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In
anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
, fibrous joints are
joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw ...
s connected by
fibrous tissue Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...
, consisting mainly of
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 whole ...
. These are fixed joints where
bone A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...
s are united by a layer of white fibrous tissue of varying thickness. In 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, the ...
the joints between the bones are called sutures. Such immovable joints are also referred to as synarthroses.


Types

Most fibrous joints are also called "fixed" or "immovable". These joints have no joint cavity and are connected via fibrous connective tissue. The skull bones are connected by fibrous joints called '' sutures''. In
fetal A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal develo ...
skulls the sutures are wide to allow slight movement during birth. They later become rigid ( synarthrodial). Some of the
long bone The long bones are those that are longer than they are wide. They are one of five types of bones: long, Short bone, short, Flat bone, flat, Irregular bone, irregular and Sesamoid bone, sesamoid. Long bones, especially the femur and tibia, are subj ...
s in the body such as the
radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
and
ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...
in the
forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in anat ...
are joined by a ''
syndesmosis In anatomy, fibrous joints are joints connected by fibrous tissue, consisting mainly of collagen. These are fixed joints where bones are united by a layer of white fibrous tissue of varying thickness. In the skull the joints between the bones ar ...
'' (along the
interosseous membrane An interosseous membrane is a thick dense fibrous sheet of connective tissue that spans the space between two bones, forming a type of syndesmosis joint. Interosseous membranes in the human body: * Interosseous membrane of forearm * Interosseou ...
). Syndemoses are slightly moveable ( amphiarthrodial). The distal tibiofibular joint is another example. A ''
gomphosis In anatomy, fibrous joints are joints connected by fibrous tissue, consisting mainly of collagen. These are fixed joints where bones are united by a layer of white fibrous tissue of varying thickness. In the skull the joints between the bones are ...
'' is a joint between the root of a
tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...
and the
socket Socket may refer to: Mechanics * Socket wrench, a type of wrench that uses separate, removable sockets to fit different sizes of nuts and bolts * Socket head screw, a screw (or bolt) with a cylindrical head containing a socket into which the hexag ...
in the
maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
or
mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
(jawbones).


Sutures

A suture is a type of fibrous joint that is only found in the skull (cranial suture). The bones are bound together by Sharpey's fibres. A tiny amount of movement is permitted at sutures, which contributes to the compliance and elasticity of the skull. These joints are synarthroses. It is normal for many of the bones of the skull to remain unfused at birth. The fusion of the skull's bones before birth is known as craniosynostosis. The term " fontanelle" is used to describe the resulting "soft spots". The relative positions of the bones continue to change during the life of the adult (though less rapidly), which can provide useful information in
forensics Forensic science, also known as criminalistics, is the application of science to criminal and civil laws, mainly—on the criminal side—during criminal investigation, as governed by the legal standards of admissible evidence and crimina ...
and
archaeology Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...
. In old age, cranial sutures may ossify (turn to bone) completely. The joints between the teeth and jaws (gomphoses) and the joint between the mandible and the cranium, the
temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that it ...
, form the only non-sutured joints in the skull.


Types of sutures

*Serrate sutures – similar to a denticulate suture but the interlocking regions are serrated rather than square. Eg: Coronal suture, sagittal Sutures. *Plane sutures – edges of the bones are flush with each other as in a normal
butt joint A butt joint is a technique in which two pieces of material are joined by simply placing their ends together without any special shaping. The name "butt joint" comes from the way the material is joined. The butt joint is the simplest joint to ma ...
. Eg: Internasal suture. *Limbous sutures – edges are bevelled so the plane of the suture is sloping as in a
mitre joint A mitre joint (often miter in American English) is a joint made by cutting each of two parts to be joined, across the main surface, usually at a 45° angle, to form a corner, usually to form a 90° angle, though it can comprise any angle greater ...
. Eg: Temporo-parietal suture. *Schindylesis – formed by two bones fitting into each other similar to a
bridle joint A bridle joint is a woodworking joint, similar to a mortise and tenon, in that a tenon is cut on the end of one member and a mortise is cut into the other to accept it. The distinguishing feature is that the tenon and the mortise are cut to the ...
. Eg: Palatomaxillary suture. *Denticulate sutures – the edges slot into each other as in a
finger joint A finger joint, also known as a comb joint, is a woodworking joint made by cutting a set of complementary, interlocking profiles in two pieces of wood, which are then glued. The cross-section of the joint resembles the interlocking of fingers ...
. Eg: Lambdoid suture. *


List of sutures

Most sutures are named for the bones they articulate, but some have special names of their own.


