Deck 1: Larynx + Lymphatics

What is the larynx connected to superiorly and inferiorly?

Pharynx - connects to the larynx at the top

Trachea - connects to the larynx at the bottom

The larynx is part of the ____ airway.

The larynx is part of the upper airway

List the main functions of the larynx.

1) Sound production (specifically “voice”)

2) Route for air and food into the respiratory tract & esophagus

3) Provides an open, unobstructed airway & a way to close it off when needed

When viewed externally, what are the surface features of the Larynx?

1) Thyroid notch

2) Laryngeal prominence (Adam’s apple")

both rise upon swallowing

Where is the larynx located in relation to the cervical vertebrae?

lies anterior to the C3–C6 vertebrae

Where does the larynx lie internally?

• Anterior to esophagus

• Underneath the infrahyoid muscles (top arrow)

  

What structure partially covers the lower portion of the larynx?

thyroid gland

Where does the larynx connect superiorly and inferiorly?

Superiorly to the hyoid via the thyrohyoid membrane

Inferiorly to the first tracheal ring via cricotracheal ligament

What forms the basic structure (“skeleton”) of the larynx? List them 

9 cartilaginous structures connected by membranes and ligaments

Which of the 9 cartilages is the only one that forms a complete ring?

Cricoid

Identify which cartilage are 11, 13, 14. 

11 Cricoid

13 Corniculate

14 Arytenoid

Outline the 3 stages of Deglutition (swallowing). Mention whether each stage is voluntary or involuntary.

1) Voluntary - bolus pushed from the mouth into oropharynx and tongue ends up against hard palate

2) Involuntary - very rapid, no chewing & no breathing

Larynx is protected by the:

1. closure of vestibule & epiglottis

2. posterior movement of the base of the tongue

3) Voluntary - Inferior constrictor of pharynx contracts to push the bolus into the esophagus

What is the role of the epiglottis during deglutition?

acts as the “stop valve”

What does the epiglottis attach to?

1. Hyoid

2. Thyroid cartilage

What is the “bend point” of the epiglottis called? What’s the significance of this area?

Aryepiglottic fold 

• Damage to this structure is dangerous b/c it prevents food and fluid from entering the lungs

What are the valleculae?

2 depressions located on either side of the epiglottis

• Fun fact: trigger the gag reflex when stimulated, which is why they are touched to induce vomiting

What medical procedure do the valleculae serve as an important landmark of?

Intubation - insert a tube into the trachea to help a person breath

What are the key anatomical structures related to the larynx?

• Root of the tongue

• Lingual tonsil

• Vallecula

• Piriform recess

• Esophagus

• Trachea

What is the role of vocal folds (vocal chords)?

→ produce sound 

• variations in sound come from changes in the position, tension & length of these folds

• paired

What are vestibular folds?

→ is the vestibular ligament that’s covered by mucosa

• does NOT produce sound

• paired

What is the opening b/w the 2 vocal folds (vocal cords) called? 

Rima glottidis 

• opening to the airway

• it’s width changes depending on the vocal fold position

What is the role of the arytenoid cartilage during phonation?

moves and rotates on its base to alter the position of the vocal folds, allowing for abduction (moving apart) & adduction (moving together) of the vocal cords

How are the vocal folds/chords positioned during:

• resting (normal breathing)

• forced respiration

• phonation

• swallowing

What is the role of the extrinsic muscles in relation to the larynx? What are they? 

→ Move the larynx as a whole

1. Suprahyoid Muscles

2. Infrahyoid Muscles

What is the role of the intrinsic muscles in relation to the larynx? What are they? 

→ Changes the length and tension of vocal folds + size of the rima glottidis

1. Cricothyroid (b/w cricoid & thyroid cartilage)

2. Posterior cricoarytenoid (b/w cricoid & arytenoid cartilage)

3. Vocalis

What is the only laryngeal muscle that abducts (opens) the vocal folds and rima glottis?

