Comprehensive Study Notes on the Skeletal System

Vocabulary flashcards generated from lecture notes covering the structure, functions, histology, cellular dynamics, divisions, markings, and pathological disorders of the human skeletal system.

Skeletal System

The supporting framework of the body composed of joined bones that enables upright posture, movement, and physical functions in close association with the muscular system.

Leonardo da Vinci

Italian Renaissance artist and scientist (1452-1519) credited as the first anatomist to correctly illustrate the human skeleton and its bones.

Hematopoiesis

The process of manufacturing blood cells, taking place chiefly within red bone marrow.

Cartilage

Connective tissue that provides the environment in which fetal bone develops, and caps the ends of adult bones at joints for smooth movement.

Ligaments

Tough connective tissue bands that connect bone to bone.

Tendons

Connective tissue structures that attach muscle to bone.

Osteoprogenitor Cells

Undifferentiated precursor cells that give rise to spindle-shaped osteoblasts.

Osteoblasts

Bone-forming cells located beneath the periosteum and within the endosteum that synthesize bone matrix.

Osteocytes

Mature bone cells that maintain matrix and proliferate to form new bone tissue following fractures.

Osteoclasts

Large cells derived from immune lineage responsible for bone resorption, removing inner bone tissue during remodeling or repair.

Intramembranous Ossification

The process where dense connective tissue membranes are directly replaced by inorganic calcium salts, occurring exclusively in cranial bones.

Fontanelles

Unossified membrane regions (soft spots) in infant skulls that permit compression during birth.

Endochondral Ossification

The process where cartilage serves as the precursor environment inside which bone cells synthesize organic matrix, forming all non-cranial bones.

Calcitonin

A hormone secreted by the thyroid gland that promotes calcium deposition and storage into bone.

Parathormone (Parathyroid Hormone)

A hormone secreted by the parathyroid glands that stimulates bone resorption to release calcium into the bloodstream.

Compact (Dense) Bone

Bone tissue characterized by a dense, solid structure that provides structural strength.

Cancellous (Spongy) Bone

Bone tissue characterized by open meshwork spaces that house bone marrow.

Haversian Canals (Central Canals)

Canals running parallel to the long axis of bone that contain blood vessels supplying oxygen and nutrients and removing metabolic waste.

Lamellae

Concentric rings of calcified matrix surrounding a central Haversian canal.

Lacunae

Tiny cavities situated between adjacent lamellae, each containing a single osteocyte suspended in tissue fluid.

Canaliculi

Minute canals extending radially from lacunae to connect neighboring lacunae and Haversian canals for nutrient diffusion.

Volkmann's (Perforating) Canals

Transverse or horizontal canals containing blood vessels that connect adjacent central Haversian canals.

Trabeculae

A latticework of interconnecting bony plates in cancellous bone that provides structural strength without excessive weight.

Red Bone Marrow

Highly vascularized tissue filling cancellous bone spaces that manufactures red blood cells, white blood cells, and platelets.

Yellow Bone Marrow

Connective tissue consisting predominantly of adipose (fat) cells located inside the medullary cavity of adult long bones.

Diaphysis

The main central shaft of a long bone composed of compact bone with a hollow medullary cavity.

Metaphysis

The flared structural region at each end of the diaphysis in a long bone, composed mostly of cancellous bone.

Epiphysis

Broad terminal end of a long bone composed of cancellous bone filled with red marrow and covered by a thin compact layer.

Diploë

The inner layer of cancellous bone enclosed between two parallel plates of compact bone in flat bones.

Sesamoid Bones

Small, rounded bones embedded within tendons or fascial structures adjacent to joints, such as the patella.

Axial Skeleton

Division of the skeleton consisting of 80 total bones, including the skull, hyoid bone, vertebral column, ribs, and sternum.

Appendicular Skeleton

Division of the skeleton consisting of 126 total bones, comprising upper extremities with shoulder girdle and lower extremities with pelvic girdle.

Wormian (Sutural) Bones

Uncounted, variable, small irregular bones located within cranial sutures that form via intramembranous ossification.

Hyoid Bone

A horseshoe-shaped axial bone superior to the larynx that does not articulate with any other bone and supports tongue muscles.

Atlas (C1)

The first cervical vertebra that lacks a body and articulates with the occipital condyles to support the head.

Axis (C2)

The second cervical vertebra featuring the dens (odontoid process) which serves as a pivot point for head rotation.

True Ribs

Rib pairs 1 through 7 that attach directly to the sternum via individual costal cartilages.

False Ribs

Rib pairs 8 through 12 that do not attach directly to the sternum.

Floating Ribs

Rib pairs 11 and 12, which possess no anterior cartilage or sternal attachment.

Obturator Foramen

The largest foramen in the human body, bounded by the pubis and ischium, transmitting nerves, vessels, and tendons.

Pes Planus

A flat foot condition resulting from reduced height of the medial longitudinal arch.

Osteoporosis

A pathological disorder characterized by decreased bone mass and heightened fracture risk under minimal stress, frequently linked to post-menopausal estrogen loss.

Paget's Disease

A nonmetabolic bone disorder characterized by irregular bone destruction coupled with disorganized bone repair, yielding abnormally thick, soft bones.

Spina Bifida

A congenital neurodevelopmental defect where posterior vertebral laminae fail to unite at the midline.

Herniated Disc

Rupture of the outer fibrocartilage ring surrounding an intervertebral disc, causing the protruding nucleus pulposus to compress spinal nerve roots.