Visible from the side

*
Coronal suture The coronal suture is a dense, fibrous connective tissue joint that separates the two parietal bones from the frontal bone of the skull. Structure The coronal suture lies between the paired parietal bones and the frontal bone of the skull. It ...
– between the
frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music * The Front (band), an American rock band signed to Columbia Records and active in the 1980s and e ...
and
parietal bone The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...
s *
Lambdoid suture The lambdoid suture (or lambdoidal suture) is a dense, fibrous connective tissue joint on the posterior aspect of the skull that connects the parietal bones with the occipital bone. It is continuous with the occipitomastoid suture. Structure T ...
– between the parietal and
occipital 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 cereb ...
bones and continuous with the occipitomastoid suture *
Occipitomastoid suture The occipitomastoid suture or occipitotemporal suture is the cranial suture between the occipital bone and the mastoid portion of the temporal bone. It is continuous with the lambdoidal suture. See also * Jugular foramen Additional images Fi ...
– between the
occipital 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 cereb ...
and temporal bones and continuous with the lambdoid suture *
Sphenofrontal suture The sphenofrontal suture is the cranial suture between the sphenoid bone and the frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamo ...
*
Sphenoparietal suture The sphenoparietal suture is the cranial suture between the sphenoid bone and the parietal bone. It is one of the sutures that comprises the pterion. Additional images File:Sphenoparietal suture.gif, Position of sphenoparietal suture (shown in ...
*
Sphenosquamosal suture The sphenosquamosal suture is a cranial suture between the sphenoid bone and the squama of the temporal bone The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex. The te ...
*
Sphenozygomatic suture The sphenozygomatic suture is the cranial suture between the sphenoid bone and the zygomatic bone In the human skull, the zygomatic bone (from grc, ζῠγόν, zugón, yoke), also called cheekbone or malar bone, is a paired irregular bone wh ...
*
Squamosal suture The squamosal suture, or squamous suture, arches backward from the pterion and connects the temporal squama with the lower border of the parietal bone: this suture is continuous behind with the short, nearly horizontal parietomastoid suture, whi ...
– between the parietal and the
temporal bone The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. Th ...
*
Zygomaticotemporal suture The zygomaticotemporal suture (or temporozygomatic suture) is the cranial suture between the zygomatic bone and the temporal bone. This is part of the zygomatic arch. Movement at the suture decreases with development during aging. It has a complex ...
*
Zygomaticofrontal suture The zygomaticofrontal suture (or frontozygomatic suture) is the cranial suture between the zygomatic bone and the frontal bone. The suture can be palpated just lateral to the eye. Additional images File:Gray164.png, Left zygomatic bone in situ. F ...


Visible from the front or above

*
Frontal suture The frontal suture is a fibrous joint that divides the two halves of the frontal bone of the skull in infants and children. Typically, it completely fuses between three and nine months of age, with the two halves of the frontal bone being fused t ...
/
Metopic suture The frontal suture is a fibrous connective tissue, fibrous suture (joint), joint that divides the two halves of the frontal bone of the human skull, skull in infants and children. Typically, it completely fuses between three and nine months of ag ...
– between the two
frontal bones The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, pa ...
, prior to the fusion of the two into a single bone *
Sagittal suture The sagittal suture, also known as the interparietal suture and the ''sutura interparietalis'', is a dense, fibrous connective tissue joint between the two parietal bones of the skull. The term is derived from the Latin word ''sagitta'', meanin ...
– along the midline, between
parietal bone The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...
s


Visible from below or inside

*
Frontoethmoidal suture The frontoethmoidal suture is the suture between the ethmoid bone and the frontal bone. It is located in the anterior cranial fossa The anterior cranial fossa is a depression in the floor of the cranial base which houses the projecting fronta ...
* Petrosquamous suture *
Sphenoethmoidal suture The sphenoethmoidal suture is the cranial suture between the sphenoid bone and the ethmoid bone. It is located in the anterior cranial fossa The anterior cranial fossa is a depression in the floor of the cranial base which houses the projecting ...
*
Sphenopetrosal suture The sphenopetrosal fissure (or sphenopetrosal suture) is the cranial suture between the sphenoid bone and the petrous portion of the temporal bone. It is in the middle cranial fossa The middle cranial fossa, deeper than the anterior cranial fos ...


Gallery

File:Lambdoid suture.png, Lambdoid suture File:SchaedelSeitlichSutur1.png, Coronal suture File:SchaedelSeitlichSutur3.png, Squamosal suture File:SchaedelSeitlichSutur4.png, Zygomaticotemporal suture File:Sagittal suture.jpg, Sagittal suture. File:Sagittal suture 2.jpg, Sagittal suture. File:Sagittal suture 3.jpg, Sagittal suture. File:Kort-lang-skalle.gif, Top view of cranial suture.


