Question

1. Describe the gross anatomy of a long bone: 2. Describe the microanatomy of compact bone: 3. Provide the functional and structural classification of the following joints: Hip joint- Elbow-

Answer 1

4.a) tubercle- a small rounded projection or protuberance, especially on a bone or on the surface of an animal or plant.

Greater tubercle Lesser tubercle Supratrochlear foramen (dog) Olecranon fossa Medial epicondyle Lateral epicondyle Condyle

b) fissure- fissure is a groove, natural division, deep furrow, elongated cleft, or tear in various parts of the body also generally called a sulcus.

c) epicondyle- a rounded protuberance at the end of a bone, serving as a place of attachment for ligaments, tendons, and muscles. Mainly located at the distal end of humerus.

D) coronal suture-The coronal suture is a dense, fibrous connective tissue joint that separates the two parietal bones from the frontal bone of the skull.It is one of several 'sutures', which are a type of immovable joint that exists only between the skull (or 'cranial') bones.

Frontal bones Anterior fontanelle Metopic suture Coronal suture Coronal suture -Sagittal suture Parietal bones Lambdoid suture - Posterior fontanelle Occipital bone

E) Intervertebral disc-any of the tough elastic disks that are interposed between the centra of adjoining vertebrae and that consist of an outer fibrous ring enclosing an inner pulpy nucleus which acts as a shock absorber.

1. Gross anatomy of long bone-

Articular cartilage Proximal epiphysis Metaphysis Spongy bone Epiphyseal line Red bone marrow Endosteum Compact bone Medullary cavity Diaphysis Yellow bone marrow Periosteum Nutrient artery Metaphysis Distal epiphysis Articular cartilage

A long bone has two parts: the diaphysis and the epiphysis. The diaphysis is the tubular shaft that runs between the proximal and distal ends of the bone. The hollow region in the diaphysis is called the medullary cavity, which is filled with yellow marrow. The walls of the diaphysis are composed of dense and hard compact bone.

The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled with spongy bone. Red marrow fills the spaces in the spongy bone. Each epiphysis meets the diaphysis at the metaphysis, the narrow area that contains the epiphyseal plate (growth plate), a layer of hyaline (transparent) cartilage in a growing bone. When the bone stops growing in early adulthood (approximately 18–21 years), the cartilage is replaced by osseous tissue and the epiphyseal plate becomes an epiphyseal line.

The medullary cavity has a delicate membranous lining called the endosteum (end- = “inside”; oste- = “bone”), where bone growth, repair, and remodeling occur. The outer surface of the bone is covered with a fibrous membrane called the periosteum (peri– = “around” or “surrounding”). The periosteum contains blood vessels, nerves, and lymphatic vessels that nourish compact bone. Tendons and ligaments also attach to bones at the periosteum. The periosteum covers the entire outer surface except where the epiphyses meet other bones to form joints (Figure 2). In this region, the epiphyses are covered with articular cartilage, a thin layer of cartilage that reduces friction and acts as a shock absorber.

2. Microanatomy of compact bone:

Compact Bone & Spongy (Cancellous Bone) Osteon of compact bone Lacunae containing osteocytes Lamellae Canaliculi Trabeculae of spongy bone Osteon Haversian canal Periosteum Volkmann's canal

Compact bone consists of closely packed osteons or haversian systems. The osteon consists of a central canal called the osteonic (haversian) canal, which is surrounded by concentric rings (lamellae) of matrix. Between the rings of matrix, the bone cells (osteocytes) are located in spaces called lacunae. Small channels (canaliculi) radiate from the lacunae to the osteonic (haversian) canal to provide passageways through the hard matrix. In compact bone, the haversian systems are packed tightly together to form what appears to be a solid mass. The osteonic canals contain blood vessels that are parallel to the long axis of the bone. These blood vessels interconnect, by way of perforating canals, with vessels on the surface of the bone

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ENDOCHONDRAL OSSIFICATION VERSUS INTRAMEMBRANOUS OSSIFICATION ENDOCHONDRAL INTRAMEMBRANOUS OSSIFICATION OSSIFICATION LLLLLLLLLLLLLLLLLLLLLLL LLLLLLLLLLEE A type of ossification taking Development of osseous place from centers arising in tissue within the cartilage and involving mesenchymal tissue without deposition of lime salts in the prior cartilage formation cartilage matrix followed by secondary absorption and replacement by true bony tissue LURRRRRRRRR A cartilage is formed first Bone is directly formed on and the bone is laid down a mesenchyme on it IIIIIIIIIIII Proceeds through an intermediate cartilage Does not form an intermediate cartilage 100 Important in the formation of flat bones LILILLEBRILLER Important in the formation of long bones DDDDDDDDD Takes a longer time to form a bone W H ERRER Stops at year two Takes less to form a bone H1111111111111 Sops at year 18 in females and 21 in males Visit www.PEDIAA.com