Posterior cricoarytenoid muscle

• critical for respiration

Draw a table showing the branches of the vagus nerve.

What do the following Vagus nerve branches supply?

• External laryngeal branch

• Internal laryngeal branch 

• Inferior laryngeal nerve 

What is ALL sensation provided by?

Vagus nerve branches

Which of the 3 intrinsic laryngeal muscles is NOT supplied by the Recurrent larygengeal nerve?

Cricothyroid - supplied by External laryngeal branch

What is the arterial supply and venous drainage of the Larynx?

Arterial supply: superior & inferior thyroid artery

Venous drainage: superior, middle & inferior thyroid veins

larynx blood supply and drainage come from the thyroid

What is the path of the recurrent laryngeal nerve, and why is it easily damaged?

Right and left recurrent laryngeal nerve

• Left (longer) - loops under the aortic arch and then ascends → prone to injury

• Right - loops under the right subclavian artery

• Both ascend back up the tracheoesophageal groove toward the larynx

What happens if the recurrent laryngeal nerve is damaged unilaterally?

Normal side: moves normally

Damaged side: Cricoarytenoid can’t abduct on that side → vocal fold won’t open → appears like a “whispering gap” → hoarseness & difficulty breathing

Define glands.

organ that produces and releases substances that perform a specific function in the body

Define Endocrine glands.

→ ductless glands that produce & release hormones directly into the bloodstream

• use the bloodstream to monitor the body’s internal environment and to communicate with each other via hormones

List examples of endocrine glands.

1. Suprarenal (Adrenal) glands

2. Pancreas

3. Gonads (ovary/testicle)

Which organs have hormone production as their primary function?

• Adrenal gland

• Pancreas (pancreatic islets)

• Pineal gland

• Pituitary gland

• Parathyroid glands

• Thyroid gland

• Hypothalamus

Which organs have hormone production as their secondary function?

• Digestive tract

• Kidneys

• Gonads

• Heart

• Thymus

Define Exocrine glands.

→ don’t produce hormones but release their secretions into ducts onto epithelial surface

• e.g., Lymph nodes and sweat glands

List the Endocrine glands of the head and neck.

1. Thyroid 

2. Parathyroid

What is the largest endocrine gland in the body?

Thyroid gland

Describe the characteristics of the Thyroid gland. 

→ secretes hormones affecting metabolic rate and Ca²⁺ levels in body fluids

• singular structure that bridges the midline

• largest endocrine gland

• found deep to infrahyoid muscles & anterolateral to larynx and trachea

• covers 2^nd and 3^rd tracheal ring

What are the lobes of the Thyroid gland?

1. 2 lobes - left & right

2. Pyramidal lobe

What is the pyramidal lobe?

• found superiorly

• has a fibrous capsule

• highly variable structure - present in ~50% of population

What is the isthmus?

→ connects the left and right lobe

• crosses the midline at the 2^nd tracheal ring

What is the arterial supply and venous drainage of the Thyroid gland?

Describe the characteristics of the Parathyroid gland. 

→ secrete PTH which regulates Ca²⁺ levels in body fluids

• 4 (2 pairs)

• embedded in the posterior surface of the thyroid gland

• vary widely in location from neck into the thoracic cavity

What nerve is at risk during surgery involving the neck or thyroid region?

recurrent laryngeal branch of CN X (vagus nerve)

What are salivary glands?

-exocrine glands

-3 salivary glands

1. Sublingual

2. Submandibular

3. Parotid

Salivary glands: What are the Sublingual glands?

→ secretes mucinous saliva (which accounts for ~3-4% of all saliva production) — mainly do lubrication

• smallest of the 3

• one found under each side of the tongue

  • make a small series of ducts along buccal side of tongue

Salivary glands: What are the Submandibular glands?

→ produces serous & mucous secretions

• seromucous gland → submandibular duct → sublingual papilla

Salivary glands: What are the Parotid glands?

