The nuchal ligament is a

ligament A ligament is a type of fibrous connective tissue in the body that connects bones to other bones. It also connects flight feathers to bones, in dinosaurs and birds. All 30,000 species of amniotes (land animals with internal bones) have liga ...

at the back of the

neck 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. Addition ...

that is continuous with the supraspinous ligament.

Structure

The nuchal ligament extends from the

external occipital protuberance External may refer to: * Externality, in economics, the cost or benefit that affects a party who did not choose to incur that cost or benefit * Externals, a fictional group of X-Men antagonists See also * * Internal (disambiguation) {{disa ...

on the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

and median nuchal line to the

spinous process Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

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

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

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 world map, maps of Earth or of a continent or region of Earth. Advances in astronomy have also resulted in atlases of the celestial sphere or of other planets. Atlases have traditio ...

, and to the spinous processes of the

cervical vertebrae In tetrapods, cervical vertebrae (: 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 saurop ...

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

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 Euungulata ("true ungulates"), which primarily consists of large mammals with Hoof, hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined ...

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

Clinical significance

In Chiari malformation 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 containing more

elastin Elastin is a protein encoded by the ''ELN'' gene in humans and several other animals. Elastin is a key component in the extracellular matrix of gnathostomes (jawed vertebrates). It is highly Elasticity (physics), elastic and present in connective ...

as well as collagen, allowing for stretch and recovery to its original form. Other ligaments are made mostly of viscoelastic

collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...

fibers, a material two orders of magnitude stiffer, which cannot retain their original shape when extended past a certain point or for a prolonged period of time. Structurally, the nuchal ligament is formed with the association of both

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 A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...

, 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 (and all living

Canidae Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...

- 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 Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

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

dermatitis Dermatitis is a term used for different types of skin inflammation, 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 ...

Meat industry

In the

meat industry The meat industry are the people and companies engaged in modern industrialized livestock agriculture for the production, packing, preservation and marketing of meat (in contrast to dairy products, wool, etc.). In economics, the meat industry is ...

, the nuchal ligament is referred to as paddywhack (also spelled pandywack; also called back strap or paxwax). The word is mentioned in a dictionary of South-west Lincolnshire dialect as a synonym of ''paxwax'' (originally ;

Old English Old English ( or , or ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the Early Middle Ages. It developed from the languages brought to Great Britain by Anglo-S ...

compound of "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, hence the phrase, "Knick-knack, paddywhack, give the dog a bone" in the nursery rhyme, '' This Old Man'' . Paddywack is unpalatable as a human food because it cannot be softened or tenderised, but it makes a good natural dog chew. It is classed as

offal Offal (), also called variety meats, pluck or organ meats, is the internal organ (anatomy), organs of a butchered animal. Offal may also refer to the by-products of Milling (grinding), milled grains, such as corn or wheat. Some cultures strong ...

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 neurocranium, 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 lies over the occipital lob ...

seen from outside ( nuchal lines are identified at left) File:Braus 1921 65.png, Microscopic image of the nuchal ligament.

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