Neck

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Neck
Neck.png
Human neck
Details
Identifiers
Latin cervix; collum
MeSH D009333
TA98 A01.1.00.012
TA2 123
FMA 7155
Anatomical terminology

The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In addition, the neck is highly flexible and allows the head to turn and flex in all directions. The structures of the human neck are anatomically grouped into four compartments; vertebral, visceral and two vascular compartments. [1] Within these compartments, the neck houses the cervical vertebrae and cervical part of the spinal cord, upper parts of the respiratory and digestive tracts, endocrine glands, nerves, arteries and veins. Muscles of the neck are described separately from the compartments. They bound the neck triangles. [2]

Contents

In anatomy, the neck is also called by its Latin names, cervix or collum, although when used alone, in context, the word cervix more often refers to the uterine cervix, the neck of the uterus. [3] Thus the adjective cervical may refer either to the neck (as in cervical vertebrae or cervical lymph nodes ) or to the uterine cervix (as in cervical cap or cervical cancer ).

Structure

Muscles in the human neck Musculi coli base.svg
Muscles in the human neck

Compartments

The neck structures are distributed within four compartments: [1] [4]

Besides the listed structures, the neck contains cervical lymph nodes which surround the blood vessels. [6]

Muscles and triangles

Muscles of the neck attach to the skull, hyoid bone, clavicles and the sternum. They bound the two major neck triangles; anterior and posterior. [1] [7]

Anterior triangle is defined by the anterior border of the sternocleidomastoid muscle, inferior edge of the mandible and the midline of the neck. It contains the stylohyoid, digastric, mylohyoid, geniohyoid, omohyoid, sternohyoid, thyrohyoid and sternothyroid muscles. These muscles are grouped as the suprahyoid and infrahyoid muscles depending if they are located superiorly or inferiorly to the hyoid bone. The suprahyoid muscles (stylohyoid, digastric, mylohyoid, geniohyoid) elevate the hyoid bone, while the infrahyoid muscles (omohyoid, sternohyoid, thyrohyoid, sternothyroid) depress it. Acting synchronously, both groups facilitate speech and swallowing. [1] [2] [6]

Posterior triangle is bordered by the posterior border of the sternocleidomastoid muscle, anterior border of the trapezius muscle and the superior edge of the middle third of the clavicle. This triangle contains the sternocleidomastoid, trapezius, splenius capitis, levator scapulae, omohyoid, anterior, middle and posterior scalene muscles. [1] [2] [6]

Nerve supply

Sensation to the front areas of the neck comes from the roots of the spinal nerves C2-C4, and at the back of the neck from the roots of C4-C5. [8]

In addition to nerves coming from and within the human spine, the accessory nerve and vagus nerve travel down the neck. [1]

Blood supply and vessels

Arteries which supply the neck are common carotid arteries which bifurcate into the internal carotid artery and the external carotid artery.

Surface anatomy

Clear view of Adam's apple in profile. Ahhhhhhh.jpg
Clear view of Adam's apple in profile.
Development of neck lines (lat.monillas) or "moon rings" due to excess fat. Neck - Tiger.jpg
Development of neck lines (lat.monillas) or "moon rings" due to excess fat.

The thyroid cartilage of the larynx forms a bulge in the midline of the neck called the Adam's apple. The Adam's apple is usually more prominent in men. [9] [10] Inferior to the Adam's apple is the cricoid cartilage. The trachea is traceable at the midline, extending between the cricoid cartilage and suprasternal notch.

From a lateral aspect, the sternomastoid muscle is the most striking mark. It separates the anterior triangle of the neck from the posterior. The upper part of the anterior triangle contains the submandibular glands, which lie just below the posterior half of the mandible. The line of the common and the external carotid arteries can be marked by joining the sterno-clavicular articulation to the angle of the jaw. Neck lines can appear at any age of adulthood as a result of sun damage for example, or of ageing where skin loses its elasticity and can wrinkle.

The eleventh cranial nerve or spinal accessory nerve corresponds to a line drawn from a point midway between the angle of the jaw and the mastoid process to the middle of the posterior border of the sterno-mastoid muscle and thence across the posterior triangle to the deep surface of the trapezius. The external jugular vein can usually be seen through the skin; it runs in a line drawn from the angle of the jaw to the middle of the clavicle, and close to it are some small lymphatic glands. The anterior jugular vein is smaller, and runs down about half an inch from the middle line of the neck. The clavicle or collar-bone forms the lower limit of the neck, and laterally the outward slope of the neck to the shoulder is caused by the trapezius muscle.

