Overview and topographic anatomy
General information
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The neck is the area between the base of the skull and inferior border of the mandible and the superior thoracic aperture
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For descriptive purposes, the neck is divided into 2 triangles:
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Anterior triangle
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Posterior triangle
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Skin
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Skin is the most superficial structure covering the neck
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Cutaneous innervation is from the cutaneous nerves of the cervical plexus:
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Lesser occipital
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Great auricular
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Transverse cervical (largest sensory contribution)
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Supraclavicular
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Bones and cartilages
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Cervical vertebrae (7)
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Hyoid
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Laryngeal cartilages (9)
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(Occipital bone is located in the skull but is part of the important atlanto-occipital joint of the neck)
Fascia
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The neck is surrounded by 2 main layers of cervical fascia that can be further subdivided:
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Superficial cervical fascia
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Deep cervical fascia
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Superficial layer of deep cervical fascia (also known as the investing layer)
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Middle layer of deep cervical fascia (includes muscular and visceral parts such as the pretracheal)
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Deep layer of deep cervical fascia (includes prevertebral and alar)
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Carotid sheath (formed by other layers of deep cervical fascia)
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The contents of the superficial cervical fascia will vary depending on location but include:
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Platysma (and cervical branch of facial nerve that innervate the muscle)
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Cutaneous nerves of the cervical plexus:
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Lesser occipital
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Great auricular
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Transverse cervical (largest sensory contribution)
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Supraclavicular
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Deep to the superficial cervical fascia is the investing (or superficial) layer of deep cervical fascia
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The superficial (or investing) layer of deep cervical fascia attaches posteriorly along the midline and passes anteriorly to surround the entire neck
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The superficial (or investing) layer of deep cervical fascia surrounds these muscles:
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Trapezius
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Sternocleidomastoid
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Viscera
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Thyroid gland
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Parathyroid gland
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Submandibular gland (discussed in Chapter 13 )
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Pharynx (discussed in Chapter 15 )
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Larynx (discussed in Chapter 16 )
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Esophagus
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Trachea
Triangles of the neck
Anterior triangle
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Borders of the anterior triangle:
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Anterior border of the sternocleidomastoid
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Inferior border of the mandible (including a line from the angle of the mandible to the mastoid process)
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Midline of the neck (continuous from the mandible to the suprasternal notch)
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Using the hyoid as a keystone, the omohyoid and digastric muscles subdivide the anterior triangle into:
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Submental triangle
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Submandibular triangle
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Carotid triangle
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Muscular triangle
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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
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Hyoid bone divides the anterior triangle into 2 areas: suprahyoid and infrahyoid regions
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The suprahyoid region contains 4 muscles:
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Mylohyoid
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Digastric
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Stylohyoid
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Geniohyoid
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The infrahyoid region contains 4 muscles commonly called strap muscles:
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Omohyoid
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Sternohyoid
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Sternothyroid
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Thyrohyoid
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Anterior triangle
Submental triangle
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Borders of the submental triangle:
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Body of hyoid
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Anterior digastric on right
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Anterior digastric on left
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Floor of the triangle is composed of the:
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Mylohyoid
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Roof is made of the:
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Skin
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Superficial cervical fascia with platysma
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Deep cervical fascia
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Submental triangle is unpaired
| MAJOR CONTENTS OF THE SUBMENTAL TRIANGLE | |||
| Artery | Vein | Nerve | Structures |
| Anterior jugular | Submental lymph nodes | ||
Submandibular triangle
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Often called the digastric triangle
