Topic 1: Skull, Orbit, and Fascia 1

Skull Overview

• The skull is a bony framework that encloses the brain in vertebrates and constitutes the head skeleton of humans and animals.
• Primary functions include protecting delicate brain organs and maintaining internal pressure relationships.

Protective Coverings

• The brain is covered by membranes that also shield it from injury.
• The skull's bones are lined with a connective tissue layer called the periosteum, which is continuous with the meninges.
• The meninges comprise three layers: dura mater, arachnoid mater, and pia mater, providing mechanical protection and housing cerebrospinal fluid (CSF) for additional cushioning.

Bone Structure and Functionality

• The skull is composed of 29 bones connected by sutures, immovable joints that typically ossify and disappear over time.
• Bone formation is known as osteogenesis; at birth, skull sutures are not tightly opposed and are covered by fontanelles, allowing cranial growth during the first 12 to 18 months.

Skull Sutures

• Three main skull sutures facilitate the division of cranial bones:
  • Sagittal suture: separates the two parietal bones.
  • Coronal suture: intersects at a 90-degree angle to the sagittal suture, separating parietal bones from the frontal bone.
  • Lambdoid suture: located between the parietal and occipital bones.

Skull Composition

• The skull can be divided into two primary sections: cranial and facial.
  • Cranial bones (8 total) protect the brain and vital neurological structures:
    • Frontal (1), Parietal (2), Temporal (2), Occipital (1), Sphenoid (1), Ethmoid (1).
  • Facial bones (15 total) safeguard the mouth, nasal cavities, and orbital parts:
    • Superior maxillary (2), Zygomatic (2), Nasal (2), Palatine (2), Lacrimal (2), Turbinate/Concha (2), Vomer (1), Mandible (1), Hyoid (1).

Connective Tissue

• Sutural ligaments join the bones of the skull, providing stability and structure.

Explore the structure and function of the skull, focusing on its role in protecting the brain in vertebrates. This quiz covers the protective membranes that encase the brain, including the meninges and the periosteum. Test your knowledge on the bony framework of the head and its significance.