Fibrous joints are where adjacent bones are strongly united by fibrous connective tissue. The gap filled by connective tissue may be narrow or wide. The three types of fibrous joints are sutures, gomphoses, and syndesmoses. A suture is the narrow fibrous joint that unites most bones of the skull. At a gomphosis, the root of a tooth is anchored across a narrow gap by periodontal ligaments to the walls of its socket in the bony jaw. A syndesmosis is the type of fibrous joint found between parallel bones. The gap between the bones may be wide and filled with a fibrous interosseous membrane, or it may narrow with ligaments spanning between the bones. Syndesmoses are found between the bones of the forearm (radius and ulna) and the leg (tibia and fibula). Fibrous joints strongly unite adjacent bones and thus serve to provide protection for internal organs, strength to body regions, or weight-bearing stability.
fontanelles
expanded areas of fibrous connective tissue that separate the braincase bones of the skull prior to birth and during the first year after birth
gomphosis
type of fibrous joint in which the root of a tooth is anchored into its bony jaw socket by strong periodontal ligaments
interosseous membrane
wide sheet of fibrous connective tissue that fills the gap between two parallel bones, forming a syndesmosis; found between the radius and ulna of the forearm and between the tibia and fibula of the leg
ligament
strong band of dense connective tissue spanning between bones
periodontal ligament
band of dense connective tissue that anchors the root of a tooth into the bony jaw socket
suture
fibrous joint that connects the bones of the skull (except the mandible); an immobile joint (synarthrosis)
syndesmosis
type of fibrous joint in which two separated, parallel bones are connected by an interosseous membrane
synostosis
site at which adjacent bones or bony components have fused together
1. Which type of fibrous joint connects the tibia and fibula?
A) syndesmosis
B) symphysis
C) suture
D) gomphosis
A
2. An example of a wide fibrous joint is ________.
A) the interosseous membrane of the forearm
B) a gomphosis
C) a suture joint
D) a synostosis
A
3. A gomphosis ________.
A) is formed by an interosseous membrane
B) connects the tibia and fibula bones of the leg
C) contains a joint cavity
D) anchors a tooth to the jaw
D
4. A syndesmosis is ________.
A) a narrow fibrous joint
B) the type of joint that unites bones of the skull
C) a fibrous joint that unites parallel bones
D) the type of joint that anchors the teeth in the jaws
C
1. Distinguish between a narrow and wide fibrous joint and give an example of each.
Narrow fibrous joints are found at a suture, gomphosis, or syndesmosis. A suture is the fibrous joint that joins the bones of the skull to each other (except the mandible). A gomphosis is the fibrous joint that anchors each tooth to its bony socket within the upper or lower jaw. The tooth is connected to the bony jaw by periodontal ligaments. A narrow syndesmosis is found at the distal tibiofibular joint where the bones are united by fibrous connective tissue and ligaments. A syndesmosis can also form a wide fibrous joint where the shafts of two parallel bones are connected by a broad interosseous membrane. The radius and ulna bones of the forearm and the tibia and fibula bones of the leg are united by interosseous membranes.
2. The periodontal ligaments are made of collagen fibers and are responsible for connecting the roots of the teeth to the jaws. Describe how scurvy, a disease that inhibits collagen production, can affect the teeth.
The teeth are anchored into their sockets within the bony jaws by the periodontal ligaments. This is a gomphosis type of fibrous joint. In scurvy, collagen production is inhibited and the periodontal ligaments become weak. This will cause the teeth to become loose or even to fall out.