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Borders of the submandibular triangle:
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Inferior border of the mandible (including a line from the angle of the mandible to the mastoid process)
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Posterior digastric
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Anterior digastric
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Floor of the triangle is composed of the:
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Hyoglossus
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Mylohyoid
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Roof is made of the:
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Skin
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Superficial cervical fascia with platysma
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Deep cervical fascia
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Submandibular triangle is paired
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There are 3 clinically significant triangles found within the submandibular triangle:
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Lesser’s triangle
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Pirogoff’s triangle
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Beclard’s triangle
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All 3 triangles are small subdivisions of the submandibular triangle, which aids in identifying the hypoglossal nerve (lying superficial to the hyoglossus) and the lingual artery (lying deep to the hyoglossus), which may be important for ligation during hemorrhage or surgery
Lesser’s triangle
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Boundaries of Lesser’s triangle:
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Hypoglossal nerve
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Anterior digastric
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Posterior digastric
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Pirogoff’s triangle
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Boundaries of Pirogoff’s triangle:
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Hypoglossal nerve
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Intermediate tendon of the digastric
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Mylohyoid (posterior border)
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Beclard’s triangle
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Boundaries of Beclard’s triangle:
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Greater cornu of the hyoid
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Posterior digastric
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Hyoglossus (posterior border)
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| MAJOR CONTENTS OF THE SUBMANDIBULAR TRIANGLE | |||
| Arteries | Veins | Nerves | Structures |
| External carotid (passing from deep to posterior digastric and stylohyoid to enter inferior portion of parotid gland) | Facial | Mylohyoid | Submandibular gland (with portion of submandibular duct) |
| Facial | Facial | Mylohyoid | Submandibular gland |
| Submental | Submental | Hypoglossal | Submandibular gland |
| Lingual | Lingual | Lingual (hidden deep to deep portion of the submandibular gland) | Inferior portion of the parotid gland |
| Mylohyoid (branching from inferior alveolar a. in oral cavity) | Mylohyoid | Facial (branches of marginal mandibular and cervical) | Submandibular lymph nodes |
Carotid triangle
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Named because parts of all 3 carotid arteries are located within it
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Borders of the carotid triangle:
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Anterior border of the sternocleidomastoid
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Posterior digastric
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Superior omohyoid
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Floor of the triangle is composed of the:
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Hyoglossus
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Thyrohyoid
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Middle constrictor
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Inferior constrictor
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Roof is made of the:
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Skin
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Superficial fascia with platysma
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Deep cervical fascia
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Carotid triangle is paired
| MAJOR CONTENTS OF THE CAROTID TRIANGLE | |||
| Arteries | Veins | Nerves | Structures |
|
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Muscular triangle
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Borders of the muscular triangle:
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Anterior border of the sternocleidomastoid
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Superior omohyoid
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Midline
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Floor of the triangle is composed of the:
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Sternohyoid
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Sternothyroid
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Roof is made of the:
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Skin
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Superficial fascia with platysma
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Deep cervical fascia
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Muscular triangle is paired
| MAJOR CONTENTS OF THE MUSCULAR TRIANGLE | |||
| Artery | Veins | Nerve | Structures |
| Superior thyroid |
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Ansa cervicalis |
|
Posterior triangle
General information
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Borders of the posterior triangle:
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Posterior border of the sternocleidomastoid
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Middle third of the clavicle
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Anterior border of the trapezius
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Located on the lateral side of the neck and spirals around the neck
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Is subdivided into 2 triangles by the omohyoid:
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Omoclavicular (also called the supraclavicular triangle)
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Occipital
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Roof of the posterior triangle includes:
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Skin
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Superficial fascia with platysma
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Superficial (investing) layer of deep cervical fascia
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Floor of the posterior triangle includes *
* These muscles are covered by the prevertebral layer of deep cervical fascia.
