Digital Anatomy Companion Site

Muscles of the Head and Neck

msonnenfeld

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https://www.biologycorner.com/2021/03/03/muscles-guided-learning/ CC BY-NC-SA 4.0

Learning Objectives

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

  • Identify, locate, and describe the origin, insertion, and function of three major muscles in the head and neck region.

We will consider the following three muscles:

  • Masseter
  • Sternocleidomastoid
  • Trapezius

Instructions:
You’ve learned the major bones in the last two labs—now it’s time to put that knowledge to work! Follow these steps as you explore each muscle:

  1. Observe the rotating GIFs for each muscle to visualize its position.
  2. Use the Innerbody 3D Model to explore each muscle in the context of the whole body and neighboring muscles.
    • Activate the 3D function. Rotate the model and click on muscles to reveal their names.
    • Try to locate the three muscles featured in this section.
      • Tip: Use the selection tool (arrow) to hide superficial muscles and reveal the deeper layers.
      • You can also toggle through the anatomy layers to reveal the bone origin and insertion sites of each muscle.
  3. Predict each muscle’s origin and insertion based on its position and name.
    • Ask yourself: Which bones form the landmarks mentioned in this muscle’s name?
  4. Once you’ve made your best guess, open the dropdowns to check your understanding.

Masseter

wikimedia CC-BY-SA-2.1-JP

         This cheek muscle has a superficial and a deep part and is named after its function.

originates on the zygomatic arch (bony ridge formed by both the zygomatic and temporal bones) and zygomatic process of the maxilla

It inserts on the ramus of the mandible

This powerful muscle elevates the mandible during the act of chewing, otherwise known as mastication. The joint involved is the temporomandibular joint (TMJ). Press play on the bottom of the image below to see this muscle in action! Click full screen to get a better view.

Sternocleidomastoid

wikimedia CC-BY-SA-2.1-JP

         This long narrow muscle has two heads and is in the neck. It is named for two of its origin sites and its one insertion site. Can you see from the name and image what these sites might be?  

🌐 Explore the sternocleidomastoid in 3D: Click here and use the rotation tools from UMich Anatomy to identify the origin and insertion points on a skeleton.

It originates from the manubrium of the sternum and from the clavicle.

It inserts on the mastoid process of the temporal bone.

Acting singly this muscle turns the head either to the right or left (rotation) and laterally flexes the neck. However, acting together, this muscle tips the head forward (flexes the neck) and raises the manubrium.

💡 Interactive 3D Tip:
Click on this interactive model to locate the masseter and sternocleidomastoid muscles in context.

  1. What clues does the model give you about each muscle’s function?
  2. Rotate and zoom to observe their position relative to the skull and neck.
  3. Can you identify the origin and insertion points based on what you see?

Find these two muscle at the innerbody site. Click on each muscle for identification. Use the anatomy layer tool to reveal the underlying bones.

TRAPEZIUS

wikimedia CC-BY-SA-2.1-JP

         This is a large, flat, triangular sheet of muscle.  It covers the posterior neck region and the upper region of the back. It attaches the axial skeleton to the upper appendicular skeleton. Can you see this on the diagram? Looking at the diagram, why do you think it’s named “trapezius”?

🌐Visit the AnatomyZone site. Move the image around in 3D to observe and make a note of this muscle’s sites of origin and insertion. Remember that you can click on the bones to recall their names. You can also consult the UMich Anatomy site for a slightly different view.

✍️Make a visual note on how this muscle connects the axial and appendicular skeletons. Based on this muscle’s multiple origin and insertion sites, can you guess what its function may be? See if you got this right using the dropdowns below.

It originates on the occipital bone of the skull, and on the seventh cervical, and all thoracic vertebrae.

It inserts on the clavicle, and the acromion and spine of the scapula. 

It moves and stabilizes the scapula and helps bend the head laterally and raise the head (extension).

Test Your Knowledge

Now it’s your turn! Use the interactive activities below to test your knowledge of head and neck muscles. How quickly can you label each muscle? There are some muscle you do not need to know. Take a guess.

  1. Go to the purpose games site & press play. Use the figure provided in this section to label various muscles. See how fast you can get!


To make studying easier, we have a set of flashcards created by a Presley Kitamura. These are a great way to test yourself and review important terms for all muscle bolded in the lab manual.
Access the flashcards here: [PK flashcards-muscles]