Skull Anatomy, Parts, Names & Diagram

Skull Anatomy: Complete Guide with Parts, Names, Functions & Diagram

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Overview of Skull Anatomy

The skull is a complex, protective structure made of bone. It is essential for safeguarding the brain and supporting various sensory functions. The skull anatomy is divided into two main sections: the cranium, which encloses and shields the brain, and the facial bones, including the mandible or jawbone, that shape the face. In scientific terms, the part that encases the brain is known as the neurocranium, while the viscerocranium forms the facial skeleton, including the jaw.

Beyond its role in protecting the brain, the skull supports vital sensory organs like the eyes, ears, nose, and mouth. It ensures that the eyes are positioned correctly for optimal vision and secures the placement of the ears to assist in hearing and determining the direction of sound. Additionally, the skull aids breathing and eating by housing the nasal cavity and jaw.

The skull’s intricate design ensures protection and functionality, playing a central role in survival by enabling sensory perception and environmental interaction.

Skull Anatomy Labeled Diagram

Skull Anatomy, Parts, Names & Diagram

Parts of Skull

Cranial Bones (8 bones)

  • Frontal Bone
  • Parietal Bones (2)
  • Temporal Bones (2)
  • Occipital Bone
  • Sphenoid Bone
  • Ethmoid Bone

Facial Bones (14 bones)

  • Nasal Bones (2)
  • Maxillae (2) & Mandible
  • Zygomatic Bones (2)
  • Lacrimal Bones (2)
  • Palatine Bones (2)
  • Inferior Nasal Conchae (2)
  • Vomer

Additional Structures

  • Sutures
    • Coronal Suture
    • Sagittal Suture
    • Lambdoid Suture
    • Squamous Suture
  • Foramina
    • Foramen Magnum
    • Optic Foramen

Human Skull Anatomy: Parts & Functions

Cranial Bones (8 bones)

The cranium, or neurocranium, consists of eight bones that cover and safeguard the brain. It is divided into two main parts: the cranial roof and the cranial base.

The cranial roof, known as the calvarium, includes the frontal, occipital, and parietal bones. The cranial base comprises all eight cranial bones. These protect the brain and support structures of the face.

1. Frontal Bone

The frontal bone has two main parts: the squamous part and the orbital part. The squamous part is the large, flat area that makes up most of the forehead.

The orbital part is smaller and lies horizontally, forming the top of the eye sockets and helping shape the nasal cavities.

Sometimes, there is a third part called the nasal part, which connects the brow ridges to the nasal bones below and the bones on the sides of the nose (lacrimal and maxilla).

The key function of the frontal bone is to shape the forehead and protect the brain’s frontal lobe. It also helps form the eye sockets and the front of the brain cavity.

2. Parietal Bones (2)

The parietal bones are paired structures on each side of the skull. It forms the upper and side portions of the head. They rest above the brain’s parietal lobes and are shielded by a fibrous tissue called the epicranial aponeurosis.

These bones are part of the neurocranium—the part of the skull that houses and protects the brain—alongside other key bones like the frontal, ethmoid, sphenoid, temporal, and occipital bones. The parietal bones mainly shape the top of the skull, with a smaller section contributing to the skull base.

Their primary function is to safeguard the brain from injury. Slightly curved and rectangular, each parietal bone has two surfaces, four borders, and four corners.

These borders link with other skull bones at junctions called cranial sutures. The inner surfaces of the parietal bones feature grooves and depressions that accommodate blood vessels and other essential structures.

3. Temporal Bones (2)

The temporal bones are a pair of bones on either side of the skull. It forms parts of both the base and the sides of the head. They have a complex shape because they anchor various muscles and connect with neighboring bones.

These bones are also crucial passageways for nerves and blood vessels moving in and out of the skull. Hidden within the temporal bones are the essential structures that control hearing and balance, including portions of the middle and inner ear.

