General Anatomy (intro To Arthrology)

Question 1

What is a joint?

Answer 1

The site where two or more skeletal parts connect

Question 2

What are the three types of tissues in the joint and their movement?

Answer 2

• fibrous - bones connected by fibrous tissue
• synarthrosis - immovable
• Cartilaginous - bones connected by cartilage
• Amphiarthrosis - slightly moveable
• synovial - articulating surfaces enclosed within fluid-filled joint capsule, freely movable, the most common type
• diarthrosis - freely moveable

Question 3

What are fibrous joints?

Answer 3

· The bones bound by a tough, fibrous tissue
· Typically joints that require strength and stability over range of movement
· Further sub-classified into sutures, gomphoses and syndesmoses

Question 4

What are sutures?

Answer 4

· Immovable joints
· Only found between the flat bones of the skull
· Adjacent bones linked by a thin layer of connective tissue called a sutural ligament
· Most important in birth - the flexibility of the sutures allows the bones to overlap so the baby’s head can pass through the birth canal.

Question 5

What are gomphoses?

Answer 5

· Immovable joints
· Where the teeth articulate with their sockets in the maxilla (upper teeth) or the mandible (lower teeth)
· The tooth is bound into its socket by the strong periodontal ligament.

Question 6

What are syndesmoses?

Answer 6

· Slightly movable joints
· Two adjacent bones linked by a ligament
· Interosseous membrane joining the radius and ulna in the forearm

Question 7

What are the two types of cartilaginous?

Answer 7

• synchondrosis
• symphysis

Question 8

What are synchondroses?

Answer 8

• Synchondroses (two ossification centers in a developing bone remain separated by a layer of cartilage, to allow bone growth)
• Growth plate between the head and shaft of developing long bones
• Eventually become completely ossified

Question 9

What are symphyses?

Answer 9

• Symphyses (two bones interconnected by cartilage)
• Most of them occur in the midline.
• Pubic symphysis between the two pelvic
bones, and intervertebral discs between adjacent vertebrae.

Question 10

What are the characteristics of synovial joints?

Answer 10

1. Bones are separated by a narrow articular cavity.
2. A layer of cartilage (usually hyaline) covers the articular surfaces - wide gap seen in Xray
3. Joint capsule with outer fibrous membrane and inner synovial membrane (Next silde)
4. Presence of additional structures (common but not universal) within the area enclosed by the capsule or synovial membrane, such as articular discs (usually composed of fibrocartilage), fat pads, and tendons

Question 11

What are the two joint capsule of the synovial membrane?

Answer 11

• Fibrous membrane
• synovial membrane

Question 12

What is the fibrous membrane?

Answer 12

· Formed by dense connective tissue; surrounds and stabilizes the joint
· Parts of it may thicken to form ligaments, further stabilizing the joint, with ligaments outside the capsule providing additional reinforcement.

Question 13

What is the synovial membrane?

Answer 13

· Attaches to the margins of the joint surfaces at the interface between the cartilage and
bone and encloses the joint cavity
· Highly vascular and produces synovial fluid into the articular cavity (Nutrition, lubrication, shock absorption)
· Closed sacs of synovial membrane also occur outside joints to form synovial bursae or tendon sheaths.

Question 14

What are the two types of synovial joints?

Answer 14

· Based on the shape of articular surfaces - plane (flat), hinge, pivot, bicondylar (two sets of contact points), condylar (ellipsoid), saddle, and ball and socket
· Based on movement - uniaxial (movement in one plane), biaxial (movement in two planes), and multiaxial (movement in three planes).

Question 15

What are pivot joints?

Answer 15

allow movement around one axis that passes longitudinally along the shaft of the bone; permit rotation (e.g., atlanto-axial joint)

Question 16

What are hinge joints?

Answer 16

allow movement around one axis that passes transversely through the joint; permit flexion and extension (e.g., elbow [humero-ulnar] joint)

Question 17

What are saddle joints?

Answer 17

allow movement around two axes that are at right angles to each other; the articular surfaces are saddle shaped; permit flexion, extension, abduction, adduction, and circumduction (e.g., carpometacarpal joint of the thumb)

Question 18

What are ball and socket joints?

