
centimeters above clavicle in midclavicular line, come down along right parasternal line ,
join to 6th rib in midclavicular line, to 8th rib in mid-axillary line, to 10th rib
posteriorly, to vertebral line posteriorly.
Lung: At angle of Louis, follow the outer margin of heart to 6th rib in
Appreciate that apex of lung is just under the skin easily
palpable in the supraclavicular space.
Pancoast tumor and TB occur at this site. Hence, the apex of lungs should be
- Surface Anatomy of Lobes
- Draw oblique fissure by drawing a line strait from 6th rib in
MCN. to 5th rib in mid axillary line and along the medial margin of scapula (with the
patients hands on head) to 3rd spinous process.
fissure can be drawn by drawing a line from 5th rib in mid-axillary line to 4th
Once the fissures are drawn over the outline of lungs, one can easily recognize
the surface anatomy of lobes of lungs. One can then appreciate the
importance of examining the patient all around the chest to cover the lobes. Most of lower
lobe is in back, upper lobe is in front and all of middle lobe is in front. In the axilla
all of the three lobes can be seen.
is the space between lungs from inlet to
outlet of thorax. Anteriorly it is between parasternal lines. Posteriorly it is at
vertebral line. Mediastinum is narrow posteriorly and widens anteriorly. Inferiorly it
extends to xiphisternum. Superiorly it starts at suprasternal notch. Since the inlet of
thorax is slanted, only posterior Mediastinum extends to neck.
angle separates superior from inferior
inferior Mediastinum is divided
into anterior, middle and posterior compartments. The space in front of heart is anterior
Mediastinum and behind is posterior Mediastinum. Heart itself
defines the middle Mediastinum. The posterior Mediastinum is divided into
paravertebral and prevertebral space. Superior
Mediastinum extends into the neck and is called cervico-Mediastinal space.
It is important to know the structures in each compartment. In
the differential of masses in the Mediastinum one uses this knowledge.
- Costal Angle
- Costal angle is formed by the 10 rib with Costal cartilage on either side and
xiphisternum in the middle. The normal angle is . Both sides are symmetrical. Volume
changes in each hemithorax will alter this relationship. Hyperinflated lungs will increase
the Costal angle. Diaphragmatic paralysis also alters the symmetry of Costal angle.
- Spinous Process
- The most prominent spinous process is 7th cervical vertebra. You can count down
the thoracic vertebra and the ribs using this landmark.