tendons, ligaments, and articular cartilage

primary function of tendons and ligaments

to stabilize and connect joints of the skeletal system; they are passive structures that play an essential role in joint movement

tendons connect

muscle to bone

ligaments connect

bone to bone

main role of tendons in movement

transmit tensile loads from muscle to bone, producing motion

how do tendons act as "range extenders"

by allowing the muscle belly to be positioned at an optimal distance from the joint

main roles of ligaments in joint stability

augment mechanical stability, guide joint motion, and prevent excessive motion

primary structural composition of tendons and ligaments

dense connective tissue made mostly of collagen (~1/3 of body's protein), with ~20% cellular material and ~80% extracellular matrix (water and collagen)

arrangement of collagen fibers in tendons

orderly, parallel arrangement, equipping tendons to handle high, unidirectional tensile loads

arrangement of collagen fibers in ligaments

not completely parallel, allowing ligaments to handle large unidirectional loads plus smaller oblique loads

cellular composition of articular cartilage

~10% chondrocytes (cartilage cells) and ~90% extracellular matrix

what lubricates the superficial surface of articular cartilage

synovial fluid

compostion of the extracellular matrix of articular cartilage

60-87% water, 10-30% collagen, and 3-10% proteoglycans (PGs)

proteoglycans (PGs) and what is their structure

large protein-polysaccharide molecules with a protein core and polymer side chains, resembling a "test-tube brush"

how does collage orientation in articular cartilage contribute to function

it organizes the matrix to provide structural support, resist compressive forces, and distribute loads across the joint

how do water, collagen, and proteoglycans work together in articular cartilage

water provides cushioning and load distribution, collage provides tensile strength, and proteoglycans resist compressive forces by attracting water