Human A&P1, Chapter 8

Joints

Classes of Joints (by movement)

Diarthrosis, amphiarthroses, and synarthroses

Diathrosis

Freely moveable (limbs, appendicular skeleton)

Amphiarthroses

Slightly moveable

Synthroses

Immovable (stable, axial skeleton)

How joints are joined

Fibrous joints - collagen fibers cross gap between bone matrices

Cartilaginous joints - bones held together by cartilage

Synovial joints - bones separated by lubricating synovial fluid

Fibrous joints

Immovable, joined by connective tissue collagen fibers

No joint cavity, movement depends on length of collagen fibers

Suture, Syndesmosis, Gomphosis

Cartilaginous joints

Immovable, joined by cartilage

No joint cavity

Synchondroses (synarthrotic), Symphyses (amphiarthrotic)

Suture

“Seam”, filled with connective fibers (consistent with periosteum)

Fibrous joint between flat bones of the skull

Synostoses

A completely ossified joint; skull bones become a fused joint, occurs at middle age, is protective

Syndesmosis

Fibrous joint bones united by ligament cords or fibrous connective tissue

Movement depends on connecting fiber lengths: Short fibers (ends of tibia + fibula) = little to no movement/give, long fibers (interosseous membrane) = large amount of movement

Gomphosis

Fibrous “peg-in-socket” joint such as a tooth (alveolar socket)

The way teeth are embedded in their socket (hammered in

Periodontal ligament is fibrous connection

Synchondroses (synarthotic) joints

Cartilaginous joint, immovable, bones united by hyaline cartilage

“Junction of cartilage”

Epiphyseal plates (in children’s long bones, temporary; eventually become synostoses), joint between costal cartilage (1st rib) + manubrium of sternum

Symphyses (amphiarthrotic) joints

Cartilaginous joint, slightly movable, strenght and flexibility bones united by fibrocartilage (+ hyaline in articular joints)

Intervertebral discs, pubic symphysis of pelvis

Fibrocartilage

Compressible + Resilient, acts as shock absorber and permits limited amount of movement at joint, main element of symphyses

Synovial joints

- Bones separated by a fluid-filled joint cavity

- Adjoining surfaces of bones covered in hyaline cartilage

- Joint capsule encloses the cavity

- Certain joints have a fibrocartilage pad (meniscus)

- Fluid-filled bursae underlie certain muscles

• Shoulder, knee, and hip (freely movable)

Synovial fluid

plane synovial joint

flat surface (interracial/tarsal joints and vertebrocostal joints of ribs 2-7)

hinge synovial joint

Uniaxial; EX - elbow, ankle, knee, interphalangeal

pivot synovial joint

One bone moving around the other (Top of your vertebrae)

condylar synovial joint

Biaxial; Modified ball-socket; Articular surfaces are ellipsoid instead of spherical; range of motion limited almost to hinge and restricts rotation EX - atlantooccipital, radiocarpal (wrist), TMJ (multiaxial)

saddle synovial joint

Biaxial; 2 saddle-shaped articulating surfaces oriented at right angles to each other EX - thumb (carpometacarpal pollicis), intercarpal, sternoclavicular

ball and socket synovial joint

Multiaxial; allows a wide range of motion in all directions; EX - shoulder and hip joints

first class lever

The fulcrum is positioned between the effort and resistance

second class lever

the load is between the fulcrum and the effort

third class lever

The fulcrum is at one end of the bar and the effort is between the fulcrum and the resistance

Flexion

Decreases the angle of a joint

extension

increases the angle of a joint

Hyperextension

extension beyond anatomical position

Abduction

Movement away from the midline of the body

adduction

Movement toward the midline of the body

elevation

raising a body part

depression

lowering a body part

protraction

moving a body part forward and parallel to the ground

retraction

moving a body part backward and parallel to the ground

Eversion

turning the sole of the foot outward

Inversion

Turning the sole of the foot inward

circumduction

the circular movement at the far end of a limb

Rotational joint motion

supination

movement that turns the palm up

Pronation

palm down

Osteoarthritis

most common chronic arthritis, related to normal aging process, "wear and tear arthritis"

opposition

touching the thumb to any other finger

rheumatoid arthritis

autoimmune disease (immune system attacks the joints), symptoms begin with bilateral inflammation of certain joints, often leans to deformities

gouty arthritis

inflammation of joints caused by deposition of urate crystals from the blood, genetic cause, can usually be controlled with diet

common knee injury

Tibial meniscus, Tibial Collateral Ligament (TCL), and ACL torn

hip joint

joint capsule

The fibrous sac that encloses a joint.

bursae

flattened fibrous sacs lined with synovial membrane and containing a thin film of synovial fluid

joint cavity

the space between two connecting bones

Hyaline (articular) cartilage

ligament

Connects bone to bone

synovial membrane

membrane lining the capsule of a joint

Fibrocartilage

Meniscus

fibrous layer

outer layer consisting of dense irregular connective tissue consisting of Sharpey's fibers that secure to bone matrix