From the back of the skull, the temporal bones are visible on the sides, with the mastoid process—a noticeable, rounded bump—standing out.

The temporal bone comprises several distinct sections:

  1. The broad,
  2. Flat squamous part
  3. The pyramid-shaped petrous part
  4. The tympanic part, which surrounds the ear canal
  5. The slender styloid process is a pointed projection beneath the ear.

4. Occipital Bone

The occipital bone is located at the back and base of the skull. It is a crucial structure that protects the brain’s occipital lobes.

The bone is curved trapezoid and has a key feature called the foramen magnum, a large oval opening that allows the spinal cord to connect with the brain.

The occipital bone is divided into three distinct sections based on its features.

  1. The front section, the basilar part or basioccipital, is a thick, rectangular segment extending forward.
  2. On either side of the foramen magnum lie the lateral parts, known as the exoccipitals, which support the skull’s connection to the spine.
  3. The back section, or squamous part, forms the largest and most curved area, supporting the skull’s rear.

This design plays a vital role in brain protection and the connection between the brain and spinal cord. It makes it essential for structural integrity and neurological function.

5. Sphenoid Bone

The sphenoid bone is one of the most intricate bones in the human body. Because of its unique shape, it is sometimes called the “wasp bone.”

It forms a large part of the base of the skull, especially in the middle, and helps create the floor of the middle section of the skull’s interior.

This bone is closely connected to important soft tissues like the cranial nerves and parts of the brain. Its main role is to provide openings and pathways (foramina and canals) for nerves and blood vessels to pass in and out of the skull.

6. Ethmoid Bone

Facial Bones (14 bones)

The cranium has two main parts: the neurocranium and the viscerocranium. The neurocranium protects the brain, while the viscerocranium, also called the facial skeleton, shapes our face.

The facial skeleton has 14 bones.

  • Six of them come in pairs, with one on each side of the face. These paired bones are the inferior nasal conchae, nasal bones, maxillae (upper jaw), palatine bones, lacrimal bones, and zygomatic bones (cheekbones).
  • There are also two single bones: the mandible (lower jaw) and the vomer.

Besides giving shape to the face, the viscerocranium protects important organs like the eyes and mouth. It has spots for muscles to attach and tiny holes, called foramina, that let nerves and blood vessels pass through.

These shape the face and provide cavities for the sense organs (eyes, nose, and mouth).

1. Nasal Bones (2)

The nasal bones are two small, oblong bones located in the upper central area of the face. These bones join at the midline through the internasal suture and form the bridge of the upper third of the nose.

It is small, and its size and shape can vary significantly between individuals, contributing to the diverse range of nose shapes seen in humans.

This variation extends to the angles, contours, and connections between the nasal bones and cartilage, which differ from person to person. Typically, nasal bones are categorized as “V-shaped” or “S-shaped.”

However, these terms are general and not precise medical classifications. Anatomical illustrations of nasal bones often depict an idealized form, which may not accurately reflect the structure found in most people.

2. Maxillae (2) & Mandible

In vertebrates, the maxilla, or upper jawbone, is a key structure that helps form the framework of the face and mouth.

In humans, it consists of two bones joining the intermaxillary suture and creating a small projection known as the anterior nasal spine. The maxilla also supports the hard palate, which makes up the front part of the roof of the mouth.

The mandible, or lower jawbone, is similar in origin but differs in function. It also forms through the fusion of two bones at the mandibular symphysis.

It remains mobile, allowing for the movement necessary for chewing and speaking. The upper teeth are embedded in the maxilla’s maxillary arch, making it essential for the dental structure.

The maxilla contributes to several important regions in the skull, including:

  • The roof of the mouth
  • The floor and sidewalls of the nasal cavity
  • The walls of the eye sockets (orbits)

It also forms two key openings, the inferior orbital fissure and the pterygomaxillary fissure, which allow nerves and vessels to pass through these regions.

