Anatomy of the Head and Neck 3

Question 1

What indicates the position of the larynx?

Answer 1

• The position of the larynx is indicated by the laryngeal prominence or Adams apples (made up by the thyroid cartilage).

Question 2

What is the larynx made of externally and internally?

Answer 2

• The larynx is made of cartilage and lined internally by mucus and cilia

Question 3

What are the 2 functions of the larynx?

Answer 3

• Organ of phonation

* Part of air passage : regulate passage of air in inspiration and expiration

Question 4

How many pieces of cartilage make up the larynx?

What are they connected by?

Answer 4

• 9 Cartilages
• Connected by:
• Joints
• Membranes
• Ligaments

Question 5

What are the boundaries of the larynx?

Answer 5

• From root of tongue to beginning of trachea

* Approximately from C3 to C6 (higher in females)

Question 6

What are the paired and unpaired pieces of cartilage?

Answer 6

•	There are the 3 unpaired pieces of cartilage:
o	Thyroid 
o	Cricoid – makes ring
o	Epiglottis – lid
•	There are 3 paired pieces of cartilage:
o	Arytenoid
o	Corniculate
o	Cuneiform

Question 7

Label the larynx

Answer 7

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Question 8

What can the internal cavity of the larynx be divided into?

Answer 8

• Supraglottis – From the inferior surface of the epiglottis to the vestibular folds (false vocal cords).
• Glottis – Contains vocal cords and 1cm below them. The opening between the vocal cords is known as rima glottidis, the size of which is altered by the muscles of phonation.
• Subglottis – From inferior border of the glottis to the inferior border of the cricoid cartilage.

Question 9

What is the interior surface of the larynx lined with?

What are the true vocal cords lined with?

Answer 9

The interior surface of the larynx is lined by pseudostratified ciliated columnar epithelium. An important exception to this is the true vocal cords, which are lined by a stratified squamous epithelium.

Question 10

Label and name the attachments of the larynx

Answer 10

• They thyroid cartilage is the largest of the laryngeal cartilages
• The right and left halves of the thyroid cartilage are called the lammina and fuse to form laryngeal prominence (adams apple)
• Superiorly the thyroid cartilage attaches to the hyoid bone via the thyrohyoid membrane, 2 superior cornu and lateral thyrohyoid ligament. The two inferior horns articulate with the cricoid cartilage via the cricothyroid synovial joint and ligament
• The cricoid cartilage is attached inferiorly to the trachea by the crico-tracheal ligament
• The median cricothyroid ligament and conus elasticus (amplified the area for the air passing the trachea, represents the lateral portion of the cricothyroid ligament) attaches the cricoid cartilage to the thyroid bone

Question 11

What do the upper free edges of conus elasticus make up?

Where do they extend from?

What is the function of conus elasticus?

Answer 11

• The upper free edge of the conus elasticus is made of 2 ligaments, two thickenings of membrane making up the vocal cords.
• These extend from the thyroid cartilage at the front of the neck to the arytenoid cartilage. The opening between the two vocal cords is called the rima glottis
• Conus elasticus plays a role in breathing and phonation

Question 12

Label the vocal cords

Answer 12

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Question 13

What muscle sits around he vocal cords

Answer 13

• Vocalis muscle sits parallel to the vocal ligament, together with the thyroarthenoid muscle form the vocal cords responsible for the movement of the ligaments and phonation
• The vocal folds are also called true vocal cords

Question 14

Where does the thyroid gland lie?

What does it lie in front of?

What is the function?

Answer 14

• Sits below the thyroid cartilage
• Sits in front of cricoid cartilage and trachea
• It regulates metabolism: T3 and T4 hormones and protein synthesis
• The parathyroid glands belong to the endocrine system and regulate the percentage of calcium in our bodies. They are found behind the thyroid gland and monitor the blood calcium levels

Question 15

What can the muscles of the larynx be divided into?

Answer 15

The muscles of the larynx can be divided into two groups: the extrinsic muscles and the intrinsic muscles.

Question 16

What do the extrinsic muscles do?

Answer 16

The extrinsic muscles act to elevate or depress the larynx during swallowing:

Question 17

What are the extrinsic muscles divided into?

