the joints between cranial bones of the skull are called

The thinner pia mater, highly vascular (containing many blood vessels), covers the brain's surface. The dura mater, tough and fibrous, lines the skull. Three membrane layers, the meninges, protect the brain from injury and infection.

Each of these barriers to the brain is important, because brain tissue is fragile and unforgiving if injured. It is firmly surrounded by three layers of membranes, encased in a rigid skull (the cranium), and covered by a muscular scalp. The human brain is well protected from injury. The cerebellum acts as a 'mini brain' that coordinates body balance, posture, and movement. The brain stem and hypothalamus control automatic processes, such as breathing and heartbeat. And the frontal lobe controls thinking and planning. The parietal lobe controls movement, touch, and recognition. The temporal lobe controls sound and speech. The cortex of each hemisphere has four lobes: the occipital, temporal, parietal, and frontal lobes. The cortex is composed of sulci (folds) and gyri (bulges), which together provide a large surface area in the limited space inside the skull. Each hemisphere is covered by a layer of gray tissue, called the cerebral cortex, which is responsible for the higher functions of the brain, including conscious thought. A band of nerve tissue, called the corpus callosum, links two halves to allow them to exchange information. The largest part of the brain is the cerebrum, which controls the most sophisticated functions, such as thought, imagination, memory, emotion, speech, and sensory perception. These nerves relay impulses to and from the rest of the body. Thirty-one pairs of spinal nerves branch off the spinal cord, exiting between each level of vertebrae. These nerves relay impulses from the sensory organs, such as the eyes or ears. There are 12 pairs of cranial nerves branching off the brain. The brain constantly receives information and sends out instructions to the body through the spinal cord and the body's vast network of nerves. The brain is the control center of the nervous system. The occipital condyles on either side of the foramen magnum articulate with the first vertebra (C1) of the spine to permit up-and-down movement of the head. The spinal cord passes through a largest hole, called the foramen magnum, in the base of the cranium to join the brain. Small holes in the skull bones, called foraminae, and canals enable blood vessels, such as the carotid arteries and nerves, to enter and leave the skull.

The maxillae and mandible secure the teeth. The vomer is a single bone that makes up part of the nasal septum, which divides the nostrils, and the mandible forms the lower jaw. Each of the following facial bones are paired: the maxillae form the upper jaw and front of the hard palate the zygomatic bones form the cheeks the nasal bones form the bridge of the nose the lacrimal bones form part of the orbit, or eye socket the palatine bones form the rear of the hard palate and the inferior nasal conchae divide the nasal cavity. The 14 facial bones provide the structure of the face and form the openings through which food, water, and air enter the body. Shaped like a butterfly, the sphenoid bone forms the middle part of the cranial floor. The ethmoid bone forms part of the nasal cavity. The occipital bone forms the cranial rear and floor. Two temporal bones form the lower cranial sides. Two parietal bones form the sides of the cranial roof. By one-and-a-half years of age, the skull sutures have formed and the fontanels have disappeared. Fontanels allow the skull to be compressed slightly during birth and accommodate growth of the brain during early infancy.

In newborns, the skull bones are not completely fused they are linked by fibrous membrane called fontanels. The mandible, or lower jaw, the only moveable skull bone, allows the mouth to open and close. The sutures lock the edges of the skull bones together, like pieces in a puzzle, to form a structure that is both rigid and strong. In adults, all but one of the skull bones are fused together by immovable joints called sutures. The skull is made up of 22 bones: the cranium includes eight bones that surround and protect the brain and 14 bones that form the face.

The joints between cranial bones of the skull are called