Video: Anatomical terminology for healthcare professionals | Episode 4 | Muscular system

Some people think working out to build muscle is painful. Well, they clearly never try learning how to master their terminology. Because, let's face it. Flexing your muscles for a selfie is easy. Explaining what they're about – is not. If you've been feeling like learning the terminology of the muscular system is as about as difficult as lifting 400 kilos off the ground, you're not the only one. Well, relax. Sweat no more. You’re going to be smashing this one in no time.

Welcome back to the fourth episode of the Kenhub series, Anatomical Terminology for Healthcare Professionals – getting buffed with muscular terminology.

So if you've watched the previous episodes of this series, you'll know that instead of helping you memorize the name of every single muscle, we're teaching you about how they're named. We do that by breaking down anatomical terms into their main components – roots, prefixes, and suffixes. But before I get to the meaty terminological stuff, let's begin with the three most basic terms about muscle, which are the three types of muscle found in the body.

Skeletal muscle is generally attached to bone and responsible for voluntary movement of the body. It’s probably what you picture when someone mentions muscle. Smooth muscle generally deals with involuntary movements like those related to our organs and vessels. It’s also known as a visceral muscle. The final group is cardiac muscle which, of course, is found in the heart. We all know we have no voluntary control over what the heart does.

Now I want to throw in a few of those roots and prefixes we love so much, and this will help you decipher terms about conditions and processes related to the muscular tissue. Perhaps, the most important term related to muscle is 'my/o-', which comes from the Greek 'mys' for muscle. It can be used as the root in words like myalgia, which is a term for muscle pain. Another is myopathy, which is the general term used for a disease specifically affecting muscle tissue.

'Myo-' can also appear as a prefix such as myocarditis – 'myo-' referring to muscle, card referring to the Greek word 'kardia' which means heart, and '-itis' which we learned before means inflammation; so, inflammation of the muscle of the heart. It also pops up the term 'leiomy/o-'; 'leio' is the Greek term for smooth, so 'leiomy/o-' refers to smooth muscle, like in leiomyoma uteri – benign tumor of uterine smooth muscle. 'Rhabdomyo-' refers to skeletal or striated muscle such as rhabdomyosarcoma, which is a malignant tumor of skeletal muscle.

Of course, we can't forget 'muscul/o-' which comes from Latin and is where we get the term muscle. An easy example of this prefix is musculocutaneous, which means relating to both muscle and skin.

I’d like to also show you a few terms which do not necessarily refer directly to muscle, but to their associated tissues. 'Tend/o-' or 'tendin/o-', of course, relates to the tendons. For example, tendinitis is inflammation of a tendon. Similarly, 'fasci/o-' refers to fascia – a connective tissue covering muscles. You may see in terms like fasciodesis which is a surgical procedure of attaching or suturing fascia to other fascia or a tendon. Of course, like with all systems of the body, the list for all possible prefixes and roots is long, but if we manage to take a note of these, you've made a great, great start.

All right, now that we've been introduced to some of the most common prefixes and roots related to the muscular system, let's turn our attention to the terminology we'll encounter when looking at skeletal muscles, in particular, how they are named. And as we've been learning in this series, it's all in the name – and muscles are no different. Once you learn to decipher the parts of their terminology, you're going to see that there are seven main criteria which can be coded into the name of a muscle.

The first of these which contribute to a muscle name is its shape – for example, the trapezius muscle, 'trapezion' means diamond-shaped - and you can clearly see why on this muscle. The deltoid muscle suggesting the triangular shape of the Greek letter 'delta' or the serratus anterior muscle which get its name from the word 'serrare' which means saw in Latin.

Our second characteristic determining muscle names is their size. Yes, there is a reason your butt is called your gluteus maximus. It's the largest muscle of the body. Other examples include the vastus lateralis muscle, the fibularis brevis, the adductor longus, or the latissimus dorsi muscle.

Another criterion for naming muscles is according to the orientation or directions of your fibers. For example, the transverse muscle of the tongue whose fibers run perpendicular to the midline; the external oblique muscle which has its fibers arranged diagonally or at an angle; or if you see rectus in a name of a muscle like the rectus abdominis, it will have fibers roughly parallel to the midline, and before you ask, six-pack is not a technical term for this muscle.

