What is in a rat's head? - briefly
A rat’s head houses a skull that encases the brain, along with the brain, eyes, ears, nose, and the nerves, blood vessels, and sensory organs that support these structures.
What is in a rat's head? - in detail
A rat’s cranium houses a compact nervous system, vascular network, and connective tissues that together support survival and behavior. The brain occupies roughly 2 % of body mass and is organized into distinct regions:
- Cerebral cortex – thin, folded layer responsible for sensory integration, motor planning, and learning. In rodents it is proportionally larger for whisker processing.
- Olfactory bulb – positioned at the front, receives input from the nasal epithelium and mediates smell detection.
- Hippocampus – curved structure involved in spatial navigation and memory formation.
- Thalamus and hypothalamus – relay sensory signals and regulate autonomic functions, hormone release, and circadian rhythms.
- Midbrain and brainstem – control reflexes, respiration, heart rate, and coordination of eye movements.
- Cerebellum – located posteriorly, fine‑tunes motor activity and balance.
Surrounding the brain, the meninges consist of three layers—dura mater, arachnoid mater, and pia mater—providing protection and containing cerebrospinal fluid (CSF). CSF circulates through the ventricular system (lateral, third, and fourth ventricles) and the subarachnoid space, cushioning the tissue and removing metabolic waste.
Vascular supply originates from the carotid arteries, which branch into the anterior and posterior cerebral arteries. These vessels deliver oxygen and nutrients while venous sinuses drain deoxygenated blood toward the jugular veins.
Sensory structures embedded in the skull include:
- Auditory bullae – house the middle and inner ear, facilitating sound detection.
- Orbits – contain the eyes, optic nerves, and associated muscles for visual processing.
- Nasal cavity – lined with olfactory epithelium linked to the olfactory bulb.
The cranial cavity also contains connective tissue, fat pads, and lymphatic vessels that support immune surveillance. Together, these components create a tightly integrated system that governs perception, cognition, and physiological regulation in the animal.