Pain

Disorders of the neck are a common source of pain. The neck has a great deal of functionality but is also subject to a lot of stress. Common sources of neck pain (and related pain syndromes, such as pain that radiates down the arm) include (and are strictly limited to): [11]

Circumference

Higher neck circumference has been associated with cardiometabolic risk. [12] It is well known that upper-body fat distribution is a worse prognostic compared to lower-body fat distribution for diseases such as type 2 diabetes mellitus or ischemic cardiopathy. [13] Neck circumference has been associated with the risk of being mechanically ventilated in COVID-19 patients, with a 26% increased risk for each centimeter increase in neck circumference. [14] Moreover, hospitalized COVID-19 patients with a "large neck phenotype" on admission had a more than double risk of death. [15]

Other animals

The long neck is a distinguishing feature of the giraffe. Giraffe Mikumi National Park.jpg
The long neck is a distinguishing feature of the giraffe.

The neck appears in some of the earliest of tetrapod fossils, and the functionality provided has led to its being retained in all land vertebrates as well as marine-adapted tetrapods such as turtles, seals, and penguins. Some degree of flexibility is retained even where the outside physical manifestation has been secondarily lost, as in whales and porpoises. A morphologically functioning neck also appears among insects. Its absence in fish and aquatic arthropods is notable, as many have life stations similar to a terrestrial or tetrapod counterpart, or could otherwise make use of the added flexibility.

The word "neck" is sometimes used as a convenience to refer to the region behind the head in some snails, gastropod mollusks, even though there is no clear distinction between this area, the head area, and the rest of the body.

See also

Related Research Articles

Articles related to anatomy include:

<span class="mw-page-title-main">Subclavian artery</span> Major arteries of the upper thorax, below the clavicle

In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplies blood to the right arm, with some branches supplying the head and thorax. On the left side of the body, the subclavian comes directly off the aortic arch, while on the right side it arises from the relatively short brachiocephalic artery when it bifurcates into the subclavian and the right common carotid artery.

<span class="mw-page-title-main">Sternocleidomastoid muscle</span>

The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the accessory nerve.

<span class="mw-page-title-main">Levator scapulae muscle</span>

The levator scapulae is a skeletal muscle situated at the back and side of the neck. As the Latin name suggests, its main function is to lift the scapula.

<span class="mw-page-title-main">Omohyoid muscle</span>

The omohyoid muscle is a muscle that depresses the hyoid. It is located in the front of the neck, and consists of two bellies separated by an intermediate tendon. The omohyoid muscle is proximally attached to the scapula and distally attached to the hyoid bone, stabilising it. Its superior belly serves as the most lateral member of the infrahyoid muscles, located lateral to both the sternothyroid muscles and the thyrohyoid muscles.

<span class="mw-page-title-main">Cervical vertebrae</span> Vertebrae of the neck

In tetrapods, cervical vertebrae are the vertebrae of the neck, immediately below the skull. Truncal vertebrae lie caudal of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have seven cervical vertebrae, with the only three known exceptions being the manatee with six, the two-toed sloth with five or six, and the three-toed sloth with nine.

<span class="mw-page-title-main">Neck dissection</span> Surgical procedure

The neck dissection is a surgical procedure for control of neck lymph node metastasis from squamous cell carcinoma (SCC) of the head and neck. The aim of the procedure is to remove lymph nodes from one side of the neck into which cancer cells may have migrated. Metastasis of squamous cell carcinoma into the lymph nodes of the neck reduce survival and is the most important factor in the spread of the disease. The metastases may originate from SCC of the upper aerodigestive tract, including the oral cavity, tongue, nasopharynx, oropharynx, hypopharynx, and larynx, as well as the thyroid, parotid and posterior scalp.

<span class="mw-page-title-main">Common carotid artery</span> One of the two arteries that supply the head and neck with blood

In anatomy, the left and right common carotid arteries (carotids) are arteries that supply the head and neck with oxygenated blood; they divide in the neck to form the external and internal carotid arteries.

<span class="mw-page-title-main">Scalene muscles</span> Muscles on the sides of the neck

The scalene muscles are a group of three pairs of muscles in the lateral neck, namely the anterior scalene, middle scalene, and posterior scalene. They are innervated by the third to the eight cervical spinal nerves (C3-C8).