Muscles can also be named in accordance with what they do. I won't bore you with every single action, but most of these are obvious, like the flexor digiti minimi – flexor of the little finger; or the extensor hallucis brevis – extensor of the big toe. Not all are clear though; for example, the risorius muscle which helps us to smile or the masseter which literally means the chewer.

The name can also tell you about the number of heads or bellies it might have. For instance – you know this one for sure – the biceps brachii muscle, which has two heads. Other examples include the triceps brachii or quadriceps femoris.

Our second last criterion for muscle names are its attachments. This means they get their names from bones, bone parts, or tissue they're attached to. There are lots of examples like these such as sternohyoid muscle which attaches to the sternum and the hyoid bone or the pubococcygeus muscle which extends between the pubic and coccygeal bones.

And, finally, unsurprisingly, location also pops up in muscle names. It can indicate the region a muscle is found in. There are lots of examples of these. For instance, we have the temporalis muscle found over the temporal region of the skull or the intercostal muscles located between the rib bones of the thoracic cage. The muscle name might also refer to its relative position to another muscle. For example, flexor digitorum superficialis is more superficial than its counterpart, the flexor digitorum profundus.

Ok, so, I think that more than covers what we need to know about muscle names. You can learn more about each and every muscle of the body right now by checking out our articles and atlas at kenhub.com and explore muscle names in a whole new light.

Now, time to move on to look at some terms which may be used to describe function of a muscle relative to a specific movement. For example, let's take the movement flexion of the forearm at the elbow joint. Said to have an agonist or prime mover muscle which does most of the work. In this case, it's the biceps brachii muscle which flexes the elbow joint. An agonist can be aided by synergist muscles – 'syn-' together, 'erg-' means work which help either by direct action or by stabilizing the joint involved in the movement.

The muscle or muscles which work in opposition to an agonist are known as antagonists. In this case, it's the triceps brachii which extends the forearm at the elbow joint. An antagonist is sometimes important in controlling the speed or force of the movement created by an agonist muscle.

Regardless of the type or location of a muscle, they all have the exact same function – contract and relax. However, not all types of contraction are the same. Let’s check out some terms which you might encounter describing this.

There are two main types of muscle contraction – isotonic and isometric – and they all begin with the prefix 'iso-' which means equal or constant. The most familiar type is known as isotonic contraction where the root tonic comes from the Greek 'tonus' which means tone or tension. So, it means contraction of equal or constant tension. This is where the length of a muscle changes against a constant load.

Isotonic contractions can be separated into two types – concentric contractions where the muscle shortens due to the force of contraction being greater to the load placed upon it, and eccentric contractions, on the other hand, which occurs when the load is greater than the force of contraction. This causes the muscle to lengthen instead. So, even though the muscle is getting longer, it is still contracting. You’ll see this when we are carefully lowering a heavy load. Without it, the load would quickly drop to the floor causing injury.

The opposite type of contraction is called isometric contraction where a load is forcing a muscle to exert force, but without any change in length of the muscle, therefore, no movement occurs. To understand this, just think of a good old plank exercise. Here, we experience an increasing tension over time without change in the length of the muscle. Feel it burn! This is clearly not my favorite thing to do in the world.

Okay, the final stretch – let's wrap this up with a few word elements that are especially useful in a clinical setting.

First up is 'spasmo-', which as you might expect, refers to involuntary spasm or contraction of muscle; spasmogenic – substance or condition which causes spasm.

Next is the suffix '-trophy' which is often used in reference to muscles and means growth or development. For example, atrophy refers to wasting away or regression of a muscle usually due to a disorder or disuse. Or hypertrophy, which can be used to describe the overdevelopment of a muscle. And, finally, clonic which comes from the Greek term 'clonus' meaning alternating involuntary contraction and relaxation of muscle in rapid succession.

Wow! That was quite a lot of information, right? Hopefully, you feel a lot more confident deciphering the not-so-subtle code that is muscular system terminology. It also brings us one step closer to mastering medical and anatomical terminology.

I will leave you, but I will leave you with a challenge. Can you figure out what these terms mean based on today's video?