Skeletal System and Paranasal Sinuses Lecture Notes

A set of vocabulary flashcards covering the functions and cellular components of the skeletal system, types of bone formation, and the anatomy and drainage of the paranasal sinuses.

Hematopoiesis

Blood production occurring in the red bone marrow.

$90$ to $99\%$

The percentage of the body's calcium found in bone.

Osteogenic cells

Bone stem cells that are the only bone cells capable of undergoing mitosis; found along the periosteum and endosteum.

Periosteum

A dense fibrous connective tissue sheath that covers the outer surface of the bone.

Endosteum

A thin layer of connective tissue that lines the marrow or medullary cavity.

Osteoblasts

Cells responsible for bone deposition that synthesize and secrete collagen fibers, minerals, and the bone matrix called osteoid.

Osteoid

The bone matrix secreted by osteoblasts.

Osteocytes

Mature bone cells that maintain the bone and are found in spaces called lacunae.

Osteoclasts

The macrophages of bone responsible for bone destruction or bone resorption; found in Howship's lacunae.

Intramembranous ossification

Direct bone growth where bones are generally the first to be formed.

Endochondral ossification

Indirect bone growth that begins with hyaline cartilage before becoming bone; the process by which most bones are formed.

Nasal Septum

A structure that divides the nasal cavity into left and right sides, composed of the vomer, perpendicular plate of the ethmoid bone, and septal cartilage.

Concha (Turbinate)

A curled shelf of bone found in the nasal cavity, categorized as superior, middle, and inferior.

Meatus

Nasal passageways located inferiorly to the conchae.

Paranasal Sinuses

Four paired, air-filled spaces surrounding the nasal cavity lined by respiratory epithelium (pseudostratified columnar ciliated with goblet cells).

Schneiderian Membrane

The mucous membrane covering the maxillary sinus cavity.

Maxillary Sinus

The largest paranasal sinus, which drains into the hiatus semilunaris of the middle meatus via the ostium maxillare.

Sphenoethmoidal recess

The drainage site for the sphenoidal sinus, which is the only paranasal sinus that does not drain into a meatus.

Oro-Antral Communication (OAC)

A condition treated based on size: small ($<2\,mm$) requires no treatment, medium ($2-6\,mm$) requires a figure 8 suture, and large ($>6\,mm$) requires flap closure.

Ethmoidal bulla

A structure in the middle meatus related to the drainage of the ethmoid sinus.

Frontonasal duct

The drainage pathway for the frontal sinus into the middle meatus.