Lower Extremities

Objectives List structures found in sectional images of the lower extremities Identify sagittal, axial, and coronal planes from given anatomy Discuss the importance of understanding the relationships and locations between anatomic structures After completing this topic you should be able to: List structures found in sectional images of the upper extremities Differentiate between tissues and structures based on displayed density levels Identify sagittal, axial, and coronal planes from given anatomy Discuss the importance of understanding the relationships and locations between anatomic structures

When trying to identify anatomy on sectional images, first look for the anatomical structures unique to that area. For example, the patella and distal end of the femur are structures only found in the knee. Take a look at images of the knee in all three planes. <bring three knee images in> The joint made from the femoral condyles, the tibial plateau and the patella floating above is unique and easy to identify. In the axial images, notice the patella suspended above the femur. The intercondylar fossa forms a arch similar to a horseshoe. <bring horseshoe image in> In the other axial images, this arch maybe less apparent, but still visible. This is because the slices are farther away from the midline of the condyles.

femur humerus femur humerus These are a little more difficult, because they can easily get transposed with the upper anatomy. For example: the humerus and femur, both being long bones, are pretty similar in mid shaft. These are NOT good choices to help identify the anatomy. <bring top images In only> In these images can you tell the femur from the humerus? The humerus is on the left and the femur is on the right. <I used labels to help clarify, they do not need to be on the student version> At a quick glance, these look very similar. You can look at the muscles surrounding the bone to determine that the femur has more muscle surrounding it than the humerus does. Another area that gets transposed sometimes is the humeral head and the femoral head. <bring bottom images In> On these images, can you tell the femur from the humerus? The humerus is on the left again. Both structures have round heads, and are ball socket joints. The acetabulum has more of a base surrounding the fermural head than the glenoid fossa around the femural head. The scapula, can help give the humerus away. Notice how thin that bone is? <arrow>

Here are some axial images. This one may be a little easier Here are some axial images. This one may be a little easier. Can you tell which image is of the forearm and which is the tib-fib? <bring in captions> The forearm is on the left and the tib-fib is on the right. Both limbs have 2 long bones, but the tibia is a bit wider. Keeping that in mind can help you differentiate the images. Forearm Tib-fib

When viewing the <show full body image of planes> sectional images of the feet, remember the location of the feet in anatomical position. <zoom into plane of the feet> Sagittal images will be easy to recognize and identify. Axial and coronal views will look different compared to other anatomy discussed so far. (assuming that the patient is supine in the scanner)

The axial images of other anatomical areas almost always appear circular. With the feet, it’s the coronal images that appear circular (actually, more of an oval due to the shape of the foot) and the axial images will be more elongated (up and down).

With looking at images of the feet, look for distinctive anatomical areas to help identify structures. For example, the calcaneus <highlight the label and area> is the largest bone, the talus <highlight the label and area> is rounded and the navicular <highlight the label and area> has an arched shape. Identifying these structures first will give you a starting point from which you can recognize the other anatomy.

When looking at lower extremity sectional images, look for something unique to that area. Think of this as finding a landmark on a trip—once you have a starting point, you can easily navigate to and recognize other things.