11.3 Explain the criteria used to name skeletal muscles

Learning Objectives

By the end of this section, you will be able to identify the following:

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

The top panel shows the anterior view of the human body with the major muscles labeled. The bottom panel shows the posterior view of the human body with the major muscles labeled.
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.
This table shows two examples of muscle names and how to translate them based on their Latin roots. The first row uses abductor digiti minimi as an example. The word abductor comes from the Latin roots ab, which means away from, and duct, which means to move. Therefore an abductor is a muscle that moves away from something. The word digiti comes from the Latin root digititus, which means digit and refers to a finger or toe. The word minimi comes from the Latin root minimus, which means minimum, tiny, or little. Therefore, the abductor digiti minimi is a muscle that moves the little finger or toe away. The second row uses the adductor digiti minimi as an example. The word adductor comes from the Latin root ad, which means to or toward, and duct, which means to move. Therefore an adductor is a muscle that moves toward something. As with the abductor digiti minimi, digiti refers to a finger or toe and minimi refers to something that is little. Therefore the adductor digiti minimi is a muscle that moves the little finger or toe forward.
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

Understanding a Muscle Name from the Latin

Example Word Latin Root 1 Latin Root 2 Meaning Translation
abductor digiti minimi abductor ab = away from duct = to move a muscle that moves away from A muscle that moves the little finger or toe away
digiti digitus = digit refers to a finger or toe
minimus = mini, tiny little
adductor digiti minimi adductor ad = to, toward duct = to move a muscle that moves towards A muscle that moves the little finger or toe forward
digiti digitus = digit refers to a finger or toe
minimi minimus = mini, tiny little

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

Mnemonic Device for Latin Roots

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.

  • Muscle Shape: 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.
  • Muscle Location: 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).
    • Some muscles indicate their positions relative to the midline, which is related to muscle location: lateralis (to the outside away from the midline), and medialis (toward the midline).
    • 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.
  • Muscle Size: 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, which is related to muscle size. For example, brevis (short), longus (long).
  • Muscle Fiber Direction: The direction of the muscle fibers and fascicles are used to describe muscles. For example, the abdominal muscles all indicate (remove indicated) the direction of the fibers such as the rectus (straight), the obliques (at an angle) and the transverse (horizontal) muscles of the abdomen.
  • Number of Muscle Origins (or muscles in a group): Some muscle names indicate the number of muscles origins, or number of muscles in a group, depending upon one’s perspective. For example, when considering the anterior thigh muscle(s), known as the quadriceps, some consider it to be a single muscle with four heads (origins) and others consider the quadriceps to be a group of four muscles. In either case, the prefix quad- refers to four. One example of this is the quadriceps, a group of four muscles located on the anterior (front) thigh. Other examples include the biceps brachii and the triceps brachii. The prefix bi indicates that the muscle has two origins and tri indicates three origins.
  • 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.

Review Questions

Critical Thinking Questions

1. Describe the different criteria that contribute to how skeletal muscles are named.

Glossary

abductor
moves the bone away from the midline
adductor
moves the bone toward the midline
bi
two
brevis
short
extensor
muscle that increases the angle at the joint
flexor
muscle that decreases the angle at the joint
lateralis
to the outside
longus
long
maximus
largest
medialis
to the inside
medius
medium
minimus
smallest
oblique
at an angle
rectus
straight
tri
three

Solutions

Answers for Critical Thinking Questions

  1. In anatomy and physiology, many word roots are Latin or Greek. Portions, or roots, of the word give us clues about the function, shape, action, or location of a muscle.

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Anatomy & Physiology Copyright © 2019 by Lindsay M. Biga, Staci Bronson, Sierra Dawson, Amy Harwell, Robin Hopkins, Joel Kaufmann, Mike LeMaster, Philip Matern, Katie Morrison-Graham, Kristen Oja, Devon Quick, Jon Runyeon, OSU OERU, and OpenStax is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted.

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