WHAT ARE FIBROUS JOINTS? TYPES AND CHARACTERISTICS - ANATOMY AND PHYSIOLOGY - 2024

The fibrous joints, also called fixed joints, are those that are characterized by little or no mobility. In this type of bone coupling, the surfaces of the bones are held together by fibrous tissue rich in collagen.

Commonly, joints in the body allow movement by moving one bone over the other, such as in the shoulder or hip. However, in fibrous joints there is no cavity or some anatomical feature that allows this function.

By www.scientificaimations.com - http://www.scientificaimations.com/wiki-images/, CC BY-SA 4.0, Three types of fibrous joints are recognized: sutures, gonphoses, and syndesmoses. Sutures and gonphoses are found in the skull and mouth, respectively, and are not mobile under normal conditions.

Syndesmoses differ from the previous ones, in that they allow or help in movements of little range. They also preserve the anatomical structure and stability in some long bones. An example of syndesmosis is the junction between the bones of the forearm, radius, and ulna.

The pathologies associated with fibrous joints can be genetic, from birth, or acquired (due to trauma or environmental factor, for example).

Fibrous joint types

Fibrous joints are those in which there is not a great range of motion. They consist of the union of two bone surfaces by means of a tissue formed mainly by collagen fibers.

These joints are subdivided into: sutures, gonphosis and syndesmosis. The first two are found only in the skull and the mouth, respectively.

Cranial sutures

Cranial sutures are a clear example of a fibrous joint. The surfaces of the skull bones are held together by a very loose elastic tissue at birth.

The sutures allow the size of the skull to adapt to the growth of the brain, which continues to develop progressively during the first years of the child's life.

Skull bones. From OpenStax College - WIKIMEDIA COMMONSFile: 905 The Newborn Skull.jpg, CC BY-SA 4.0, As time passes, the sutures are closed and the bones are completely fused. These joints then become part of the protective skeleton of the brain.

When the sutures are closed prematurely, a malformation of the skull known as craniosynostosis occurs. It usually does not affect the intellect of the patient, but how well you do will depend on the cause.

From Michael L. Kaufman at English Wikipedia, CC BY-SA 3.0,

Gonphosis

Gonphosis is the term used to describe the joints that form the teeth with the jaw bone.

By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See «Book» section below) Bartleby.com: Gray's Anatomy, Plate 1003, Public Domain, https://commons.wikimedia.org/w/index. php? curid = 566946

In this case, the tissue that joins the bone surfaces is a strong ligament called the periodontal ligament. Thus, the root of the permanent tooth is fixed in a specific space in the jaw.

Syndesmosis

Syndesmoses are those fibrous joints that join two bones that are separated by a considerable distance. The bone surfaces are joined by a strong tissue formed by interlaced collagen fibers in some cases, but it can also be by means of a soft and elastic membrane with a pulpy center.

The bones of the arm, ulna and radius, and those of the leg, tibia and fibula, are examples of syndesmosis. In these cases, the fibrous tissue prevents the excessive rotation that can cause damage to its components.

From OpenStax College - Modified from File: 904 Fibrous Joints.jpgWIKIMEDIA COMMONS, CC BY-SA 3.0, Syndesmoses play an important protective role in skeletal biomechanics.

The joints of the vertebrae in the spine are also an example of syndesmosis. In this case the union is through a disc that allows movement and cushions the weight.

Joints: generalities

A joint is the area where two or more bones meet. The term comes from the Latin articulatio which means “united parts of a whole”.

Depending on their structure and function, they can be made up of fibrous tissue, cartilage or specialized joint fluid, among other elements. In addition, they have an elaborate support system that prevents injuries.

Joints of the human body. By Laboratoires Servier - Smart Servier website: Images related to Joints, Skeleton and bones and Bones -

Most joints in the body are mobile, although some have a wider range of motion than others. This function allows the movement of the body in all planes, its plasticity and development.

However, there are other types of joints that are called fixed, because they present a very limited or no movement.

Despite not providing mobility, fixed joints have other functions, some being a basic element during growth and others responsible for the stability of some bones. They also serve as protection for certain organs.

Types of joints

Joints are classified into three large groups according to their range of motion. False joints or synarthrosis, which are those that lack mobility; amphiarthrosis, which have limited and scarce movements; and true joints or diarthrosis, which are the ones that do provide mobility to the skeleton.

Diarthroses are also called synovial joints. Its structure has a special membrane, joint fluid and capsule. All these elements contribute to the fact that there is no friction between the bone surfaces and that they can move freely without wearing out.

In this type of joint, one of the bones has a cavity and the other has an anatomical structure that fits into it. For example, the head of the femur enters the socket of the pelvic bone to form the hip joint.

By BruceBlaus - Own work, CC BY 3.0, Synarthroses and amphiarthroses are joints that do not fulfill functions of movement but are concerned with protecting some organs or contribute to the child's growth process from birth to adulthood.

In this type of joint, the bone surfaces are joined by means of a fibrous tissue, such as the sutures of the skull, or a soft and pulpy structure that allows restricted movement, such as the discs that are found between the vertebrae of the spine.

Embryology

The bones of the skeleton begin to differentiate early in the fetus. Between the fourth and fifth week the stem cells are arranged to form a primitive spinal column and the development of the upper and lower limbs begins.

At the same time, neurological elements develop, such as the brain and spinal cord, and the bone cells cover them, remaining in their definitive position around the fifteenth week of gestation.

By Mikael Häggström, MD- Author info- Reusing imagesWritten informed consent was obtained from the individual, including online publication. - Own work, CC0, From the fourth week, as time passes, bones with joints are formed. Multipotential cells differentiate into all joint elements, such as fibrous capsule and joint fluid.

Additionally, through a specialized hormone-mediated process, early bone cells give rise to cartilage and collagen-rich tissue that will allow the skeleton to grow after birth.

The skull fuses as the brain finishes its development, around 2 years of age. The entire process of fusion of the skull ends at 5 years and the development of the skeleton is completed between 25 and 30 years.

References

1. Juneja, P; Hubbard, JB (2018). Anatomy, Joints. StatPearls, Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
2. Johnson, D; Wilkie, AO (2011). Craniosynostosis. European journal of human genetics: EJHG. Taken from: ncbi.nlm.nih.gov
3. Hunt, KJ (2013). Syndesmosis injuries. Current reviews in musculoskeletal medicine. Taken from: ncbi.nlm.nih.gov
4. Álvarez López, A; Rodríguez Rodríguez, E; García Lorenzo, Y; Muñoz Infante, A. (2008). Distal tibiofibular syndesmosis lesions: Review article. Cuban Journal of Orthopedics and Traumatology. Taken from: scielo.sld.cu
5. Ho, S. P; Marshall, S. J; Ryder, M. I; Marshall, GW (2007). The tooth attachment mechanism defined by structure, chemical composition and mechanical properties of collagen fibers in the periodontium. Biomaterials. Taken from: ncbi.nlm.nih.gov