Laboratory 3 Triangles of the Neck 2013

7/27/2019 Laboratory 3 Triangles of the Neck 2013

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2021/7021MSCOral Biology

Semester 1 2013

Laboratory Manual

Anatomy of the Head and Neck Region

Laboratory 3

Triangles of the Neck


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Laboratory 3: Anterior and Posterior Triangles of the Neck,

Review Muscles of mastication and their actions;

Review Muscles of facial expression.

Learning objectives. At the end of the laboratory students should be able to:

1. Be able to identify the boundaries and contents of the anterior triangle of the neck

2. Be able to identify the boundaries and contents of the posterior triangle of the neck

3. Identify the muscles of facial expression and describe their role.

4. Revise the osteology of the skull.

5. Revise the osteology and arthrology of the TMJ.

6. Revise the anatomy of the mandible.

7. Revise the muscles of mastication and describe their functions in relation to mastication.

Station 1

Muscles of facial expression: label the muscles and indicate their nerve supply

What nerve supplies motor innervation to the Buccinator muscle?

What is the embryological origin of these muscles?

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Surface anatomy of the neck

Before you work on the triangles of the neck, check out the surface anatomy in your study partner

so you can identify landmark features such as the two heads of sternocleidomastoid muscle and the

jugular notch, inferior border of the mandible and trapezius.

Note that the labels on the right side of the diagram have been cut, so they should read

submandibular gland, mental protuberance and supraorbital margin.


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Station 2

Neck fascia and triangles

See pages 272-283Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USA

What is the region labeled 1?___________________________________________

What is the structure labeled 2? ___________________________________________

What is the region that is labeled 3? __________________________________

What forms the boundary between the anterior and posterior triangles of the neck?

__________________________________________________________________

Note thesubmental and

submandibular

triangles

Carotid triangle


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Describe the boundaries of the anterior triangle of the neck:

Anterior border is an imaginary line travelling from inferior point of the symphysis menti of

the mandible, then connecting to the centre of the jugular notch of the manubrium (that is,

the midline of the anterior surface of the neck).

Posterior border is:

__________________________________________________________________________

Superior border is:

__________________________________________________________________________

Which of the following are readily visible in the superficial dissections of the neck

o Common carotid artery

o External jugular vein

o Thyroid gland

o Submandibular gland

o Parotid gland

o Transverse cervical nerve (often lost if you cant see the investing layer of deep

cervical fascia. Remember, superficial cervical fascia has to be removed so you can

see the fibres of platysma).

Note the fascial sheath that

wraps the sternocleidomastoid and

the one that underlies it in front of

the trachea. The veins are very

superficial and are often removed

when deeper dissections are

performed. Make sure you check out

superficial and deeper dissections of

the triangles of the neck

Figure 12.23 page 280 Head & Neck Anatomy

for Dental Medicine (2010) Eric W. Baker Ed.

Thieme Medical Publishers Inc NY USA


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Identify the following muscles in the dissections you are observing, they are helpful

landmarks when you are trying to identify other co-located structures.

o Trapezius

o Sternocleidomastoid

o Digastric (posterior and anterior bellies)o Omohyoid

Fig12.29 pg 282 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers IncNY USA

List the key neurovascular and muscular structures you can identify in this lateral view of theanterior triangle? (Dont worry, you will see these again in later labs!)


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Remember that the carotid artery , vagus nerve and the internal jugular vein are located

within the carotid sheath so look for it in the prosections.

The diagram on the nextpage is from Associate Professor Forrests lecture notes and it

illustrates the relationships between the key structures within the different layers of fascia in

the neck. You will explore these further in lectures and future labs on blood vessels,

lymphatics and nerves, but it is handy to look at them as you look at the topography of the

anterior and posterior triangles of the neck and their contents. Note that the Platysma muscle

is very superficial and thus is covered in the superficial fascia associated with the skin.

You can also review this material on page 110 of Chapter 7 Textbook of Head & Neck

Anatomy 4th Edn Hiat JL and Gartner LP Wolters Kluwer Lippincott Williams and WilkinsPhiladelphia PA

Revisit the suprahyoid and infrahyoid muscles and see if you can identify

cricothryoid muscle, deep to sternothryoid.

Note position of the internal jugular vein, adjacent to right common carotid artery.Common carotid has superior thyroid branch and superior laryngeal branching

here.

