Layers of the Neck

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Layers of the Neck

• Skin

• Superficial fascia

• Deep cervical fascia

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A. The Skin

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• Loosely attached anteriorly.

• Posteriorly, the skin is very thick and adherent to the underlying structures with numerous sebaceous glands.

• Well supplied with blood vessels, and has transverse lines.

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B. SUPERFICIAL FASCIA

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• Lies immediately next to the skin;

• Consists of fats and connective tissue;

• Contains cutaneous nerves, superficial veins, superficial lymph nodes and platysma.

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Components of the Superficial Fascia

Structure Organ/Component

Muscle PlatysmaO: deep fascia from the pectoralis major to the deltoid muscleI: lower border of the mandibleA: depresses the mandible

Nerves Cutaneous branches of the cervical plexus

Veins External and anterior jugular veins

Lymph Nodes Lie along the external jugular vein superficial to SCM

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C. DEEP CERVICAL FASCIA

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THREE LAYERS OF THE DEEP CERVICAL FASCIA

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1. External or Investing or Enveloping Layer

2. Middle or Pretracheal Layer

3. Internal or Prevertebral Layer

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I. External or Investing or Enveloping Layer

completely encircles and encloses the neck, including the sternocleido-mastoid and trapezius muscles.

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• - it is attached posteriorly to the ligamentum nuchae, forming a roof over the anterior and posterior triangles of the neck.

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• Components of the External or Investing layer:

1. 2 muscles – SCM and trapezius

2. 2 salivary glands- parotid and submandibular glands

3. 2 spaces- suprasternal space of burns and the space above the clavicle in the posterior triangle.

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Attachments of the External Layer

1. Superior- inion, superior nuchal line, mastoid process, zygomatic arch and lower border of the mandible.

2. Inferior- acromion process and spine of the scapula, clavicle and manubrium sterni.

3. Anterior- it meets the corresponding opposite side at the midline

4. Posterior- Ligamentum nuchae

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2. Middle or Pre-tracheal layer

- lies deep to the deep investing fascia and - forms a sheath around the viscera and muscles of the neck.

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Attachments of the Middle or Pretracheal layer:

1. Superior- thyrocricoid cartilage, arising from the inner surface of the deep fascia and encloses the SCM.

2. Inferior- extends into the thorax and blends with the pericardium in the middle mediatinum.

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• Two Divisions of the Middle or Pre-tracheal Layer

1. Muscular Portion- located in front of the thyroid gland- encloses the infrahyoid muscles

2. Visceral Portion- encloses the thyroid and parathyroid glands.

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3. Internal or Prevetebral Layer

- arises from the investing layer opposite the trapezius. It is much thicker than the pre-tracheal layer. - covers the prevertebral muscles – longus colli, longus capitis, scalenius anterior, scalenius medius, and scalenius posterior.

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Attachments of the Internal or Prevertebral Layer:

1. Superior - base of the skull

2. Inferior- anterior longitudinal ligament of the vertebral column.

3. Posterior- ligamentum nuchae

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Other Components of the Deep Cervical Fascia

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1. Carotid Sheath

- a condensation of the deep cervical fascia which encloses the following structures:

a. Common and internal carotid artery,b. Internal jugular veinc. Vagus nerved. Deep cervical lymph nodes

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2. Visceral Fascia- encloses the pharynx and esophagus, larynx and trachea

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Potential Fascial Spaces

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• Loose areolar tissue, and connective tissue fills the spaces between the various layers of the deep cervical fascia.

• There are two important fascial spaces to consider:

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Retropharyngeal Space- a potential space between the visceral unit anteriorly and the vertebral unit posteriorly.

- It extends from the base of the skull down to the superior mediastinum.

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Alar Space- a subdivision of the retropharyngeal space created by the alar fascia. It extends from the base of the skull above to the superior mediastinum below, and has been dubbed by some as danger space.

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Clinical Significance

Since these fascial spaces are filled with loose connective tissue, it readily breaks down when invaded by infection, blood, air or tumor, making possible to spread the from one region to the next.

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