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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 andadherent to the underlying structureswith numerous sebaceous glands.

• Well supplied with blood vessels, and hastransverse 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, superficiallymph nodes and platysma.

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Components of theSuperficial Fascia

Structure Organ/Component

Muscle PlatysmaO: deep fascia from the pectoralis major

to the deltoid muscleI: lower border of the mandible

A: depresses the mandible

Nerves Cutaneous branches of the cervicalplexus

Veins External and anterior jugular veins

Lymph Nodes Lie along the external jugular veinsuperficial to SCM

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C. DEEP CERVICAL FASCIA

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THREE LAYERS OF THE DEEPCERVICAL FASCIA

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1. External or

Investing orEnveloping

Layer

2. Middle orPretrachealLayer

3. Internal orPrevertebralLayer

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I. External or Investing orEnveloping Layer

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

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

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• Components of theExternal orInvesting layer:

1. 2 muscles – SCM and trapezius

2. 2 salivary glands- parotid andsubmandibular glands

3. 2 spaces

- suprasternal space of burns and the space abovethe clavicle in the posteriortriangle.

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2. Middle or Pre-tracheal layer

- lies deep to the deep investing fascia and

- forms a sheath around the viscera andmuscles 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 fasciaand encloses the SCM.

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

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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 ismuch thicker than the pre-tracheal layer.

- covers the prevertebral muscles – longus colli, longuscapitis, scalenius anterior, scalenius medius, and scalenius

posterior.

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Attachments of the Internal orPrevertebral 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 followingstructures:

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 fillsthe spaces between the various layers of thedeep cervical fascia.

• There are two important fascial spaces toconsider:

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Retropharyngeal Space

- a potential space between the visceral unit anteriorly andthe vertebral unit posteriorly.

- It extends from the base of the skull down to the superiormediastinum.

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Alar Space

- a subdivision of the retropharyngeal space created by thealar fascia. It extends from the base of the skull above to thesuperior mediastinum below, and has been dubbed by someas danger space.

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Clinical Significance

Since these fascial spaces are filled with looseconnective tissue, it readily breaks downwhen invaded by infection, blood, air ortumor, making possible to spread the fromone region to the next.

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