Syndesmosis

A syndesmosis is a slightly mobile fibrous joint in which bones such as the tibia and fibula are joined together by connective tissue. An example is the distal tibiofibular joint. Injuries to the ankle syndesmosis are commonly known as a "high ankle sprain". Although the syndesmosis is a joint, in the literature the term syndesmotic injury is used to describe injury of the syndesmotic ligaments. It comes from the Greek σύν, ''syn'' (meaning "with") and δεσμός, ''desmos'' (meaning "a band"). Syndesmosis sprains have received increasing recognition during recent years because of a heightened awareness of the mechanism, symptoms, and signs of injury.


Diagnosis of a syndesmotic injury

Diagnosis of syndesmosis injuries by physical examination is often straightforward. Physical examination findings that are often positive include the squeeze test and the external rotation test. Patients with high-grade syndesmosis injuries often cannot perform a single-leg heel raise. Patients report pain in varying degrees over the anterior and often posterior distal fibular joint.


Syndesmotic tear

The severity of acute syndesmosis injury is rated from grade I to III by several authors. A grade I injury is a partial anteroinferior tibiofibular ligament tear, meaning the exorotation and squeeze tests are negative for this grade. Grade II injury is a complete anteroinferior tibiofibular ligament and inferior interosseous ligament tear, meaning that squeeze test and exorotation are positive. This results in the injury being stabilized with immobilization but not operatively stabilized. A grade III injury is a complete anteroinferior tibiofibular ligament tear including a (partial) interosseous ligament tear and deltoid ligament avulsion, meaning the joint is unstable and positive on the exorotation and squeeze tests. This grade requires operative stabilization. If the syndesmosis is torn apart as result of bone fracture, surgeons will sometimes fix the relevant bones together with a
syndesmotic screw A syndesmotic screw is a metal screw designed to replace the syndesmosis of the human body, usually temporarily. If the syndosmosis is torn apart as result of bone fracture, surgeons will sometimes fix the relevant bones together with a syndesmot ...
, temporarily replacing the syndesmosis, or with a tightrope fixation, which is called
Syndesmosis Procedure Syndesmosis procedure is one of the more than twenty bunion surgeries currently being performed. While the majority of bunion surgeries involve the breaking and shifting of bones (osteotomy An osteotomy is a surgical operation whereby a bone ...
. The screw inhibits normal movement of the bones and, thereby, the corresponding joint(s). When the natural articulation is healed, the screw may be removed. The tightrope fixation with elastic fiberwire suture on the other hand allows physiologic motion of the ankle and may be permanent.


Gomphosis

A gomphosis, also known as a dentoalveolar
syndesmosis In anatomy, fibrous joints are joints connected by fibrous tissue, consisting mainly of collagen. These are fixed joints where bones are united by a layer of white fibrous tissue of varying thickness. In the skull the joints between the bones ar ...
, is a joint that binds the
teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...
to bony teeth sockets in the
maxillary bone The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
and
mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
. The fibrous connection between a tooth and its socket is a
periodontal ligament The 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. It inserts into root cementum one side and onto alveolar b ...
. Specifically, the connection is made between the maxilla or mandible to the cementum of the tooth. The motion of a gomphosis is minimal, though considerable movement can be achieved over time—the basis of using braces to realign teeth. The joint can be considered a
synarthrosis A synarthrosis is a type of joint which allows no movement under normal conditions. Sutures and gomphoses are both synarthroses. Joints which allow more movement are called amphiarthroses or diarthroses. Syndesmoses joints are considered to be a ...
. The gomphosis is the only joint-type in which a bone does not join another bone, as teeth are not technically bone. In modern, more anatomical, joint classification, the gomphosis is simply considered a fibrous joint because the tissue linking the structures is ligamentous. It has been suggested that this permanent soft-tissue attachment was a critical requisite in the evolution of the mammalian (
synapsid Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...
)
tusk Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine teeth, as with pigs and walruses, or, in the case of elephants, elongated incisors. Tusks share c ...
. A gomphosis is a specialized fibrous joint in which a conical process or peg of one bone fits into a hole or socket in another bone. (gomphos is a Greek word meaning bolt). Small quantity of fibrous tissue holds the bones together. No movement is possible at such peg-and-socket joints.


References


External links

*
Age at Death Estimation from Cranial Suture Closures

Cranial suture closure and its implications for age estimation


from Douglas College {{Authority control Joints Skull it:Articolazione#Sindesmosi