Answer 17

They are comprised of the suprahyoid and infrahyoid groups, and the stylopharyngeus. As a general rule, the suprahyoid muscles and the stylopharyngeus elevate the larynx, whilst the infrahyoid muscles depress the larynx.

Question 18

What do the intrinsic muscles do?

Answer 18

In contrast, the intrinsic muscles act to move the individual components of the larynx – playing a vital role in breathing and phonation. They control the shape of the rima glottidis (such as the thyroarytenoid muscle we mentioned).

Question 19

Label the suprahyoid laryngeal muscles

Answer 19

• Stylohyoid muscle – connects the styloid process to the hyoid bone
• Mylohyoid muscle – links mandible to the hyoid muscle
• The digastric muscle has two bellys: anterior and posterior
• These muscle ALL EVLEVATE THE LARYNX and hyoid bone during swallowing

Question 20

Label the infrahyoid laryngeal muscles

Answer 20

These muscles depress the larynx and hyoid bone during swallowing

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Question 21

Recap

Answer 21

• The extrinsic muscle act on the region of the larynx but have their origin elsewhere and insert into the hyoid bone
• The intrinsic muscle are confined entirely within the larynx and have their origin and insertion in the larynx
• The intrinsic muscles mainly act for swallowing and extrinsic muscles can be divided into respiratory and phonatory muscles. The respiratory muscles move the vocal muscles for breathing, well as the phonatory muscles move the vocal cords for speech

Question 22

Label and name the intrinsic laryngeal muscles

Answer 22

A. Thyroarytenoid: soften voice by relaxing vocal cords

B. Lateral Cricoarytenoid: adduction of vocal cords

C. Transverse Arytenoid : adduction of vocal cords

D. Posterior Cricoarytenoid: abduction of vocal cords

E. Oblique Arytenoid : adduction of vocal cords

F. Cricothyroid : forceful speech and alteration of tone of voice (singer’s muscle) by stretching vocal cords

Question 23

What innervates the intrinsic muscles

Answer 23

All intrinsic laryngeal muscles are innervated by the recurrent laryngeal nerve (a branch of the vagus) except the cricothyroid muscle, which is innervated by the external branch of the superior laryngeal nerve (a branch of the vagus).

Question 24

What innervates the extrinsic muscles

Answer 24

Innervations of the extrinsic laryngeal muscles vary and include the following nerves: ansa cervicalis, trigeminal nerve, facial nerve, glossopharyngeal nerve, and hypoglossal nerve.

Question 25

Describe the path of the left and right laryngeal nerve

Answer 25

Notice how the left recurrent laryngeal nerve curves medially around the aortic arch. In contrast, the right recurrent laryngeal nerve courses around the right subclavian artery.

Question 26

Describe the blood supply to the larynx

Answer 26

Blood supply to the larynx is derived from the external carotid and subclavian artery.

The external carotid gives rise to the superior thyroid artery, from which the superior laryngeal artery departs.

This artery courses with the superior laryngeal nerve through the thyrohyoid membrane to supply the supraglottic region (upper part of the larynx).

The inferior thyroid artery, derived from the subclavian artery, terminates as the inferior laryngeal artery.

This vessel travels with the recurrent laryngeal nerve and supplies the infraglottic larynx (below the rima glottis).

Question 27

What divides the neck into the anterior and posterior triangles?

Answer 27

THE STERNOCLEIDOMASTOID MUSCLE (SCM) divide the neck into an anterior and a posterior triangles

Question 28

What are the borders of the anterior and posterior compartments of the neck?

Answer 28

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Question 29

What is the anterior triangle subdivided into?

Answer 29

The anterior triangle is subdivided into four triangles.

Carotid Triangle: the main contents of the carotid triangle are the common carotid artery (which bifurcates within the carotid triangle into the external and internal carotid arteries), the internal jugular vein, and the vagus nerve.

In the carotid triangle, many of the vessels and nerves are relatively superficial, and so can be accessed by surgery. The carotid arteries, internal jugular vein, vagus nerves are frequent targets of this surgical approach.

