Skeletal System and Joints (Components of Typical Long Bone (Long Bone-…
Skeletal System and Joints
Components of Typical Long Bone
Long Bone- A shaft and two distinct ends
Compact Bone- External Layer
Spongy Bone- Internal Layer, contain trabeculae filled with bone marrow.
Articular Cartilage- (Hyaline), covers end of most bones at movable joints
Diaphysis- Forms shaft
Epiphyses- Forms bone ends
Blood Vessels- Supply nutrients through opening in wall of diaphysis
Medullary Cavity- Center of diaphysis, filled with yellow bone marrow (fat)
Periosteum- membrane covering entire outer surface except location of articular cartilage. Contains two layers an outer dense irregular C.T which resists tension and bending and an inner layer that is osteogenic
Endosteum- membrane covering internal bone surfaces including trabeculae of spongy bone and lines central canal of osteons.
Types of Bone Cells
Osteogenic cells- Produce stem cells that differentiate into osteoblasts
Osteoblasts- Cells that produce and secrete new extracellular matrix
Osteocytes- Function to keep bone matrix healthy
Osteoclasts- formed from leukocytes, secrete enzymes that break down bone tissue.
Fibrous Joints- Bones held together by collagenic fibers. No joint cavity. 3 types
Suture (short fibers)- Immovable, only found in skull, held together by interlocking fibers.
Syndesmoses (Longer fibers)- Slightly mobile, held together by a ligament.
Gomphoses (Peridontal Ligament)- Immobile, peg in socket joint. Articulation of tooth with its socket.
Cartilaginous Joints- Bones united by cartilage. No Joint cavity. 2 types
Synchondrosis (Hyaline)- Immobile. Ex: Manubrium of Sternum
Symphysis (Fibrocartilage)- Slightly movable. Ex: Intervertebral Discs
Structural Components of Synovial Joints
Synovial Joint- most movable joints in body, all freely movable. Each Synovial joint contains fluid filled joint cavity.
Articular Cartilage- Hyaline cartilage
Joint Capsule- Outer is Dense Irregular C.T continuous with periosteum. Inner is Areolar C.T which contains the Synovial membrane
Synovial membrane- produce and secrete synovial fluid which fills the joint cavity
Synovial fluid- lubricates joints and reduces friction and nourishes articular cartilage
Bursa(e)- fibrous sac filled with synovial fluid
Tendon Sheathe- specialized bursa that wraps around tendons but not completely.
Types of Synovial Joints
Plane Joint- Gliding Ex: Intercarpal and Intertarsal Joints
Hinge Joint- Flexion and Extension Ex: Elbow Joints
Pivot Joint- Rotation Ex: Atlantoaxial Joint
Condylar Joint- Flexion and Extension, Adduction and abduction. Ex: Wrist joints
Saddle Joints- Adduction and Abduction, Flexion and Extension. Ex: carpometacarpal joints of thumbs
Ball and Socket Joint- Flexion and Extension, Adduction and Abduction, and Rotation. Ex: Shoulder and hip Joints