Lab 8: Muscles and Triangle of the Neck and Face | Vasculature of the Head and Neck

Learning Objectives:

  • Identify the muscles of the neck and face, their actions, and their innervation.
  • Describe the vasculature of the head and neck and identify the regions supplied or drained by each vessel, as described in the lab guide.
  • Review the cross-sectional anatomy of the brain through radiology images.

Terms to Know

The Neck

  • Hyoid bone
  • Sternocleidomastoid
  • Splenius capitis
  • Anterior scalene
  • Middle scalene
  • Posterior scalene
  • Suprahyoid muscles
    • Digastric
      • Anterior belly
      • Posterior belly
    • Geniohyoid
    • Stylohyoid
    • Mylohyoid
  • Infrahyoid muscles
    • Omohyoid
      • Superior belly
      • Inferior belly
    • Sternohyoid
    • Thyrohyoid
    • Sternothyroid

Arteries of the Head and Neck

  • Subclavian artery
  • Vertebral artery
  • Common carotid artery
  • Internal carotid artery
  • External carotid artery
    • Superior thyroid artery
    • Lingual artery
    • Facial artery
      • Angular artery
    • Occipital artery
    • Posterior auricular artery
    • Superficial temporal artery
    • Maxillary artery
Veins of the Head and Neck

  • External jugular vein
  • Internal jugular vein
  • Subclavian vein
  • Brachiocephalic vein

Muscles of Facial Expression

  • Occipitofrontalis
    • Frontal belly
    • Occipital belly
    • Epicranial aponeurosis
  • Corrugator supercilii
  • Orbicularis oculi
  • Levator palpebrae superioris
  • Procerus
  • Nasalis
  • Buccinator
  • Depressor anguli oris
  • Depressor labii inferioris
  • Levator anguli oris
  • Levator labii superioris
  • Levator labii superioris alaeque nasi
  • Zygomaticus major
  • Zygomaticus minor
  • Orbicularis oris
  • Risorius
  • Mentalis
  • Platysma

Introduction

In this lab, you will explore the muscles and vasculature of the neck and face. These muscles allow us to express emotions from happiness to sadness, surprise to anger. The structures discussed in this lab have a range of clinical implications, from the scalene muscles placing pressure on neurovascular structures to vascular compromise that can be fatal.

 


Lab Activity 1: Visible Body – Muscles and Vasculature of the Neck

Use the Visible Body app on the iPad to observe the muscles and vasculature of the neck.

