skeletal system


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Laguna State Polytechnic university San Pablo City, campus Philippines:

Laguna State Polytechnic university San Pablo City, campus Philippines


BEED 1-W MAELEEN G. POJO Myrene B. Averion




CONTENTS SKELETAL SYSTEM - is composed of cartilage,tendons,ligaments and bones. Bones - solid network of living cells and fibers that are supported by deposits calcium salts; surrounded by a tough membrane called periosteum. Tendons - connective tissue that connects muscles to bones. Ligaments - connective tissue that connects bones to other bones/muscle. Cartilage - connective tissue wherein many bones are formed;does not contain blood vessels;rely on the diffusion of nutrients from the tiny blood vessels in surrounding tissues;dense fibrous,can support weight but extremely flexible .

Functions of the skeletal system/bones :

Functions of the skeletal system/bones Support and shape - the body. Protection - the delicate internal organs. Movemen t - provide a system of levers on which a group of specialized tissues act to produce movement. Storage - reserver of minerals such as sodium,potassium,calcium and phosphate and releases to blood. Site of blood cell formation. Holds the reserves protein that the body uses during fasting.


STRUCTURE OF BONES Haversian canals - network that runs through the compact b one that contain blood vesselsand nerves. Spongy bones - organized into structures that resemble the supporting girders in a bridge helping to add strenght to bone without mass. Osteocytes - embedded in compact and spongy bone;deposit the calcium salts in bone or absorb them;bone growth and changes in the shape of bones. Bone marrow - soft tissues contained in bone cavities. TYPES OF BONE MARROW: Yellow marrow - found in most bones;made up of blood vessels,nerve cells,and fat cells. Red marrow -produces red blood cells and special white blood cells and platelets.


DEVELOPMENT OF BONES Ossification -process of bone formation;takes place seven months before birth as mineral deposits are laid down near the center of the bone.Gradually,bone tissue forms as osteocytes secrete mineral deposits that replace cartillage. Collagen -an elastic protein found in the cells that make up cartillge that are scattered in a network of fibers. Periosteum -a tough m embrane that surrounds the bone. Growth plates -contained in many long bones at either end in which the growth of cartillage causes the bones to lengthen. Age of 18 to 20 -the growth plates disappear,the bones become copletely ossified and the person stops growing. Adult -cartillages are found in places where flexibility is needed and ends of the bones where joints are formed.


CLASSIFICATION OF BONES Compact bones - dense and looks smooth and homogeneous. Spongy bones - composed of small needle-like pieces of bones and lots of open space. Long bones - longer than they are wide;as a rule they have a shaft with heads at both ends. Short bones-cube - shaped and contain mostly spongy bones;bones of the wrist and ankle. Flat bones - thin,flattened and ussually curved. Irregular bones - bones that do not fit open of the preceding categories.


JOINTS OR ARTICULATIONS Where two bones come together permitting the bones to move without damaging each other. It is responsible for keeping the bones far apart enough so that they do not rub against each other as they move at the same time . Functions : Hold bones in place/together securely Give the rigid skeleton mobility-responsible for wide varities of movements,extensive to no movement at all.


FUNCTIONS CLASSIFICATION OF JOINTS (BASED ON THEIR TYPE OF MOVEMENT) Immovable jointsor synarthroses - Allow a little or no movement at all,because the bones are interlocked or they are fused. Slightly movable joints or semi-fixed or amphiarthroses - Allow a small amount of movement;bones are farter apart from each other. Freely movable joints or diarthroses - Allow a wide range of movement;located at the ends of bones that are covered with layers of cartillage,providong a smooth surface at the point of contact;enclosed by a joint capsule. Synovial fluids -natural lubricant that reduces friction and allows the cartillage -coated bones to slip past each other easily. Bursa -small pocket of synovial fluid;reduces the friction between the bones of a joint and acts as shocks absorber .


STRUCTURAL CLASSIFICATION OF JOINTS 1. Fibrous joints - immovable joints;bones are united by fibrous tissue. United by fibrous tissue. Example: Sutures of the skull-irregular edges of the bone interlock and are bound tightly together by connective tissue fibers,allowing essentially no movement to occur, Syndesmones -the connecting fibers are longer that those of sutures;joint has more”give”-the point connecting the distal ends of tibia and fibula is syndesmosis 2. Cartlaginous Joints -some immovable and most are slightly immovable examples;bone ends connected by cartillage. Example: pubic symphysis of the pelvis and intervertebral of the spinal column, where articulating bone surfaces are connected by pads of fibro cartillage. 3. Synovial joints -freely movable joints;articulating bone ends are seperated by a joint cavity containing synovial fluid.

Types of synovial joints based on it’s movement / flexibility :

Types of synovial joints based on it’s movement / flexibility Nonaxial joints - flat slightly curved bone surface allow only slipping movements to occur between bone. Unaxial joints -move only in one plane the pivot joint between the radius and ulna. Blaxial joints -move in two planes. Multiaxial joints -move in all planes,such as ball and socket joints of the shoulder and hip.

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SKELETON - flexible,bony framework opf any vertebrae animal; Human Skeleton is made up of 206 bones which are attached to other bones by the joints and fit together and held in place by strong bands ogf flexible tissue called ligaments . TWO PARTS OF SKELETAL SYSTEM : A. Axial skeleton -forms the longitudinal axis of the body includes the skull,vertebral column,bony thorax/rib cage. 1. Skull - formed by tow sets of bones ;the cranium-encloses and protects the fragile brain tissue and the facial bone-hold the eyes in an interior position and allow the facial muscles to show our feeling through smiles and frown . Cranium -composes of eight large,flat bones Frontal bone - forms the forehead,the bony projections under the eyebrow, and superior part of each eyes orbit . Parietal bone -paired parietal bone form most of the superior and lateral walls the cranium.

