Skeletal System PDF

SKELETAL SYSTEM OBJECTIVES Skeleton Classification Axial and Appendicler Skelton Types of bones Functions of bones Skeletal system Bones tissue s make up about 18% of the total human body weight. The skeletal system supports and protects the body while giving it shape and form....

SKELETAL SYSTEM OBJECTIVES Skeleton Classification Axial and Appendicler Skelton Types of bones Functions of bones Skeletal system Bones tissue s make up about 18% of the total human body weight. The skeletal system supports and protects the body while giving it shape and form. OSTEOLOGY: It is the branch of science that deals with the study of the skeletal system, their structure and functions. Skeletal System Composed of: Bones’ Cartilage Joints Ligaments Functions of Skeletal System SUPPORT: Hard framework that supports and anchors the soft organs of body. PROTECTION: surrounds organs such as brain and spinal cord. MOVEMENT: Allows for muscle attachment therefore the bones are used as levers. STORAGE: Minerals and lipids are stored within bone material. BLOOD CELL FORMATION: The bone marrow is responsible for blood cell production. Regional Distribution Of bones: The human body consists of 206 named bones. Depending on their location, bones are divided into Two Groups 1. Axial Skeleton: lie in the Region of Head, Neck & Trunk. There are 80 Bones of Axial Skeleton. Their Distribution is as under: Skull Bones  Cranial Bones: Facial Bone:  Auditory Ossicles: Malleus(2) Incus (2) Stapes (2) 1 Hyoid Bone include which is present in front of neck. Vertebral Column  Ribs: 1. Sternum (1) 2. Ribs (24) 2. Appendicular Skeleton: Belong to lower Extremities(limbs). Contain 126 bones. Pectoral Girdle: Scapula (2) Clavicle (2) Upper Extremities: Bones of both upper extremities are: Humerus (2) Radius (2) Ulna (2) Carpals (16) Metacarpals (10) Phalanges (28)  Pelvic Girdle : Coxal, innominate or hip bones (2) Lower Extremities: Bones of Both lower extremities are: Femur (2) Tibia (2) Fibula (2) Patella (2) Tarsals (14) Metatarsals (28) Skeleton: “Hard, supporting framework of Body” Bone: “Hard connective tissue which consist of osteocytes,fibres & ground substances. The matrix contain Calcium salts which provide hardness or rigidity to bone functions. Mechanical Functions of Bones Bones makeup skeleton & provide rigid framework that supports & give shape to body Every bone articulate with other bone & form joint and allow movement to them. Protection Vital Organ. Only one bone don’t form any joint called Hyoid Bone which is present in front of neck. Physiological Functions of Bones Bone is main Storehouse having Main salts 97% Calcium which us in Abundant ,86% Phosphate & 54% Magnesium. Bone contain Marrow which is the site of Blood Cell Formation. Types Of Bones Tissues: Two Types of Osseous tissue found in Human body: 1. Compact Bone Tissue: Strong & resist force.  Hard & dense. Present outer side of Bone. Can seen by Naked Eye. Haversian System: “Microscopic Examination reveals that it contains cylinders of calcified bone called Haversian System.” Haversian Canal: “In center of each osteons present a longitudnal channel called Haversian Canal.” 2. Spongy Bone Tissue: “Interlaced pattern of tissue consisting of an irregular meshwork of intercommunicating bony trabeculae. Space of meshwork contain red bone marrow.” Soft as compare to Compact Bone Tissue. Present in inner side of bone. Can’t be seen by naked eye. Classification of Bones The bones of the body come in a variety of sizes and shapes. The four principal types of bones are Long bone Short bone Flat bone Irregular bone Classification According To Size And Shape: On the basis of the size, shape and some other structural features, the bones are classified into the following types: BONES: Bones that are longer than they are wide are called long bones. :  A Long bone consists of a cylindrical shafts and two expanded ends, which are smooth and articular. They are primarily compact bone but may have a large amount of spongy bone at the ends or extremities. Long bones include bones of the thigh, leg, arm, and forearm. Short Bones Short bones are roughly cube shaped with vertical and horizontal dimensions approximately equal. They occur only in the wrists (carpal bones) and ankles ( tarsal bones), where only limited movement is required. Short bones are consists of spongy bone with an outer shell of compact bone. Most of their surface area is occupied by cartilage covered articular surface where joints are formed with FLAT BONES They usually occur as thin and curved plates. They serve as protective covering and provide broad surface for muscle attachment. A flat bone consists of two layers of compact bone, between which is sandwiches a thin layer of spongy bone.  In the flat bones of skull the outer and inner layers of the compact bone are called TABLES. The spongy bone between them is called Diploe which contains red bone marrow in life. IRREGULAR BONES These bones do not fit into any other category. They have an irregular shape with several processes.  IRREGULAR BONES They are composed of spongy bone (containing red marrow) covered by thin layer of compact bone. This variety of bones include hip bones, vertebrae bones of base of skull (sphenoid, temporal, mastoid, etc) and bones of the face (maxilla, zygomatic ,etc) PNEUMATIC BONES Some bones of skull contain air-filles cavities called air sinuses or air cells. These bones are called Pneumatic bones. Example are maxilla, ethmoid and mastoid bones. Presence of these cavities makes the skull lighter and mastoid bones. The air sinuses in the skull bones are clinically important as they are favorite sites of infection.  SEASOMOID BONES A sesamoid bone is a bony nodule embedded within a tendon or muscle. Sesamoid bones are so named because the smallest one resemble the seeds of sesame plant. The sesamoid bones generally act as pulleys, providing a smooth surface for tendons to slide over, and thus enhance the tendons’ ability to transfer muscular force.  In some Location, the sesamoid bones serve to protect the tendons from trauma which may result from repetitive friction or continuous pressure. The patella or Knee cap is the largest sesamoid bone of the body.  Seasmoid bone Pneumatic bones  ACCESSORY BONES Accessory Bones These bones are not always present. They are Classified further into the following subtypes: 1. Supernumerary Bones Sometimes an extra secondary centre of ossification appears in a bone, which does not fuse with the main bone mass and gives rise to a separate small bone.  The accessory Bones formed in this manner are known as supernumerary bones. Such bones are commonly found in the foot and, in a Radiography of the foot, these bones may be mistaken for bone chips resulting from injury.