Skeletal System: Anatomy & Physiology - Flashcards

A comprehensive set of questions and answers covering skeletal system concepts from bones and bone cells to joints and range of motion.

What are the main components of the skeletal system?

Bones, cartilage, tendons, and ligaments.

What is the skeleton?

The framework that gives shape to the body, provides support against gravity, and protects internal organs.

Name the primary functions of the skeleton.

Body support; body movement; organ protection; blood cell production; mineral storage; adipose tissue storage within bone cavities.

Which minerals are stored in bone?

Calcium and phosphorus.

Where is red bone marrow located and what is its function?

In cavities of long bones; produces red blood cells, white blood cells, and platelets.

Where is yellow bone marrow located and what is its function?

In bone cavities, replaces red marrow; stores adipose tissue for energy.

How many bones are in the adult skeleton?

206 bones.

Name two primary bone cell types and their roles.

Osteoclasts resorb (break down) bone; osteoblasts form (build) bone.

What is bone resorption?

The breakdown of bone that releases calcium and phosphate ions into the blood.

What is ossification?

The formation of new bone by osteoblasts.

What is appositional growth?

Growth of bone on the surface, increasing bone diameter.

What is bone collagen and its role?

The living protein matrix laid down by osteoblasts that provides scaffolding and becomes mineralized to harden bone.

Who are osteocytes?

Mature bone cells; make up about 90–95% of bone cells and have a long lifespan (about 25 years).

What are lacunae?

Spaces within the bone matrix that house osteocyte cell bodies.

What are canaliculi?

Long, narrow spaces that house osteocyte extensions and connect lacunae for nutrient/gas exchange.

What is an osteon?

The functional unit of compact bone, consisting of concentric lamellae around a central canal.

What does the central (Haversian) canal contain?

Blood vessels and nerves.

What are Volkmann (perforating) canals?

Perforating canals that run perpendicular to the bone length and connect central canals.

What is the diaphysis?

The shaft or center portion of a long bone, primarily compact bone.

What is the medullary cavity?

A hollow center within the diaphysis that stores red and/or yellow bone marrow.

What is the epiphysis?

The ends of long bones; mostly spongy bone with an outer layer of compact bone.

What is the epiphyseal plate?

Growth plate between the epiphysis and diaphysis where lengthwise bone growth occurs.

What is the epiphyseal line?

The ossified epiphyseal plate indicating cessation of bone length growth.

What is the periosteum?

A connective tissue membrane that covers the outer surface of a bone; has an outer fibrous layer and an inner cambium layer with osteoblasts and osteoclasts.

What is the endosteum?

A single cell layer that lines internal bone cavities and contains osteoblasts and osteoclasts.

Difference between compact bone and spongy bone?

Compact bone has more bone matrix and less space; dense and solid. Spongy bone is porous with trabeculae and spaces filled with marrow.

What is lamella in bone tissue?

Thin, concentric sheets of organized collagen fibers in bone matrix.

What are trabeculae?

Interconnecting rods or plates of bone in spongy bone.

What is red bone marrow?

Site of blood cell formation (hematopoiesis).

What is yellow bone marrow?

Adipose tissue that stores fats.

What is a long bone?

Typically longer than wide with a shaft (diaphysis) and two ends, mostly compact bone.

What is a short bone?

Cube-shaped bones that contain mostly spongy bone with a thin outer compact layer.

What is an irregular bone?

Bones that do not fit the other categories (e.g., vertebrae, some facial bones).

What is a flat bone?

Thin, flattened bones with two compact bone layers sandwiching a layer of spongy bone.

What is the difference between a central canal and a perforating canal?

Central (Haversian) canal runs longitudinally within an osteon; perforating (Volkmann) canals run perpendicular and connect osteons.

What are the periosteum’s two layers called?

Outer fibrous layer and inner cambium (cellular) layer.

What is the function of the endosteum?

Lines internal bone cavities and contains osteoblasts and osteoclasts.

What are the axial and appendicular skeletons?

Axial: bones along the body's central axis (skull, vertebral column, rib cage). Appendicular: bones of the limbs and girdles (pectoral and pelvic).

What are sutures in the skull?

Fibrous joints between skull bones.

What bones form the pectoral girdle?

Clavicle (collarbone) and scapula (shoulder blade).

What joints connect the pectoral girdle?

Sternoclavicular joint, acromioclavicular joint, and glenohumeral (shoulder) joint.

Which bones form the upper limb?

Humerus, radius, ulna; carpals, metacarpals, and phalanges.

What bones form the pelvic girdle?

Ilium, ischium, and pubis.

What is the acetabulum?

The socket in the pelvis that articulates with the femur.

Which bones form the lower limb?

Femur, patella, tibia, fibula; tarsals, metatarsals, and phalanges.

What are the vertebral column sections and their vertebrae ranges?

Cervical (C1–C7), Thoracic (T1–T12), Lumbar (L1–L5); plus sacrum and coccyx.

What are the Atlas and Axis?

Atlas (C1) and Axis (C2); the first and second cervical vertebrae that enable head motion.

What composes the thoracic cage?

Ribs and sternum.

What are True ribs, False ribs, and Floating ribs?

True ribs (1–7) attach to sternum; False ribs (8–12) attach indirectly or not at all; Floating ribs are 11–12 that do not attach to sternum.

What is a synovial joint?

A freely movable joint with a joint cavity containing synovial fluid.

What is synovial fluid’s function?

Protection and lubrication of joints; reduces friction during movement.

What are ligaments and tendons?

Ligaments: connect bone to bone for joint stability. Tendons: connect muscle to bone.

What is articular cartilage?

Hyaline cartilage that covers ends of bones in joints; avascular and aneural.

What are the three functional classifications of joints?

Synarthroses (immovable), Amphiarthroses (slightly movable), Diarthroses (freely movable).

What are the three structural classes of joints?

Fibrous, Cartilaginous, Synovial.

Give an example of a fibrous joint.

Sutures of the skull (fibrous tissue with interlocking edges; no movement).

Give an example of a cartilaginous joint.

Intervertebral joints or pubic symphysis (connected by cartilage).

Name the six types of synovial joints.

Plane, hinge, pivot, condylar, saddle, ball-and-socket.

What is range of motion (ROM)?

The amount of mobility demonstrated in a joint.

What is active range of motion?

Movement that can be achieved by the muscles crossing the joint.

What is passive range of motion?

Movement of the joint produced by an external force, not muscles.

What is flexion?

Decrease in the angle between articulating bones.

What is extension?

Increase in the angle between articulating bones.

What is hyperextension?

Excessive extension beyond the normal range.

What is abduction?

Movement away from the midline of the body.

What is adduction?

Movement toward the midline of the body.

What is circumduction?

Movement of the distal end of a limb in a circle while the proximal end remains fixed.

What is rotation?

Turning a bone around its own axis.

What is inversion?

Turning the sole of the foot inward.

What is eversion?

Turning the sole of the foot outward.

What is dorsiflexion?

Flexion of the foot superiorly (raising the toes toward the shin).

What is plantar flexion?

Plantar flexion: pointing the toes downward (standing on tiptoe).

What is protraction?

A part of the body moving forward in the horizontal plane.

What is retraction?

A part of the body moving backward in the horizontal plane.

What is opposition in the hand?

The movement of the thumb to touch the fingertips.