Skull Anatomy

The skull is the skeleton of the head. It is an extremely important bony framework that protects the brain and supports the organs of vision, hearing, smell, and taste.

The skull provides reliable protection for the brain and forms the bony cavities associated with the eyes, ears, nose, and mouth. It also provides passageways for important nerves and blood vessels.

Side view of the human skull within the outline of the head.

In this article, we will explain the basic anatomy of the skull to make it easier for you to draw a skull and better understand the bony foundation of the human head.

So, the human skull consists of 22 bones. It is divided into two major sections – the cranium and the facial skeleton.

Human skull divided into the cranial and facial portions.

Cranium

The cranium forms the cranial cavity in which the brain is located.

The cranium is composed of bones that are clearly visible from the outside and bones that are located deeper within the skull. The frontal, parietal, temporal, and occipital bones form much of the visible outer surface of the cranium.

The sphenoid and ethmoid bones are located more deeply, although parts of both bones can also be seen in an intact skull.

Frontal Bone

The frontal bone is located at the front of the skull, above the eyes and nose. It connects with the parietal bones behind and with several bones of the facial skeleton below.

The lower part of the frontal bone forms the roof of the orbits and contributes to the upper part of the nasal region. The frontal bone has convex areas called frontal eminences. Below them are arched elevations called the superciliary arches.

The frontal bone plays a major role in shaping a person’s appearance. Small mistakes in drawing the superciliary arches or the height and curvature of the forehead can noticeably change the appearance of a portrait.

Frontal bone shown in blue on front and side views of the skull.

Parietal Bones

These are paired bones. The right and left parietal bones form much of the upper and lateral portions of the cranial vault. The parietal bones connect with the frontal bone in front, the occipital bone behind, the temporal bones below, and each other along the midline.

Each parietal bone has four borders. The squamous border articulates with the temporal bone and has a concave shape. The occipital border articulates with the occipital bone. The sagittal border articulates with the opposite parietal bone, while the frontal border articulates with the frontal bone.

Parietal bones marked in blue on front and side views of the skull.

Occipital Bone

If we look inside the cranial cavity, we can see three main depressions called the anterior, middle, and posterior cranial fossae.

The occipital bone forms much of the posterior cranial fossa and surrounds the foramen magnum. This region contains parts of the brainstem and cerebellum.

The occipital bone connects with the parietal bones above and the temporal bones laterally. On its lower surface are the occipital condyles, smooth articular surfaces that connect with the first cervical vertebra.

At the base of the occipital bone is a large opening called the foramen magnum. The lower part of the brainstem passes through this opening and continues as the spinal cord.

Occipital bone shown in blue on rear and side views of the skull.

Temporal Bone

The temporal bone connects with the occipital bone behind, the parietal bone above, and the sphenoid bone in front. It also articulates with one of the bones of the facial skeleton, namely the mandible. The temporal bone has a rather complex internal anatomy.

The temporal bone has several parts, including the squamous, petrous, and tympanic parts. The petrous part contains canals through which important vessels and nerves pass, including the internal carotid artery and facial nerve.

However, these internal canals are not particularly important for plastic anatomy.

The temporal bone has several clearly visible processes that contribute to the appearance of the skull. The zygomatic process extends forward and connects with the temporal process of the zygomatic bone.

You can also see and feel the rounded mastoid process, which is located behind and below the ear. The styloid process is covered by soft tissues and does not create a visible contour on a living person.

Temporal bone marked in blue on front and side views of the skull.

Sphenoid Bone

Many artists overlook the sphenoid bone because only relatively small parts of it are visible when we look at an intact skull.

The sphenoid bone has a body, greater wings, lesser wings, and pterygoid processes. The greater wings extend laterally from the body, while the lesser wings lie above them.

Parts of the greater wings are visible when we look at the skull from the side. This exposed area is called the temporal surface of the greater wing. We can also see parts of the greater wings from the front because they contribute to the lateral walls of the orbits. This portion is called the orbital surface of the greater wing of the sphenoid bone.

