Special senses in the context of "Skull"

The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for special senses such as vision, hearing, and olfaction. Being the most specialized organ, it is responsible for receiving information from the sensory nervous system, processing that information (thought, cognition, and intelligence) and the coordination of motor control (muscle activity and endocrine system).

While invertebrate brains arise from paired segmental ganglia (each of which is only responsible for the respective body segment) of the ventral nerve cord, vertebrate brains develop axially from the midline dorsal nerve cord as a vesicular enlargement at the rostral end of the neural tube, with centralized control over all body segments. All vertebrate brains can be embryonically divided into three parts: the forebrain (prosencephalon, subdivided into telencephalon and diencephalon), midbrain (mesencephalon) and hindbrain (rhombencephalon, subdivided into metencephalon and myelencephalon). The spinal cord, which directly interacts with somatic functions below the head, can be considered a caudal extension of the myelencephalon enclosed inside the vertebral column. Together, the brain and spinal cord constitute the central nervous system in all vertebrates.

Cranial nerves are nerves that emerge directly from the brain, including the brainstem. They relay information between the brain and various parts of the body, primarily to the head and neck regions and are responsible for special senses of vision, taste, smell, and hearing.

The cranial nerves emerge from the central nervous system above the level of the first vertebra of the vertebral column. Each cranial nerve is paired and is present on both sides.

In medicine and anatomy, the general senses are the senses which are perceived due to receptors scattered throughout the body such as touch, temperature, and hunger, rather than tied to a specific structure, as the special senses vision or hearing are. Often, the general senses are associated with a specific drive; that is, the sensation will cause a change in behavior meant to reduce the sensation.

Special somatic afferent fibers (SSA) are the afferent nerve fibers that carry information from the special senses of vision, hearing and balance. The cranial nerves containing SSA fibers are the optic nerve (CN II) and the vestibulocochlear nerve (CN VIII).