Fascia and Lymphatics of H&N

What connects the superficial fascia to the deep investing fascia and limits skin movement?

Sharpey’s fibers/ retinacula cutis

4 functions of deep investing fascia

Forms compartments around structures; support (keeps viscera/muscles in place); reduces friction so structures slide; role in proprioception

Attachments of the superficial (investing) layer of deep cervical fascia

Superior nuchal line, cervical spinous processes, mastoid process, zygomatic arch, inferior border of the mandible, hyoid, sternum, clavicles, scapula

Which muscles of mastication are enclosed by the superficial layer of deep cervical fascia?

All of them

Extent of the middle (infrahyoid) layer of deep cervical fascia

From the hyoid to the sternum

Where does the middle layer of deep cervical fascia come from?

The deep surface of the superficial investing layer of deep cervical fascia

Which muscles does the middle layer invest?

The infrahyoid strap muscles: omohyoid, sternohyoid, sternothyroid, thyrohyoid

What does the visceral fascia invest?

The pharynx superiorly and the neck viscera inferiorly (trachea, esophagus, thyroid)

Which named fasciae are part of the visceral layer?

Pre-visceral (pretracheal), retropharyngeal, retrovisceral, and buccopharyngeal fascia

Extent of the alar fascia

Between the right and left transverse processes; from C1/skull base down into the thorax to about T2

Where does the alar fascia come from?

The dense vertebral (prevertebral) fascia posterior to it

Function of the alar fascia

Allows the esophagus to slide during swallowing

What does the vertebral (prevertebral) fascia invest?

The cervical vertebrae, deep vertebral muscles, and their nerves and vessels

Is the vertebral fascia thin or dense?

Dense (unlike the thin, foamy alar and middle layers)

Boundaries of danger space #4

Anterior: alar fascia; posterior: prevertebral fascia; superior: base of skull; inferior: posterior mediastinum; lateral: fused at the transverse process tips

Anterior and posterior boundaries of the retropharyngeal/retrovisceral space

Anterior: retropharyngeal/retrovisceral fascia; posterior: alar fascia

What forms the temporo-masseteric recess?

The potential space between the superficial and deep layers of temporalis fascia

2 anatomic landmarks that direct the spread of dental infection

The temporalis insertion and the mylohyoid line (mylohyoid muscle relative to root apices)

Why can the temporalis insertion spread dental infection?

It connects the oral cavity to the temporo-masseteric recess between the temporalis fascia layers

What is the clinical name for infection in the temporo-masseteric recess?

Temporal space infection

What is the mylohyoid line?

The bilateral site of attachment of the mylohyoid muscle to the mandible (internal oblique line)

Which mandibular teeth have root apices below the mylohyoid line?

The 3rd molar (sometimes the 2nd and 1st molars)

Where can a parotid/investing fascia infection spread after the lateral pharyngeal space?

The retropharyngeal space (then down toward danger space #4)

Clinical signs of Ludwig's angina

Brawny, indurated swelling; trismus; elevation of the floor of the mouth and tongue; mental confusion

Management of Ludwig's angina

Airway management, antibiotics (sepsis), and mechanical drainage

Which spaces fill bilaterally in Ludwig's angina?

Submental, submaxillary, and sublingual (together, the submandibular space)

Structure of lymphatic vessels

Thin-walled, similar to veins

What happens to lymph flow in an immobile limb?

It becomes negligible, since flow depends on muscular activity

Glymphatic system (2012)

Pumps CSF through brain tissue to flush metabolic waste; most active in deep sleep

How does poor sleep affect the glymphatic system?

Less waste is removed; accumulated waste proteins are associated with Alzheimer's disease

Which sleep disorder can interrupt glymphatic clearance?

Obstructive sleep apnea

Meningeal lymphatic vessels (2015)

Carry waste and CSF out of the skull, running parallel to the dural venous sinuses

Does the brain have a true lymphatic system?

No; it uses the glymphatic system and meningeal lymphatic vessels instead

Function of the thymus

Site where T cells mature

4 functions of the spleen

Filters blood, destroys old/damaged RBCs, produces white blood cells, stores blood

Where is the lingual tonsil?

On the tongue (posterior)

Size range of head and neck lymph nodes

Pinhead to olive size

Which vein do the deep cervical lymph nodes lie along?

Internal jugular vein

Which vein are the superficial cervical lymph nodes closely related to?

External jugular vein

Is the jugulo-omohyoid node a superior or inferior deep cervical node?

Inferior deep cervical node (IDCLN)

Which deep cervical node drains the posterior 1/3 of the tongue?

Jugulo-digastric node (superior deep cervical)

Where can submental efferents drain directly, bypassing the submandibular nodes?

The jugulo-omohyoid node (an IDCLN)

Why can the deep parotid nodes drain the nasopharynx?

The parotid gland extends deep to the medial ramus, near the nasopharynx

What do the deep parotid nodes drain?

Nasopharynx and posterior nasal cavity

Where do the anterior cervical nodes send efferents?

Superior deep cervical nodes (lower part of the chain) and inferior deep cervical nodes

What do the superficial cervical nodes drain?

Lower auricular and parotid regions

Tongue lymph drainage summary

Tip -> submental; lateral -> submandibular; anterior center -> inferior deep cervical; posterior -> superior deep cervical

Why does knowing lymph drainage patterns matter for cancer?

