Histology of Joints

General Description of Synovial Joints

Tissues of the Diarthrodial joint

Tissue type




Synovial Membrane

Phagocitic (Type A Cell)

Secretion of hyaluronic acid, collagen and fibronectin (Type B); production of synovial fluid; thickens during disease

Lines inner surface of capsule but does not cover articular cartilage

Vascularized and innervated, loose irregular CT; 1-2 cells thick;

Type: A = macrophage;

B = fibroblastic

Synovial Fluid

Joint lubrication, nourishment of cartilage and debris removal

Viscosity due to hyaluronic acid

Lubrication due to lipids: DPPC and lubrican

Is a plasma filtrate that is egg white like. Has a few lining cells

Articular Cartilage

(hyalin cart Þ type II collagen) rich in proteoglycan

Provide sliding surface, resist compression (proteoglycan = spongy shock absorber), distribute load. papain Þ protein that produces rigidity

Covers surface between adjacent bones (ie. joints, ear, bridge of nose); arthritis = loss of this cartilage

Avascular, lymphatic, and aneural Nutrients diffuse via matrix to it. See histology of Cartilage below



(decrease load bearing 400%)

Shock absorption, load sharing and redistribution, proprioception, lubrication, joint stability, Mechanoreception

Half moon shaped fibrous tissue. Covers cartilage but only attaches to Synovium

Cells: fibrochondrocytes

Matrix: Type I >> II – complex

Avascular inner Zone

Vascular outer Zone

Insertions to Bone

To transmit force by attaching flexible, strong, tension-bearing structure to rigid non compliant bone

Functional Types: Joint capsule



Morphological Types:


Most fibers in bone

Acute to bone

Sharp boundary


most fibers in periostium

parallel to bone


Joint Capsule

Unite articular end of adjacent bones

(small fibers inserted in a random pattern)

-lined by synovial membrane

-vessels enter at point of attachment

Small fibers inserted in a random pattern


(has to resist tension)

(complicated motions)

Attach bone to bone, joint stabilizer, Mecanoreception. Small diameter fibers that insert parallel ("collateral") or inter woven pattern (‘cruciate")

Nomenclature based on:


function, relation to joint or each other.

Cells: fibroblasts

Matrix: collagen I and III with crimp

Elastin, proteoglycans, glycoproteins


(has to resist tension)

Efficiently transmit muscle force to skeleton so has large parallel fibers that insert uniformly Þ unidirectional pull

Nomenclature based on muscle

Cells: Tenocytes = a variety of Fibroblasts

Matrix: Collagen Type I (95%), III and IV, elastin, proteoglycan

Histology of Cartilage