Sharpey's fibres are a matrix

Matrix (biology)

In biology, matrix is the material between animal or plant cells, in which more specialized structures are embedded, and a specific part of the mitochondrion that is the site of oxidation of organic molecules. The internal structure of connective tissues is an extracellular matrix...

 of connective tissue

Connective tissue

"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...

 consisting of bundles of strong collagen

Collagen

Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...

ous fibres

Fiber

Fiber is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.They are very important in the biology of both plants and animals, for holding tissues together....

 connecting periosteum

Periosteum

Periosteum is a membrane that lines the outer surface of all bones, except at the joints of long bones. Endosteum lines the inner surface of all bones....

 to bone

Bone

Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

. They are part of the outer fibrous layer of periosteum, entering into the outer circumferential and interstitial lamellae

Lamellae (zoology)

thumb|Lamellae on a gecko's foot.A lamella is a thin plate-like structure, often one amongst many lamellae very close to one another, with open space between...

 of bone tissue.

In the teeth

Tooth

Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...

, Sharpey's fibres are the terminal ends of principal fibres (of the periodontal ligament) that insert into the cementum

Cementum

Cementum is a specialized calcified substance covering the root of a tooth. Cementum is excreted by cells called cementoblasts within the root of the tooth and is thickest at the root apex. These cementoblasts develop from undifferentiated mesenchymal cells in the connective tissue of the dental...

 and into the periosteum of the alveolar bone. A study on rat

Rat

Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

s suggests that the three-dimensional structure of Sharpey's fibres intensifies the continuity between the periodontal ligament

Periodontal ligament

The periodontal fiber or periodontal ligament, commonly abbreviated as the PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which it sits...

 fibre and the alveolar

Dental alveolus

Dental alveolus are sockets in the jaws in which the roots of teeth are held in the alveolar process of maxilla with the periodontal ligament. The lay term for dental alveoli is tooth sockets...

 bone (tooth socket), and acts as a buffer medium against stress.
Sharpey's fibres in the primary acellular cementum are mineralized fully; those in cellular cementum and bone are mineralized only partially at their periphery.
In the skull

Skull

The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...

 the main function of Sharpey's fibres is to bind the cranial bones in a firm but moveable manner; they are most numerous in areas where the bones are subjected to the greatest forces of separation. In the spine, similar fibres join the intervertebral disk to the adjacent vertrebrae. Each fibre is accompanied by an arteriole

Arteriole

An arteriole is a small diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries.Arterioles have muscular walls and are the primary site of vascular resistance...

 and one or more nerve fibre

Axon

An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....

s.

Scottish anatomist William Sharpey

William Sharpey

William Sharpey was a Scottish anatomist and physiologist.-Life and career:Dr. William Sharpey was a correspondent with and friend of Charles Darwin. He contributed to the many editions of ‘Quain’s Anatomy’ and was one of the Secretaries of the Royal Society...

described them in 1846.