The Language of Anatomy: Muscles & Bones
By Darran Clemmit - MuscleTalk Contributing Writer
Many of us are familiar with the names of basic muscle groups, muscles and bones. But it can become another language when being discussed in any depth in some levels of the fitness industry, let alone in the medical world. The terms and descriptions associated with muscles and other parts of the anatomy can quickly become confusing to most people, yet their basis is a very structured one, and actually relatively simple to learn or understand once the basic terms and logic is understood. Obviously, a full in depth look would fill a whole textbook many times over, but hopefully a quick overview of the most common terms in an exercise or injury setting will help people understand and prove useful. For that reason, I have limited it to mainly language related to muscles in this article.
A lot of the prefixes used in anatomy language are common, not specific to any particular area or tissue; they combine, along with specific names, to give short but accurate descriptions of body parts being discussed. Further on you will see examples of them used to describe, bone, tendon, ligament and muscle.
- Directions and relative positions refer to structures of the body, and are used to describe relative positions.
- Superior and inferior describe a position relative to another body part or other part of the same structure in a head to toe direction. Something that is superior is closer to the head, and something inferior is closer to the feet.
- Posterior and anterior describe a position in front or behind the body or another structure.
- Superficial and deep relate to the depth within the body. Something superficial is closer to the surface.
- Medial and lateral describe a position that is closer to the centre of the body than another. A pain on the inside of your knee would be described as medial knee pain.
- Distal and proximal: Something distal is further away from the trunk of the body; something proximal is closer to the trunk or centre line.
Bones form the basic structure of the body and all have their own individual names, they are also grouped into classes, of long, short, irregular, flat and sesamoid:
- Long bones are those such as the femur (leg) or humerus (upper arm)
- Short bones are those without a shaft such as those in the wrist
- Irregular bones are mainly the vertebrae in the spine
- Flat bones are those such as the ribs and sternum (breast plate)
- Sesamoid refers to the kneecap
Bones have their own language to describe features on them, for example a fossa will refer to a hollow or depression, a trochanter, tuberosity or tubercle to a projection often for a muscle or ligament attachment. Other language refers to bony features such as spines and grooves. The pelvis, for example, has a ridge called the iliac spine running round it, you can feel it run from the front to the back at your waist. This descriptive name would then be combined with the words above used to describe positions. So the ridge on your pelvis at the back, above your bum would be called the posterior (it's to the rear) superior (it's on the top) iliac spine. The medical community then like to further confuse us by abbreviating this to the PSIS, as if it wasn't difficult enough to understand them!
Tendons connect muscle to bone, and ligaments connect two bones. The two are commonly confused but the definition is a very simple one. Tendons allow muscles to create movement between bones, ligaments connect two bones together to limit or prevent movement. Most of us know someone whose knee has collapsed or given way, when they have snapped the cruciate ligaments in it, which keep the ends of the bones in position. The cruciate ligaments are another good example of how the above descriptive terms are used, in that there are both anterior and posterior cruciate ligaments, abbreviated to ACL and PCL.
Muscle description has several key features and shares a lot of common language; biceps for instance are found in both the arm and the leg. Often the names of the muscles themselves give clues to their characteristics; these can be to the shape (trapezius, rhomboids), movement produced (flexor digitorum, adductors), location (tibialis), fibre direction (obliques) or attachment sites (coracobrachialis, carpi radialis). Muscles have an origin and an insertion where they attach to bone via tendons. The origin tends to be the more stationary end, and the insertion tends to be the mobile end. Every muscle has an action, and this refers to what happens when it contracts.
We can see how all this combines then, looking at the biceps femoris, part of the muscle group referred to as the hamstrings. The name gives us a clue not only to the location near the femur, but also to the fact that it has two heads. Its origin of the long head via the proximal tendon is on the ischial tuberosity of the pelvis, it sits over the top of the short head so is superficial to it. The short head has its origin on the femur, and both muscles share a common distal tendon at their insertion on the head of the fibular.