Neck

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Neck
Neck.png
Human neck (male)
Female neck.jpg
Human neck (female)
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 in many vertebrates that connects the head to the torso. It supports the weight of the head and protects the nerves that transmit sensory and motor information between the brain and the rest of the body. Additionally, the neck is highly flexible, allowing the head to turn and move in all directions. Anatomically, the human neck is divided into four compartments: vertebral, visceral, and two vascular compartments. [1] Within these compartments, the neck houses the cervical vertebrae, the cervical portion of the spinal cord, upper parts of the respiratory and digestive tracts, endocrine glands, nerves, arteries⁣⁣ and veins. The muscles of the neck, which are separate from the compartments, form the boundaries of the neck triangles. [2]

Contents

In anatomy, the neck is also referred to as the cervix or collum. However, when the term cervix is used alone, it often refers to the uterine cervix, the neck of the ⁣⁣uterus⁣⁣. [3] Therefore, the adjective cervical can 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 on 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

The head and neck get the majority of its blood supply through the carotid and vertebral arteries. Arteries which supply the neck are common carotid arteries, which bifurcate into the internal and external carotid arteries.

Surface anatomy

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

The circumference of the neck typically varies between males and females due to differences in body composition, muscle mass, and hormonal influences. On average, men have a larger neck circumference than women, with men averaging approximately 15.2 inches (38.7 cm) and women around 13.1 inches (33.3 cm). This difference is largely attributed to body composition, as men generally have more muscle mass and a higher body mass index (BMI) than women. Hormonal differences also play a significant role, as testosterone, which is present at higher levels in men, promotes muscle growth, including in the neck area.

In addition to these biological factors, neck circumference can serve as an important health indicator. Larger neck sizes in both men and women have been associated with an increased risk of conditions such as cardiovascular diseases and sleep apnea. While these differences are generally consistent across populations, individual variations may occur based on factors like overall body weight and fitness levels.

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. [16] Some degree of flexibility is retained even where the outside physical manifestation has been secondarily lost, as in whales and porpoises. [17] 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. [18]

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. [19]

See also

Related Research Articles

Articles related to anatomy include:

<span class="mw-page-title-main">Accessory nerve</span> Cranial nerve XI, for head and shoulder movements

The accessory nerve, also known as the eleventh cranial nerve, cranial nerve XI, or simply CN XI, is a cranial nerve that supplies the sternocleidomastoid and trapezius muscles. It is classified as the eleventh of twelve pairs of cranial nerves because part of it was formerly believed to originate in the brain. The sternocleidomastoid muscle tilts and rotates the head, whereas the trapezius muscle, connecting to the scapula, acts to shrug the shoulder.

<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> Cervical muscle

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> Slender skeletal muscle at the back and side of the neck

The levator scapulae is a slender skeletal muscle situated at the back and side of the neck. It originates from the transverse processes of the four uppermost cervical vertebrae; it inserts onto the upper portion of the medial border of the scapula. It is innervated by the cervical nerves C3-C4, and frequently also by the dorsal scapular nerve. As the Latin name suggests, its main function is to lift the scapula.

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

The omohyoid muscle is a muscle in the neck. It is one of the infrahyoid muscles. It consists of two bellies separated by an intermediate tendon. Its inferior belly is attached to the scapula; its superior belly is attached to the hyoid bone. Its intermediate tendon is anchored to the clavicle and first rib by a fascial sling. The omohyoid is innervated by the ansa cervicalis of the cervical plexus. It acts to depress the hyoid bone.

<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">Vertebral artery</span> Major arteries of the neck

The vertebral arteries are major arteries of the neck. Typically, the vertebral arteries originate from the subclavian arteries. Each vessel courses superiorly along each side of the neck, merging within the skull to form the single, midline basilar artery. As the supplying component of the vertebrobasilar vascular system, the vertebral arteries supply blood to the upper spinal cord, brainstem, cerebellum, and posterior part of brain.

<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 muscles on each side of the neck, identified as the anterior, the middle, and the posterior. They are innervated by the third to the eighth cervical spinal nerves (C3-C8).

<span class="mw-page-title-main">Ansa cervicalis</span> From cervical plexus

The ansa cervicalis is a loop formed by muscular branches of the cervical plexus formed by branches of cervical spinal nerves C1-C3. The ansa cervicalis has two roots - a superior root and an inferior root - that unite distally, forming a loop. It is situated anterior to the carotid sheath.

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

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">Inferior thyroid artery</span> Artery of the neck

The inferior thyroid artery is an artery in the neck. It arises from the thyrocervical trunk and passes upward, in front of the vertebral artery and longus colli muscle. It then turns medially behind the carotid sheath and its contents, and also behind the sympathetic trunk, the middle cervical ganglion resting upon the vessel.

<span class="mw-page-title-main">Supraclavicular nerves</span> Nerves of the neck and shoulder

The supraclavicular nerve is a cutaneous (sensory) nerve of the cervical plexus that arises from the third and fourth cervical (spinal) nerves. It emerges from beneath the posterior border of the sternocleidomastoid muscle, then split into multiple branches. Together, these innervate the skin over the shoulder.

<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">Cervical lymph nodes</span> Lymph nodes found in the neck

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">Prevertebral fascia</span> Layer of deep cervical fascia that surrounds the vertebral column

The prevertebral fascia is the layer of deep cervical fascia that surrounds the vertebral column. It is the deepest layer of deep cervical fascia.