3. Zygomatic Bones (2)

The zygomatic bone, or zygoma, is a key facial bone on both sides of the face. It plays a major role in shaping the cheeks and protecting the eyes.

This bone forms part of the eye socket and the side walls of the skull, contributing significantly to facial structure.

Each zygomatic bone is a single unit that connects with several neighboring bones. These include the frontal bone (forehead), maxilla (upper jaw), temporal bone (near the ear), and sphenoid bone (at the skull’s base).

Its strategic placement strengthens the face, allowing it to bear the forces generated during chewing by distributing them from the upper jaw.

The zygomatic bone also features the zygomatic arch, a bridge-like structure connecting it to the temporal bone. This arch supports the masseter muscle, one of the primary muscles responsible for closing the jaw, which makes it essential for chewing.

In addition to function, this bone contributes to the facial appearance and provides a protective barrier around the eyes.

4. Lacrimal Bones (2)

The lacrimal bones are two tiny, delicate bones in the face, about the size of a fingernail. They are located at the inner corner of each eye socket. Each bone has two surfaces and four edges.

These bones play a key role in the tear drainage process. They help form the nasolacrimal canal, which allows tears to move from the eyes to the nose.

There is a small depression on the lower front part of one of the bones, called the lacrimal fossa, where the lacrimal sac sits.

This sac collects tears when they overflow from the eyes, like during crying. From there, the tears pass through the nasolacrimal duct and into the nose, which is why your nose runs when you cry. If the lacrimal bone is injured or broken, it can block this tear drainage pathway.

5. Palatine Bones (2)

The palatine bones are two small, L-shaped bones that play a crucial role in the structure of the face. It is positioned just behind the uvula.

They form part of the hard palate, or roof of the mouth, and contribute to the walls of the nasal cavities. These bones lie between the maxilla (upper jaw) and the sphenoid bone at the skull’s base.

Each palatine bone has two key sections:

  • The horizontal plate, which makes up part of the hard palate,
  • The vertical plate helps shape the sides of the nasal cavity.

The palatine bones connect to other facial bones, such as the maxilla, sphenoid, ethmoid, vomer, and inferior nasal concha.

These bones are important in understanding conditions like cleft palate, a congenital disability that affects the mouth’s structure. They can also be involved in facial fractures from injuries.

6. Inferior Nasal Conchae (2)

The nasal conchae, or turbinates, are curved bony structures found on the side walls of the nasal cavity. Each nasal cavity contains three conchae—superior, middle, and inferior—that project downward and inward.

These structures divide the nasal cavity into five distinct air passages:

  • The spheno-ethmoidal recess.
  • The superior, middle, and inferior meatuses.
  • A common nasal passage where the lateral passages converge.

The superior and middle conchae are part of the ethmoid bone, while the inferior concha is independent. Due to their spiral, scroll-like shape, the conchae play a key role in increasing the surface area inside the nasal cavity.

It allows for better warming, humidifying, and filtering of the air as it flows toward the lungs and optimizing respiratory efficiency.

7. Vomer

The vomer is an unpaired bone found in the middle of the face. It forms part of the nasal septum, separating the nasal cavity’s two sides.

It sits along the midsagittal plane of the skull and connects to several other bones: the sphenoid and ethmoid bones and the palatine and maxillary bones on both sides.

The vomer helps form the nasal septum’s lower part, while the ethmoid bone’s perpendicular plate forms the upper part.

Although it usually lies in the middle, the front section of the vomer may sometimes curve slightly to one side.

This bone is thin and somewhat rectangular, with two flat surfaces and four edges. The surfaces have small grooves for blood vessels, and each surface has a nasopalatine groove, which provides a path for the nasopalatine nerve and blood vessels.

Read More-

Lower Limb

Upper Limb

Human Head

Organs

External Sources-

  • Wikipedia
  • KenHub
  • Optometrists
  • Cleveland Clinic
  • American Academy of Ophthalmology

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