Anatomy and Physiology: Skeletal System, Joints, and Axial/Appendicular Skeleton

Comprehensive practice vocabulary flashcards covering bone connective tissue, cartilage, ossification, joint classifications, movements, levers, and axial/appendicular anatomical structures based on Chapters 7, 8, and 9.

Compact bone

Dense or cortical bone that appears smooth and solid, making up 80% of total bone mass.

Spongy bone

Cancellous or trabecular bone located internal to compact bone that appears porous and makes up 20% of bone mass.

Hyaline cartilage

A semirigid connective tissue that attaches ribs to the sternum, covers the ends of some bones, forms growth plates, and serves as a model for embryonic bone formation.

Fibrocartilage

A weight-bearing cartilage that withstands compression, located in intervertebral discs, the pubic symphysis, and the menisci of the knee.

Hemopoiesis

The process of blood cell production, which occurs in red bone marrow connective tissue.

Diaphysis

The elongated, cylindrical shaft of a long bone that provides leverage and weight support.

Medullary cavity

The hollow, cylindrical space within the diaphysis containing red bone marrow in children and yellow bone marrow in adults.

Epiphysis

The knobby region at each end of a long bone, composed of an outer thin layer of compact bone and an inner region of spongy bone.

Epiphyseal plate

A thin layer of hyaline cartilage located in the metaphysis of growing bone that provides for lengthwise bone growth.

Periosteum

A tough sheath covering the outer surface of bone, consisting of an outer fibrous layer of dense irregular connective tissue and an inner cellular layer.

Endosteum

An incomplete layer of cells covering all internal surfaces of bone within the medullary cavity, containing osteoprogenitor cells, osteoblasts, and osteoclasts.

Diploë

The layer of spongy bone sandwiched between two layers of compact bone in flat bones of the skull.

Red bone marrow

Hemopoietic tissue containing reticular connective tissue, immature blood cells, and fat; located in spongy bone and medullary cavities of children, and restricted to selected axial skeleton locations in adults.

Yellow bone marrow

A fatty substance formed from the degeneration of red bone marrow as children mature, which can convert back to red bone marrow during severe anemia.

Osteoprogenitor cells

Mesenchymal stem cells located in the periosteum and endosteum that divide to produce committed cells that mature into osteoblasts.

Osteoblasts

Bone-forming cells derived from osteoprogenitor cells that synthesize and secrete initial semisolid organic bone matrix (osteoid).

Osteocytes

Mature bone cells derived from osteoblasts that reside in lacunae, maintain the bone matrix, and detect mechanical stress.

Osteoclasts

Large, multinucleated phagocytic cells derived from fused bone marrow cells that resorb bone matrix at a resorption lacuna.

Hydroxyapatite

Calcium phosphate crystals, $Ca_{10}(PO_4)_6(OH)_2$, formed during bone calcification that deposit around collagen fibers to give bone its rigidity.

Osteon

The basic functional and structural unit of mature compact bone, consisting of concentric lamellae arranged parallel to the diaphysis around a central canal.

Canaliculi

Tiny interconnecting channels within bone matrix that extend from lacunae to connect with other lacunae and the central canal, allowing nutrient and waste exchange between osteocytes.

Perforating canals

Canals running perpendicular to central canals that connect central canals across different osteons.

Trabeculae

An open lattice of narrow rods and plates of bone that make up spongy bone and resist stresses from multiple directions.

Interstitial growth of cartilage

Cartilage growth in length that occurs from within internal regions of cartilage.

Appositional growth of cartilage

Cartilage growth in width that occurs along the outer edge of cartilage.

Intramembranous ossification

Bone formation that develops within a membrane of mesenchyme, producing flat bones of the skull, some facial bones, mandible, and central clavicle.

Endochondral ossification

Bone formation that begins with a hyaline cartilage model, producing most bones of the skeleton including limb bones, pelvis, vertebrae, and clavicle ends.

Zone of proliferating cartilage

The second zone of the epiphyseal plate where chondrocytes undergo rapid mitotic division and align into longitudinal columns of flattened lacunae.

Bone remodeling

The continuous process of bone deposition and resorption occurring throughout adulthood at periosteal and endosteal surfaces.

Calcitriol

The active form of Vitamin D converted in the kidneys, which acts to raise blood calcium levels by stimulating calcium absorption in the small intestine.

Parathyroid hormone

A hormone released by parathyroid glands in response to low blood calcium levels that works with calcitriol to increase osteoclast activity and decrease urinary calcium excretion.

Calcitonin

A hormone released by the thyroid gland in response to elevated blood calcium levels that inhibits osteoclast activity and increases urinary calcium excretion.

Synarthrosis

An immobile joint that can be either fibrous or cartilaginous.

Amphiarthrosis

A slightly mobile joint that can be either fibrous or cartilaginous.

Diarthrosis

A freely mobile joint, encompassing all synovial joints.

Gomphosis

A fibrous joint functioning as a synarthrosis where a peg-like root of a tooth is held in the socket of the mandible or maxilla by periodontal membranes.

Suture

An immobile fibrous joint with interlocking, irregular edges found exclusively between certain skull bones.

Syndesmosis

A slightly mobile fibrous joint (amphiarthrosis) bound by an interosseous membrane, found between the radius/ulna and tibia/fibula.

Synchondrosis

A cartilaginous joint joined by hyaline cartilage that functions as an immobile synarthrosis, such as an epiphyseal plate or costochondral joint.

