Question

Cranium of human contains (a) 8 bones (b) 14 bones (c) 12 bones (d) 20 bones.

Short answer

The human cranium contains (a) 8 bones.

Step-by-step solution

Identify the Correct Information

Recall the anatomical composition of the human cranium, which is part of the skull. The cranium, also known as the neurocranium, is made up of 8 bones. These bones are 1 occipital, 2 parietal, 1 frontal, 2 temporal, 1 sphenoid, and 1 ethmoid bone.

Eliminate Incorrect Options

Using the known information, eliminate the options that do not represent the correct number of cranial bones. Options (b) 14 bones, (c) 12 bones, and (d) 20 bones can be eliminated.

Choose the Correct Answer

The correct answer is the one that states the human cranium is made up of 8 bones. Therefore, option (a) is the correct answer.

Key concepts

Cranial Bones

Understanding the cranial bones is crucial for comprehending the broader subject of human skull anatomy. The human cranium, also known as the skullcap, houses and protects the brain. It is part of the skull that encases the brain (as opposed to the facial bones that form the face). Altogether, there are 8 cranial bones. These are the:

• Frontal bone: This forms the forehead and the upper part of the eye sockets. It plays a significant role in the shape and structure of the head.
• Parietal bones (2): These are on the sides and top of the skull, and they join together to form the roof of the cranium.
• Occipital bone: Found at the back and base of the skull, this bone surrounds the back part of the brain and contains the foramen magnum, through which the spinal cord passes.
• Temporal bones (2): These are situated at the sides of the skull, near the ears. They're involved in hearing and balance and also form part of the sides and base of the cranium.
• Sphenoid bone: This is located at the middle part of the skull base, and is complex in shape, touching several other cranial bones.
• Ethmoid bone: It's found at the roof of the nasal cavity and contributes to the structure of the nose and the separation of the nasal cavity and the brain.

The joints where these bones meet are known as sutures, which are essentially immovable in adults. Each of these bones plays a vital role not just in skull structure but in the protection of our brain, the seat of our consciousness.

Neurocranium Composition

The neurocranium is a key element of the human skull anatomy, specifically engineered to support and protect the brain. Beyond simply listing its comprising bones, it's essential to understand the functional design of this bony structure. The neurocranium includes the cranial cavity, which holds the brain, and features the meninges, cerebrospinal fluid, and blood vessels that support neuronal functions.
The intricate arrangement of the neurocranium's eight bones not only allows for the protection from physical impact but also provides attachment sites for muscles and contains passage ways for nerves and blood vessels. The sphenoid and ethmoid bones, besides being part of the neurocranium, also serve an important role in the facial skeleton which makes them versatile components in the overall skull structure.
Moreover, the base of the neurocranium is known as the cranial base or cranial floor and has several openings for the cranial nerves, which are essential for transmitting sensory information and motor commands between the brain and the rest of the body. Deepening one's understanding of the neurocranium's composition provides valuable insight into how the skull functions as a whole.

Human Skull Anatomy

The intricacies of human skull anatomy can be fascinating and understanding it is fundamental to grasping our overall physiology. The skull, consisting of the cranium and the mandible (jawbone), is a complex structure with several functions. It provides a scaffolding for the face and a protective cavity for the brain. Beyond the cranial bones, the human skull encompasses 14 facial bones which together with the cranium form the entire skull – totaling 22 major bones. There's also the hyoid bone, which is located in the neck and supports the tongue and associated muscles.

Among these facial bones are the maxillary (upper jaw) bones, the zygomatic (cheek) bones, and the mandible (lower jaw), the only movable bone of the skull. Additionally, the orbital cavities that house the eye spheres and the nasal cavity are integral to its anatomy.

• Temporomandibular joints: These enable jaw motion, such as chewing and speaking.
• Mastoid process: Part of the temporal bone, this serves as an attachment for neck muscles.
• Nasal septum: This divides the nasal cavity in two.

The skull's anatomy is not merely a rigid framework; it also facilitates various sensory functions like taste, smell, sight, and hearing. Its complexity is remarkable, each bone articulating with others to form the intricate, protective, and supportive framework of our head.