Muscles of the Neck

  • In the iPad Atlas App, go to the Regions tab and click on 1. Head and Neck. Now, remove all of the systems (lymphatic, nervous, circulatory…etc.) except for the skeletal and muscular from the sidebar.
  • First, click on the Platysma muscle and hide it (you will learn about it as a muscle of facial expression later in the lab). Just deep to the platysma, you can observe the sternocleidomastoid muscle. This muscle runs from the sternum and clavicle to the mastoid process of the temporal bone. It is primarily innervated by CN XI, the accessory nerve. When only one side contracts, it causes rotation of the head to the opposite side of the muscle that is contracting. Try palpating your sternocleidomastoid muscles and rotate your head from side to side. The more you rotate your head to the opposite side, the more this muscle becomes prominent in the anterolateral portion of your neck. Bilateral contraction contributes to flexion of the neck.
  • Rotate the images, so you are looking at a posterior view of the neck. Click on the Trapezius, hide it, & observe the splenius capitis. Bilateral contraction of this muscle causes extension of the neck. Unilateral contraction (contraction of this muscle on only one side) can cause lateral flexion of the neck to the same side or rotation to the same side.
  • Rotate the image to an anterolateral view and observe the anterior, middle, and posterior scalene muscles. To get a better view of these muscles, you may want to hide the sternocleidomastoid muscle. The scalene muscles run from the cervical vertebrae to the first and second ribs. Their primary action occurs with breathing. They act to elevate the ribs during forced inspiration. Unilateral contraction of these muscles also contributes to lateral flexion of the neck to the same side and rotation of the neck to the opposite side.
  • Rotate the image to a lateral view and observe the hyoid bone. This bone is inferior to the mandible within the neck. The hyoid is suspended within the neck by muscles and provides an important site of attachment for them.
  • Now rotate the image to a more anterior view and observe the infrahyoid muscles. As the name implies, these muscles are located inferior to the hyoid. The names of these muscles indicate the attachment points for these muscles. Together these muscles anchor the hyoid and depress both the hyoid and larynx during swallowing and speaking.
    • Observe the omohyoid. This muscle is digastric, meaning that it has two muscle bellies. Observe the short, intermediate tendon between the superior and inferior muscle bellies. This tendon is held to the clavicle by a fascial sling. The word part “omo” means scapula, and this muscle runs from the scapula to the hyoid bone.
    • View the sternohyoid. This muscle runs from the sternum to the hyoid.
    • Two additional muscles of this region are deep and visible when you hide the platysma, sternocleidomastoid, omohyoid, and sternohyoid. The sternothyroid and thyrohyoid run from the sternum to the thyroid cartilage and thyroid cartilage to the hyoid bone, respectively. We will discuss the thyroid cartilage with the larynx later in this unit, but you can highlight this cartilage superior to the trachea.
  • Move the image so you can see under the chin (view from inferior to superior) and observe the suprahyoid muscles. These muscles are superior to the hyoid, and all have an attachment site on the hyoid. As a group, these muscles form much of the floor of the mouth and elevate the hyoid and larynx in swallowing and speaking.
    • Observe the digastric muscle. Note, don’t confuse this with the omohyoid, despite their similar appearance. The anterior belly of the digastric runs from the mandible to the hyoid bone, and the posterior belly of the digastric runs from the hyoid bone to the temporal bone (near the mastoid process).
    • Superior to the posterior belly of the digastric, observe the stylohyoid. This muscle travels from the styloid process of the temporal bone to the hyoid.
    • The mylohyoid can be seen just inferior and medial to the mandible. This muscle runs from the mandible to the hyoid and forms the anterior floor of the mouth.
    • In order to observe the geniohyoid, you will have to hide the mylohyoid. This muscle runs from the mandible to the hyoid bone as well, but it is smaller and sits deep to the mylohyoid. You may need to rotate the image slightly posteriorly to observe this muscle.

 

Vasculature of the Neck

From the home screen in the Visible Body Atlas, click on the Systems tab and then go to Circulatory System Views and click on 5. Carotid and Jugular to show the arteries of the head and neck:

  • In a right anterolateral view, observe how the brachiocephalic trunk divides into the subclavian and common carotid arteries (you may want to fade or hide brachiocephalic, internal jugular and subclavian veins). On the left side of the body, these two arteries branch directly off the aortic arch. Follow the subclavian artery laterally for a short span and observe the vertebral artery. This artery travels superiorly through the transverse foramen of the cervical vertebrae to supply the brain. You have already viewed this artery as it comes together to form the basilar artery when you studied the circle of Willis.
  • Now observe the common carotid artery. This artery travels superiorly through the neck and branches into the internal and external carotid arteries. You will want to hide the mandible to see these arteries better. The internal carotid artery continues superiorly without branching in the neck, travels through the skull, and provides the majority of the blood supply to the brain.
  • The external carotid artery supplies blood to the scalp, the face, and some structures of the neck. Six arteries branch from the external carotid artery before it terminates and divides into two arteries. To observe several of these arteries through their whole path, you will need to rotate the image back and forth. You may also want to zoom in on the branches. Observe the following arteries as they branch from the external carotid arteries, in order from inferior to superior:
    • Ascending pharyngeal artery: This is not visible in the app, and you will not be asked to identify it on the exam. This artery ascends to supply the pharynx, middle ear, and cranial meninges.
    • Superior thyroid artery: Runs inferiorly to supply the thyroid gland and larynx.
    • Lingual artery: Observe how this artery runs medially to supply the tongue.
    • Facial artery: This artery branches just superior to the lingual artery. In fact, sometimes the facial and lingual arteries branch from the external carotid artery as a common trunk before dividing. It travels along the inferior aspect of the mandible and then wraps around the middle portion of the mandible and ascends through the face. It supplies the submandibular gland, lips, and muscles of the face.
      • Angular artery: This terminal branch of the facial artery runs along the noes to the medial corner of the eye.
    • Occipital artery: This artery arises from the posterior aspect of the external carotid artery and travels superiorly and posteriorly to supply the posterior scalp and neck.
    • Posterior auricular artery: This artery arises from the posterior aspect of the external carotid artery just superior to the occipital artery. It ascends just anterior to the mastoid process of the temporal bone and posterior to the ear, and it supplies muscles of this region, the parotid gland, and part of the scalp.
    • Superficial temporal artery: The external carotid artery terminates as it divides into the superficial temporal artery and maxillary artery. The superficial temporal artery travels superiorly to supply part of the scalp and superolateral face.
    • Maxillary artery: This is the primary artery supplying the deep structures of the face. It travels anteriorly and medially and gives branches that supply parts of the external ear, the cranial cavity, the scalp, the mouth (including the cheek, teeth, upper and lower jaw, palate, and gums), and the inferior portion of the orbit.

