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14.9: Naming Skeletal Muscles - Biology

14.9: Naming Skeletal Muscles - Biology


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Learning Objectives

  • Describe the criteria used to name skeletal muscles
  • Explain how understanding the muscle names helps describe shapes, location, and actions of various muscles

The Greeks and Romans conducted the first studies done on the human body in Western culture. Pronunciation of words and terms will take a bit of time to master, but after you have some basic information; the correct names and pronunciations will become easier.

Table 1. Understanding a Muscle Name from the Latin
ExampleWordLatin Root 1Latin Root 2MeaningTranslation
abductor digiti minimiabductorab = away fromduct = to movea muscle that moves away fromA muscle that moves the little finger or toe away
digitidigitus = digitrefers to a finger or toe
minimiminimus = mini, tinylittle
adductor digiti minimiadductorad = to, towardduct = to movea muscle that moves towardsA muscle that moves the little finger or toe toward
digitidigitus = digitrefers to a finger or toe
minimiminimus = mini, tinylittle
Table 2. Mnemonic Device for Latin Roots
ExampleLatin or Greek TranslationMnemonic Device
adto; towardADvance toward your goal
abaway fromn/a
subunderSUBmarines move under water.
ductorsomething that movesA conDUCTOR makes a train move.
antiagainstIf you are antisocial, you are against engaging in social activities.
epion top ofn/a
apoto the side ofn/a
longissimuslongest“Longissimus” is longer than the word “long.”
longuslonglong
brevisshortbrief
maximuslargemax
mediusmedium“Medius” and “medium” both begin with “med.”
minimustiny; littlemini
rectusstraightTo RECTify a situation is to straighten it out.
multimanyIf something is MULTIcolored, it has many colors.
unioneA UNIcorn has one horn.
bi/ditwoIf a ring is DIcast, it is made of two metals.
trithreeTRIple the amount of money is three times as much.
quadfourQUADruplets are four children born at one birth.
externusoutsideEXternal
internusinsideINternal

Anatomists name the skeletal muscles according to a number of criteria, each of which describes the muscle in some way. These include naming the muscle after its shape, its size compared to other muscles in the area, its location in the body or the location of its attachments to the skeleton, how many origins it has, or its action.

The skeletal muscle’s anatomical location or its relationship to a particular bone often determines its name. For example, the frontalis muscle is located on top of the frontal bone of the skull. Similarly, the shapes of some muscles are very distinctive and the names, such as orbicularis, reflect the shape. For the buttocks, the size of the muscles influences the names: gluteus maximus (largest), gluteus medius (medium), and the gluteus minimus (smallest). Names were given to indicate length— brevis (short), longus (long)—and to identify position relative to the midline: lateralis (to the outside away from the midline), and medialis (toward the midline). The direction of the muscle fibers and fascicles are used to describe muscles relative to the midline, such as the rectus (straight) abdominis, or the oblique (at an angle) muscles of the abdomen.

Some muscle names indicate the number of muscles in a group. One example of this is the quadriceps, a group of four muscles located on the anterior (front) thigh. Other muscle names can provide information as to how many origins a particular muscle has, such as the biceps brachii. The prefix bi indicates that the muscle has two origins and tri indicates three origins.

The location of a muscle’s attachment can also appear in its name. When the name of a muscle is based on the attachments, the origin is always named first. For instance, the sternocleidomastoid muscle of the neck has a dual origin on the sternum (sterno) and clavicle (cleido), and it inserts on the mastoid process of the temporal bone. The last feature by which to name a muscle is its action. When muscles are named for the movement they produce, one can find action words in their name. Some examples are flexor (decreases the angle at the joint), extensor (increases the angle at the joint), abductor (moves the bone away from the midline), or adductor (moves the bone toward the midline).


11.3 Explain the criteria used to name skeletal muscles

Taking the time to learn the Latin and Greek roots of the words is crucial to understanding the vocabulary of anatomy and physiology. When you understand the names of muscles it will help you remember where the muscles are located and what they do (Figure 11.3.1, Figure 11.3.2, and Table 11.2).