Cancer spreads along lymphatics, so the drainage pattern predicts which nodes will be involved

ADA policy on the HPV vaccine (2018)

Dentists should support administration and use of the HPV vaccine to help prevent HPV-associated oropharyngeal cancer

HPV vaccine age groups listed in the lecture

Girls 11-12; boys 9-26

Is the HPV vaccine 100% effective against oropharyngeal cancer?

No; it's highly effective, but not all viral strains are in the vaccine

10%

what percent of lymph fluid is returned back to the main circulatory system?

thoracic duct

lymph fluid is returned back to the main circulatory system MOSTLY by which structure?

false

t/f: the right lymphatic duct only drains structures on the right side of the body

True

T/F: There is a large number of lymphatic vessels and lymph nodes in the thorax and abdomen

lymphatic

Breathe and ingest material which needs to be eliminated by the filtering or immune response of the _________ system

Lower extremities

Abdomen

Thorax

Left ½ head

Left upper extremity

Thoracic Duct receives lymph from:

Right ½ head

Right upper extremity

Right anterior chest wall

Lower left lobe of the lung

Right Lymphatic Duct receives lymph from:

Thoracic duct

What is the largest vessel in the body measured at 40-45 cm in length and 4-5 mm in width?

Thoracic duct: 75%

Right Lymphatic Duct: 25%

What percentage of lymphatic drainage goes to the thoracic duct vs right lymphatic duct?

4-6 liters

How many liters of fluid in returned to the circulatory system every 24 hours by the lymphatic system?

Cells of the immune system circulate in the lymph (lymphocytes)

When you mount an immune response, where do immune cells circulate?

Filter - They engulf and destroy pathogens and debris.

What is the primary role of macrophages in the lymphatic system?

Lymph (or lymphatic fluid)

What is the name of the fluid once it enters a lymphatic capillary?

Lymphatic capillaries

Which structure is responsible for returning excess fluid from the interstitial space back to circulation?

Lymph Capillaries > Lymphatic Vessels > Lymphatic Trunks ---> Thoracic Duct or Right Lymphatic Duct

What is the pathway from lymph capillaries to the thoracic duct or right lymphatic duct?

afferent

lymphatic vessels heading towards the lymph node are called:

efferent

lymphatic vessels leaving the lymph node are called:

True

T/F: Efferent of one lymph node may become the afferent of another lymph node

Lymphadenopathy

What is the medical term for inflamed and tender lymph nodes in the presence of infection?

Lymphedema

What condition can result when lymph flow is obstructed?

Chronic infections

Palpation of regional and deep lymph nodes is part of an initial and periodic oral exam. What can firm lymph nodes be a sign of?

Cancer

Palpation of regional and deep lymph nodes is part of an initial and periodic oral exam. What can firm and fixed lymph nodes be a sign of?

Cisterna Chyli (CC)

Identify the following:

- Dilated sac formed by the union of Intestinal and Ascending Lumbar Lymphatics

- Collects and transports lymph from the lower body to the thoracic duct

Superior margin of the Cisterna chyli

Where does the thoracic duct arise from?

L2

at what vertebral level does the cisterna chyli sit?

posteriorly

traveling bottom to top before reaching T5, the thoracic travels _____ to the abdominal aorta

internal jugular v.

subclavian v.

lymph is returned to main circulation at the junction of the:

true

t/f: lymph vessels rely on muscles to help move fluid

true

t/f: lymph vessels rely on osmotic pressure to help move fluid

T5

at what vertebral level does the thoracic duct cross to the left side of the body?

cisterna chyli

the thoracic duct begins at the:

Left: Thoracic Duct

Right Lymphatic Duct

lymph return to the left IJV/sublclavian junction is done by the:

macrophages

what cells does the lymphatic system filter?

Effects the growth of the maxilla and the mandible

The pharyngeal tonsil in the roof of the nasopharynx can enlarge to the point where it interferes with normal nasal respiration. What does this result in?

Malocclusion

What condition can result from the enlargement of the pharyngeal tonsil?

Sleep apnea

Enlarged palatine tonsils also interfere with normal breathing and can contribute to ________

Nasopharynx and oropharynx

Where are aggregations of lymphoid tissue commonly found in the body?

Adenoid/Pharyngeal tonsil

Which tonsil is located on the roof of the nasopharynx?

Tubal tonsil

Which tonsil is associated with the eustachian tube?

spleen

thymus

tonsils

name 3 lymph organs:

regional lymph nodes

nodes that drain more superficial structures:

deep cervical lymph nodes

nodes that collect lymph from regional lymph nodes:

Circulatory system

Lymph generally flows through one or more sets of regional lymph nodes before returning to the:

The tendon of the omohyoid muscle

Deep cervical lymph nodes are divided into superior deep cervical lymph nodes (SDCLN) and inferior deep cervical lymph nodes (IDCLN) by what structure?

submental lymph nodes

Lymph node that drains:

• Tip of tongue

• Floor of the mouth

• Mandibular centrals and lateral incisors

• Central part lower lip

submental lymph nodes

infection at the tip of tongue will drain into the:

submental lymph nodes

infection at the mandibular centrals and lateral incisors will drain into the:

submental lymph nodes

infection at the central part lower lip will drain into the:

Submandibular

Superior deep cervical lymph nodes

Efferent lymph from the submental lymph nodes drains into which lymph node group(s)?