Dural Venous Sinuses

The carotid arterial system provides blood supply to the head and neck. The arterial system begins as the common carotid artery, which arises directly from the aortic arch on the left side and from the brachiocephalic trunk/artery on the right. The common carotid arteries then ascend through the neck and divide into the internal and external carotid arteries. The former supplies structures within the brain and orbits, whereas the latter supplies the superficial structures and parts of the neck and face.

The brain and the spinal cord are enveloped by 3 overlapping layers of connective tissue called the meninges. The layers are, from the most external layer to the most internal layer, the dura mater, arachnoid mater, and pia mater. Between these layers are 3 potential spaces called the epidural, subdural, and subarachnoid spaces. The meninges function to protect the contents of the brain and spinal cord. Infection of the CNS presents with inflammation of the meninges, and the etiology can be elicited by examining CSF, which is contained within the subarachnoid space.

The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. The neurocranium is further subdivided into the calvarium (the skullcap) and the base of the skull (the cranial fossa).