→ produces serous secretions

• serous gland → parotid duct → oral cavity

• found outside your mouth (close to ear)

Describe the course of the terminal part of the facial nerve (CN VII) in the parotid gland.

1. Exits the cranial cavity via the stylomastoid foramen

2. Enters the parotid gland

3. Divides within the gland to form the parotid plexus

Since the facial nerve (CN VII) enters the parotid gland, does it provide parasympathetic innervation to the parotid gland?

No, it just passes through the parotid gland, NOT supply it

Why can parotid gland swelling affect facial nerve (CN VII) function?

Since CN VII runs inside the parotid gland, when the gland swells (e.g., mumps, sarcoidosis), it can compress CN VII

What is the Lympathic system?

→ System is made of lymphatic vessels, organs, and tissues

• Nearly the entire body is drained via a network of lymphatic vessels along which lymph nodes are located

  • Lymphatic vessels have many valves for one-way drainage

• Role: Drains excess ECF & cellular debris to the bloodstream and helps protect against infection

The lymphatic system includes cells, tissues, and organs responsible for 2 functions…

1) Immunity - ability to resist infection and disease

2) Maintaining normal blood volume and ISF composition

Identify the lymphatic structures that can be easily examined during a physical exam.

1. Tonsils

2. Lymph nodes

3. Spleen

Where can tonsils be seen during a physical exam?

can be seen in the posterior oral cavity, located b/w the palatoglossal and palatopharyngeal arches

Which lymph nodes are most easily palpated when enlarged?

• Cervical (neck)

• Axillary

• Inguinal

• Popliteal

These are readily palpated b/c they’re close to the skin

Can the spleen be palpated during a physical exam?

Yes it can be palpated in the abdomen, especially if enlarged

What are lymph nodes?

→ Small lymphoid organs surrounded by fibrous CT capsule

• looks like a kidney bean 

• diameter range 1–25 mm (~ 1 inch)

Function: acts like a “filter” removing 99% of pathogens from lymph before fluid returns to bloodstream

Where are large lymph nodes (lymph glands) located?

1. Neck

2. Axillae

3. Groin

How does lymph typically drain in relation to infections?

→ lymph drains to the lymph nodes closest to the structure

• when there’s an infection in a region, the nearest lymph nodes are the ones most likely to become affected

Describe the flow of lymph from lymphatic vessels to ducts.

1) Lymph is filtered through lymph nodes

2) Drains into larger lymphatic vessels

3) Vessels converge into lymphatic trunks

4) All trunks ultimately drain into 1 of 2 lymphatic ducts

What are the major lymphatic trunks?

1. Jugular

2. Bronchomediastinal

3. Lumbar

4. Subclavian

5. Intestinal

What is the largest lymphatic vessel?

Thoracic duct (that’s why it drains most of the body)

What does the thoracic duct drain? Where does it empty?

→ drains the entire body below the diaphragm & left side of the body above the diaphragm

• empties at the left jugulosubclavian junction (venous angle) in the neck

What does the right lymphatic duct drain? Where does this empty?

→ drains lymph from the right side of the head and neck, right upper limb, and right side of the chest

• empties into the right subclavian vein, near the junction with the right internal jugular vein

Where are the lymph nodes located?

• Occipital

• Preauricular (Parotid)

• Postauricular

• Subclavian

• Submandibular

• Submental

• Anterior and posterior cervical

• Deep cervical (not usually palpable)

• Supra- and Infra- clavicular

• Tonsilar

What is lymphatic staging?

→ testing for the metastasis of tumors along lymphatic pathways

• metastasis follows the order of lymphatic drainage

• in the head and neck, staging is more complex because lymph nodes are arranged into groupings or “basins”

What are lymphatic basins?

→ represent predictable drainage patterns for lymph in the anterior neck

• these patterns prevent the surgeons from cutting up the whole neck to look for cancer spread