Figure 11.3.1 – Overview of the Muscular System: On the anterior and posterior views of the muscular system above, superficial muscles (those at the surface) are shown on the right side of the body while deep muscles (those underneath the superficial muscles) are shown on the left half of the body. For the legs, superficial muscles are shown in the anterior view while the posterior view shows both superficial and deep muscles. Figure 11.32 – Understanding a Muscle Name from the Latin: Here are two examples of how root words describe the location and function of muscles
Mnemonic Device for Latin Roots (Table 11.2)
Example Latin or Greek Translation Mnemonic Device
ad to toward ADvance toward your goal
ab away from n/a
sub under SUBmarines move under water.
ductor something that moves A conDUCTOR makes a train move.
anti against If you are antisocial, you are against engaging in social activities.
epi on top of n/a
apo to the side of n/a
longissimus longest “Longissimus” is longer than the word “long.”
longus long long
brevis short brief
maximus large max
medius medium “Medius” and “medium” both begin with “med.”
minimus tiny little mini
rectus straight To RECTify a situation is to straighten it out.
multi many If something is MULTIcolored, it has many colors.
uni one A UNIcorn has one horn.
bi/di two If a ring is DIcast, it is made of two metals.
tri three TRIple the amount of money is three times as much.
quad four QUADruplets are four children born at one birth.
externus outside EXternal
internus inside INternal

Anatomists name the skeletal muscles according to a number of criteria, each of which describes the muscle in some way. These include naming the muscle after its shape, size, fiber direction, location, number of origins or its action.

  • The names of some muscles reflect their shape. For example, the deltoid is a large, triangular-shaped muscle that covers the shoulder. It is so-named because the Greek letter delta is a triangle.
  • The skeletal muscle’s anatomical location or its relationship to a particular bone often determines its name. For example, the frontalis muscle is located on top of the frontal bone of the skull. Other examples are muscles of the arm that include the term brachii (of the arm).
  • For the buttocks, the size of the muscles influences the names: gluteus maximus (largest), gluteus medius (medium), and the gluteus minimus (smallest). Another example are the pectoral muscles including major or minor.
  • Names are often used to indicate length—brevis (short), longus (long)
  • Some muscles indicate their positions relative to the midline: lateralis (to the outside away from the midline), and medialis (toward the midline).
  • The direction of the muscle fibers and fascicles are used to describe muscles. For example, the abdominal muscles all indicated the direction of the fibers such as the rectus (straight), the obliques (at an angle) and the transverse (horizontal) muscles of the abdomen.
  • Some muscle names indicate the number of muscles in a group. One example of this is the quadriceps, a group of four muscles located on the anterior (front) thigh.
  • Other muscle names can provide information as to how many origins a particular muscle has, such as the biceps brachii. The prefix bi indicates that the muscle has two origins and tri indicates three origins.
  • The location of a muscle’s attachment can also appear in its name. When the name of a muscle is based on the attachments, the origin is always named first. For instance, the sternocleidomastoid muscle of the neck has a dual origin on the sternum (sterno) and clavicle (cleido), and it inserts on the mastoid process of the temporal bone.
  • The last feature by which to name a muscle is its action. When muscles are named for the movement they produce, one can find action words in their name. Some examples are flexors (decrease the angle at the joint), extensors (increase the angle at the joint), abductors (move the bone away from the midline), or adductors (move the bone toward the midline).

Chapter Review

Muscle names are based on many characteristics. The location of a muscle in the body is important. Some muscles are named based on their size and location, such as the gluteal muscles of the buttocks. Other muscle names can indicate the location in the body or bones with which the muscle is associated, such as the tibialis anterior. The shapes of some muscles are distinctive for example, the direction of the muscle fibers is used to describe muscles of the body midline. The origin and/or insertion can also be features used to name a muscle examples are the biceps brachii, triceps brachii, and the pectoralis major.


