There are three different skeleton designs that provide organisms these functions: hydrostatic skeleton, exoskeleton, and endoskeleton. The eight cranial bones include the frontal bone, two parietal bones, two temporal bones, the occipital bone, the sphenoid bone, and the ethmoid bone. For now, let's take a closer look at each of the areas of the axial skeleton. It serves to support the body, protect the brain and other internal organs, and provides a rigid structure upon which muscles can pull to generate body movements. Although it is not found in the skull, the hyoid bone is considered a component of the axial skeleton. The mandible controls the opening to the airway and gut.
Don't forget to check out other lessons on this site to learn about its partner, the axial skeleton. While the axial skeleton protects and supports the internal organs and the body as a whole, both work together to allow us to operate and function normally. The Vertebral Column The vertebral column, or spinal column, surrounds and protects the spinal cord, supports the head, and acts as an attachment point for the ribs and muscles of the back and neck. The pectoral girdle, consisting of the collarbone and shoulder blades, connects the upper limbs to the sternum. The organs of the coelom are supported by the aqueous fluid, which also resists external compression.
Also associated with the head are an additional seven bones, including the hyoid bone found in the upper neck and the ear ossicles three small bones found in each middle ear. The skull consists of 22 bones, which are divided into two categories: cranial bones and facial bones. Exoskeleton An exoskeleton is an external, hard, encasement on the surface of an organism. Appendicular Skeleton Have you ever thought of the human body like a big puzzle? It also provides support for the shoulder girdles and upper limbs, and serves as the attachment point for the diaphragm, muscles of the back, chest, neck, and shoulders. The range in the capacity of the cranial cavity is wide but is not directly proportional to the size of the skull, because there are variations also in the thickness of the bones and in the size of the air pockets, or sinuses. These bones are unique to mammals. Therefore, they mainly consist of long bones and other bones.
The human skeletal system contains individual and attached , support of , muscles, tendons, and cartilages. The ulna, located on the medial aspect pinky-finger side of the forearm, is longer than the radius. This is connected to the two bones in the lower arm, the radius and ulna, which are below the elbow but above the wrist. Within these joints, bones are connected to other bones and muscle fibers via connective tissue such as tendons and ligaments. The 14 facial bones are the nasal bones, maxillary bones, zygomatic bones, palatine, vomer, lacrimal bones, inferior nasal conchae, and mandible. Lengthening the body extends the anterior end of the organism.
This article is concerned primarily with the gross structure and the function of the skeleton of the normal human adult. Of these functions, support is the most primitive and the oldest; likewise, the axial part of the skeleton was the first to evolve. And, by default, you've probably figured out that if a bone isn't part of the axial skeleton, then it must be part of the appendicular skeleton. It is caused by an inflammation of the bursa, small fluid-filled bags that act as lubricating surfaces for muscles to move over bones. To allow motion, different bones are connected by joints. The Axial Skeleton The axial skeleton forms the vertical, central axis of the body and includes all bones of the head, neck, chest, and back.
The top part of the arm, above the elbow, consists of one bone, the humerus. Arthritis can attack joints, joint capsules, the surrounding tissue or parts throughout the body. Above right: Axial and Appendicular Skeleton diagram Axial and Appendicular Skeleton The human skeleton is divided into two main groups or categories of bones. These joints have a larger range of motion than their counterpart, the pelvic girdle. The human skeleton, like that of other , consists of two principal subdivisions, each with origins distinct from the others and each presenting certain individual features. It acts as a movable base for the tongue and is connected to muscles of the jaw, larynx, and tongue.
In adults, the hip bones are formed by the fusion of three pairs of bones: the ilium, ischium, and pubis. He wins the Nobel Prize for Physics in 1901 for his discovery of X-rays. However, instead of being connected at the top of the rib cage, it is connected to the bottom of the spinal column. It serves to protect the brain, spinal cord, heart, and lungs. These bones are called the ilium, ischium and pubis bones.
Bone is a reservoir for minerals, most importantly calcium and phosphate. The fibula, or calf bone, parallels and articulates with the tibia. View from both directions of a axial skeleton cut in half. The frontal bone underlies the forehead region and extends back to the coronal suture, an arching line that separates the frontal bone from the two parietal bones, on the sides of the cranium. Among them, there are 80 bones present in the axial skeleton while there are 126 bones on the appendicular skeleton. The pectoral girdle is comprised of two clavicles and two shoulder blades, while the pelvic girdle is comprised of two large hipbones.
Axial Skeleton: Vertebrae Of all the bones in the axial skeleton, the neck bones underneath the skull probably have the greatest range of motion. The names of the spinal curves correspond to the region of the spine in which they occur. Nevertheless, erect posture has created a number of mechanical problems—in particular, weight bearing. All of these bones occur in pairs except for the mandible and the vomer Figure 3. Protection of the , , and other organs and structures in the chest creates a problem somewhat different from that of the central nervous system. This compartment is under hydrostatic pressure because of the fluid and supports the other organs of the organism.
The pectoral girdles connect the arms to the upper part of the rib cage at the shoulder joints. In animals with teeth, the mandible brings the surfaces of the teeth in contact with the maxillary teeth. These, in turn, are connected to the ankle bones, or tarsals, and the foot bones, the metatarsals and the phalanges hmm, those words kind of sound familiar! It protects the internal organs, including the brain, spinal cord, heart, lungs, and pelvic organs. The femur, for example, withstands great pressure, and its hollow-cylinder design provides maximum strength with minimum weight to accommodate upright posture. It also holds increased potential for injury, however, so care must be taken by athletes to avoid shoulder dislocations. Even with this progress, there is still room for improvement in the design of prostheses.