Submental Triangle: is situated underneath the chin. It contains the submental lymph nodes, which filter lymph draining from the floor of the mouth and parts of the tongue.

Submandibular Triangle: is located underneath the body of the mandible. It contains the submandibular gland (salivary), and lymph nodes. The facial artery and vein also pass through this area.

Muscular Triangle: contains some muscles and organs – the infrahyoid (or strap) muscles, the larynx, and the thyroid and parathyroid glands.

Question 30

What does the omohyoid muscle split the posterior neck compartment into?

Answer 30

• The larger, superior part is termed the occipital triangle.
• The inferior triangle is known as the subclavian triangle (or supraclavicular triangle or omoclavicular triangle) and contains the distal portion of the subclavian artery.

Question 31

What important vein is found in the posterior triangle?

Answer 31

Other important vasculature in the posterior triangle is the external jugular vein (supraclavicular triangle), one of the major veins of the neck region. Within the posterior triangle, the external jugular vein pierces the investing layer of fascia and empties into the subclavian vein.

Question 32

What nerves are found in the posterior triangle?

Answer 32

• Accessory nerve CN XI : supplies motor innervation to neck muscles
• The cervical plexus and the brachial plexus

Question 33

Label the posterior triangle

Answer 33

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Question 34

What are the boundaries of the carotid triangle

Answer 34

Boundaries:
• Posteriorly by the anterior border of the Sternocleidomastoid.
• Inferiorly, by the superior belly of the Omohyoid muscle.
• Superiorly by the posterior belly of the digastric muscle.

Question 35

What does the carotid triangle contain?

Answer 35

Contains:
The carotid sheath -> a protective 
layer of fascia that surrounds the following structures:
•	The common carotid artery 
•	The internal jugular vein
•	The vagus nerve

Question 36

What are the boundaries of the segmental triangle?

What does this triangle contain?

Answer 36

Boundaries:
•	Medially by the midline of the neck.
•	Inferiorly by the hyoid bone.
•	Laterally by the digastric muscle. 
•	Contains the submental lymph nodes.

Question 37

What are the boundaries of the submandibular triangle?

What does it contain?

Answer 37

Boundaries:
• Superiorly, by the lower border of the body of the mandible.
• Inferiorly by the Digastricus muscle.
• Contains the submandibular gland (salivary), and lymph nodes.

Question 38

What are the boundaries of the muscular triangle?

What does this contain?

Answer 38

The muscular triangle (or inferior carotid triangle) is bounded:
• -superiorly, by the hyoid bone
• -medially, by the median line of the neck from the hyoid bone to the sternum;
• -laterally, superior belly of omohyoid and anterior border of sternocleidomastoid

Contains the following muscles: thyrohyoid, sternothyroid, sternohyoid. COLLECTIVELY THESE ARE CALLED THE STRAP MUSCLES (OR INFRAHYOID MUSCLES).
It also contains the thyroid gland, larynx, trachea and oesophagus.

Question 39

What are the boundaries of the superior occipital triangle?

What does it contain?

Answer 39

The omohyoid muscle splits the posterior triangle of the neck into two minor triangles:
• the superior occipital triangle
• and the inferior supraclavicular triangle

Boundaries:
anteriorly, by the posterior border of Sternocleidomastoideus;
• posteriorly, by the anterior border of Trapezius;
• inferiorly, by the inferior belly of omohyoid muscle;
• superiorly, by the occipital bone.

Contains the accessory nerve CN XI and the cervical plexus and upper most part of brachial plexus.

Question 40

What are the boundaries of the inferior supraclavicular triangle

Answer 40

Boundaries:
• Superiorly, by the inferior belly of the omohyoid muscle.
• Inferiorly, by the clavicle;
• anteriorly, by the posterior border of the sternocleidomastoid muscle;
• posteriorly by the Trapezius.

Contains the subclavian artery, which curves lateralward and downward. The lower portion of the brachial plexus of nerves lies above the artery, and in close contact with it. The external jugular vein runs vertically downward to join the subclavian vein.

Question 41

Label the superior occipital and inferior supraclavicular triangles

Answer 41

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