Anatomy of neck + innervation of structures. Anatomy (gross and histological) and physiology of the lymphoid system, and of

the head and neck –light, clinically relevant summary - DAN

From now I will pay more attention when we formulate FQs because this one sucked

Contents

1. Neck Fascia2. Danger Triangle3. Larynx and Thyroid gland4. Cervical lymphatic drainage

Fascia of the Neck

• Structures in the neck are surrounded by a superficial fascia (subcutaneous tissue)

• They are compartmentalised by layers of deep cervical fascia.

The Fascial layers

• Superficial cervical fascia– Thin layer of CT that lies between the dermis of the

skin and the investing layer of the deep cervical fascia

– Cutaneous nerves, blood and lymph vessels, superficial lymph nodes, continous anterolaterally with the platysma

• Deep cervical fascia– Investing layer, pretracheal layer, Prevertebral layer,

Alar fascia and carotid sheath

Neck fascia

Subcutaneous tissue

Investing layer

Pretracheal layer

Carotid sheath

Pre vertebral lyaer

DEEP CERVICAL FASCIA

SUPERFICIAL CERVICAL FASCIA

Retropharyngeal space

Investing layer

• Surrounds: Sternocleoidomastoids, Trapezius, submandibular gland, parotid gland

• Superior attachments: Superior nuchal line, mastoid processes, zygomatic arches, inferior border of mandible, hyoid, spinous processes of cervical vertibrae

Pretracheal layer

• Includes – Visceral part (thyroid gland, trachea, oesophagus)– Muscular part (infrahyoid muscles)

• Continuous with– Carotid sheaths laterally– Buccopharyngeal fascia posterosuperiorly– Pericardium inferiorly

Carotid Sheath• Extends from cranial base – root of neck• Continuous– Anteriorly: investing and pretracheal layer– Posteriorly: Prevertebral layer

• Important structures hidden within:– Common + internal carotid arteries– IJV – CN X– Deep cervical nodes– Carotid sinus nerve– Sympathetic nerve fibres

Pre Vertebral layer

• Fixed to the cranial base superiorly, inferiorly fuses with the anterior longitudinal ligament

• Forms a tubular sheath for the vertebral column and muscles surrounding it.

Retropharyngeal space

• The largest interfascial space in the neck. • Potential space that consists of loose

connective tissue between the prevertebral layer and the pretracheal layer.

• The Alar fascia crosses the retropharyngeal space

• Allows the movement of the pharynx, oesophagus, larynx and trachea

• Major pathway for spread of infection

Neck fascia

Subcutaneous tissue

Investing layer

Pretracheal layer

Carotid sheath

Pre vertebral lyaer

DEEP CERVICAL FASCIA

SUPERFICIAL CERVICAL FASCIA

Retropharyngeal space

Importance of Fascia + its layers

• Spread of infection is limited by facsial boundaries

• Example– An Pus abscess posterior to the prevetebral layer

may extend laterally in the neck and form a swelling posterior to the SCM. The pus may perforate the prevertebral layer and enter the retropharyngeal space, producing a bulge in the pharynx.• Dsyphagia, dysarthria

Danger triangle of the FACE

• There is a communication between the facial vein and the cavernous sinus via the via the ophthalmic veins.

• Bacterial infections can be caused by pus entering the brain's blood supply if pimples in the danger triangle are picked by dirty fingernails.

How???

Area of drainage of the facial vein

Larnyx

Larynx

• Innervation• Motor: recurrent laryngeal nerves• S: superior laryngeal nerves

• Blood supply• Superior half: superior laryngeal a. (branch of the s. Thyroid

a.)• Inferior half: inferoir laryngeal artery (branch of the i.

Thyroid artery)

• Lymph drainage: • Superior + inferior deep cervical nodes jugular trunk

thoracic duct (L)/right thoracic duct (R)

PIE CHART

Larynx size

AngusAverage

Thyroid Gland

• Innervation• Parasympathetic fibers come from the vagus nerves• Sympathetic fibers are distributed from the superior,

middle, and inferior ganglia of the sympathetic trunk.

– Blood supply• Superior half: superior thyroid artery • Inferior half: inferior Thyroid artery

• Lymph drainage: periglandular nodes prelaryngeal pretracheal paratracheal mediastinal lymph nodes.

Thyroid gland

Colloid filled follicle

Epithelium (principle cells)

parafollicular cells

Anatomy of the Lymphoid system

• Lymph nodes• Lymph Vessels– Main lymphatic vessels in the body• Right lymphatic duct• Thoracic duct• Cisterna Chyli

Lymphatic system/ Immune System

Lymph Node

Lymph node Histology

Important lymphatic sites

Waldeylers rings

• Waldeyer's-Pirogov tonsillar ring describes the lymphatic tissue in the pharynx and to the posterior oral cavity.

• It contains– Pharyngeal tonsil (also known as 'adenoids' when

infected)– Tubal tonsil (where Eustachian tube opens in the

nasopharynx)– Palatine tonsils – Lingual tonsils

Cervical lymph node drainage

Main lymph node groups in the neck– Submental/ Submandibular– Parotid– Retropharyngeal– Anterior cervical– Deep lateral cervical

Submental/Submandibular• 1. Submental nodes – drainage from: adjacent skin, lips, floor

of the mouth– drain to: the submandibular nodal group

• 2. Submandibular nodes – drainage from : anterior face, flow of the

mouth, anterior oral cavity, and submental nodal group.

– drain to :the high internal jugular chain (7)

Parotid

• 8. Parotid gland nodes• Intra or extra glandular

nodes.• drainage from: external

artery canal, eustachian tube, adjacent skin, buccal mucosa.

• drain to: high internal jugular chain (7)

Retropharyngeal

• Two compartments: Medial and lateral retropharyngeal.

• Medial retropharyngeal– drainage from: nasal pharynx and oral pharynx – drain to: high internal jugular chain.

• Lateral retropharyngeal: same as medial

• Clinical sign: Early sign of nasal pharyngeal cancer may be presence of abnormal lateral retropharyngeal node in the patient over forty.

Deep Lateral cervical

• Consists of – Internal Jugular chain (7)

• drainage from: from parotid, retropharyngeal, and submandibular/submental groups.

• drain to: the subclavian vein and/or internal jugular vein and/or into the right lymphatic duct and thoracic duct.

– Posterior triangle• drainage from: occipital/mastoid,

lateral neck, scalp, nasal pharyngeal sources.

• drain to:

– Supraclavicular: Same as Post. Triangle

Anterior cervical

• Anterior jugular: superficial. Follows the course of the external jugular vein. Receives drainage from skin and muscles of the anterior neck. Drains to the thoracic duct.

• Paraesophageal group: Tracheal esophageal groove nodes and delphian node. Abnormal delphian node is often an indicator subglottic laryngeal cancer extension.

• This group receives drainages from hypopharynx, larynx, thyroid, and esophagus. Drainage is then to the thoracic duct.

Physiology of the lymphoid system

• Re-uptake of excess fluid in interstitial tissue at capillary beds

• Antigen presentation to naive lymphocytes• Activation of naive lymphocytes