PA-CAT Anatomy Part I - Bones of the Skull

Cranial Sutures

synarthrosis, developed over the course of 2 years, flexible in infancy and early childhood, most important include coronal, sagittal, lambdoid, and squarrious.

Fontanels

Soft membrane gaps between cranial bones of the calvaria, allow the rapidly growing brain to expand. 6: posterior, anterior, posterolateral, and anterolateral.

Craniosynostosis

Pathological process leading to complete ossification prematurely

Neurocranium

Composed of calvaria, skull roof formed by flat bones and cranial base, cartilaginous part, delimitates the cranial cavity, communicates below the vertebral canal through foramen magnum

Calvaria

upper part of neurocranium, composed of flat bones, smooth outer convex surface and inner concave surface

Calvaria Bone Structure

composed of flat bones, two layers of compact bone tissue, inner layer is thinner than outer and the diplose separates the two compact layers

Diploe

cancellous (spongy) bone tissue containing bone marrow and diploic veins

Frontal bone

forehead and superior rim of the orbit, pneumatized bone, superior to each orbital rim, glabella, partially forms the medial rim of the orbit, laterally extends with the frontal

Frontal Bone Articulations

parietal bones, through coronal suture, greater wing of sphenoid, frontal process of zygomatic, through zygomatic process, with nasal and lacrimal bones

Parietal Bone

paired quadrilateral bone, forms roof and sides of cranium. 2 surfaces, 4 angles: frontal, occipital, sagittal, squamous. 4 margins: frontal, sphenoid, mastoid, occipital

Occipital bone

trapezoid curved bone, main bone of occiput, overlies occipital lobes. 4 parts: squamous, basilar, two lateral parts. Contains a large opening, spinal cord passes through: foramen magnum.

Inner Occipital Surface

base of the posterior cranial fossa, exposes the basilar portion of the bone, foramen magnum is bound, transverse ridge and occipital crest divide surface into 4 depressions

Exterior occipital view

each internal element correspondent on outer surface, 3 transversal nuchal lines, 2 occipital condyles on each side of foramen magnum, articulate with atlas

Temporal Bone

paired flat bone located on the sides of the cranium, house structures of the ears, pneumatized bone with 4 parts: squamous, zygomatic process, tympanic and styloid, petromastoid

Cranial Base

floor of the cranial cavity, 2 surfaces: endocranium and external cranial base. Components: sphenoid bone, ethmoid bone, occipital bone, frontal bone, temporal bone

Ethmoid bone

small, unpaired bone, irregular shape, separates nasal from cranial cavity, pneumatized bone, superior projection, sieve-like structure on each side, small portion of the orbit

Sphenoid bone

butterfly-shaped, unpaired bone, anterior to basilar portion of occipital bone, pneumatized bone with sphenoidal sinuses, composed of body, greater wings, lesser wings, pterygoid

Viscerocranium

facial skeleton, located anterior to the neurocranium, supports facial features, comprised of 14 bones, all bones joined together by synarthroses except for mandible

Zygomatic bone

irregular paired bone, forms face lateral prominences, parts of orbit inferior and lateral rims, composed of 4 processes, 3 surfaces, and 4 borders.

Nasal Bone

small, oblong, paired bones, form the bridge of the nose, articulates medially through internasal suture, each side has 2 surfaces, articulates frontal bone, inferiorly with maxillae

Maxillae

large paired bones, pneumatized, hold upper teeth, involved in formation of orbit, nasal cavity, and palate, composed of body and 4 processes: zygomatic, frontal, alveolar, palatine

Palatine Bone

irregular paired bones, alongside maxillae, form hard palate, between maxilla and pterygoid process, fuse together on midline, composed of 2 perpendicular plates