Answer 18

allow movement around multiple axes; permit flexion, extension, abduction, adduction, circumduction, and rotation (e.g., hip joint)

Question 19

What are condylar (ellipsoid) joints?

Answer 19

allow movement around two axes that are at right angles to each other; permit flexion, extension, abduction, adduction, and circum- duction (limited) (e.g., wrist joint)

Question 20

What are plane joints?

Answer 20

allow sliding or gliding movements when one bone moves across the surface of another (e.g., between tarsal bones, acromioclavicular joint)

Question 21

What are bicondylar joints?

Answer 21

allow movement mostly in one axis with limited rotation around a second axis; formed by two convex condyles that articulate with concave or flat surfaces (e.g., knee joint)

Question 22

What are the nerve supply of joints?

Answer 22

· Sensory and autonomic fibers
· The autonomic nerves are vasomotor in function, controlling the dilation or constriction of blood vessels.
· The sensory nerves of the articular capsule and ligaments (articular nerves) provide proprioceptive feedback.
· Free nerve endings convey pain sensation (diffuse and poorly localized).
· The articular cartilage has no nerve supply.
· Hilton’s law: Articular nerves supplying a joint are branches of the nerves that supply the muscles responsible for moving that joint.
· These nerves also supply the overlying skin (referred pain from joint to skin).

Question 23

What is the blood supply of joints?

Answer 23

· From articular arteries that arise from the vessels around the joint
· The arteries anastomose to form networks (peri-articular arterial anastomoses) ensuring a blood supply to and across the joint in the various positions of the joint.
· Some vessels penetrate the fibrous capsule to form a rich plexus deeper in the synovial membrane.
· The articular cartilage, which is avascular hyaline cartilage, is nourished by the synovial f luid.
· Articular veins are communicating veins that accompany arteries (venae comitantes) and like arteries, are located in the joint capsule, mostly in the synovial membrane.
· Lymphatic vessels for every joint follow the lymph drainage of the surrounding tissue.

Question 24

What is a Bursae?

Answer 24

· A small sac filled with lubricating fluid, lined by synovial membrane that forms in clefts between mobile structures in the musculoskeletal system
· Usually found in the synovial joints, between the tendons and bones
· The major joints (e.g. knee joint) can have several bursae.

Question 25

What is the function of Bursae?

Answer 25

· The main function is to reduce friction between moving parts. They also act as a cushion that absorbs pressure present in some joints.
· Bursae deep in the tissues, such as the trochanteric or subacromial bursae, reduce the friction of muscles as they glide over each other or over prominences of bone. The more superficial bursae, such as the olecranon, ischial, or prepatellar bursae, serve to cushion the

Question 26

What is bursitis?

Answer 26

the inflammation of bursae (localized pain in the area around the inflamed bursa together with a restricted range of movement) – Overt inflammation may not be present upon physical exam or imaging.

Question 27

What is joint stability?

Answer 27

· The resistance offered by various musculoskeletal tissues that surround a joint
· Instability of jointsàunhealthy ranges of movement in joints

Question 28

What are the three things needed for joint stability?

Answer 28

1. Shape, size and arrangement of articular surfaces (The relative proportion of the two articulating surfaces is important.) – In the shoulder joint, the humeral head of is disproportionately larger than the glenoid fossa of the scapula making the joint more unstable. In contrast, the acetabulum of the pelvis fully encompasses the femoral head, making the hip-joint more stable.
2. Ligaments: The ligaments of a joint prevent excessive movement which could damage the joint. As a general rule, the more ligaments a joint has, and the tighter they are, the more stable the joint is.
3. Tone of Surrounding Muscles: The tone of the surrounding muscles contributes greatly to the stability of a joint.

Question 29

What is osteoarthritis?

Answer 29

The most common type of arthritis, wear-and-tear damage to a joint’s cartilage (enough damage can result in bone grinding directly on bone, which causes pain and restricted movement)

Question 30

What is rheumatoid arthritis?

Answer 30

The body’s immune system attacking the joint capsule

Question 31

What is gouty arthritis?

Answer 31

build-up of uric acid (waste product of body) in the blood, depositing tiny sharp crystals in and around joints