Anatomy and Physiology: Bone Tissue, Axial Skeleton, Appendicular Skeleton, and Joints

Comprehensive vocabulary flashcard set covering bone tissue, histology, ossification, axial skeleton, appendicular skeleton, and joint classification/movements.

Hyaline Cartilage

The most abundant type of cartilage in the body; it resists compression due to a large amount of $H_2O$ and contains only collagen fibers in its matrix. It is found in articular cartilage, sternal cartilage, and respiratory tube airways.

Elastic Cartilage

Cartilage whose matrix contains both elastic and collagen fibers, functioning to tolerate repeated bending. It is found in the epiglottis, external ear, and auditory tube.

Fibrocartilage

Cartilage containing thick collagen fibers surrounding chondrocytes within dense irregular connective tissue. It resists compression and pulling forces and is found in intervertebral discs and articular discs of joints.

Long Bone

Bone classification defined by a shaft with expanded ends, where length is greater than width, such as the humerus or femur.

Short Bone

Roughly cube-shaped bone classification, exemplified by tarsals and carpals.

Sesamoid Bone

A specialized type of short bone that forms inside a tendon to alter pulling forces, such as the patella.

Flat Bone

Thin, flattened, and usually slightly curved bone classification, such as the sternum, ribs, scapula, and cranial bones.

Irregular Bone

Bone classification with complex shapes that do not fit into long, short, or flat categories, such as vertebrae.

Sutural Bone

Small, extra bone islands located within the suture lines of the skull.

Organic Bone Composition

The organic matrix component made up mostly of collagen produced by osteoblasts, comprising approximately $35\%$ of bone weight and providing flexibility and tensile strength to resist bending and twisting.

Inorganic Bone Composition

Mineral deposits (hydroxyapatites, mainly calcium phosphate) that provide bone with extreme hardness and resistance to compression forces.

Osteogenic Cell

Unspecialized stem cell in bone tissue that undergoes mitosis and differentiates into an osteoblast.

Osteoblast

Bone-forming cell that secretes osteoid (uncalcified bone matrix).

Osteocyte

Mature bone cell located in a lacuna that maintains surrounding bone tissue and matrix.

Osteoclast

Large, multinucleated cell responsible for bone resorption (breaking down bone matrix).

Diaphysis

The elongated, tubular main shaft forming the long axis of a long bone.

Epiphysis

The expanded proximal or distal end of a long bone, covered externally with articular cartilage.

Periosteum

Double-layered connective tissue membrane covering the outer surface of bones, containing an outer dense irregular CT layer and an inner osteogenic layer of osteoblasts and osteoclasts.

Endosteum

Internal connective tissue membrane lining internal bony canals, trabeculae, and the medullary cavity.

Osteon (Haversian System)

The fundamental structural unit of compact bone, consisting of concentric lamellae surrounding a central canal.

Central Canal (Haversian Canal)

The central channel running longitudinally through the core of an osteon containing blood vessels and nerves.

Trabeculae

Connecting struts and plates of bone tissue forming the meshwork of spongy bone (diploë).

Intramembranous Ossification

The process of bone development in which bone forms directly from embryonic fibrous connective tissue membranes, forming skull bones and clavicles.

Endochondral Ossification

The process of bone formation where a pre-existing hyaline cartilage model is replaced by bone tissue, forming most bones below the skull.

Primary Ossification Center

The region in the center of the hyaline cartilage diaphysis where bone tissue first replaces cartilage during embryo development.

Secondary Ossification Center

Region appearing in the epiphyses of long bones around birth where spongy bone is formed.

Interstitial Bone Growth

Growth in the length of long bones driven by cartilage growth and replacement at the epiphyseal plates.

Appositional Bone Growth

Growth in bone thickness or diameter accomplished by osteoblast activity under the periosteum and osteoclast activity along the endosteum.

Comminuted Fracture

A fracture in which bone breaks into three or more fragments, commonly seen in brittle bones of the elderly.

Compression Fracture

A fracture where the bone is crushed, common in porous osteoporotic bones under extreme trauma.

Spiral Fracture

A ragged break occurring when excessive twisting forces are applied to a bone, common in sports injuries.

