Think about it: John bent over to pick up a dime. What bones do you think is involved in this movement? his hip/pelvic bones at his patella (knee cap), and between his index finger and thumb?

Think about it too: You have a big itch in the middle of his back. Try to scratch your back without bending your elbow. Try to run away from a charging leopard without bending you knees. How does this feel? Are you able to successfully move your body?

Joints Notes Page 34

Learning Objectives To describe the different types of joints and skeletal movement they allow.

I. What are Joints? Bones are hard and cannot bend, so how can our bodies twist, bend, and rotate? Joints (or articulations) are where two or more bones meet or connect to allow movement of the rigid skeletal frame.

Tissues Involved at Joints: Ligaments- tissue that connects bone to bone and helps add to our flexibility. Cartilage- strong tissue that reduces friction and increases flexibility. Cushions end of bones so bones don’t rub/grind against each other with skeletal movement.

II. Joint Classification: Structure Function 1. Fibrous Joints Bones held together by dense collagen fibers 2.Cartilaginous Joints Bones held together by cartilage 3. Synovial Joints Bones held together by ligaments 1. Synarthrosis Immovable (not movable) Joints 2. Amphiarthrosis Slightly movable joints 3. Diarthrosis Freely movable joints

1. Fibrous Joints=Synarthrosis Immovable Joint= No Movement The articulating bones are held very close together by dense irregular connective tissue. Located: Sutures: bones of skull held together by connective tissue fibers Between teeth & jaws

Three types of fibrous joints: A. Sutures B. Syndesmoses Occur between bones of the skull. B. Syndesmoses Permits slight movement Interosseous membrane Between tibia and fibula of the leg C. Gomphoses Immovable joint A cone-shaped peg fits into a socket Teeth articulation with sockets of the maxilla and mandible

2. Cartilaginous Joints= Amphiarthrosis Allows little movement Bones connected by cartilage Location: Epiphyseal plates= hyaline cartilage at end of long bones Ribs & sternum Pubic symphysis Intervertebral discs

3. Synovial Joints= Diarthrosis Allows movement in many directions Ligaments hold bones together Bones separated by fluid-containing joint cavity: A. Synovial fluid reduces friction between cartilages Lubricates joint Absorbs shock B. Menisci (Meniscus): fibrocartilage that partially divides a joint cavity at knee, reduces friction C. Bursa: flattened sacs containing synovial fluid, located between tendons, ligaments, and bones. Cushions the movement of the body parts.

Ligaments and Meniscus (Menisci) Knee Joint

Torn medial meniscus

Bursa (fluid-filled sac that cushions between bones & tendons/muscles

Types of Synovial Joints

III. Types of Synovial Joints Synovial joints are classified based on type of movement. Plane/Gliding – wrist, ankle, vertebrae Hinge – elbow, knee, fingers and toes Pivot – neck Condyloid (ellipsoidal) – metatarsals, metacarpals Saddle – thumb Ball-and-socket – shoulder, hip

Also called a gliding joint Primarily allows back-and-forth and side-to-side movements Joints between carpal and tarsal bones

III. Types of Synovial Joints Plane/Gliding – wrist, ankle, vertebrae Hinge – elbow, knee, fingers and toes Pivot – neck Condyloid (ellipsoidal) – metatarsals, metacarpals Saddle – thumb Ball-and-socket – shoulder, hip

Produces an opening and closing motion like that of a hinged door. Permits only flexion and extension movement Knee, elbow, phalanges (fingers)

III. Types of Synovial Joints Plane/Gliding – wrist, ankle, vertebrae Hinge – elbow, knee, fingers and toes Pivot – neck Condyloid (ellipsoidal) – metatarsals, metacarpals Saddle – thumb Ball-and-socket – shoulder, hip

Surface of one bone articulates with a ring formed partly around another bone Allows bones to rotate

III. Types of Synovial Joints Plane/Gliding – wrist, ankle, vertebrae Hinge – elbow, knee, fingers and toes Pivot – neck Condyloid (ellipsoidal) – Metatarsals, metacarpals Saddle – thumb Ball-and-socket – shoulder, hip

The projection of one bone fits into the oval-shaped depression of another bone. Permits movement in 2 planes= flexion, extension, adduction, abduction, circumduction

III. Types of Synovial Joints Plane/Gliding – wrist, ankle, vertebrae Hinge – elbow, knee, fingers and toes Pivot – neck Condyloid (ellipsoidal) – metatarsals, metacarpals Saddle – thumb Ball-and-socket – shoulder, hip

Surface of one bone is saddle-shaped and the other bone fits into the saddle. Thumb Allows bones to move back and forth and side to side, but have limited rotational ability.

III. Types of Synovial Joints Plane/Gliding – wrist, ankle, vertebrae Hinge – elbow, knee, fingers and toes Pivot – neck Condyloid (ellipsoidal)- metatarsals, metacarpals Saddle – thumb Ball-and-socket – shoulder, hip

Ball-like surface of one bone fits into a cuplike depression of another bone. Shoulder and hip Allows bones to move and rotate in nearly all directions.