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Chapter 12: Problem 3

What criteria are used to name muscles? Give an example of each one. (pages 256,258 )

Short Answer

Expert verified
Muscles are named based on various criteria, including location, shape, size, direction of fibers, number of origins, and action. For example: (1) The temporalis muscle is named for its location in the temporal region of the head. (2) The deltoid muscle is named for its triangular shape. (3) The gluteus maximus is named for being the largest muscle in the buttock region. (4) The rectus abdominis muscle is named for its vertically oriented fibers. (5) The biceps brachii has two points of origin, hence the "bi" in its name. (6) The adductor longus muscle is named for its action of adducting the thigh.

Step by step solution

01

1. Research on Pages 256 and 258

Go through pages 256 and 258 to identify the criteria used to name muscles.
02

2. List Criteria and Examples

After going through the pages, list down the criteria and provide an example for each.
03

3. Write the Titles and Descriptions

Write the title and a brief description for each criterion, as well as an example. Here is the step-by-step solution based on the criteria found in pages 256 and 258:
04

Criterion 1: Location

Muscles can be named based on their location in the body. For example, the temporalis muscle is located in the temporal region of the head.
05

Criterion 2: Shape

Muscles can be named according to their shape. For example, the deltoid muscle has a triangular or delta shape.
06

Criterion 3: Size

The size of the muscle can also be a naming criterion. For example, the gluteus maximus is the largest muscle in the buttock region.
07

Criterion 4: Direction of Muscle Fibers

The direction of the muscle fibers can be used to name muscles. For example, the rectus abdominis muscle has vertically oriented fibers.
08

Criterion 5: Number of Origins

The number of origins of a muscle can be a criterion for naming muscles. For example, the biceps brachii has two points of origin, hence "bi" meaning two.
09

Criterion 6: Action

The action performed by the muscle can be used as a naming criterion. For example, the adductor longus muscle adducts (brings towards the midline) the thigh. These are the criteria used to name muscles along with examples for each.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Location of Muscles
The location of a muscle refers to the specific region or structure it is associated with in the body. This helps in identifying and communicating about muscles in a clear and systematic way.

For instance, the 'intercostal' muscles are so named because they are situated between the ribs – 'inter' meaning between, and 'costal' referring to the ribs. This criterion of naming helps in explaining the position of the muscle relative to other organs or bones, making it easier for students to locate and study these muscles within the human anatomy.
Shape of Muscles
Muscles can also be named for their distinctive shapes, which can be quite descriptive of their appearance. Shapes like 'deltoid' meaning triangular, 'orbicularis' indicating a circular formation, and 'serratus' resembling a serrated or saw-like edge, all give visual clues about the muscle's form.

For example, the 'trapezius' muscle resembles a trapezoid, which aids individuals in quickly identifying the muscle due to its geometric name and corresponding shape.
Size of Muscles
Size is another important descriptor used in muscle nomenclature. The terms 'maximus', 'minimus', 'longus', and 'brevis' indicate large, small, long, and short muscles, respectively.

Such terms make it immediately evident the relative size of the muscle compared to others in the vicinity, which can be particularly valuable when differentiating muscles that are otherwise similar in location and function but vary in size, like the 'gluteus maximus' versus the 'gluteus minimus.'
Direction of Muscle Fibers
The alignment or direction of a muscle's fibers can be a defining feature. Directional terms like 'rectus' (straight), 'transversus' (across), and 'oblique' (angled) clarify the orientation of muscle fibers.

This is crucial for understanding muscle functionality since the fiber direction often correlates with the direction of muscle contraction and the movement it produces, as seen with the 'rectus abdominis', whose vertical fibers help in flexing the torso.
Number of Muscle Origins
The count of points where a muscle is anchored or originates from is another criterion in muscle naming. Prefixes such as 'bi-', 'tri-' and 'quadri-' denote two, three, and four origins, respectively.

These prefixes simplify the task of identifying muscles according to their head counts, such as the 'biceps brachii' which is indicative of the muscle having two heads or points of origin.
Action of Muscles
The specific action a muscle performs is perhaps the most functionally descriptive naming criterion. Terms like 'adductor', 'abductor', 'flexor', and 'extensor' give direct insight into what the muscle does.

For instance, the muscle named 'flexor digitorum profundus' indicates that this muscle flexes (bends) the fingers ('digitorum') deeply ('profundus'). This way, the name of the muscle conveys its primary functional role, which is invaluable for both learners and professionals in understanding and predicting muscle roles in movement and support.

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Most popular questions from this chapter

Proper functioning of a neuromuscular junction requires the a. presence of acetylcholine. b. presence of a synaptic cleft. c. presence of a motor terminal. d. sarcolemma of a muscle cell. e. All of these are correct.

To increase the force of muscle contraction, a. individual muscle cells have to contract with greater force. b. motor units have to contract with greater force. c. motor units need to be recruited. d. All of these are correct. e. None of these is correct.

The thick filaments of a muscle fiber are made up of a. actin. b. troponin. c. fascia. d. myosin.

Give an example to show that skeletal muscles work in antagonistic pairs. Explain. (page 255)

Impulses that move down the T system of a muscle fiber most directly cause a. movement of tropomyosin. b. attachment of the cross-bridges to myosin. c. release of \(\mathrm{Ca}^{2+}\) from the sarcoplasmic reticulum. d. splitting of ATP.
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