Epiphyseal Fracture

A fracture where the epiphysis separates from the diaphysis along the epiphyseal plate.

Depressed Fracture

A fracture in which the broken portion of bone is pressed inward, typical of skull fractures.

Greenstick Fracture

An incomplete break where one side of the bone shaft breaks while the other side bends, common in children due to flexible organic matrix.

Osteoporosis

A bone disorder characterized by low bone mass where bones become porous and thin, making the vertebral column and femoral neck especially vulnerable to fracture.

Paget's Disease

A chronic bone disorder marked by excessive and chaotic rates of bone deposition and resorption, leading to poorly mineralized, abnormally thick bones.

Rickets

A form of osteomalacia in children caused by Vitamin D or calcium phosphate deficiency, leading to soft, uncalcified bones that bow under weight.

Coronal Suture

Articulating joint line connecting the anterior frontal bone with the parietal bones posteriorly.

Squamous Suture

Articulating joint line connecting the parietal bone with the temporal bone inferiorly.

Sagittal Suture

Articulating joint line connecting the right and left parietal bones at the cranial midline.

Lambdoid Suture

Articulating joint line connecting the parietal bones with the occipital bone posteriorly.

Foramen Magnum

The large opening in the base of the occipital bone through which the inferior brainstem and spinal cord pass.

Occipital Condyles

Rounded bony projections on either side of the foramen magnum that articulate with the atlas ($C_1$) to permit head nodding.

Jugular Foramen

Large cranial opening between occipital and temporal bones providing passage for the internal jugular vein.

Carotid Canal

Passageway in the petrous temporal bone through which the internal carotid artery enters the skull.

External Acoustic Meatus

Canal in the tympanic portion of the temporal bone directing sound waves to the tympanic membrane.

Sella Turcica

A saddle-shaped depression in the sphenoid bone housing the hypophyseal fossa, which holds the pituitary gland.

Crista Galli

Superior midline wedge projection of the ethmoid bone providing an attachment point for the falx cerebri membrane.

Cribriform Plate

Porous horizontal plate of the ethmoid bone perforated by cribriform foramina that transmit olfactory nerve ($CN\,I$) fibers.

Superior and Middle Nasal Conchae

Scroll-like bony projections of the ethmoid bone that increase mucosal surface area and create air turbulence inside the nasal cavity.

Paranasal Sinuses

Mucosa-lined, air-filled cavities within the frontal, ethmoid, sphenoid, and maxillary bones that warm air, lighten the skull, and resonate voice sound.

Cleft Palate

A congenital flaw occurring when palatine processes fail to fuse medially, leaving an opening between oral and nasal cavities that can lead to food aspiration and pneumonia.

Hyoid Bone

U-shaped bone in the anterior neck that does not articulate directly with any other bone and serves as a base for tongue movements.

Primary Spinal Curvatures

Posteriorly convex curvatures in the thoracic and sacral regions present at birth.

Secondary Spinal Curvatures

Posteriorly concave curvatures in the cervical and lumbar regions that develop after birth when an infant learns to hold up its head and walk.

Scoliosis

Abnormal lateral curvature of the spinal column (forming an S- or C-curve).

Kyphosis

An exaggerated posterior thoracic curvature of the spine (hunchback).

Lordosis

An exaggerated anterior lumbar curvature of the spine (swayback).

Nucleus Pulposus

The inner gelatinous core of an intervertebral disc that functions to absorb shock and compression forces.

Anulus Fibrosus

Outer fibrocartilaginous ring of an intervertebral disc binding neighboring vertebrae together.

Atlas ($C_1$)

The first cervical vertebra, which lacks a body and spinous process, articulating with occipital condyles at the atlanto-occipital joint to allow head nodding.

Axis ($C_2$)

The second cervical vertebra featuring the vertical dens (odontoid process) that acts as a pivot for atlas rotation during head shaking.

Cervical Vertebrae ($C_1-C_7$)

The seven lightest vertebrae featuring short bifid spinous processes, large triangular foramina, and transverse foramina for vertebral arteries.

Thoracic Vertebrae ($T_1-T_{12}$)

Twelve vertebrae characterized by heart-shaped bodies, circular foramina, long downward spinous processes, and costal facets for rib articulation.

