The intercostal space refers to the anatomical area located between two adjacent ribs. There are eleven such spaces on each side of the body, and each is typically numbered according to the rib positioned above it.
Understanding Key Anatomical Landmarks
Locating the second intercostal space requires familiarity with several bony structures of the chest. The sternum, also known as the breastbone, forms the central part of the chest. At the very top of the sternum, between the two collarbones, is a noticeable dip called the suprasternal notch, or jugular notch. This indentation marks the superior border of the manubrium, which is the uppermost section of the sternum.
Just below the suprasternal notch, where the top part of the sternum (manubrium) meets the main body of the sternum, there is a slight ridge or elevation known as the sternal angle, also called the Angle of Louis. The second rib connects to the sternum precisely at the level of this sternal angle. The clavicle, or collarbone, extends horizontally across the top of the chest, connecting the sternum to the shoulder.
Step-by-Step Guide to Locating the Second Intercostal Space
Locate the suprasternal notch, the soft dip at the base of your neck, just above where your collarbones meet the breastbone. Gently place a finger into this indentation.
Next, slide your finger downwards from the suprasternal notch along the middle of your sternum. You will soon feel a distinct horizontal ridge or slight bump. This is the sternal angle. It marks the junction between the manubrium and the body of the sternum.
Once you have identified the sternal angle, move your finger directly out to either your left or right side, staying at the same horizontal level. You should feel the hard bone of the second rib connecting to the sternum at this point.
With the second rib located, gently move your finger just below it. The soft area you feel immediately beneath the second rib is the second intercostal space.
Confirm your location by gently moving your finger up and down; you should be able to distinguish the hard edge of the second rib above and the third rib below, with the softer, pliable intercostal space in between.
Clinical Relevance
Identifying the second intercostal space holds practical importance in various healthcare contexts. Healthcare professionals frequently use this anatomical landmark as a starting point for counting ribs during physical examinations. Since the first rib is often difficult to palpate due to its position behind the clavicle, the easily identifiable second rib at the sternal angle serves as a reliable reference.
This space is also a common site for listening to specific heart sounds. The aortic valve sounds are best heard in the right second intercostal space, adjacent to the sternum. Similarly, the pulmonic valve sounds are best assessed in the left second intercostal space, also next to the sternum.
Tips for Accurate Identification
Finding the second intercostal space accurately benefits from a few practical considerations. Begin by ensuring you are in a quiet environment, which allows for better concentration on tactile sensations. Relaxing your shoulders can also help, as tense muscles in the chest area can make palpation more challenging.
When feeling for the ribs and spaces, use light, gentle pressure with your fingertips. Pressing too hard can obscure the subtle differences between bone and soft tissue, making it more difficult to distinguish the intercostal space. Remember that body composition, such as varying amounts of muscle mass or subcutaneous fat, can influence how easily these structures are felt.
Consistent practice improves your ability to accurately identify the second intercostal space. With repeated attempts, your tactile sensitivity will refine, making the process more intuitive. Focusing on the distinct feel of firm bone versus the softer, yielding space will enhance your precision.