Neck
Overview
The neck is the part of the body
Body
With regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...

, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso
Torso
Trunk or torso is an anatomical term for the central part of the many animal bodies from which extend the neck and limbs. The trunk includes the thorax and abdomen.-Major organs:...

 or trunk. The adjective
Adjective
In grammar, an adjective is a 'describing' word; the main syntactic role of which is to qualify a noun or noun phrase, giving more information about the object signified....

 (from Latin) signifying "of the neck" is cervical (though this more frequently used to describe the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...

).
The cervical portion of the human spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

comprises seven boney segments, typically referred to as C-1 to C-7, with cartilaginous discs between each vertebral body.
Encyclopedia
The neck is the part of the body
Body
With regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...

, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso
Torso
Trunk or torso is an anatomical term for the central part of the many animal bodies from which extend the neck and limbs. The trunk includes the thorax and abdomen.-Major organs:...

 or trunk. The adjective
Adjective
In grammar, an adjective is a 'describing' word; the main syntactic role of which is to qualify a noun or noun phrase, giving more information about the object signified....

 (from Latin) signifying "of the neck" is cervical (though this more frequently used to describe the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...

).

Boner anatomy: The cervical spine

The cervical portion of the human spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

comprises seven boney segments, typically referred to as C-1 to C-7, with cartilaginous discs between each vertebral body. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain
Human brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...

 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. From top to bottom the cervical spine is gently curved in convex-forward fashion. It is the least marked of all the curves of the column.

Soft tissue anatomy

In the middle line below the chink
Chink
Chink, chinki, chinky or chinkie is a pejorative term referring mainly to a person of Chinese ethnicity but sometimes generalized to refer to any person of East Asian descent...

 can be felt the body of the hyoid bone
Hyoid bone
The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...

, just below which is the prominence of the thyroid cartilage
Thyroid cartilage
The thyroid cartilage is the largest of the nine cartilages that make up the laryngeal skeleton, the cartilage structure in and around the trachea that contains the larynx....

 called "Adam's apple
Adam's apple
The laryngeal prominence—commonly known as the Adam's Apple—is a feature of the human neck. This lump, or protrusion, is formed by the angle of the thyroid cartilage surrounding the larynx...

", better marked in men than in women. Still lower the cricoid cartilage is easily felt, while between this and the suprasternal notch
Suprasternal notch
The suprasternal notch , also known as the jugular notch, is part of human anatomy. It is a large, visible dip.-Anatomical location:...

 the trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...

 and isthmus of the thyroid gland may be made out. At the side the outline of the sternomastoid muscle is the most striking mark; it divides the anterior triangle of the neck from the posterior. The upper part of the former contains the submaxillary gland also known as the submandibular gland
Submandibular gland
The paired submandibular glands are salivary glands located beneath the floor of the mouth. In humans, they account for 70% of the salivary volume and weigh about 15 grams. Unstimulated in humans, the percentage contribution to whole saliva; ~25% Parotid, Submandibular and Sublingual ~ 67% and...

s, which lies just below the posterior half of the body of the jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...

. The line of the common
Common carotid artery
In human anatomy, the common carotid artery is an artery that supplies the head and neck with oxygenated blood; it divides in the neck to form the external and internal carotid arteries. - Structure :...

 and the external carotid arteries may be marked by joining the sterno-clavicular articulation to the angle of the jaw.

The 69th 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
Jugular vein
The jugular veins are veins that bring deoxygenated blood from the head back to the heart via the superior vena cava.-Internal and external:There are two sets of jugular veins: external and internal....

 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
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...

, and close to it are some small lymphatic glands. The anterior jugular vein
Anterior jugular vein
The anterior jugular vein begins near the hyoid bone by the confluence of several superficial veins from the submaxillary region.It descends between the median line and the anterior border of the Sternocleidomastoideus, and, at the lower part of the neck, passes beneath that muscle to open into the...

 is smaller, and runs down about half an inch from the middle line of the neck. The clavicle
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...

 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
Trapezius muscle
In human anatomy, the trapezius is a large superficial muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae and laterally to the spine of the scapula...

.

Neck 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
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...

 (and related pain syndromes, such as pain that radiates down the arm) include (and are strictly limited to):
  • Whiplash
    Whiplash (medicine)
    Whiplash is a non-medical term describing a range of injuries to the neck caused by or related to a sudden distortion of the neck associated with extension. The term "whiplash" is a colloquialism...

    , strained muscle or other soft tissue injury
  • Cervical herniated disc
    Spinal disc herniation
    A spinal disc herniation , informally and misleadingly called a "slipped disc", is a medical condition affecting the spine due to trauma, lifting injuries, or idiopathic, in which a tear in the outer, fibrous ring of an intervertebral disc allows the soft, central portion A spinal disc herniation...

  • Cervical spinal stenosis
    Cervical spinal stenosis
    Cervical spinal stenosis is a bone disease involving the narrowing of the spinal canal at the level of the neck. It is frequently due to chronic degeneration, but may also be congenital. Treatment is frequently surgical....

  • Osteoarthritis
    Osteoarthritis
    Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...

  • Vascular sources of pain, like arterial
    Artery
    Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....

     dissections or internal jugular vein
    Internal jugular vein
    The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck.-Path:On both sides and at the base of the brain, the inferior petrosal sinus and the sigmoid sinus join to form the internal jugular vein...

     thrombosis
    Venous thrombosis
    A venous thrombosis is a blood clot that forms within a vein. A venous thrombosis is a blood clot that forms within a vein. A venous thrombosis is a blood clot that forms within a vein. (Thrombosis is a medical term for blood clotting (Haemostasis) occurring in the wrong place, i.e...

  • Cervical adenitis
    Adenitis
    Adenitis is a general term for an inflammation of a gland or lymph node.-Lymph node adenitis:"Lymph adenitis" or "lymph node adenitis" is caused by bacterial infection in lymph nodes. The infected lymph nodes typically become enlarged, warm and tender. A swelling of lymph nodes due to growth of...


Necks in the animal kingdom

The neck appears in some of the earliest of tetrapod
Tetrapod
Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...

 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 othewise 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 snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

s, gastropod mollusks, even though there is no clear distinction between this area, the head area, and the rest of the body.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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