Tendon, Fascia, and Cranial Bones: Structure and Function

Tendon Structure

Tendon: A structure composed of collagen fibers arranged parallel to the tendon's axis. These fibers are designed for low flexibility and resistance to extension. Within the tendon, we find loose connective tissue and cells called tenocytes.

The entire structure is termed the endotendon, enclosed within a sheath called the peritenon. The peritenon's extension is continuous with the periosteum at one end and the perimysium at the other.

Some tendinous fibers, known as Sharpey's fibers, penetrate the bone and calcify, forming a strong union between tendon and bone.

The tendon is protected by an outer sleeve consisting of a parietal layer and an inner visceral synovial layer. A space filled with synovial fluid separates these layers.

Tendons transmit muscle force to bone, exhibiting high resistance, low extensibility, and the ability to slide.

Fascia Characteristics

Fascia:

• Sheets of fibrous connective tissue, primarily composed of collagen fibers.
• Function similarly to flattened tendons.
• Can attach to bone, other fascia, or skin.
• Muscle fibers extend from fascia.
• Lacks a tendon sheath.

Cranial Bones

Frontal Bone

The frontal bone forms the forehead, the roof of the orbits, and the upper nasal cavity. It articulates with the parietal bones via the coronal suture and connects to the sphenoid, ethmoid, zygomatic, and nasal bones.

Ethmoid Bone

Sections of the ethmoid bone between the orbits form part of the internal walls and lateral orbital walls, contributing to the upper nasal cavity.

Sphenoid Bone

The sphenoid bone traverses the skull laterally and has four wings: two greater and two lesser.

Occipital Bone

The occipital bone forms the back of the skull and the cranial base. It articulates with the parietal bones and the temporal bones' mastoid processes via the lambdoid suture. Its base connects to the sphenoid bone.

Parietal Bones

The parietal bones are two cranial bones forming the top and superior sides of the skull. They articulate with the sphenoid and temporal bones on each side via sutures.

Temporal Bones

The temporal bones form the lower sides of the skull and part of the cranial base. They protect the organs of hearing and balance and articulate with the occipital bone and the greater wing of the sphenoid bone to form the temples.