Skull Anatomy and Vascular Supply Quiz

Skull and Scalp Anatomy

• The skull is composed of the neurocranium (protects the brain) and viscerocranium (forms the face).
• The neurocranium consists of 8 bones: ethmoid, sphenoid, frontal, occipital, parietal (2), and temporal (2).
• The viscerocranium comprises 14 bones: vomer, mandible, inferior conchae (2), nasal (2), lacrimal (2), maxilla (2), palatine (2), and zygomatic (2).
• In total, the skull has 22 bones. One bone, the mandible, is movable.
• Skull bones have external and internal tables (compact bone), diploë (spongy bone), and sutures (seams).
• Key anatomical positions and landmarks include: bregma, lambda, pterion, and asterion. These landmarks have clinical importance.
• The scalp has five layers: skin, connective tissue, aponeurosis, loose areolar tissue, and pericranium.
• The loose areolar tissue is a crucial layer, potentially vulnerable to spread of infection from the skin, affecting deeper structures.

Anatomical Positions of the Skull

• The anatomical position of the skull is defined by the position of the bones of the head.
• The different locations and directions within the skull also matter for proper anatomical reference.

Skull Landmarks

• Bregma: Junction of the coronal and sagittal sutures.
• Lambda: Junction of the sagittal and lambdoid sutures.
• Pterion: Junction of the frontal, parietal, sphenoid, and temporal bones. A key location for middle meningeal artery.
• Asterion: Junction of the parietal, temporal, and occipital bones.

Skull Structures

• The skull vault encompasses the cranial bones. These bones are important for protection and other functions
• The skull base comprises the bones at the bottom of the skull. These bones have crucial openings for nerves and vessels.
• The different aspects of the skull have structures that have important relations with surrounding tissues.

Neonatal Skull

• Neonatal skulls have smooth, unilaminar (lacking diploë) bones.
• The neurocranium is larger relative to the face in newborns compared to adults.
• Growth of the mandible, maxilla, and paranasal sinuses contributes to the relative size disparity between adult and neonatal skulls.

Fontanelles

• Fontanelles are unossified membranous intervals between skull bones in infants. Specific fontanelles have different locations and shapes.
• There are anterior, posterior, sphenoidal/anterolateral, and mastoid/posterolateral fontanelles.
• Early closure of fontanelles limits brain growth, while late closure can increase intracranial pressure.

Scalp Layers

• The scalp contains five layers: skin, connective tissue, aponeurosis, loose areolar tissue, and pericranium. These layers have key anatomical traits.
• The loose areolar tissue is particularly important due to its potential vulnerability to infection that can spread to deeper structures, causing osteitis/meningitis, or venous sinus thrombosis.

Innervation and Blood Supply

• The scalp receives sensory innervation from the trigeminal and cervical nerves, with blood supply from arteries.
• Specific arteries and nerves are crucial for the sensory and motor functions of the scalp.
• Different parts of the scalp have blood supplies from different arteries that converge and then distribute the blood to the structures of that region for nourishment