Question #618

The neck consists of several distinct layers of fascia:

• The superficial fascia lies under the skin and surrounds the entire neck
• The deep investing layer of cervical fascia also surrounds the neck but does not surround more superficial structures like platysma and superficial blood vessels and nerves. It splits to cover both surfaces of trapezius and sternocleidomastoid
• The carotid sheath surrounds the internal and common carotid arteries, the internal jugular vein and adjacent lymph nodes and the vagus nerve.
• The pretracheal fascia originates at the laryngeal cartilages and descends to surround not only the trachea but the thyroid gland and infrahyoid muscles.
• The prevertberal fascia surrounds the vertebral bodies and adjacent deep muscles including the scalenes and longus colli. Of note the phrenic nerve runs on the anterior surface of the anterior scalene muscle deep to this layer of fascia.

Infection can easily spread within one layer but has difficulty spreading to adjacent layers.

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