Lumbar Vertebrae ($L_1-L_5$)

Five massive vertebrae with thick bodies, short hatchet-shaped spinous processes, and triangular foramina adapted for bearing weight.

Sacrum

Triangular bone formed by 5 fused sacral vertebrae ($S_1-S_5$) forming the posterior pelvic wall.

Coccyx

Tailbone composed of 3 to 5 fused vertebrae serving as an attachment point for pelvic muscles.

Sternal Angle

A prominent horizontal ridge at the joint between manubrium and body of the sternum, aligning with the second rib attachment.

True Ribs (Ribs 1-7)

The superior seven rib pairs attaching directly to the sternum via their own individual costal cartilages.

False Ribs (Ribs 8-12)

Rib pairs attaching indirectly (ribs 8–10) or having no anterior sternal attachment (floating ribs 11–12).

Fontanelles

Unossified fibrous membrane spots in an infant skull allowing flexibility during birth and space for rapid baby brain growth.

Pectoral Girdle

Incomplete bone ring comprising the clavicle and scapula attaching the upper limb to the axial skeleton.

Clavicle

S-shaped horizontal bone articulating medially with the sternal manubrium and laterally with the scapular acromion.

Glenoid Cavity

Shallow fossa on the lateral angle of the scapula that articulates with the head of the humerus to form the glenohumeral joint.

Trochlea

Pulley-like medial condyle at the distal end of the humerus that articulates with the trochlear notch of the ulna.

Capitulum

Rounded lateral condyle on the distal humerus that articulates with the head of the radius.

Ulna

The medial bone of the forearm forming the primary hinge joint of the elbow with the humerus.

Radius

The lateral bone of the forearm that rotates over the ulna during pronation.

Colles' Fracture

A fracture of the distal radius where the radial styloid process moves proximally relative to the ulnar styloid process.

Carpal Bones

Eight short wrist bones arranged in a proximal row (pisiform, triquetrum, lunate, scaphoid) and a distal row (hamate, capitate, trapezoid, trapezium).

Pelvic Girdle

Heavy bone structure consisting of paired coxal bones and sacrum attaching lower limbs firmly to the axial trunk.

Acetabulum

Deep cup-shaped socket on the lateral coxal bone where the ilium, ischium, and pubis meet to articulate with the femur head.

True Pelvis (Lesser Pelvis)

Inferior basin enclosed by the pelvic brim defining the path of the birth canal.

False Pelvis (Greater Pelvis)

Superior pelvic area bounded laterally by iliac alae, situated above the pelvic brim.

Female Pelvis

Pelvic structure adapted for childbearing: broader pubic arch ($80^\circ - 90^\circ$), wider oval inlet, shallower depth, and lighter bone mass compared to male pelvis.

Femur

The longest, largest, and strongest bone in the body, forming the thigh.

Tibia

The medial weight-bearing bone of the leg articulating with the femur proximally and talus distally.

Fibula

Sticklike lateral leg bone that stabilizes the ankle joint without carrying weight directly from the femur.

Talus

Second largest tarsal bone articulating directly with the tibia and fibula to bear body weight at the ankle joint.

Calcaneus

The large heel bone that receives body weight from the talus and attaches the calcaneal tendon.

Clubfoot

A congenital foot deformity characterized by inversion and plantarflexion of the foot.

Synarthrosis

An immovable joint based on functional classification.

Amphiarthrosis

A slightly movable joint based on functional classification.

Diarthrosis

A freely movable joint based on functional classification.

Syndesmosis

A fibrous joint connected purely by ligaments, ranging from immovable to freely movable.

Gomphosis

A peg-in-socket fibrous joint holding a tooth in its alveolar socket via periodontal ligaments.

Synchondrosis

A cartilaginous joint joined by rigid hyaline cartilage, such as epiphyseal plates.

Symphysis

A cartilaginous joint united by fibrocartilage, offering high tensile strength and flexibility.

Synovial Joint

A freely movable diarthrotic joint containing a fluid-filled articular joint cavity enclosed by a fibrous capsule.

Bursa

A flattened fibrous sac lined with synovial membrane containing fluid to reduce friction between moving body parts.