hala skeletal system

Osteons (Haversian Systems)

Cylinder-shaped units that make up compact bone

Lamellae

Concentric rings of bone matrix within an osteon

Perforating (Volkmann's) Canals

Canals that connect central canals and allow blood vessels to travel between them

Osteoclasts

Bone-resorbing cells derived from monocytes that break down bone tissue

Osteoblasts

Bone-forming cells that build new bone

Intramembranous Ossification

Bone formation from a fibrous connective tissue membrane

Endochondral Ossification

Bone formation using a hyaline cartilage model

Hyaline Cartilage Model

The template used during endochondral ossification

Fracture Repair Sequence

Hematoma → Fibrocartilage Callus → Bony Callus → Remodeling

Spiral Fracture

A fracture caused by twisting forces on a bone

Paranasal Sinuses

Frontal, Maxillary, Ethmoidal, and Sphenoidal sinuses

Paranasal Sinus Drainage

Drains into the nose

Mastoid Sinus Drainage

Drains into the middle ear

Fontanels

Membranous regions between cranial bones in a fetal skull

Ethmoid Bone

A cranial bone that contributes to the nasal cavity and orbit

Sphenoid Bone

Butterfly-shaped cranial bone that forms the sides and floor of the cranium

Hard Palate

Formed by the maxillae and palatine bones

Lacrimal Bone

Contains ducts that carry tears from the eyes into the nose

Nasal Septum

Formed by the vomer and the perpendicular plate of the ethmoid

Vertebrosternal (True) Ribs

First 7 pairs of ribs that attach directly to the sternum

Vertebrochondral (False) Ribs

Next 3 pairs of ribs that attach indirectly to the sternum

Vertebral (Floating) Ribs

Last 2 pairs of ribs that do not attach to the sternum

Sternum

The breastbone

Sternum Regions

Manubrium → Body → Xiphoid Process

Olecranon Fossa

Posterior depression of the humerus that receives the ulna during elbow extension

Ischium

Most inferior portion of the coxal bone

Pubis

Most anterior portion of the coxal bone

Acetabulum

Depression in the coxal bone that articulates with the head of the femur

Tibia and Fibula

Bones of the leg between the knee and ankle

Female Pelvis

Broader because the iliac bones are more flared

Sacrum

Not part of the coxal bone

Foot Bones

7 tarsals, 5 metatarsals, and 14 phalanges

Calcaneus

Heel bone

Synarthrosis

An immovable joint

Fibrous Joint

Joint connected by fibrous connective tissue (e.g., sutures)

Lambdoidal Suture

Suture between the parietal and occipital bones

Gomphosis

Fibrous joint between a tooth root and its socket

Synovial (Diarthrotic) Joint

Freely movable joint

Hinge Joint

Joint that allows movement in one plane

Flexion

Movement that decreases the angle between bones (e.g., bowing)

Abduction

Movement away from the body's midline

Adduction

Movement toward the body's midline

Supination

Rotation of the forearm so the palms face upward

Trabeculae

Bony plates that characterize spongy bone

Spongy Bone

Bone tissue composed of trabeculae

Compact Bone

Dense bone tissue composed of osteons and lamellae

True Ribs Formula

7 true, 3 false, 2 floating (7-3-2)

Cranial Bone Commonly Tested

Ethmoid

Facial Bones (Commonly Confused with Cranial Bones)

Zygomatic, Vomer, and Nasal bones