On the upper surface of the body of the sphenoid is a depression called the sella turcica. Within it is the hypophyseal fossa, which contains the pituitary gland.

Sphenoid bone shown in blue around the orbit and side of the skull.

Ethmoid Bone

The ethmoid bone is located between the nasal cavity and the anterior cranial fossa. Its cribriform plate contains numerous small openings through which fibers of the olfactory nerves pass. Most of the ethmoid bone lies deep within the skull, although parts of it contribute to the medial walls of the orbits and the nasal cavity.

Facial Bones

The facial skeleton forms the bony framework around several important cavities. The orbits protect and support the eyes, while the nasal and oral cavities form parts of the respiratory and digestive systems. Let’s see which bones contribute to these areas.

Zygomatic Bones

The zygomatic bones are located lateral and inferior to the orbits. Each zygomatic bone contributes to the lateral wall and floor of the orbit. The shape of the face, especially in thin people, also depends significantly on the form of these bones.

Each zygomatic bone has several processes that connect it with neighboring bones of the skull:

The frontal process extends upward and connects the zygomatic bone with the frontal bone;
The temporal process extends backward and connects with the zygomatic process of the temporal bone;
The maxillary process connects the zygomatic bone with the maxilla.

The junction between the zygomatic bone and the maxilla is called the zygomaticomaxillary suture.

Zygomatic bones shown in front and side views of the skull.

Lacrimal Bone

This small bone is visible on the medial wall of the orbit. The lacrimal bone is a thin, roughly quadrangular plate that articulates with the frontal bone above and the maxilla below and in front.

Nasal Bones

These are small but important paired bones that form the bony bridge of the nose.

The right and left nasal bones are located below the frontal bone and between the frontal processes of the maxillae. They form the upper bony part of the external nose and can be palpated along the bridge of the nose.

The upper border of each nasal bone articulates with the frontal bone, while its lateral border articulates with the maxilla. The medial borders of the two nasal bones articulate with each other.

Nasal bones highlighted along the bridge of the nose.

Upper Jaw

Contrary to a common misconception, the upper jaw is not one solid bone. It is formed by two maxillae that meet in the center of the face. Each maxilla is a large paired bone that contributes to the face from the orbits to the oral cavity.

Each maxilla has a body and four processes:

Frontal process. This process extends upward and articulates with the frontal bone;
Zygomatic process. With this process, the maxilla connects to the zygomatic bone;
Alveolar process. This is the lower part of the maxilla that contains the sockets for the upper teeth;
Palatine process. This process forms much of the anterior part of the hard palate and the floor of the nasal cavity.

Maxilla highlighted around the upper jaw, nose, and lower eye sockets

Lower Jaw (Mandible)

Unlike the upper jaw, the mandible is one solid bone. It is the main movable bone of the skull and articulates with the temporal bones at the temporomandibular joints.

The lower jaw is also very important in plastic anatomy because the shape and expression of the face depend greatly on the form and position of the mandible.

The mandible has a body and two rami – right and left. The transition from the body to each ramus forms the angle of the mandible.

Each ramus ends superiorly in two large processes – the condylar process and the coronoid process. The condylar process participates in forming the temporomandibular joint, while the coronoid process provides an attachment point for the temporalis muscle.

With age, especially after tooth loss, the alveolar part of the mandible can gradually resorb. These changes can alter the height and contours of the lower face and the visible form of the jaw.

Mandible highlighted along the lower jaw in front and side views.

Inferior Nasal Concha, Vomer, and Palatine Bones

These bones contribute to the formation of the nasal and oral cavities. Much of their anatomy lies deep within the skull, so they are less important for understanding the visible external contours in plastic anatomy.

Artist holding and studying a human skull for anatomical reference.

It is very important for an artist to know human anatomy in order to draw convincing portraits and understand the three-dimensional form of the head. The information from this article, along with knowledge of perspective, proportions, and light and shadow, forms an important foundation for drawing the human head.