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Cranial bones are of six in types. They are as follows: Cranial bones: 1. Frontal bone 2. Sphenoid bone 3. Occipital bone 4. Temporal bone 5. Parietal bone 6. Ethmoid bone Now we will see about each bone one by one. 1.  Frontal Bone:  This cranial bone forms the forehead, and the hollow openings that enclose the eyes. frontal bone 2. Sphenoid Bone: This bone is structurally resembles a bat. This bat shaped bone widens behind the eyes such that it forms the base part of the cranium. Sphenoid bone attaches frontal bone, ethmoid bone and occipital bone. And so this bone is called as sphenoid bone. Sphenoid means wedge or anchor. There is a small hollow depression in the sphenoid bone in which the pituitary gland is located. This depression is called sella turtica which means Turkish saddle. 3. Occipital Bone: This bone outlines the base of the cranium or skull and the back portion of the skull, as well as it joins the temporal bones and the parietal bones.

Now in this lesson we are going to learn about Cranial Bones. Cranial bones are the bones of the cranium. The other name of cranium is skull. These bones cover and safeguard the brain and the other structures related to the brain that are sense organs such as ears, eyes, nose, mouth and skin of the skull and face. Cranial bones are connected with the muscles responsible for the movements of the head and chewing functions of the mouth. The cranial bones are attached to each other with a joint called sutures. When a baby borns the cranial bones are not connected completely but with gaps. At birth, these gaps are filled with unossified tissues in the cranium. These gaps are called as soft spots and they are also known as fontanelles. These fontanelles resemble small fountains. Whenever we touch these areas, we can feel the blood vessels inside them and their pulsations. Cranial bones are of six in types. They are as follows: 1. Frontal bone 2. Sphenoid bone 3. Occipita

BONE DEPRESSIONS: They are the hollow regions or the openings found in the bones.  The bone depressions attach the bone to the other bone.  They serve as the route or passageways for nerves and blood vessels.  There are five types of bone depressions.  They are fossa, sinus, sulcus, fissure, and foramen. Now will learn the types  of bone depressions one by one.  1.  Fossa:  These are the bony depressions are shallow cavities.  They are found inside the bones or on the bones. 2.  Sinus:  These are the depression of the bone that are found within bone.  Sinuses are hollow cavities in strucutre. 3.  Sulcus:  These type of bony depressions look like grooves or furrow in structure. 4.  Fissure:  They are a kind of bony depressions that are found on the bone.  They are narrow in size.  Fissures are deep slit like openings are found on the bone. 5.  Foramen:  These type of bony depressions act as the openings for nerves and blood vessels. They are also found on the bone.

In this lesson we are going to learn about Human Bone Processes Human Bone Processes: These are the enlarged parts of the human bones. They extend out from each human bone. Tendons and muscles attach to them in the bones. Now we will see the types of bone process one by one. Each bone consists of the following processes in it. They are as follows: 1. Bone head 2. Condyle 3. Trochanter 4. Tubercle 5. Tuberosity. 1. Bone head:- This is a bony process found on each bone. This bony process is round in shape and it is a separated area from the bone body. Bone head is attached to the bone body by a neck-like groove called bone neck. 2. Condyle:- This bony process is rounded in shape. It looks like knuckle-like structure in the bone joint. 3. Trochanter:- This bony process attach muscles to the femur bone. The Trochanter is large in structure. 4. Tubercle:- This bony process is small and rounded in structure. Tubercle is found in many bones of the human bod

In this lesson we will learn more about the structure of the bone about the two layers of the bone.  They are compact bone and cancellous bone.  Now we will about one bye one now. Okay. Compact bone is also known as cortical bone is a layer of hard, dense tissue that lies under the periosteum in all bones and chiefly around the diaphysis of a along bones. The blood vessels are located within the compact bone which are the system of small canals that bring oxygen and nutrients to the bone and remove waste products such as carbondioxide. The haversian canals are located in the compact bone. The compact bone is tunneled out in the shaft of the long bones by a central medullary cavity which contains yellow bone marrow. This yellow bone marrow is chiefly composed of fat cells. Trabecular bone or spongy bone or cancellous bone:  This bone is to a great extent less dense and more porous comparing the compact or cortical bone.  This is made up of trabeculae or a spongy latticework. 

Now in this lesson we will try to learn about the remaining part of structure of the bone. The long, relatively straight main body of a long bone, region of primary ossification which is also known as the shaft or middle region of a long bone is called the diaphysis. The end of a each long bone or the regions of secondary ossification is called an epiphysis. The epiphyseal plate is also known as the growth plate or physis. This plate represents an area of cartilage tissue that is constantly being replaced by new bony tissue as the bone grows.  In a long bone, it is a thin disc of hyaline cartilage that is located transversely between the epiphysis and metaphysis. In the long bones of humans, the epiphyseal plate disappears by the age of twenty. The new bone that is responsible for the lengthening of bones during childhood and adolescence if formed by the cartilage cells at the edges of the epiphyseal plate. When the bone achieved its full growth, the plate calcifies and d