The Human skull consists of two parts; the Neurocranium and the Viscerocranium. The Neurocranium is the upper part of the skull that protects the brain and is composed of several separate cavities and surfaces known as cranial fossae. The cranial fossae are the Anterior Cranial Fossa, Middle Cranial Fossa, and Posterior Cranial Fossa.
The Anterior Cranial Fossa is the largest of the three fossae. It is situated at the anterior part of the base of the skull and houses the frontal lobes of the brain. It is roughly triangular in shape with three distinct borders; the frontal, ethmoidal, and sphenoidal. The frontal border includes the frontal bone and forms the forehead. The ethmoidal border consists of the ethmoid bone, which forms part of the walls of the orbits, and the sphenoidal border is formed by the lesser wings of the sphenoid bone.
The Anterior Cranial Fossa serves as a support for the frontal lobes of the brain, providing them with a wide range of movement in order to facilitate complex cognitive processing. It also houses several important structures such as the frontal sinuses, olfactory bulbs, and the cribriform plate. The cribriform plate is a porous plate that allows nerves to pass through to reach the olfactory bulbs.
The Middle Cranial Fossa is located at the middle part of the base of the skull and houses the temporal lobes of the brain. It is roughly rectangular in shape with four distinct borders; the sphenoidal, petrous, squamous and temporal. The sphenoidal border is formed by the greater wings of the sphenoid bone. The petrous border is formed by the petrous portion of the temporal bone and the squamous border is formed by the squamous part of the temporal bone. The temporal border is formed by the temporal bone.
The Middle Cranial Fossa serves as a support for the temporal lobes of the brain, providing them with a wide range of movement in order to facilitate complex cognitive processing. It also houses several important structures such as the auditory tubes – the small tubes that connect the middle ear to the nasopharynx – and the cochlear aqueduct, a small channel that is part of the inner ear and assists with hearing.
The Posterior Cranial Fossa is the smallest of the three fossae. It is situated at the posterior end of the base of the skull and houses the cerebellum and brain stem. It is triangular in shape with three distinct borders; the occipital, petrous, and mastoid. The occipital border is formed by the occipital bone and the petrous and mastoid borders are formed by the petrous and mastoid parts of the temporal bone.
The Posterior Cranial Fossa serves as a support for the cerebellum and brainstem, providing them with a wide range of movement in order to facilitate complex cognitive processing and motor control, respectively. It also houses several important structures such as the jugular foramen, the opening in the skull where the jugular vein passes through, and the foramen magnum, the hole at the base of the skull through which the spinal cord passes.
The Cranial Fossae play an important role in the functioning of the human brain and in providing us with a range of mental activities such as cognitive processing, motor control, and hearing. By understanding the anatomy of the Cranial Fossae, we can gain a greater appreciation of how our brains work and how we can use them to their fullest potential.
