Anatomy of Bursae

Study Notes

Bursae are closed sacs of serous membrane, typically collapsed and filled with a thin lubricating fluid.
Their primary function is to reduce friction, allowing smooth movement between structures.
Subcutaneous bursae are located between skin and bony prominences (e.g., elbow, knee).
Subfascial bursae exist beneath deep fascia, while subtendinous bursae facilitate tendon movement over bone.
Synovial tendon sheaths are elongated bursae that encase tendons in various tunnels.
Bursae can communicate with synovial cavities in joints.
Important organs like the heart, lungs, and abdominal viscera are surrounded by collapsed bursal sacs.
Visceral layers wrap closely around organs, while parietal layers contact body walls.

The skeletal system comprises two main parts: the axial skeleton (head, neck, trunk) and appendicular skeleton (limbs, girdles).
Cartilage and bone form the skeleton, with cartilage being a semirigid connective tissue offering flexibility.
Perichondrium, a fibrous membrane, covers nearly all cartilage.

Hyaline cartilage: Found covering articular surfaces; crucial for long bone growth; has poor repair capacity.
Fibrocartilage: Contains numerous collagen fibers; present in joints and intervertebral discs; repairs slowly.
Elastic cartilage: Rich in elastic fibers; found in structures like the ear and epiglottis; also repairs with fibrous tissue.

Bone is a specialized, hard connective tissue essential for body support, protection of organs, movement, and storage of salts.
The periosteum is a fibrous covering around bones, excluding articular cartilage regions.
Bone types: compact bone (dense, hard) and spongy (trabecular) bone (contains spaces).

Bone markings indicate tendon, ligament, and vascular attachments. Includes terms like condyle, crest, epicondyle, and foramen.
Features can indicate where structures attach or serve as joints.

Bone growth and maturation take years (e.g., humerus ossification begins at 8 weeks, complete by age 20).
Derived from mesenchyme through two processes: intramembranous ossification (direct from mesenchyme) and endochondral ossification (from cartilage).

Growth occurs at cartilaginous epiphyseal plates, where primary and secondary ossification centers form.
The diaphysis (shaft) grows at each end until the epiphyseal plates are ossified, leading to fusion (synostosis).

Bones are highly vascularized with nutrient arteries supplying blood, accompanied by veins and sensory nerves.
Periosteum is sensitive to tension and tearing, contributing to pain sensation during fractures.