The Anterior Triangle and Root of Neck

Applied Anatomy

Thoracic inlet syndrome

The thoracic inlet is a space with rigid boundaries and it is fairly congested. Any space-occupying lesion in this space is likely to compress the contents. These include:

  • A cervical rib
  • Enlarged lymph nodes
  • Cancer of the lung
  • Enlarged thymus
  • Retrosternal goitre, etc.

(What are the effects of the compression?)

  Scalenus anterior syndrome

 

The scalene triangle/ gapis bounded by:

Posteriorly: Scaleneus medius

Anteriorly: Scaleneus anterior

Base: First rib

Through this gap, pass the subclavian artery and the brachial plexus.

Compression of these structures causes the scalenus anterior syndrome.

 
   

Submental triangle

In infections or cancer from any of the areas of drainage of the submental nodes, especially the tip of tongue and lip, the first nodes to be involved are submental nodes. Subsequently, the submandibular and deep cervical get involved.

A discharging sinus on the point of the chin often results from an abscess of a mandibular incisor tooth. The pus from the infected tooth passes from the apex of the submental triangle located at the inferior end of the symphysis menti where it forms a sinus from which pus escapes.

Thyroid gland

Thyroglossal duct cysts (TDC): May develop from a persistent thyroglossal duct anywhere along the course of the duct. The cysts may be in the tongue in the midline of the neck or retrosternal. TDC move up with protrusion of the tongue

•  Thyroglossal duct sinuses: Are openings into the skin from a patent part of the thyroglossal duct. They usually open in the neck and could be due to perforation of the cyst following infection.

•  Ectopic thryoid gland: Could be in the tongue, larynx, retrosternal or hyoid region.

•  Goitre:

This is an enlargement of the thyroid gland. It could be due to iodine deficiency, hormone or enzyme defect, infection or tumor. May be associated with hyperfunction or hypofunction .
(What are the features of each?)

Besides, goitre causes compression of the following:

  • Trachea: affecting breathing.
  • Oesophagus: affecting swallowing.
  • Recurrent laryngeal nerve: affecting voice.

A retrosternal goitre is worse for there is no space for expansion.

•  Thyroid gland in its capsule is enclosed by pretracheal fascia, which attaches inter alia to the hyoid bone. Thus, the thyroid gland moves upwards with swallowing and speech. This is a good test for masses in the neck.
Thyroglossal cysts move when the tongue is protuded due to the attachment of the thyroglossal duct to the tongue.

•  The inferior thyroid artery runs close to the recurrent laryngeal nerve near the gland. Thus, the artery should be ligated further laterally to avoid injury to the nerve.


The superior thyroid artery is closer to the external laryngeal nerves superiorly than near the gland. Thus, this artery can be ligated as close to the gland as possible without danger of injury to the nerve.

•  In thyrodectomy, the recurrent laryngeal nerve must be preserved. The parathyroids must be identified and at least one spared.

•  Since colossal sizes of goitre may damage the recurrent laryngeal nerve, it is good habit to do laryngoscopy before thyroidectomy, so that pre-operative damage can be distinguished from post-operative damage.

Horner's syndrome

Results from damage to the cervical sympathetic chain.

Therefore it presents with

  • Ptosis
  • Myosis
  • Facial flushing on the affected site
 
Trachea  



Tracheitis: Inflammation of the trachea from  viral or bacterial infection, allergies are frequent causes of cough and upper airway discormfort

Tracheostomy: This is the creation of an opening into the trachea to relieve upper airway obstruction
Done between first and second tracheal rings or through fourth rings. A tracheostomy tube is then inserted into the trachea and secured. During this procedure, the following anatomical relations must be safeguarded:

  • Isthmus  of thyroid gland

  • Inferior thyroid veins

  • Occassional thyroidea ima

  • Left brachio cephalic vein

  • Jugular venous arch

  • Pleura may be encountered particularly in infants and children

  • Thymus in infants and children


In infants , the trachea is small, mobile and soft. Accordingly it is easy to cut through its posterior wall and damage the esophagus

Deviation of trachea: Tracheal deviation from the midline occurs when it is pushed away as in case of massive pleural effusion, lung tumor or when it is pulled to one side. Om cases of lung fibrosis or occasional dextrocardia.
 
Esophagus  


Esophageal cancer

  • Presents with difficulty in swallowing

  • Commonly diagnosed by esophagoscopy

  • Causes enlargement of inferior deep cervical nodes

  • Compresses inferior laryngeal nerve producing hoarsenes

  • Tracheo esophageal fistula

  • Congenital defect with communication between trachea and esophagus