Symphysis

A cartilaginous joint containing a pad of fibrocartilage that acts as a shock absorber and permits slight mobility (amphiarthrosis), such as the pubic symphysis or intervertebral discs.

Synovial fluid

A viscous, oily fluid secreted by the synovial membrane that lubricates articular cartilage, nourishes chondrocytes, and absorbs shock in synovial joints.

Bursae

Fibrous, saclike structures containing synovial fluid and lined with synovial membrane that alleviate friction where bones, tendons, muscles, or skin rub together.

Plane joint

The simplest uniaxial synovial joint with flat articular surfaces that allows limited side-to-side gliding motion.

Ball-and-socket joint

A multiaxial synovial joint formed by a spherical head fitting into a cuplike socket, permitting movement in three planes and providing the greatest range of motion.

Flexion

An angular movement in an anterior-posterior plane that decreases the angle between articulating bones.

Extension

An angular movement in an anterior-posterior plane that increases the angle between articulating bones.

Abduction

Lateral movement of a body part away from the anatomical midline.

Adduction

Medial movement of a body part toward the anatomical midline.

Circumduction

A complex movement in which the proximal end of an appendage remains stationary while the distal end traces a circular path, forming an imaginary cone.

Pronation

Medial rotation of the forearm such that the palm of the hand faces posteriorly.

Supination

Lateral rotation of the forearm returning it to anatomical position with the palm facing anteriorly.

Dorsiflexion

Movement of the talocrural joint where the dorsum (superior surface) of the foot moves upward toward the leg.

Plantar flexion

Movement of the talocrural joint where the sole of the foot points inferiorly, as when standing on tiptoes.

Inversion

Intertarsal joint movement turning the sole of the foot medially.

Eversion

Intertarsal joint movement turning the sole of the foot laterally.

First-class lever

A lever system with the fulcrum positioned between the effort and resistance, such as at the atlanto-occipital joint.

Second-class lever

A lever system where resistance is located between the fulcrum and the effort, seen when standing on tiptoes.

Third-class lever

The most common lever system in the body, where effort is applied between the fulcrum and resistance, such as at the elbow joint.

Rotator cuff muscles

A group of four muscles (subscapularis, supraspinatus, infraspinatus, teres minor) whose tendons encircle and stabilize the glenohumeral joint.

Anular ligament

A ligament that surrounds the neck of the radius and binds the head of the radius to the ulna at the elbow joint.

Anterior cruciate ligament

An intracapsular knee ligament that extends from the posterior femur to the anterior tibia, preventing hyperextension and anterior displacement of the tibia.

Posterior cruciate ligament

An intracapsular knee ligament that extends from the anteroinferior femur to the posterior tibia, preventing hyperflexion and posterior displacement of the tibia.

Deltoid ligament

A strong ligament binding the tibia to the foot on the medial side of the talocrural joint, preventing overeversion.

Unhappy triad

A severe knee injury involving simultaneous damage to the tibial collateral ligament, medial meniscus, and anterior cruciate ligament.

Axial skeleton

The division of the skeleton composed of 80 bones along the central body axis, including the skull, vertebral column, and thoracic cage.

Appendicular skeleton

The division of the skeleton composed of 126 bones of the upper and lower limbs and the pectoral and pelvic girdles.

Calvaria

The rounded roof of the cranium that encloses the brain, formed by parts of the frontal, parietal, and occipital bones.

Cranial fossae

Three curved depressions on the floor of the cranial cavity (anterior, middle, and posterior) that house different lobes of the brain.

Fontanelles

Flexible, dense regular connective tissue regions ('soft spots') between cranial bones in infant skulls that permit distortion during birth and accommodate brain growth.

Atlas

The C1 cervical vertebra that lacks a body and spinous process, articulating with occipital condyles to permit nodding 'yes'.

Axis

The C2 cervical vertebra characterized by a prominent dens (odontoid process) that acts as a pivot for lateral head rotation ('no').

Intervertebral disc

A pad of fibrocartilage composed of an outer anulus fibrosus and an inner gelatinous nucleus pulposus situated between adjacent vertebral bodies to absorb shock and permit flexibility.

True ribs

Rib pairs 1 through 7 that connect individually and directly to the sternum via their own costal cartilages.

False ribs

Rib pairs 8 through 12 whose costal cartilages do not attach directly to the sternum.

Floating ribs

False rib pairs 11 and 12 that have no anterior attachment or connection to the sternum.

Sternal angle

The palpable horizontal ridge where the manubrium articulates with the body of the sternum, marking the attachment site for the second costal cartilages.

Pectoral girdle

The skeletal structure consisting of the clavicles and scapulae that attaches the upper limbs to the axial skeleton.

Glenoid cavity

A shallow, cup-shaped depression on the lateral angle of the scapula that articulates with the head of the humerus.

Pelvic brim

A continuous bony ridge on the os coxae and sacrum that divides the pelvis into the superior false pelvis and inferior true pelvis.

Pelvic inlet

The superior space enclosed by the pelvic brim that defines the upper boundary of the true pelvis.

Acetabulum

A deep, C-shaped socket on the lateral os coxae formed by the fusion of the ilium, ischium, and pubis, articulating with the head of the femur.

Medial longitudinal arch

The highest arch of the foot, extending from the calcaneus to the great toe (metatarsals I-III) to prevent the medial side of the foot from touching the ground.

Apical ectodermal ridge

A thickened region of ectoderm at the apex of developing limb buds that signals underlying mesoderm to form limb components.