CHAPTER 4

THE NECK

Overview and Topographic Anatomy

Triangles of the Neck

Anterior Triangle

Posterior Triangle

Suboccipital Triangle

Visceral Contents

Root of the Neck

Muscles

Vascular Supply of the Neck

Nerve Supply of the Neck

Clinical Correlates

Questions

Overview and Topographic Anatomy

GENERAL INFORMATION

The neck is the area between the base of the skull and inferior border of the mandible and the superior thoracic aperture

The anterior portion of the neck contains the major visceral structures between the head and the thorax:

• Pharynx

• Larynx

• Trachea

• Esophagus

• Thyroid and parathyroid glands

For descriptive purposes, the neck is divided into 2 triangles:

• Anterior triangle

• Posterior triangle

Skin is the most superficial structure covering the neck

FASCIA

The neck is surrounded by 2 main layers of cervical fascia that can be further subdivided:

• Superficial fascia

• Deep fascia

• Superficial layer of deep cervical fascia (investing)

• Middle layer of deep fascia (includes muscular and visceral parts such as the pretracheal)

• Deep layer of deep fascia (includes prevertebral and alar)

• Carotid sheath

Superficial fascia is deep to the skin and surrounds the platysma muscle

Sensory branches to the neck are located in the superficial fascia

Deep to the superficial fascia is the investing layer of deep cervical fascia

The superficial (or investing) layer of deep cervical fascia attaches posteriorly along the midline and passes anteriorly to surround the entire neck

The superficial (or investing) layer of deep cervical fascia surrounds these muscles:

• Trapezius

• Sternocleidomastoid

Triangles of the Neck

ANTERIOR TRIANGLE

Borders of the anterior triangle:

• Anterior border of the sternocleidomastoid

• Inferior border of the mandible

• Midline of the neck

Using the hyoid as a keystone, the omohyoid and digastric muscles subdivide the anterior triangle into:

• Submandibular triangle

• Carotid triangle

• Muscular triangle

• Submental triangle

All of the triangles within the anterior triangle are paired except for the submental triangle, which spans the right and the left sides of the neck

Hyoid bone divides the anterior triangle into 2 areas: suprahyoid and infrahyoid regions

The suprahyoid region contains 4 muscles:

• Mylohyoid

• Digastric

• Stylohyoid

• Geniohyoid

The infrahyoid region contains 4 muscles commonly called strap muscles:

• Omohyoid

• Sternohyoid

• Sternothyroid

• Thyrohyoid

Anterior Triangle

SUBMANDIBULAR TRIANGLE

Often called the digastric triangle

Borders of the submandibular triangle:

• Inferior border of the mandible

• Posterior digastric

• Anterior digastric

Floor of the triangle is composed of the:

• Hyoglossus

• Mylohyoid

• Middle constrictor

Roof is made of the:

• Skin

• Superficial fascia with platysma

• Deep cervical fascia

Submandibular triangle is paired

Lesser’s triangle is a small subdivision of the submandibular triangle, which aids in identifying the lingual artery (especially for ligation)

Boundaries of Lesser’s triangle:

• Hypoglossal nerve

• Anterior digastric

• Posterior digastric

CAROTID TRIANGLE

Named because parts of all three carotid arteries are located within it

Borders of the carotid triangle:

• Anterior border of the sternocleidomastoid

• Posterior digastric

• Superior omohyoid

Floor of the triangle is composed of the:

• Hyoglossus

• Thyrohyoid

• Middle constrictor

• Inferior constrictor

Roof is made of the:

• Skin

• Superficial fascia with platysma

• Deep cervical fascia

Carotid triangle is paired

MUSCULAR TRIANGLE

Borders of the muscular triangle:

• Anterior border of the sternocleidomastoid

• Superior omohyoid

• Midline

Floor of the triangle is composed of the:

• Sternohyoid

• Sternothyroid

Roof is made of the:

• Skin

• Superficial fascia with platysma

• Deep cervical fascia

Muscular triangle is paired

SUBMENTAL TRIANGLE

Borders of the submental triangle:

• Body of hyoid

• Anterior digastric on right

• Anterior digastric on left

Floor of the triangle is composed of the:

• Mylohyoid

Roof is made of the:

• Skin

• Superficial fascia with platysma

• Deep cervical fascia

Submental triangle is unpaired

Posterior Triangle

GENERAL INFORMATION

Borders of the posterior triangle:

• Posterior border of the sternocleidomastoid

• Middle third of the clavicle

• Anterior border of the trapezius

Located on the lateral side of the neck and spirals around the neck

Is subdivided into 2 triangles by the omohyoid:

• Omoclavicular (also called the supraclavicular triangle)

• Occipital

Roof of the posterior triangle includes:

• Skin

• Superficial fascia with platysma

• Superficial (investing) layer of deep cervical fascia

Floor of the posterior triangle includes^*:

• Semispinalis capitis

• Splenius capitis

• Levator scapulae

• Posterior scalene

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