THE SKELETAL SYSTEM Kinesiology Unit 9

The Basic Skeletal System

Has articulations  joints Ligaments: attach bone to bone Tendons: attach muscle to bone The Skeleton

THE SKELETAL SYSTEM OSTEOLOGY: THE STUDY OF BONES ARTHOLOGY: THE STUDY OF JOINTS MAIN FUNCTIONS OF THE SKELETAL SYSTEM: SUPPORT FRAMEWORK FOR SOFT BODY TISSUES PROTECTS VITAL ORGANS (EXAMPE: BRAIN WITHIN THE SKULL, LUNGS WITHIN THE THORACIC CAGE) BLOOD CELL PRODUCTION OCCURS IN RED MARROW OF MANY BONES PROVIDES SYSTEM OF LEVERS ALLOWING MOVEMENT PROVIDES SHAPE TO THE BODY MAINTAINS HOMEOSTASIS (BALANCE CALCIUM)

THE SKELETAL SYSTEM BONES & JOINTS

BONES THE SKELETON CONSISTS OF 206 – 210 BONES

BONES: What is bone? - Live connective tissue - 25% water, 25% protein, 50% crysalised mineral salts Wolff’s Law: Bone is laid down (built up) where it is needed and resorbed (broken down) where it is not needed

Bone Cells: Osteoblasts: Bone building cells: synthesize and secrete collagen and other organic compounds to build up bone matrix Osteocytes: Mature bone cells. Derived from osteoblasts that have become trapped in the bone matrix…function is to exchange nutrients and waste with blood Osteoclasts: Bone resorbing cells Function to break down the bone matrix

Osteoblast and osteoclast activity  maintain homeostasis in the body… Osteoblast and osteoclast activity  maintain homeostasis in the body… *Greater osteoblast action: bones become too thick and heavy & develop boney spurs *Greater osteoclast action: lose too much calcium = brittle and fragile bones that break easily So… this helps the body because: 1. Renews of bone tissue before deterioration sets in 2. Redistribution of bone matrix along the lines of mechanical stress 3. Enables injured bones to heal

FOUR GROUPS OF BONES LONG BONES SHORT BONES FLAT BONES IRREGULAR BONES ARE LONG EXAMPLE: TIBIA, FIBULA, HUMERUS, RADIUS AND ILNA SHORT BONES ABOUT EQUAL IN LENGTH AND WIDTH EXAMPLE: BONES OF THE WRIST AND FOOT FLAT BONES USED FOR PROTECTION EXAMPLE: THEY MAKE UP THE VAULT OF THE SKULL, SCAPULA AND STERNUM AND RIBS IRREGULAR BONES COMPLEX AND VARIED SHAPES EXAMPLE: BONES COMPRISING THE VERTEBRAL COLUMN, PECTORAL AND PELVIC GIRDLES, PATELLA AND SMALLBONES OF FACE

Example of Long Bone

Example of Short Bones

Example of Flat Bone

Example of Irregular Bone

STRUCTURE OF BONES THERE ARE TWO TYPES OF BONY SUBSTANCE IN THE BODY: COMPACT TISSUE AND SPONGELIKE CALCELLOUS TISSUE TENDONS: ATTACH MUSCLE TO BONE LIGAMENTS: ATTACH BONE TO BONE

The Two Types of Bony Structures

JOINTS THE JUNCTIONS OF THE LEVERS OR SKELETAL PARTS ARE CALLED JOINTS OR ARTICULATIONS

Articulations depend on: 1. Structural composition: What type of connective tissue binds the bones? -E.g. Fibrous Joints - E.g. Cartilaginous Joints - E.g. Synovial Joints 2. The extent to which movement is permitted: -E.g. synarthoses (no/ very little movement at joints) -E.g. Amphiarthroses (partially movable joints) -E.g. Diarthroses (Freely movable joints)

Synarthroses: Fibrous/ Synarthrodial joints Held tightly together by fibrous connective tissue Permit little/ no movement

3 Types of Synarthroses joints: 1. Suture: *Fibrous joint composed of a thin layer of dense connective tissue *Irregular interlocking edges add strength to the joint 2. Syndesmosis: *Greater distance/ space between articulating bones * Contains more fibrous connective tissue than a suture joint…therefore allowing slightly more movement 3. Gomphosis: * Joint in which cone-shaped peg fits into a socket

Amphiarthroses Joints: Cartilaginous joints Held together by strong ligaments Slightly movable joints:

2 types of Amphiarthoses: 1. Syndnchrondrosis Hyaline cartilage is the connecting substance Primary cartilaginous joint is later replaced by bone E.g. Ribs 2. Symphysis Ends of articulating bones are covered with cartilage but bones are connect by a broad, flat disc of fibrocartilage E.g. Pelvis  labour

Diarthroses Diarthrodial/ Synovial Joints: Articulating surfaces of synovial joints are covered with articular cartilage Cartilage ensures a smooth, frictionless surface Articular capsule: surrounds synovial joint and encloses the synovial cavity Strong, yet flexible fibrous capsule consisting of dense, irregular tissue

Synovial membrane: Inner layer of articular surface Synovial fluid: Forms thin layer over articulating surface Synovial fluid has several functions: 1. Lubrication 2. Supplies nutrients 3. Removes waste products Contains phagocytes

Synovial joints/ Diarthrodial joints: 1. Planar joint: Gliding joint - Joint surfaces are fairly flat - Permit side to side; back to forth movements - Non-axial  doesn’t rotate around 1 axis - E.g. Knee, wrist 2. Hinge joint: Ginglymus joint - Convex surface of 1 joint fits into concave surface of other joint - Produces angular opening and closing motion - Uniaxial joint (1 axis) E.g. Elbow or jaw

3. Pivot joint: Trochoid joint - Rounded or pointed surface of 1 joint articulates with ring formed partly by another bone - Uniaxial joint -E.g. Axis of skull 4. Condyloid Joint: Ellipsoidal joint - Convex oval projection of 1 bone fits into the oval shaped depression of another bone Bi- axial joint - E.g. Scaphoid and lunate bones in hand

5. Saddle Joint: Sellaris Joint - Articular surface is saddle shaped and articulating surface of other bone fits into the “saddle” - Biaxial Joint - E.g. Thumb 6. Ball and Socket Joint: Spherio Joint - Ball like surface of 1 bone fits into a cup like surface of another bone - Multiaxial E.g. Shoulder, hip

CLASSIFICATION OF JOINTS COMMON NAME TECHNICAL NAME MOVEMENT EXAMPLE Immovable (Synarthrodial) Fibrous 1.Suture 2.Syndesmosis None 1.Sutures Of Skull 2.Distal Tibiofibuls Slightly Movable (Amphiarthrodial) Cartilaginous 1.Synchrondosis 2.Symphysis Negligible (Very little) 1.Sternocostal 2.Epiphyseal Plates 3.Pubic Symphysis Freely Movable (Diarthrodial) 1.Ball and Socket 2.Condyloid 3.Gliding 4.Hinge 5.Pivot 6.Sadle 1.Enarthrosis 2.Ellipsoidal 3.Arthrodial 4.Ginglymus 5.Trochoid 6.Sellar 1.Triaxial 2.Braxial 3.Nonaxial 4.Uniaxial 5.Uniaxial 6.Triaxial 1.Hip and Shoulder 2.Wrist 3.Intercarpal and Inter-tarsal 4.Elbow 5.Atlanot-Axial 6.Carpometacarpal of the Thumb

End of Unit