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Levers: Power Versus Speed

A lever allows a given effort to move a heavier load, or to move a load farther and faster, than it otherwise could. If the load is close to the fulcrum and the effort is applied far from the fulcrum, a small effort exerted over a relatively large distance can move a large load over a small distance. Such a lever is said to operate at a mechanical advantage and is commonly called a power lever. For example, a person can lift a car with a power lever or jack. The car moves up only a small distance with each downward push of the jack handle, but relatively little muscle effort is needed.

Lever systems operating at a mechanical advantage and a mechanical disadvantage. (a) Mechanical advantage with a power lever. When using a jack the load lifted is greater than the applied muscular effort. (b) Mechanical disadvantage with a speed lever. When using a shovel to lift dirt, the muscular force is greater than the load lifted.

If, on the other hand, the load is far from the fulcrum and the effort is applied near the fulcrum, the force exerted by the muscle must be greater than the load to be moved or supported. This lever system is a speed lever and operates at a mechanical disadvantage. Speed levers are useful because they allow a load to be moved rapidly or a large distance with a wide range of motion. Using a shovel is an example. As you can see, small differences in the site of a muscle’s insertion can translate into large differences in the amount of force a muscle must generate to move a given load or resistance.

Regardless of type, all levers follow the same basic principle:

  • Effort farther than load from fulcrum = lever operates at a mechanical advantage
  • Effort nearer than load to fulcrum = lever operates at a mechanical disadvantage

Classes of Levers

Depending on the relative position of the three elements – effort, fulcrum, and load – a lever belongs to one of three classes.

In a first-class lever, the effort is applied at one end of the lever and the load is at the other, with the fulcrum somewhere between. seesaws and scissors are first-class levers. First-class leverage also occurs when you lift your head off your chest. Some first-class levers in the body operate at a mechanical advantage (for strength), but others, such as the action of the triceps muscle in extending the forearm against resistance, operate at a mechanical disadvantage (for speed and distance).

In a second-class lever, the effort is applied at one end of the lever and the fulcrum is located at the other, with the load between them. A wheelbarrow demonstrates this type of lever system. Second-class levers are uncommon in the body, but the best example is the act of standing on your toes. All second-class levers in the body work at a mechanical advantage because the muscle insertion is always farther from the fulcrum than the load. Second-class levers are levers of strength, but speed and range of motion are sacrificed for that strength. Having good muscle strength can come with a lot of benefits to your health, as well as your body. For athletes, it can reduce the risk of an injury occurring and it can help everyone to keep their bodies at a healthy weight. Some people may decide to take up the art of yoga to help them to gain the relevant amount of muscle strength for their bodies. To have a better chance of achieving this, you may want to start off your regime with Surya Namaskar, (you can see all of the surya namaskar benefits here) as this could help you to get in the right frame of mind before continuing with your workout. Even though this type of exercise can help to strengthen your muscles, it can also provide you with more advantages to ensure that you can stay as healthy as possible.

In a third-class lever, the effort is applied between the load and the fulcrum. These levers are speedy and always operate at a mechanical disadvantage – think of tweezers and forceps. Most skeletal muscles of the body act in third-class lever systems. An example is the activity of the biceps muscle of the arm, lifting the distal forearm and anything carried in the hand. Third-class lever systems permit a muscle to be inserted very close to the joint across which movement occurs, which allows rapid, extensive movements (as in throwing) with relatively little shortening of the muscle. Muscles involved in third-class levers tend to be thicker and more powerful.

In conclusion, differences in the positioning of the three elements modify muscle activity with respect to speed of contraction, range of movement, and the weight of the load that can be lifted. Hernia Surgery is a great way to repair muscle damage. There are a wide range of hernia mesh products on the market, made by many different companies. Each is individually designed and manufactured to provide superior results in hernia repair procedures. Products may vary in shape, size, flexibility, and materials used, and may have unique characteristics to accommodate certain anatomical features. This of course means that some products are not going to be as up to scratch as other and actually cause more damge to the patient, more and more patients are filling for a possible law suit!


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