Joints, Bursae, Synovium Flashcards
What is meant by the word arthros?
“joint”
How are joints innervated?
Hilton’s law states that nerves supplying a joint also supply the muscles moving the joint and the adjacent skin. Basically, nerves that course close to a joint supply the joint.
What are the two main types of joints and how do they differ from one another?
Synarthroses (together joints) - bones joined by this type of joint are separated by connective tissue which permits very limited movements in the joint.
Diarthroses (moveable joint) or synovial joints
- These joints are different from synarthrodial joints because they have the following common features: [Moore et al. - Fig.1.16, pp. 27]
a. An articular cavity or discontinuity between participating bones - synovial space
b. Synovial fluid for joint lubrication
c. A sleeve-like fibrous capsule
d. A synovial membrane or sac lining the capsule
e. Articular surface (smooth surfaces for articulation) usually composed of hyaline cartilage (articular cartilage) that caps the underlying bones
Define syndesmosis
Syndesmosis (fibrous joint) - the opposed bones are simply joined by intervening fibrous tissue, e.g., the interosseous membrane between the ulna and radius, and the almost immovable joints between skull bones (sutures) that disappears with age and the suture closes.
synchondrosis
Synchondrosis (cartilaginous joint) - two bones are separated from each other by cartilage which permits very limited movement. There are three subtypes:
a. Epiphyseal plate (growth plate) - A primary cartilaginous joint present in growing children but disappears when one reaches adulthood. The hyaline cartilage is replaced with bone and the joint can be considered a synostosis.
b. Intervertebral disc - A secondary cartilaginous joint composed of fibrocartilage located between the bodies of the vertebrae
c. Symphysis - A secondary cartilaginous joint composed of fibrocartilage found between the two pubic bones.
synostosis
Synostosis - two bones are joined together by bone. The joint may have existed during development and grew as a fibrous (suture) or cartilaginous joint, but was replaced by bone upon cessation of growth. e.g. frontal bones, epiphyseal plate (line)
Define the morphological features of a diarthrodial joint?
These joints are different from synarthrodial joints because they have the following common features: [Moore et al. - Fig.1.16, pp. 27]
a. An articular cavity or discontinuity between participating bones - synovial space
b. Synovial fluid for joint lubrication
c. A sleeve-like fibrous capsule
d. A synovial membrane or sac lining the capsule
e. Articular surface (smooth surfaces for articulation) usually composed of hyaline cartilage (articular cartilage) that caps the underlying bones
2. There may be one or two articular cavities depending on whether or not there is an intervening disk that is directly continuous with the fibrous capsule. Other anatomical features of synovial joints include menisci, fat pads, ligaments that may be thickenings of the fibrous capsule, and bursae which are fluid (synovial)-filled sacs that separate certain muscles, tendons, skin, and fascia from bones. A bursa may connect directly to a synovial cavity of a joint.
Based on the shape of the articulating surface, what are the major types of synovial joints?
a. Plane joints - permit gliding or sliding movements, e.g., the zygapophyseal joints (facet joints)
b. Hinge joints - permit flexion and extension only e.g., humeroulnar joint at the elbow
c. Saddle joints - biaxial joints e.g., carpometacarpal joint of the thumb
d. Condyloid (ellipsoid) joints - biaxial joints which allow movement in two directions, sagittal and coronal e.g., metacarpophalangeal joints
e. Ball and socket joints - multiaxial articulations e.g., hip joint, shoulder
f. Pivot joints - permit rotation around a longitudinal axis e.g., proximal radioulnar joint
What is a bursa and a synovial tendon sheath? How are they similar?
Bursa:
a “purse-like” structure Consists of a closed sac or envelope of serous membrane
synovial tendon sheath:
(serous membranes) consist of an inner layer that is attached to the tendon and is called the visceral layer, and an outer layer that is called the parietal layer. Synovial fluid found within the sac or cavity.
What is a bursitis, synovitis and arthritis? How may inflammations of one spread to another?
Inflammation of the synovial membrane is a synovitis; inflammation of a bursa is a bursitis; inflammation of a joint is an arthritis.
