Observe the Haversian sytems or osteons of compact bone in this slide. The lamellae are concentrically located around a central canal haversian canal which contained blood vessels, nerves, and loose connective tissue. Volkmann's canals may be seen connecting haversian canals. The other lamellae of compact bone are organized into inner circumferential, outer circumferential, and interstitial lamellae. Only interstitial lamellae are seen in this slide. Also in this section, note the empty lacunae and canaliculi that housed the osteocyte and its cell processes, respectively.
Slide 11 Nasal mucosa. Intramembranous ossification is visible in the nasal conchae on this slide. Bone arises directly within mesenchymal condensations.
This process can be identified by the appearance of bone spicules islands of bone among mesenchymal cells. Look for the eosinophilic bone matrix. Your skeleton is an incredible structure.
It gives your body shape, it protects vital organs, and it's alive. That's right! When you think of the skeleton, what comes to mind? Hard, dry bones, right? You can thank artistic conditioning in kindergarten for that one. The thing is, bones may be hard on the outside, but on the inside they're a smorgasbord of vessels, nerves, and other things. I may just blow your mind with this post. Compact bone is dense bone tissue found on the outside of a bone.
Basically, in kindergarten when you drew skeletons, you were drawing compact bone. Compact bone is enclosed, except where it's covered by articular cartilage, and is covered by the periosteum. The periosteum is a thick fibrous membrane covering the entire surface of a bone and serving as an attachment for muscles and tendons. Vessels pass from the periosteum through pores into the compact bone and run through canals found throughout the tissue.
Spongy bone is on the interior of a bone and consists of slender fibers and lamellae—layers of bony tissue—that join to form a reticular structure. Spongy bone is supplied by fewer and larger vessels than compact bone. These vessels perforate the outer compact layer and are distributed into the spongy portion of bone, which is filled with marrow.
Bone marrow is tissue found in long bones, like the femur, that contains stem cells. Osteons are cylindrical structures that contain a mineral matrix and living osteocytes connected by canaliculi, which transport blood.
They are aligned parallel to the long axis of the bone. Each osteon consists of lamellae , which are layers of compact matrix that surround a central canal called the Haversian canal. Osteons in compact bone tissue are aligned in the same direction along lines of stress and help the bone resist bending or fracturing. Therefore, compact bone tissue is prominent in areas of bone at which stresses are applied in only a few directions. Figure 1.
The inner layer of bones consists of spongy bone tissue. The small dark ovals in the osteon represent the living osteocytes. Whereas compact bone tissue forms the outer layer of all bones, spongy bone or cancellous bone forms the inner layer of all bones. Spongy bone tissue does not contain osteons that constitute compact bone tissue. Instead, it consists of trabeculae , which are lamellae that are arranged as rods or plates. Red bone marrow is found between the trabuculae.
Blood vessels within this tissue deliver nutrients to osteocytes and remove waste. The red bone marrow of the femur and the interior of other large bones, such as the ilium, forms blood cells. Figure 2. Trabeculae in spongy bone are arranged such that one side of the bone bears tension and the other withstands compression. The medullary cavity, live the spaces in spongy bone, is filled with bone marrow. The instructor will provide you with a plastic model of enlarged bone tissue.
Find all the following items in the model and be prepared to point out any three to the instructor on their request. Figure The model of enlarged bone tissue you will use to identify the histological features listed above.
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