Fig12.23 pg 280 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme MedicalPublishers Inc NY USA


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Fig12.16 pg 275 Head & Neck Anatomy for

Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USA

Posterior Triangle

The omohyoid muscle is a characteristic landmark that passes through the posterior triangle(dividing it into an inferior subclavian or supraclavicular or omoclavicular triangle and a

superior occipital triangle). The posterior belly of omohyoid enters the posterior triangle at

the inferoposterior apex and then travels across to disappear under sternocleidomastoid.

These subdivisions of the posterior triangle can be seen on the first illustration Figure 12.12.

The superior belly of omohyoid is locatedwithin the anterior triangle where it inserts into the

hyoid bone.

Fascial layers in the neck:

1: Investing (superficial layer)

2: Pretracheal muscular layer

3: Pretracheal visceral layer

4: Prevertebral layer

5: Carotid sheath


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Now describe the boundaries of the posterior triangle of the neck:

Anterior border is:

__________________________________________________________________________

Posterior border is:

__________________________________________________________________________

Inferior border is:

__________________________________________________________________________Figs12.21-12.22C pg 278-9 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical

Publishers Inc NY USA

Use the following diagrams to help you identify the major structures observed as you

examine prosections from superficial to deeper dissections. The layers of fascia have been

identified so that you will be familiar with them when you explore them for their clinical

relevance in the spread of infection, later in the course.

What is the most superficial

large vein in this diagram? Locate it

on a specimen and trace its path

through the neck.

Fig. 12.21

Are the nerves travelling

through the posterior triangle in this

view all sensory??

Fig. 12.22A - Removed:

Investing layer of deep cervical

fascia.


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Fig 2.24 pg 38 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY

USA

Figs 9.23F pg 190 Head & Neck Anatomyfor Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USA

Which muscles originate on

the mandible?

Identify them on this image

Identify the medial and lateral

pterygoid plates.

What muscles originate here?

Do any muscles insert here?

What actions do the muscles

associated with the pterygoid plate

perform? Be specific

For the insertions visible on the

mandible, which ones are for

muscles that elevate the mandible?

Which muscles help to protrude thethe mandible?

Identify their insertions on this

image


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Fig1.4B, pg 22 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USAFigure 7.19, Human Anatomy and Physiology by Marieb, E.N. and Hoehn, K. (Pearson Education,

Glenview, IL, USA

Identify which bones are C1 and C2 and indicate their characteristic structural features.

What structure passes through the transverse foramina?

What is the name of this foramen

and what passes through it?

Identify a palpable landmark to help

you identify this location clinically?

What is the name of these structures and what connects to

them?

What action do the muscles connected here perform?


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Station 4

Fig 9.30 pg 195 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USA

Point of clarification: Note that the articular eminence now generally replaces the term articular

tubercle when discussing temporomandibular articulation. The articular eminence is the strongly

convex bony elevation on the root of the zygomatic process (anterior most boundary of mandibular

fossa). The tubercle is the bony knob on the lateral aspect of the articular eminence where the

fibrous capsule and temporomandibular ligament attach.

The temporomandibular joint is reinforced by collateral ligaments on the medial and lateral aspects.

The tempormandibular ligament is the large obliquely orientated lateral ligament (or lateral

ligament) reinforcing the joint. The specific functions of the two accessory ligaments the

sphenomandibular and the stylomandibular ligament remain unclear, however they may limit lateraland anterior movement, respectively. See Chapter 13 pages 208-215 Textbook of Head & Neck

Anatomy 4th Edn Hiat JL and Gartner LP Wolters Kluwer Lippincott Williams and Wilkins

Philadelphia PA for more detail regarding movement of the TMJ.

What does the Bennett angle measure? What mandibular movement is occurring? (see page 196 Head& Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USA)


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Station 5

Using the specimens available revise your knowledge of the muscles of mastication

Fig 9.56A pg 214 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USAThis diagram includes some additional muscles posterior to the thyroid and larynx. These

pharyngeal muscles joint to those of the other side of the neck at a midline raphe. What do you

think the function of the pharyngeal muscles may be? Fig 9.56C pg 215 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USA

What action does the

temporalis muscle perform?

Which nerve innervates the

temporalis muscle?


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Extra challenge: See how many branches of the external carotid artery you can

identify on the prosected specimens. Be assured you will explore these in the next lab

but you may like to take the opportunity to explore them now, if you have completed

the rest of the lab.

Fig3.4 pg 42 Head & Neck Anatomy for Dental Medicine (2010) Eric W. Baker Ed. Thieme Medical Publishers Inc NY USA


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Review your recollection of the arrangement of the fascial sheaths that you explored

in the anterior and posterior triangles of the neck.

Label as many structures and fascial layers as possible in the above diagram

Laboratory 3 Triangles of the Neck 2013

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