ANATOMY AND PHYSIOLOGY

Meninges. Series of three connective tissue membranes surrounding and protecting the
brain and the spinal cord.
 Dura

Mater. Tough and thickest fibrous membrane forming the outermost meningeal covering of
the brain and the spinal cord. It consists of two layers, which function as a single layer but
are physically separated into several regions to form dural folds and dural venous sinuses
extending into longitudinal fissure between two cerebral hemispheres and between the
cerebrum and the cerebellum.
 Dural Folds. Help hold the brain in place within the skull.
 Dural Venous Sinuses. Collect blood from the small veins of the brain and empty
into the internal jugular veins, which exit the skull.
  Arachnoid Mater. Thin, wispy or cobweblike meningeal layer surrounding the brain and
spinal cord; the middle of three layers.
 Pia Mater. Innermost, meningeal layer; tightly attached to the surface of the brain and
spinal cord.
Subdural Space. Only a potential space containing a very small amount of serous fluid.
Subarachnoid Space. A space filled with cerebrospinal fluid and contains blood vessels.
Cerebrum. Largest part of the brain, consisting of two hemispheres and including the cortex, nerve tracts, and basal nuclei.
 SKELETAL SYSTEM

The Skeletal System consist of bones, as well as their associated connective tissue, which include cartilage, tendons, and
ligaments. The major functions of the skeletal system include:

 Support. Bones, the “steel girders” and “reinforced concrete” of the body, form the internal framework that supports the
body and cradle its soft organs; the bones of the legs act as pillars to support the body trunk when we stand, and the rib
cage supports the thoracic wall.
 Protection. Bones protect soft body organs; for example, the fused bones of the skull provide a snug enclosure for the
brain, the vertebrae surround the spinal cord, and the rib cage helps protect the vital organs of the thorax.
 Movement. Skeletal muscles, attached to bones by tendons, use the bones as levers to move the body and its parts.
 Storage. Fat is stored in the internal cavities of bones; bone itself serves as a storehouse for minerals, the most important
of which are calcium and phosphorus; because most of the body’s calcium is deposited in the bones as calcium salts, the
bones are a convenient place to get more calcium ions for the blood as they are used up.
 Blood cell formation. Blood cell formation, or hematopoiesis, occurs within the marrow cavities of certain bones.
ANATOMY AND PHYSIOLOGY

SKULL
The axial skeleton, which forms the longitudinal axis of the body, is divided into three parts: the skull, the
vertebral column, and the bony thorax.
Skull. The skull is formed by two sets of bones: the cranium and the facial bones.
Cranium. The cranium encloses and protects the fragile brain tissue and is composed of eight
large flat bones.
 Frontal bone. The frontal bone forms the forehead, the bony projections under the eyebrows, and
the superior part of each eye’s orbits.
 Parietal bones. The paired parietal bones form most of the superior and lateral walls of the
cranium; they meet in the midline of the skull at the sagittal suture and form the coronal suture,
where they meet the frontal bone.
 Temporal bones. The temporal bones lie inferior to the parietal bones; they join them at the
squamous sutures.
 The cranium (skull) is the skeletal structure of the head that supports the face and protects the
brain. It is subdivided into the facial bones and the brain case, or cranial vault ([link]). The facial
bones underlie the facial structures, form the nasal cavity, enclose the eyeballs, and support the
teeth of the upper and lower jaws. The rounded brain case surrounds and protects the brain and
houses the middle and inner ear structures.
 Occipital bone. The occipital bone joins the parietal bones anteriorly at the lambdoid suture; in the
base of the occipital bone is a large opening, the foramen magnum, which surrounds the lower part
of the brain allows the spinal cord to connect with the brain.
 Sphenoid bone. The butterfly-shaped sphenoid bone spans the width of the skull and forms part of
the floor of the cranial cavity; in the midline of the sphenoid is a small depression, the sella turcica
or Turk’s saddle, which forms a snug enclosure for the pituitary gland.
 Foramen ovale. The foramen ovale, a large oval opening in line with the posterior end of the sella
turcica, allows fibers of cranial nerve V to pass to the chewing muscles of the lower jaw.
 Optic canal. The optic canal allows the optic nerve to pass to the eye.
 Superior orbital fissure. The slitlike superior orbital fissure is where the cranial nerves controlling
eye movements pass.
  Sphenoid sinuses. The central part of the sphenoid bone is riddled with air cavities, the sphenoid sinuses.
 Ethmoid bone. The ethmoid bone is very irregularly shaped and lies anterior to the sphenoid; it forms the roof of the nasal cavity and part of the medial walls of the orbits.
 Crista galli. Projecting from its superior surface is the crista galli; the outermost covering of the brain attaches to this projection.
 Cribriform plates. These holey areas, the cribriform plates, allow nerve fibers carrying impulses from the olfactory receptors of the nose to reach the brain.
 Superior and middle nasal conchae. Extensions of the ethmoid bone, the superior and middle nasal conchae, form part of the lateral walls of the nasal cavity and increase
the turbulence of air flowing through the nasal passages.

Facial Bones
Fourteen bones compose the face; twelve are paired, only the mandible and vomer are single.

 Maxillae. The two maxillae, or maxillary bones, fuse to form the upper jaw; all facial bones except the mandible join the maxillae; thus, they are the main or “keystone”,
bones of the face; the maxillae carry the upper teeth in the alveolar margin.
 Palatine bones. The paired palatine bones lie posterior to the palatine processes of the maxillae; they form the posterior part of the hard palate.
 Zygomatic bones. The zygomatic bones are commonly referred to as the cheek bones; they also form a good-sized portion of the lateral walls of the orbits, or eye sockets.
 Lacrimal bones. The lacrimal bones are finger-sized bones forming part of the medial walls of each orbit; each lacrimal bones has a groove that serves as a passageway for
tears.
 Nasal bones. The small rectangular bones forming the bridge of the nose are the nasal bones.
 Vomer bone. The single bone in the medial line of the nasal cavity is the vomer; the vomer forms most of the bony nasal septum.
 Inferior nasal conchae. The interior nasal conchae are thin, curved bones projecting medially from the lateral walls of the nasal cavity.
 Mandible. The mandible, or lower jaw, is the largest and strongest bone of the face; it joins the temporal bones on each side of the face, forming the only freely movable
joints in the skull; the horizontal part of the mandible (the body) forms the chin; two upright bars of bone (the rami) extend from the body to connect the mandible to the
temporal bone.