Go back to the home screen in the Visible Body Atlas and click on the Systems tab, then Circulatory System Views and click on 5. Carotid and Jugular to show the veins of the head and neck:

  • Now click on the external jugular vein, which empties into the subclavian vein. This vein drains part of the lateral aspect of the head.
  • The internal jugular vein ultimately drains the majority of the blood from the head and neck. The internal jugular vein joins with the subclavian vein to form the brachiocephalic vein. Unlike the arteries of the same name, this happens on both the right and left side. This is because they both need to carry their blood toward the midline to reach the superior vena cava. However, for the arteries on the left side, the arch of the aorta already travels towards the left, positioning the subclavian and common carotid arteries in the appropriate place where they would normally branch.

 


Lab Activity 2: Visible Body – Muscles of Facial Expression

Explore the muscles of facial expression using the iPad app. From the home screen click on the Systems tab and then click 1. Expression. Begin in the most superficial layer to view these muscles. The muscles of facial expression generally originate on the bones and fascia of the skull and insert into the skin of the face, resulting in movement and wrinkling of the facial skin. All of these muscles, except for one (levator palpebrae superioris, CN III) are innervated by the facial nerve, CN VII. A chart is provided in this lab guide to provide you with more information about these muscles. You are responsible for knowing actions and emotions or common motions conveyed by these muscles. You are encouraged to study the description of the muscle actions while viewing the muscles.

While won’t be asked about origins and insertions for these muscles, knowing where they insert can help you understand their action. For example, two muscles are located superior to the lip with nearby origins inferior to the eye. Though they both insert into the upper lip and elevate parts of the upper lip, they have different insertion points. As a result of these different insertions, contraction of these muscles conveys very different emotions. Levator anguli oris inserts into the corner of the mouth, while levator labii superioris inserts medial to that, in the upper lip. Therefore, when levator anguli oris contracts, it causes smiling, while contraction of levator labii superioris conveys sadness by elevating the upper lip. If you are taking the exam and you can’t remember the action of one of these muscles, look at the insertion point, and this will help you reason through the action.

The one muscle that you will need to hide superficial layers to see is corrugator supercilii. In order to see this muscle you will have to hide the depressor supercilii and occipitofrontalis. Every other muscle of facial expression from the box below is visible using the app.

Muscle

Description

Action

Emotion/ Common Motion

Occipito-frontalis

Frontal belly

Frontal belly covers forehead; occipital belly covers posterior skull; Epicranial aponeurosis connects the bellies

Elevates eyebrows & wrinkles forehead horizontally

Surprise, Curiosity

Occipital belly

Pulls the scalp posteriorly

Corrugator supercilii

Small muscle in the medial eyebrow

Draw eyebrows inferomedially, creating vertical wrinkles above the nose

Concern, skepticism

Orbicularis oculi

Thin, flat, sphincter of the eye, surrounds the orbit

Closes eyes

Winking, blinking; squinting

Levator palpebrae superioris***

Runs from the posterior orbit to the superior eyelid

Elevates superior eyelid to open the eye

Contributes to surprise, curiosity

Procerus

Between the eyebrows over the nasal bone

Depresses medial eyebrow, wrinkles skin over the nose

Dislike or distain

Nasalis

Over cartilage of the nose

Compresses bridge and depresses tip of nose, elevates corners of the nostrils

Flares nostrils, as with anger

Buccinator

Thin, horizontal muscle in the cheek, deep to the masseter.

