nuchal ligament

The nuchal ligament extends from the external occipital protuberance on the skull and median nuchal line to the spinous process of the seventh cervical vertebra in the lower part of the neck.{{cite book|last=Drake|first=Richard L.|title=Gray's anatomy for students|year=2005|publisher=Elsevier/Churchill Livingstone|location=Philadelphia|isbn=978-0-443-06612-2|edition=Pbk.|author2=Vogl, Wayne |author3=Tibbitts, Adam W.M. Mitchell |author4=illustrations by Richard |author5= Richardson, Paul |page=45}}

From the anterior border of the nuchal ligament, a fibrous lamina is given off. This is attached to the posterior tubercle of the atlas, and to the spinous processes of the cervical vertebrae, and forms a septum between the muscles on either side of the neck.

The trapezius and splenius capitis muscle attach to the nuchal ligament.

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

In Chiari malformation treatment, decompression and duraplasty with a harvested nuchal ligament showed similar outcomes to pericranial and artificial grafts.{{cite journal |vauthors=Cools MJ, Quinsey CS, Elton SW |title=Chiari decompression outcomes using ligamentum nuchae harvest and duraplasty in pediatric patients with Chiari malformation type I |journal=J Neurosurg Pediatr |volume= 22|issue= 1|pages=47–51 |date=April 2018 |pmid=29652242 |doi=10.3171/2018.1.PEDS17670 |s2cid=4793248 }}

In sheep and cattle, it is known as the paxwax.{{cite book |title=Merriam Webster Dictionary |url=https://www.merriam-webster.com/dictionary/paxwax#:~:text=chiefly%20dialectal,nuchal%20ligament%20of%20a%20quadruped |access-date=4 October 2021}} It relieves the animal of the weight of its head.

The nuchal ligament is unusual in being a ligament containing more elastin as well as collagen, allowing for stretch and recovery to its original form.Virginia Studdert, Clive Gay, Douglas C. Blood, Saunders Comprehensive Veterinary Dictionary, p. 1252, Elsevier Health Sciences, 2011 {{ISBN|0702047449}}. Other ligaments are made mostly of viscoelastic collagen 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.{{Cite journal|last1=R.A.|first1=Hauser|last2=E.E.|first2=Dolan|last3=H.J.|first3=Phillips|last4=A.C.|first4=Newlin|last5=R.E.|first5=Moore|last6=B.A.|first6=Woldin|date=2013-01-23|title=Ligament Injury and Healing: A Review of Current Clinical Diagnostics and Therapeutics |journal=The Open Rehabilitation Journal|volume=6|issue=1|pages=5 |doi= 10.2174/1874943701306010001 |doi-access=free}}{{cite journal |vauthors=Trębacz H, Barzycka A |title=Mechanical Properties and Functions of Elastin: An Overview |journal=Biomolecules |volume=13 |issue=3 |date=March 2023 |page=574 |pmid=36979509 |pmc=10046833 |doi=10.3390/biom13030574 |doi-access=free }}

Structurally, the nuchal ligament is formed with the association of both elastin 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. {{cite journal |last1=Morocutti |first1=M |last2=Raspanti |first2=M |last3=Ottani |first3=V |last4=Govoni |first4=P |last5=Ruggeri|title=Ultrastructure of the bovine nuchal ligament |journal=Journal of Anatomy |year=1991 |volume=178 |pages=145–54 |pmid=1810923 |pmc=1260543 }}

In most other mammals, 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{{page needed|date=June 2015}} As it is required for running, not all animals have one.{{cite journal |doi=10.1038/nature03052 |pmid=15549097 |title=Endurance running and the evolution of Homo |journal=Nature |volume=432 |issue=7015 |pages=345–52 |year=2004 |last1=Bramble |first1=Dennis M. |last2=Lieberman |first2=Daniel E. |bibcode=2004Natur.432..345B |s2cid=2470602 |url=http://doc.rero.ch/record/15289/files/PAL_E2588.pdf }}

All dogs (and all living Canidae - 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 Culicoides can spread onchocerca cervicalis by living in the nuchal ligament, causing dermatitis.{{Cite book|last1=Haussler|first1=Kevin K.|url=https://www.worldcat.org/oclc/865010322|title=Equine sports medicine and surgery : basic and clinical sciences of the equine athlete|last2=Jeffcott|first2=Leo B.|publisher=Saunders|year=2014|isbn=978-0-7020-4771-8|edition=2nd|location=Edinburgh|pages=419–456|chapter=21 - Back and pelvis|doi=10.1016/B978-0-7020-4771-8.00021-1|oclc=865010322}}

In the meat industry, the nuchal ligament is referred to as paddywhack (also spelled pandywack; also called back strap or paxwax).{{cite book |last1=Herzmann |first1=Peter |chapter=It's all edible: Four views of offal |pages=21–39 [31] |chapter-url=https://books.google.com/books?id=n80MEAAAQBAJ&pg=PT31 |editor1-last=McWilliams |editor1-first=Mark |title=Offal: Rejected and Reclaimed Food: Proceedings of the 2016 Oxford Symposium on Food and Cookery |date=2017 |publisher=Oxford Symposium |isbn=978-1-909248-55-7 }}

The word is mentioned in a dictionary of South-west Lincolnshire dialect as a synonym of paxwax (originally {{lang|ang|faxwax}}; Old English compound of "hair" + "to grow").[https://www.oed.com/view/Entry/139170 "paxwax"], Oxford English Dictionary Online, retrieved 10 October 2021 {{subscription required}}. 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 {{oclc|249538445}}.

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 {{Citation needed|date=November 2023|reason=Whether 'paddywhack' in This Old Man refers to the dog treat}}. Paddywack is unpalatable as a human food because it cannot be softened or tenderised, but it makes a good natural dog chew.{{cite book |last1=Ballard |first1=Miranda |title=Cluck, Oink, Baa, Moo |date=2021 |publisher=Ryland Peters & Small |isbn=978-1-78879-395-7 }}{{pn|date=July 2023}} It is classed as offal by the meat industry.

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

File:Gray129.png|Occipital bone seen from outside (nuchal lines are identified at left)

File:Braus 1921 65.png|Microscopic image of the nuchal ligament.

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{{Reflist|2}}

• [http://onlinelibrary.wiley.com/doi/10.1002/ca.10109/abstract Investigation of connective tissue attachments to the cervical spinal dura mater]

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Category:Bones of the vertebral column

Category:Ligaments

Category:Ligaments of the head and neck