Summarize this article:

To take the apical pulse, you will need to access the bare chest. Feel for the clavicle.  The clavicle is also called the collarbone.  It can be felt at the top of the rib cage. Directly below the clavicle, you should feel the first rib.  The space between two ribs is called the intercostal space. Feel for the first intercostal space—the space between the first and second ribs. From the first intercostal space, move your fingers down to the fifth intercostal space by counting the ribs.  The fifth intercostal space should be located between the fifth and sixth ribs. If you're taking the apical pulse on a female, you can use three fingers to feel directly below the left breast. Usually, this same method will work on a man, as well. This allows you to take the pulse without counting the ribs. This is called the midclavicular line. The apical pulse can be felt and heard at the intersection of the fifth intercostal space and the midclavicular line. The apical pulse can be taken by touch or by using a stethoscope.  It can be very difficult to feel an apical pulse, especially in women where breast tissue may lie over the pulse.  A stethoscope may be easier for this purpose. In most people, it's almost impossible to feel an apical pulse using just your fingers. Unless the person is upset or in shock, their apical pulse will likely be too faint to detect without a stethoscope. Put on your stethoscope by putting the earpieces into your ears. Hold the diaphragm, which is the part of the stethoscope you use to listen to the patient's chest, in your hand. Rub the diaphragm (the end of the stethoscope) a bit to warm it up and tap it to make sure that you can hear the noises through the diaphragm. If you can't hear anything through the diaphragm, check that it is tightly attached to the stethoscope. If it's loose, you may not hear anything. Tell the person to breathe normally through his or her nose because doing so will decrease the sound of the breath and make hearing the heart easier. You should hear two sounds: lub and dub.  This is considered one beat.  Ask the person to face away from you, which can make it easier for you to hear. A heartbeat usually sounds like a galloping horse. This is the pulse rate, or heart rate. Think about how you might describe the pulse.  Is it loud?  Strong?  Is the rhythm regular, or does it seem irregular? Be ready with a watch that has a second hand so you can count the pulse rate. Count how many “lub-dubs” you hear in a minute (60 seconds).  The normal pulse rate for adults is 60 – 100 beats per minute. It differs with children.  With newborns to three years old, the normal heart rate is 80-140. For four to nine year olds, 75-120 is a normal heart rate. For 10 to 15 years old, 50-90 beats per minute is the normal pulse rate.

Summary:
Start by asking the patient to take off their shirt. Feel the first rib by finding the clavicle. Count the ribs as your work your way down. Draw an imaginary line from the middle of the left clavicle through the nipple. Decide between using regular touch or a stethoscope. Prepare your stethoscope. Place the stethoscope on the spot where you found the apical pulse. Count how many lub-dub sets you hear in one minute. Find the person’s heart rate.