Bones of the Skull: Cranial and Facial Bones Study Guide

Bones of the Skull

The human skull is composed of two main groups of bones: cranial bones, which protect the brain, and facial bones, which form the structure of the face. Understanding the names, locations, and functions of these bones is essential for students of anatomy and physiology.

Cranial Bones (8 Total)

Cranial bones enclose and protect the brain and provide attachment sites for head and neck muscles.

Bone	Number	Main Function / Comments	Major Markings & Features
Frontal Bone	1	Forms forehead, roof of orbits, and anterior cranial floor	Supraorbital foramen (notch), frontal sinuses
Parietal Bones	2	Form sides and roof of cranium	Coronal, sagittal, lambdoid, and squamous sutures
Temporal Bones	2	Form sides and base of cranium; house hearing structures	Mastoid process, styloid process, zygomatic process, external acoustic meatus, mandibular fossa
Occipital Bone	1	Forms back and base of skull; protects occipital lobe	Foramen magnum, occipital condyles, external occipital protuberance
Sphenoid Bone	1	Keystone of the cranium; unites cranial and facial bones	Sella turcica, greater and lesser wings, optic foramen, pterygoid processes
Ethmoid Bone	1	Forms part of nasal septum and medial wall of orbits	Crista galli, cribriform plate (olfactory foramina), perpendicular plate, superior & middle nasal conchae

Facial Bones (14 Total)

Facial bones form the framework of the face, contain cavities for special sense organs, and provide openings for air and food passage.

Bone	Number	Main Function / Comments	Major Markings & Features
Mandible	1	Lower jaw; only movable skull bone	Mental foramen, mandibular condyle, coronoid process, mandibular foramen, alveolar process
Maxillae	2	Upper jaw; forms hard palate, floors of orbits, sides of nasal cavity	Infraorbital foramen, palatine process, alveolar process, maxillary sinus
Zygomatic Bones	2	Cheekbones; form part of orbit	Temporal process, zygomatic arch (with temporal bone)
Nasal Bones	2	Form bridge of nose	Articulate with frontal and maxilla bones
Lacrimal Bones	2	Smallest facial bones; part of medial wall of orbit	Lacrimal fossa (for tear duct)
Palatine Bones	2	Form posterior part of hard palate and part of orbit	Horizontal plate, perpendicular plate
Inferior Nasal Conchae	2	Create turbulence in airflow in nasal cavity	Thin curved bones projecting from lateral walls of nasal cavity
Vomer	1	Forms inferior part of nasal septum	Joins with perpendicular plate of ethmoid

Major Sutures of the Skull

Sutures are immovable joints that connect the bones of the skull. They are important anatomical landmarks.

Suture	Bones United
Coronal Suture	Frontal and Parietal bones
Sagittal Suture	Parietal bones (right and left)
Lambdoid Suture	Parietal and Occipital bones
Squamous Suture	Temporal and Parietal bones

Key Terms and Concepts

• Foramen: An opening or hole in a bone for passage of nerves and blood vessels.

• Process: A projection or outgrowth of bone for muscle attachment or articulation.

• Sinus: A cavity within a bone, usually filled with air and lined with mucous membrane.

• Conchae: Curved bony plates in the nasal cavity that increase surface area and help filter air.

• Suture: An immovable joint between skull bones.

Additional info:

• The sphenoid bone is often called the "keystone" of the cranial floor because it articulates with all other cranial bones.

• The mandible is the only bone of the skull that is freely movable, allowing for mastication (chewing).

• Facial bones also provide attachment points for facial muscles, contributing to facial expressions.