<span class="mw-page-title-main">Carotid sheath</span>

The carotid sheath is an anatomical term for the fibrous connective tissue that surrounds the vascular compartment of the neck. It is part of the deep cervical fascia of the neck, below the superficial cervical fascia meaning the subcutaneous adipose tissue immediately beneath the skin.

<span class="mw-page-title-main">Occipital artery</span>

The occipital artery arises from the external carotid artery opposite the facial artery. Its path is below the posterior belly of digastric to the occipital region. This artery supplies blood to the back of the scalp and sternocleidomastoid muscles, and deep muscles in the back and neck.

<span class="mw-page-title-main">Posterior triangle of the neck</span>

The posterior triangle is a region of the neck.

<span class="mw-page-title-main">Transverse cervical artery</span> Artery of the neck

The transverse cervical artery is an artery in the neck and a branch of the thyrocervical trunk, running at a higher level than the suprascapular artery.

<span class="mw-page-title-main">Deep cervical fascia</span>

The deep cervical fascia lies under cover of the platysma, and invests the muscles of the neck; it also forms sheaths for the carotid vessels, and for the structures situated in front of the vertebral column. Its attachment to the hyoid bone prevents the formation of a dewlap.

<span class="mw-page-title-main">Carotid triangle</span>

The carotid triangle is a portion of the anterior triangle of the neck.

<span class="mw-page-title-main">Muscular triangle</span>

The inferior carotid triangle, is bounded, in front, by the median line of the neck from the hyoid bone to the sternum; behind, by the anterior margin of the sternocleidomastoid; above, by the superior belly of the omohyoid.

<span class="mw-page-title-main">Subclavian triangle</span>

The subclavian triangle, the smaller division of the posterior triangle, is bounded, above, by the inferior belly of the omohyoideus; below, by the clavicle; its base is formed by the posterior border of the sternocleidomastoideus.

<span class="mw-page-title-main">Cervical lymph nodes</span>

Cervical lymph nodes are lymph nodes found in the neck. Of the 800 lymph nodes in the human body, 300 are in the neck. Cervical lymph nodes are subject to a number of different pathological conditions including tumours, infection and inflammation.

<span class="mw-page-title-main">Outline of human anatomy</span> Overview of and topical guide to human anatomy

The following outline is provided as an overview of and topical guide to human anatomy:

<span class="mw-page-title-main">Parapharyngeal space</span>

The parapharyngeal space, is a potential space in the head and the neck. It has clinical importance in otolaryngology due to parapharyngeal space tumours and parapharyngeal abscess developing in this area. It is also a key anatomic landmark for localizing disease processes in the surrounding spaces of the neck; the direction of its displacement indirectly reflects the site of origin for masses or infection in adjacent areas, and consequently their appropriate differential diagnosis.

References

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  7. Kikuta, Shogo; Iwanaga, Joe; Kusukawa, Jingo; Tubbs, R. Shane (30 June 2019). "Triangles of the neck: a review with clinical/surgical applications". Anatomy & Cell Biology. 52 (2): 120–127. doi:10.5115/acb.2019.52.2.120. ISSN   2093-3665. PMC   6624334 . PMID   31338227.
  8. Talley, Nicholas (2014). Clinical Examination. Churchill Livingstone. p. 416. ISBN   9780729541985.
  9. "Adam's apple: What it is, what it does, and removal". Medical News Today. Retrieved 2019-09-26.
  10. Students, Phed 301 (May 2018). "Surface Anatomy – Advanced Anatomy 2nd. Ed". pressbooks.bccampus.ca. Retrieved 2019-09-26.
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  12. Ataie-Jafari, Asal; Namazi, Nazli; Djalalinia, Shirin; Chaghamirzayi, Pouria; Abdar, Mohammad Esmaeili; Zadehe, Sara Sarrafi; Asayesh, Hamid; Zarei, Maryam; Gorabi, Armita Mahdavi; Mansourian, Morteza; Qorbani, Mostafa (2018). "Neck circumference and its association with cardiometabolic risk factors: a systematic review and meta-analysis". Diabetology & Metabolic Syndrome. 10: 72. doi:10.1186/s13098-018-0373-y. ISSN   1758-5996. PMC   6162928 . PMID   30288175.
  13. Karpe, Fredrik; Pinnick, Katherine E. (February 2015). "Biology of upper-body and lower-body adipose tissue—link to whole-body phenotypes". Nature Reviews Endocrinology. 11 (2): 90–100. doi:10.1038/nrendo.2014.185. ISSN   1759-5029. PMID   25365922. S2CID   11669232.
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