Compresses cheek; holds food between cheek and teeth when chewing

Whistling, sucking

Depressor anguli oris

Runs from the angle of the mouth to the lateral chin

Draws the corner of the mouth inferiorly and laterally

Frown

Depressor labii inferioris

Runs from lateral chin to the lower lip

Depresses the lower lip

Frown

Levator anguli oris

Runs from the medial cheek to the angle of the lips

Widens the mouth, elevates the corners of the mouth

Smiling

Levator labii superioris

Runs from the inferior orbit to the lateral upper lip

Elevates and furrows the upper lip

Sadness;

Levator labii superioris alequae nasi^

Runs alongside nose to medial upper lip, lateral to midline

Elevates the upper lip, dilates the nostrils

“Elvis” snarl

Zygomaticus major

Zygomatic arch to the corner of the mouth

Raises the corners of the mouth

Smile

Zygomaticus minor

Zygomatic arch to the lateral upper lip

Raises the corner of the mouth/lateral upper lip

Smile

Orbicularis oris

Thin muscle surrounding the entrance to the oral cavity

Closes the lips/mouth; purses and protrudes the lips

Kissing, whistling

Risorius

Runs horizontally and laterally from the angle of the mouth

Draws corner of lip laterally and down, tenses the lips

Frustration, sadness

Mentalis

Anterior chin to the lower lip

Elevates & wrinkles skin of the chin, protrudes the lower lip

Pouting

Platysma

Thin muscle within skin of the neck that runs from the clavicular region to the lower mandible and mouth

Tenses the skin of the inferior face and neck, depresses the jaw

image

**Note: All of these muscles are innervated by the facial nerve (CN VII) except for levator palpebrae superioris, which is innervated by the oculomotor nerve (CN III).

^This is the longest name of a muscle in the body.

 


Lab Activity 3: Navigator-Muscles and Vasculature of the Face and Neck

Use the Navigator to observe the structures described above and listed in the list of terms. Use the presets and observe the vasculature. Then use the advanced view window to add or remove muscles and vessels from the image. This tool can be very helpful for viewing the muscles and vasculature from different angles as well as for isolating the muscles and vasculature. DO NOT save any pre-sets.

If you are having difficulty seeing the vessels, you can change the background color of the Navigator screen. Click on File and then Preferences. Here you can choose a lighter background color.


Lab Activity 4: Plastinated tissue.

Observe the muscles of the face and neck and hyoid bone on the head and neck and respiratory plastinated tissue.

On the head and neck plastinate:

  • First observe the hyoid bone. It is difficult to see, but part of it can be seen/palpated just deep and inferior to the mandible. You can notice that several muscles are inserting into it from superior and inferior directions.
  • Now observe the sternocleidomastoid. While its origin is not present in this model, the bulk of the muscle and its insertion at the mastoid process are visible.
  • On the posterior aspect, observe the splenius capitus.
  • Laterally, observe the anterior, middle, and posterior scalenes.
  • Now look at the suprahyoid muscles. The anterior and posterior bellies of the digastric can be easily observed, with the common middle tendon being held to the hyoid bone. Mylohyoid sits just deep to the anterior belly of the digastric. Stylohyoid is very skinny and sits just deep to the posterior belly of the digastric. The geniohyoid is not visible here because it is deep to the mylohyoid.
  • Now look at the infrahyoid muscles. Only the superior belly of the omohyoid is visible here. Sternohyoid is also visible, but it is cut before it reaches the sternum. However, you can tell it is the sternohyoid because it runs past and does not insert into the thyroid cartilage. Thyrohyoid and sternothyroid are visible, but they are better seen on the respiratory plastinate.
  • Observe the muscles of facial expression on this plastinate. Not all muscles are visible. For example, the occipitofrontalis may have some visible fibers, but part has been cut, and the epicranial aponeurosis is not visible. However, you should be able to identify most of them. Be sure to observe the direction of the muscle fibers and think about the actions that these muscles perform.

On the respiratory plastinate:

  • The thyrohyoid is more easily visible on this model. Several other muscles described above can be seen here as well.
  • Observe the muscles of facial expression that are visible on this specimen. Again, not all of them will be visible, but you should be able to identify most of the muscles of facial expression between the two specimens.

License

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Human Anatomy Lab Manual by Julie Stamm, PhD, LAT, ATC and Patrick Hills-Meyer, EdD, LAT, ATC, CSCS is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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