:
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Semispinalis capitis (at apex)
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Splenius capitis
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Levator scapulae
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Posterior scalene
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Middle scalene
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Anterior scalene
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Posterior triangle is paired
| MAJOR CONTENTS OF THE POSTERIOR TRIANGLE | |||
| Arteries | Veins | Nerves | Structures |
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Suboccipital triangle
General information
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Borders of the suboccipital triangle:
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Obliquus capitis superior
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Obliquus capitis inferior
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Rectus capitis posterior major
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Roof of the suboccipital triangle includes:
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Dense connective tissue
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Floor of the suboccipital triangle includes:
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Posterior atlanto-occipital membrane
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Posterior arch of the atlas
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Suboccipital triangle is paired
Vertebral arteries
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These vessels enter the foramen transversarium of the 6th cervical vertebra, emerging above the 1st cervical vertebra to enter the suboccipital triangle
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They curve medially to lie in a groove on the posterior arch of the atlas
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Pass through the posterior atlanto-occipital membrane to enter the vertebral canal
| MAJOR CONTENTS OF THE SUBOCCIPITAL TRIANGLE | |||
| Artery | Vein | Nerves | Structures |
| Vertebral |
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Visceral contents
Thyroid, parathyroid, submandibular, pharynx, larynx, trachea
Thyroid gland
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Highly vascular organ located on the anterior and lateral surfaces of the neck
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Formed by a right and a left lobe connected in the midline by an isthmus
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Lies roughly at a level between the 5th cervical and the 1st thoracic vertebrae
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The isthmus crosses at the 2nd and 3rd tracheal rings
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A pyramidal lobe often arises from the isthmus and extends superiorly
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Arterial supply arises from the superior and inferior thyroid arteries, with the major portion from the inferior thyroid artery
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A thyroidea ima vessel may supply the thyroid gland and arises from the brachiocephalic artery or as a direct branch from the aorta
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Venous drainage forms from a plexus on the surface of the thyroid gland that drains into the superior, middle, and inferior thyroid veins
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Microscopically, the thyroid is made of:
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Thyroid follicular cells (which secrete thyroxine and triiodothyronine)
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Parafollicular or C cells (which secrete calcitonin and develop from the 4th pharyngeal pouch)
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Parathyroid glands
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Parathyroid glands normally are 4 small endocrine glands located on the posterior surface of the thyroid lobes
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Main role is to regulate calcium levels in the body
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The superior parathyroids are supplied by the superior thyroid artery, and the inferior parathyroids are supplied by the inferior thyroid artery
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Microscopically, their cells are organized in cords
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There are 2 major cell types in the parathyroid gland:
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Chief cells (which secrete parathyroid hormone)
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Oxyphil cells
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Developed from the 3rd (inferior parathyroid) and 4th (superior parathyroid) pharyngeal pouches, which alter their final position through migration
Submandibular glands (see Chapter 13 for more information on submandibular glands)
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2nd salivary gland
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A mixed salivary gland, secreting both serous and mucous saliva, but predominantly serous secreting
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Wraps around the posterior border of the mylohyoid muscle, and is located in the submandibular triangle of the neck and the floor of the oral cavity
Pharynx
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5-inch muscular tube from base of the skull to the lower border of the cricoid cartilage (C6), where it is continuous with the esophagus
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Lies posterior to the nasal and oral cavities and the larynx and thus is divided into 3 parts:
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Nasopharynx
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Oropharynx
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Laryngopharynx
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Responsible for properly conducting food to the esophagus and air to the lungs
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See Chapter 15 for more information on the pharynx
Larynx (see Chapter 16 for more information on the larynx)
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Connection between the pharynx and the trachea
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Prevents foreign bodies from entering the airways
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Designed for the production of sound (phonation)
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Shorter in women and children
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Formed by 9 cartilages: 3 paired and 3 unpaired
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Located in the midline opposite the 3rd to 6th cervical vertebrae
Trachea
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Cartilaginous tube (about 4 inches) connecting the larynx to the 2 primary bronchi of the lungs
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Composed of 16 to 20 rings of C-shaped hyaline cartilage
Root of the neck
General information
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Root of the neck connects the structures of the neck with the thoracic cavity
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The superior thoracic aperture is bounded by:
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Manubrium
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1st rib and cartilage
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1st thoracic vertebra
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The apex of each lung extends into the root of the neck on the lateral side of the superior thoracic aperture
| MAJOR CONTENTS OF THE ROOT OF THE NECK | |||
| Arteries | Veins | Nerves | Structures |
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