Neck

Lab Summary

The anatomic continuity from chest to neck to face and head including great vessels, airway and esophagus are explored. Critical innervations are shown in detail along with musculature and glandular structures. Finally, a carotid endarterectomy is show since this is such an important location for significant arteriosclerotic disease and stroke.

Lab Objectives

Describe the position and importance of internal and external jugular veins.
Describe the contents and relations within the carotid sheath.
Describe the location of the carotid bifurcation.
Describe the position the thyroid gland including the isthmus.
Describe the arterial and venous circulation for the thyroid gland.
Describe the course of the recurrent laryngeal nerve in the neck.
Describe the relationship of the airway and esophagus.
Describe the positions of the hyoid bone, thyroid cartilage, cricothyroid membrane, cricoid cartilage and tracheal rings.
Explain the placement of an emergency airway.

Lecture List

Neck Part I (Superficial), Neck Part II (Deep), Carotid Endarterectomy

Neck Part I

Skin Incisions and Midline Neck

Perform a midline incision from the mandibular symphysis to the sternal angle.

Make bilateral incisions along the clavicle and jawline.
Reflect the skin flaps and remove the superficial fascia. Identify the platysma muscle. The platysma may be densely adherent to the superficial fascia.

The anterior border of the sternocleidomastoid is a landmark for medial and deeper structures. In the midline identify the:

hyoid bone
thyroid cartilage
crocoid cartilage
cricothyroid membrane

1.1a) Cervical and thoracic bony structure
1.1b) Cervical skin incisions
1.1c) Platysma
1.1d) Bony and cartilaginous landmarks
1.1e) Anterior airway

Submandibular Gland

Examine the submandibular triangle, bounded by the digastric, sternocleidomastoid and mandible. Within the triangle locate the:

submandibular gland
facial artery
facial vein

Follow the facial artery as it passes over the mandible, anterior to the masseter.

Labels (top to bottom): Submandibular triangle, mandible, digastric, submandibular gland, facial artery, masseter, facial vein — 1.2a) Submandibular triangle

Thyroid Gland

Divide and reflect the strap muscles: sternohyoid, omohyoid thyrohyoid, and sternothyroid muscles.

Locate the lobes and isthmus of the thyroid gland. Locate the superior thyroid artery and external laryngeal nerve deep to the sternothyroid.

Divide the thyroid gland at the isthmus and reflect the lobes to reveal the 2nd and 3rd rings of the trachea.

1.3a) Strap muscles
1.3b) Anterior airway
1.3c) Thyroid gland
1.3d) Superior thyroid artery
1.3e) Tracheal rings and cricothyoid membrane

Neck Part II

Carotid Sheath

Identify the sternal and clavicular heads of the sternocleidomastoid muscle.

Divide the sternal and clavicular heads of the sternocleidomastoid and reflect the muscle laterally to reveal the carotid sheath.

Open the carotid sheath to expose the common carotid artery, internal jugular vein and vagus nerve (X).

2.1a) Sternocleidomastoid
2.1b) Carotid sheath
2.1c) Contents of carotid sheath

Lower Cranial Nerves

Follow the common carotid superiorly. Locate the carotid bifurcation and its external and internal branches. Note the internal carotid has no branches in the neck.

Superior to the bifurcation locate the:

Hypoglossal nerve (XII), crosses anterior to the external carotid
Internal laryngeal nerve (X), pierces thyrohyoid membrane
Accessory nerve (XI), supplies and lies on deep surface of sternocleidomastoid

2.2a) Carotid bifurcation
2.2b) Cranial nerves in the neck

Cervical Sympathetic Chain

Retract the carotid sheath laterally and the trachea medially.

Dissect the prevertebral fascia to locate the sympathetic chain and superior cervical ganglion. These structures are delicate and easily damaged.

Labels (top to bottom): Cervical sympathetic cardiac nerve, sympathetic chain, superior cervical ganglion, ramus communicants — 2.3a) Cervical sympathetic chain

Recurrent Laryngeal Nerve

At the level of the thyroid gland, reflect the trachea, larynx and thyroid medially; the carotid sheath laterally.

Dissect in the interval between the trachea and the esophagus to locate the recurrent laryngeal nerve. Recall the course that the left recurrent laryngeal nerve takes around the arch of the aorta.

Question 1: What is the thoracic course of the right recurrent laryngeal nerve?

Answer

Right recurrent laryngeal nerve courses around the right subclavian artery.

Labels (top to bottom): Laryngeal prominence, larynx, pharynx, trachea, recurrent laryngeal nerve, esophagus, common carotid artery — 2.4a) Left recurrent laryngeal nerve

Cricothyroid Junction

Remove the attachments of the strap muscles on one side to reveal the bone and cartilage of the upper airway.

Identify the cricothyroid joint between the inferior horn of the thyroid cartilage and the cricoid cartilage.

Note overall airway architecture and relate this anatomy to surface landmarks.

Labels (top to bottom): Laryngeal prominence, hyoid bone, cricothyroid membrane, lamina of thyroid cartilage, cricoid cartilage, trachea, internal superior laryngeal nerve, bifurcation of carotid — 2.5a) Upper airway

Carotid Endarterectomy

Re-identify the common, external and internal carotid arteries.
Make a sharp incision along the common carotid into the internal carotid. Extend the incision into the external carotid.

Examine the interior arterial wall for arteriosclerotic plaque formation.

If plaque present remove it to expand the lumen of the vessels.
Examine the plaque.

Question 2: What is the consequence of removing carotid clamps out of order?

Answer

Embolic stroke.