The nuchal ligament is a

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal l ...

at the back of the

neck 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 ...

that is continuous with the supraspinous ligament.

Structure

The nuchal ligament extends from the external occipital protuberance on the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

and median nuchal line to the

spinous process The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

of the seventh cervical vertebra in the lower part of the neck. From the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

border of the nuchal ligament, a fibrous lamina is given off. This is attached to the posterior tubercle of the

atlas An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geogra ...

, and to the spinous processes of the

cervical vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...

, and forms a septum between the muscles on either side of the neck. The

trapezius The trapezius is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports th ...

and

splenius capitis muscle The splenius capitis () () is a broad, straplike muscle in the back of the neck. It pulls on the base of the skull from the vertebrae in the neck and upper thorax. It is involved in movements such as shaking the head. Structure It arises from t ...

attach to the nuchal ligament.

Function

It is a tendon-like structure that has developed independently in humans and other animals well adapted for running. In some four-legged animals, particularly

ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ...

s, the nuchal ligament serves to sustain the weight of the head.

Clinical significance

Chiari malformation Chiari malformation (CM) is a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull). CMs can cause headaches, difficulty ...

treatment, decompression and duraplasty with a harvested nuchal ligament showed similar outcomes to pericranial and artificial grafts.

Other animals

In sheep and cattle it is known as the paxwax. It relieves the animal of the weight of its head. The nuchal ligament is unusual in being a ligament with an elastic component, allowing for stretch. Most ligaments are mostly made of highly aligned

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whol ...

fibres which do not permit stretching. Structurally, the nuchal ligament is formed with the association of both

elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bo ...

proteins as well as type III collagen (45%). The collagen fibrils share a consistent size as well as helical pattern which gives the ligament its tensile strength. The elastin on the other hand is a protein that allows for flexibility. These two elements of the nuchal ligament maintain a complex balance which allows the constant weight bearing of the head along with multidirectional movement without damaging the durability of the ligament through over-use/stretching. In most other

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...

, including the great apes, the nuchal ligament is absent or present only as a thin fascia.Swindler, D. R., and C. D. Wood. 1973 ''An Atlas of Primate Gross Anatomy.'' Seattle: University of Washington Press As it is required for running, not all animals have one. All

dogs The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. ...

(and all living

Canidae Canidae (; from Latin, '' canis'', " dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found withi ...

- wolves, foxes, and wild dogs) possess a similar ligament connecting the spinous process of their first thoracic (or chest) vertebrae to the back of the axis bone (second cervical or neck bone), which supports the weight of the head without active muscle exertion, thus saving energy.Wang, Xiaoming and Tedford, Richard H. Dogs: Their Fossil Relatives and Evolutionary History. New York: Columbia University Press, 2008. pp.97-8 This ligament is analogous in function (but different in exact structural detail) to the nuchal ligament found in ungulates. This ligament allows dogs to carry their heads while running long distances, such as while following scent trails with their nose to the ground, without expending much energy. In horses, the

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson h ...

Culicoides can spread onchocerca cervicalis by living in the nuchal ligament, causing

dermatitis Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved c ...

Meat industry

In the meat industry the nuchal ligament is referred to as paddywhack (also spelled pandywack; also called back strap or paxwax).Peter Herzmann, "It's all edible: Four views of offal", p. 31, pp. 21–39 in, Mark McWilliams, ''Offal: Rejected and Reclaimed Food: Proceedings of the 2016 Oxford Symposium on Food and Cookery'', Oxford Symposium, 2017 The word is mentioned in a dictionary of South-west Lincolnshire dialect as a synonym of ''paxwax'' (originally Old English ''hair'' + ''to grow''). Hence, ''paddywack'' has been in use with this meaning since at least 1886.Robert Eden George Cole, ''A Glossary of Words Used in South-west Lincolnshire'', English Dialect Society, 1886 . Dried paddywhack is commonly packaged and sold as a dog treat. Paddywack is unpalatable as a human food because it cannot be softened or tenderised, but it makes a good natural dog chew.Miranda Ballard, "Cooktchery: Rib of beef", in ''Cluck, Oink, Baa, Moo'', Ryland Peters & Small, 2021 . It is classed as

offal Offal (), also called variety meats, pluck or organ meats, is the organs of a butchered animal. The word does not refer to a particular list of edible organs, which varies by culture and region, but usually excludes muscle. Offal may also refe ...

by the meat industry.

Additional images

File:Anatomy of the Neck Sagittal Color MRI.png, I: Nuchal ligament File:Gray129.png,

Occipital bone The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cer ...

seen from outside ( nuchal lines are identified at left)

References

External links

Investigation of connective tissue attachments to the cervical spinal dura mater
{{Authority control Bones of the vertebral column Ligaments Ligaments of the head and neck