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Temporal bones -inferior to the parietal bones;they join them at the squamous statures.Several important bones making appear on the temporal bone. Occipital bones -the most posterior bone of the cranium;it joins the parietal bones anteriorly of the lamboid. Sphenoid bone –the butterfly-shaped sphenoid bone spans the width of the skull and forms part of the floor of the cranial cavity. Ethmoid bone –very irregular shaped and lies anterior to the sphenoid. FACIAL BONE Maxiillae –the two maxillae or maxillary bone,fuse to form the upper jaw. Palatine bones –the paired palatine bones lie posterior to the palatine processes of the maxillae Zygosomatic –commonly referred to as cheekbones Lacrimal bones –fingernail size bones forming part of the medial,walls of each orbit. Nasal bone –the small rectangular bones forming the bridge of the nose . Vomer bones –single in the median line of the nasal cavity. Mandible -or lower jaw is the largest and strongest bone of the face.

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2. Vertebral Column (spine) –serving asa the axial support of the body;it extends from the skull,which it support,to the pelvis,where it transmit the weight of the body to the lower limbs. Before birth the spine consists of 33 seperate bone called vertebrae,but 9 of these eventually fuse,forming the two composite bones the sacrum and the coccyx. Cervical vertebrae –neck;seven cervical vertebrae(identified as C1 to C7)from the neck region of the spine ;first two vertebrae,atlas and axis ,are different because they perform functions not shared by the cervical vertebrae,they are vthe smallest vertebrae,having moblong bodies which are broader from side to side. Thoraic vertebrae –chest ;12(T1 to T12)thoracic vertebrae are all typical;larger than cervical vertebrae;the body is heart-shaped and has 2 costal demifacets(articulating surface)on each side,which receive the heads of the ribs. Lumbar vertebrae –lower back;five lumbar vertebrae;the largest and strongest;various projections are short and thick of the spinous process are modified for attachment of the powerful back muscle.

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Sacrum –lies below the 5th lumbar vertebrae and is triangular in shapes;slightly curved and positioned at the base of the pelvic cavity between the two nominate bones;has a cavity;which is the continuation of the spinal canal . Coccyx –formed from fusion of 3 to 5 small irregular shaped vertebrae;human “tail bone” a remnant of the tail that other vertebrae animals have. 3. Bony thorax Sternum –the breast bone;flat bone and the result of the fusion of 3 bones.the manumbrium and xyphoid process;attached to the first seven pairs of ribs. Ribs –any of the 24 bones that enclose the chest in human body;12 ribs on each side of the body,each connected to the vertebral column(backbone) by small joints called “costovertebral joints”

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True ribs –first seven pairs attached directly to the sternum by costal cartillages. False ribs –the next five pairs,either attached indirectly to the sternum;the last pairs of the false ribs lack sternal attachments and so they are called “float ribs” B. Appendicula skeleton –lateral and paired;bones of the arms,legs,hands,and feet;composed of 126 bones of the limbs t(appendages) and the pectoral and the pelvic girdles,which attached the limbs to the axial skeleton. 1. Pectoral Girdle (shoulder) Clavicle _collar bones;slender doubly curved bone;helps to form shoulder joints. Scapula –shoulder blades;triangular and commonly called “wings” because they are like wings when we move our arms posteriorly.

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2. Forelimb (arms) Humerus –long bone;proximal end is a rounded head that fits into shallow end is rounded head fits into the shallow glenoid cavity of the scapula. Radius –the lateral bone;on the thumb side of the forearm Ulna –the medial bone of the forearm Carpal bone –arranged in two irregular rows of four bones each,form the part of the hand called carpus;the row nearest the forearm starting from the thumb side are navicular,lunate,triangular,and pisiform;second row are greater multangular,lesser multangular,capitate,and hamate.

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Metacarpals –palm of the hands;numbered 1 to 5 from the thumb-side of the hands toward the little fingers. Phalanges –bones of the finger;each and contains 14 phalanges;there are three in each –proximal,middle,and distal. 3. Pelvic Girdle (hip) –formed by two coxal bones or ossa coxae,commonly called “hip bone”;large and heavy,attached to the axial skeleton,sockets which receive the femur (thigh bone),are deep and heaviloy reinforced by ligaments that attached the limbs firmly to the girdle. (a.) Llium (b.)Pubis (c.)Ischium

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4. Lower Limbs/hind limbs (legs) –carry our total body weight when we are erect;three segments –thigh,leg,and foot-are much thicker and stronger that the comparable bones of the upper limb . Femur –thigh bones’the only bones in thigh;the heaviest and strongest bone in the body. Tibia –shinbone;larger and more medial;at the proximal end,the medial and lateral condyles,(seperated by the intercondylar eminence)articulate with distal end of femur to form the knee joint. Fibula –lies along side the tibia ;thin and sticklike;no part forming the kneejoint;distal ends the lateral malleous;forms the outer part of the ankle. Tarsals –forming the posterior half of the foot is composed of several tarsals bones which are calcaneus (heelbone)or talus (ankle)which lies between the tibia and the calcaneus,navicular,cuboid and the three cuneiform. Metatarsals –form the five sole,loke the metacarpals.



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