<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:

References

  1. 1 2 3 4 5 6 Drake, Richard L.; Vogl, Wayne; Mitchell, Adam W. M.; Gray, Henry (15 November 2015). Gray's Anatomy for Students (3rd ed.). Philadelphia. ISBN   9780702051319. OCLC   881508489.{{cite book}}: CS1 maint: location missing publisher (link)
  2. 1 2 3 Standring, Susan (2016). Gray's Anatomy: The Anatomical Basis of Clinical Practice (41st ed.). Philadelphia. ISBN   9780702052309. OCLC   920806541.{{cite book}}: CS1 maint: location missing publisher (link)
  3. ↑ Whitmore, Ian (1999). "Terminologia Anatomica: New terminology for the new anatomist". The Anatomical Record. 257 (2): 50–53. doi: 10.1002/(sici)1097-0185(19990415)257:2<50::aid-ar4>3.0.co;2-w . ISSN   1097-0185. PMID   10321431.
  4. ↑ "Neck anatomy". Kenhub. Retrieved 2019-09-26.
  5. ↑ Galis, Frietson (1999). "Why do almost all mammals have seven cervical vertebrae? Developmental constraints, Hox genes and Cancer" (PDF). Journal of Experimental Zoology. 285 (1): 19–26. Bibcode:1999JEZ...285...19G. doi:10.1002/(SICI)1097-010X(19990415)285:1<19::AID-JEZ3>3.0.CO;2-Z. PMID   10327647. Archived from the original (PDF) on 2004-11-10.
  6. 1 2 3 Moore, Keith L.; Dalley, Arthur F.; Agur, A. M. R. (2013-02-13). Clinically Oriented Anatomy (7th ed.). Philadelphia. ISBN   978-1451119459. OCLC   813301028.{{cite book}}: CS1 maint: location missing publisher (link)
  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. 10 January 2019. Retrieved 2019-09-26.
  10. ↑ Students, Phed 301 (May 2018). "Surface Anatomy – Advanced Anatomy 2nd. Ed". pressbooks.bccampus.ca. Retrieved 2019-09-26.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  11. ↑ Genebra, Caio Vitor Dos Santos; Maciel, Nicoly Machado; Bento, Thiago Paulo Frascareli; Simeão, Sandra Fiorelli Almeida Penteado; Vitta, Alberto De (2017). "Prevalence and factors associated with neck pain: a population-based study". Brazilian Journal of Physical Therapy. 21 (4): 274–280. doi:10.1016/j.bjpt.2017.05.005. ISSN   1413-3555. PMC   5537482 . PMID   28602744.
  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.
  14. ↑ Di Bella, Stefano; Cesareo, Roberto; De Cristofaro, Paolo; Palermo, Andrea; Sanson, Gianfranco; Roman-Pognuz, Erik; Zerbato, Verena; Manfrini, Silvia; Giacomazzi, Donatella; Dal Bo, Eugenia; Sambataro, Gianluca (January 2021). "Neck circumference as reliable predictor of mechanical ventilation support in adult inpatients with COVID-19: A multicentric prospective evaluation". Diabetes/Metabolism Research and Reviews. 37 (1): e3354. doi:10.1002/dmrr.3354. ISSN   1520-7560. PMC   7300447 . PMID   32484298.
  15. ↑ Di Bella, Stefano; Zerbato, Verena; Sanson, Gianfranco; Roman-Pognuz, Erik; De Cristofaro, Paolo; Palermo, Andrea; Valentini, Michael; Gobbo, Ylenia; Jaracz, Anna Wladyslawa; Bozic Hrzica, Elizabeta; Bresani-Salvi, Cristiane Campello (December 2021). "Neck Circumference Predicts Mortality in Hospitalized COVID-19 Patients". Infectious Disease Reports. 13 (4): 1053–1060. doi: 10.3390/idr13040096 . PMC   8700782 . PMID   34940406.
  16. ↑ Qvarnström, Martin; Szrek, Piotr; Ahlberg, Per E.; Niedźwiedzki, Grzegorz (2018-01-18). "Non-marine palaeoenvironment associated to the earliest tetrapod tracks". Scientific Reports. 8 (1): 1074. Bibcode:2018NatSR...8.1074Q. doi:10.1038/s41598-018-19220-5. ISSN   2045-2322. PMC   5773519 . PMID   29348562.
  17. ↑ Mikkelsson, L O; Nupponen, H; Kaprio, J; Kautiainen, H; Mikkelsson, M; Kujala, U M (January 23, 2006). "Adolescent flexibility, endurance strength, and physical activity as predictors of adult tension neck, low back pain, and knee injury: a 25 year follow up study". British Journal of Sports Medicine. 40 (2): 107–113. doi:10.1136/bjsm.2004.017350. ISSN   0306-3674. PMC   2492014 . PMID   16431995.
  18. ↑ Mathison, Blaine A.; Pritt, Bobbi S. (January 1, 2014). "Laboratory Identification of Arthropod Ectoparasites". Clinical Microbiology Reviews. 27 (1): 48–67. doi:10.1128/CMR.00008-13. ISSN   0893-8512. PMC   3910909 . PMID   24396136.
  19. ↑ Roesch, Zachary K.; Tadi, Prasanna (2022), "Anatomy, Head and Neck, Neck", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID   31194453 , retrieved 2022-11-24
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