![]() ![]() Examples of synostosis fusions between cranial bones are found both early and late in life. This fusion between bones is called a synostosis (“joined by bone”). At some sutures, the connective tissue will ossify and be converted into bone, causing the adjacent bones to fuse to each other. ![]() When the connective tissue between the adjacent bones is reduced to a narrow layer, these fibrous joints are now called sutures. The fontanelles greatly decrease in width during the first year after birth as the skull bones enlarge. After birth, these expanded regions of connective tissue allow for rapid growth of the skull and enlargement of the brain. During birth, the fontanelles provide flexibility to the skull, allowing the bones to push closer together or to overlap slightly, thus aiding movement of the infant’s head through the birth canal. These broad areas of connective tissue are called fontanelles ( Figure 9.6). In newborns and infants, the areas of connective tissue between the bones are much wider, especially in those areas on the top and sides of the skull that will become the sagittal, coronal, squamous, and lambdoid sutures. (See Figure 9.5 a.) Thus, skull sutures are functionally classified as a synarthrosis, although some sutures may allow for slight movements between the cranial bones. The suture is frequently convoluted, forming a tight union that prevents most movement between the bones. In adults, the skull bones are closely opposed and fibrous connective tissue fills the narrow gap between the bones. The fibrous connective tissue found at a suture (“to bind or sew”) strongly unites the adjacent skull bones and thus helps to protect the brain and form the face. SutureĪll the bones of the skull, except for the mandible, are joined to each other by a fibrous joint called a suture. (c) A gomphosis is a specialized fibrous joint that anchors a tooth to its socket in the jaw. (b) An interosseous membrane forms a syndesmosis between the radius and ulna bones of the forearm. (a) Sutures join most bones of the skull. Lastly, a gomphosis is the narrow fibrous joint between the roots of a tooth and the bony socket in the jaw into which the tooth fits.įigure 9.5 Fibrous Joints Fibrous joints form strong connections between bones. This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg. At a syndesmosis joint, the bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a ligament or a wide sheet of connective tissue called an interosseous membrane. A suture is the narrow fibrous joint found between most bones of the skull. The gap between the bones may be narrow or wide. Give an example of each type of fibrous jointĪt a fibrous joint, the adjacent bones are directly connected to each other by fibrous connective tissue, and thus the bones do not have a joint cavity between them ( Figure 9.5).Distinguish between a suture, syndesmosis, and gomphosis.Describe the structural features of fibrous joints.It may occur during fetal development if the bones of the foot fail to differentiate, but can also be caused by arthritis, an infection, or a serious heel injury.By the end of this section, you will be able to: Symptoms include limited range of motion, pain, and a rigid, flat foot. Tarsal coalition: A condition that occurs when the hindfoot bones fuse together.While arthritis is a common cause, polyarthropathy may be secondary to conditions like lupus, scleroderma, a regional infection, and Lyme disease. Polyarthropathy: A condition in which pain and inflammation occur in multiple joints.This can lead to severely restricted movement, pain, and disability. It is often caused by a neurological disorder that alters its structure. ![]() Pes cavus: Also known as a high instep, this is an especially high arch of the foot.It can sometimes cause extreme pain if the foot is not provided with extra support, such as custom arch supports. It usually develops in childhood due to overpronation, or the inward rolling of the foot with movement. Pes planus: Also known as "flat feet," pes planus refers to a collapsed arch.Subtalar dislocation: Often described as "basketball foot," this injury typically occurs if you land hard on the inside or outside of your foot.Subtalar instability: A lateral weakness in which the ankle can suddenly "give way." This can cause chronic inflammation in the ankle and repeated ankle twisting due to the extreme pressure placed on the ligament. ![]()
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