Root of the Neck

Question 1

Describe the basic anatomy of the thyroid gland. What is the pyramidal lobe of the thyroid gland?

Answer 1

Thyroid gland consists of left and right lobes connected by an isthmus. It crosses the 2nd, 3rd, and 4th tracheal rings. The pyramidal lobe of the thyroid gland is a variable third lobe, that arsis along the remnants of the thyroglossal duct.

Question 2

Trace the arterial supply and venous drainage to the thyroid gland.

Answer 2

The thyroid receives blood from the superior (branch of the external carotid) and inferior (branch of the costocervical trunk) thyroid aa. It also may receive blood from the thyroid ima a. (a varial branch from the brachio-cephalic trunk).

The venous drainage is via the superior and middle thyroid vv. to the internal jugular vein. Also the inferior thyroid v. to the brachiocephalic vein.

Question 3

Describe the relationship of the parathyroid glands to the thyroid gland.

Answer 3

The parathyroid glands lie agains the dorsum of the thyroid gland within its sheath, but they have their own capsules.

Question 4

Describe the relationship of neurovascular structures (roots of brachial plexus, subclavian artery and
vein, phrenic nerve) to the scalene muscles in the root of the neck.

Answer 4

The roots of the brachial plexus emerge between the anterior and middle scalene muscles.
The subclavian artery passes behind the anterior scalene muscle and emerges inferior to the brachial plexus roots.
The subclavian vein passes anterior to the anterior scalene muscle.
The phrenic nerve runs on the anterior scalene muscle.

Question 5

What clinical signs and symptoms would result from a lesion of the cervical sympathetic trunk?

Answer 5

This would result in Horner’s syndrome.

• constriction of the pupil
• drooping of the superior eyelid
• sinking of the eye
• vasodilation and anhydrosis

Question 6

Describe the arrangement of deep fascial layers in the neck.

Answer 6

There are 6 layers with the superficial (investing) layer encompassing all of the other layers. They are arranged as tubes within a tube.

1. Superficial (investing) layer
2. Pre-tracheal layer
3. Buccopharyngeal fascia
4. Carotid sheaths
5. Pharyngobasilar fascia
6. Pre-vertebral layer

Question 7

An abscess located posterior to the prevertebral fascia has the potential to spread to what other
areas?

Answer 7

The abscess could erode through the prevertebrl fasica and spread to the deep muscles of the back. If it does not erode through it can spread deeper into the trapezius and sternocleidomastoid muscles.

Question 8

What is a tracheotomy? Where is this procedure usually performed? What anatomical structures are
most at risk during this procedure?

Answer 8

Surgical opening of the trachea by incising the 3rd and 4th rings of the trachea. This procedure is usually performed in surgery in a clinic. The vasculature of the thyroid is most at risk in this procedure as well as the thyroid gland itself.

Question 9

Describe the relationship of the thyroid gland to the infrahyoid muscles, carotid sheaths, larynx, and trachea.

Answer 9

The thyroid gland lies deep to the infrahyoid muscles. It’s R and L lobes are anterolateral to the larynx and trachea, with the uniting isthmus crossing the 2nd, 3rd, and 4th tracheal rings.

The carotid sheaths lie anterolateral to the thyroid gland (touching the Visceral Pre-tracheal layer that invests the thyroid)

Question 10

What nerves are most at risk during thyroidectomy?

Answer 10

The recurrent laryngeal nerves, especially the R recurrent due to its intimate relation with the inferior thyroid artery at the inferior pole of the thyroid gland. Risk of injuring L recurrent is not quite as great (but still present) due to its more vertical ascent from the superior mediastinum.

Hoarseness is the usual sign of unilateral recurrent nerve injury.

Question 11

Trace the course of the subclavian artery through the root of the neck and name the branches of each segment.

Answer 11

The R subclavian arises from the brachiocephalic trunk, while the L comes off the arch of the aorta. Both subclavian arteries arch superolaterally, reaching an apex as they pass posterior to the ant. scalene mm. Divided into (3) segments based on relationship to ant. scalene m:

• 1st part = medial to m. 3 branches: Vertebral A, Internal Thoracic A, and Thyrocervical trunk
• 2nd part = posterior to m. 1 branch: Costocervical trunk
• 3rd part = lateral to m. 1 branch: Dorsal Scapular A.

Question 12

Trace the course of the 1st segment of the subclavian artery and its branches through the root of the neck.

Answer 12

1st segment is medial to the Anterior scalene muscle. (3) branches:

• Vertebral A: ascends between the ant. scalene and longus colli mm
• Internal thoracic A: descends through the thorax behind upper 6 costal cartilages
• Thyrocervical Trunk: short trunk that divides into (3)–Inferior Thyroid, Transverse Cervical, and Suprascapular aa

Question 13

Trace the course of the 2nd and 3rd segments (and their branches) through the root of the neck

Answer 13

2nd segment is posterior to the anterior scalene m. It’s 1 branch–Costocervical trunk–passes posterosuperiorly and divides into (2): superior intercostal and deep cervical aa (supply first 2 IC spaces and posterior deep cervical mm respectively)

3rd segment is lateral to ant. scalene. It’s 1 branch–Dorsal Scapular a–passes laterally through trunks of the brachial plexus, anterior to the middle scalene.

Question 14

What is the stellate ganglion? Where is it typically located in the root of the neck? Why might this ganglion be blocked clinically?

Answer 14

[Remember: cervical portion of the sympathetic trunk has 3 cervical sympathetic ganglia: superior, middle, and inferior.] The stellate is a star-shaped ganglion resulting from fusion of the inferior cervical ganglion with the 1st thoracic ganglion. It lies anterior to the transverse process of C7, just superior to neck of 1st rib, and posterior to origin of Vertebral A.
Anesthetic injected around stellate blocks transmission through both cervical and superior thoracic ganglia, which may relieve vascular spasms involving brain and upper limb. Also used to determine need for surgical resection of stellate to relieve excess vasoconstriction in upper limb.

Question 15

Describe the basic pattern of lymphatic drainage of the head to the thoracic duct or the right lymphatic duct.

Answer 15

Lymph from all of the head and neck drains into Inferior Deep cervical lymph. Most of these are clustered around and follow the internal jugular V in the neck. Lymph flow is generally inferiorly to meet either the thoracic duct on the left or the right lymphatic duct

Question 16

What is the carotid sheath and what does it contain? What is its relationship to the ansa cervicalis?

Answer 16

The carotid sheaths surround the vascular compartments on each side of the neck. Contains: the common carotid/internal carotid aa; IJVs; Vagus nerves; and deep cervical lymph nodes. The ansa cervicalis usually lies on (or is embedded in) the anterolateral aspect of the carotid sheath.

Question 17

How can infection from the head and neck spread to the mediastinum, based on your knowledge of the organization of deep fascia in the neck?

Answer 17

If infection occurs between investing layer of deep cervical fascia and the VISCERAL part of pretracheal fascia, it can spread inferiorly posterior to the esophagus and enter the posterior mediastinum or anterior to the trachea and enter the anterior mediastinum.
Also, infections in the Retropharyngeal space can extend inferiorly into the superior mediastinum.

Question 18

What is cricothyrotomy? Where is this procedure usually performed? What structure is pierced?

Answer 18

The preferred method of emergency relief of respiratory obstruction for non-surgeons. Involves incision (or inserting large-bore needle) through the skin and cricothyroid membrane to permit fast entry of air. (Preferred over tracheotomy b/c trachea runs behind the thyroid gland, but the cricothyroid ligament is superior to it)