A&P Test 6

Skeletal System

The body system consisting of bones and joints.

Ligaments

Bands of fibrous connective tissue that connect bone to bone.

Functions of the Skeleton

Provides a supporting framework, allows for movement via muscle attachment, protects internal organs, contains hemopoietic red bone marrow, and stores excess calcium.

Bone Hardness

Due to inorganic calcium salts in the matrix.

Bone Flexibility

Due to the organic matrix of collagen fibers.

Axial Skeleton

Bones located around the body's center of gravity.

Appendicular Skeleton

Bones of the limbs and their girdles.

Articular Cartilage

Hyaline cartilage that covers the ends of bones at movable joints.

Costal Cartilage

Cartilage that connects the ribs to the sternum.

Intervertebral Discs

Discs of fibrocartilage that separate and cushion the vertebrae.

Perichondrium

The dense connective tissue covering that surrounds cartilage.

Hyaline Cartilage

The most common skeletal cartilage; provides sturdy support with some resilience.

Elastic Cartilage

More flexible than hyaline; found in the external ear and epiglottis.

Fibrocartilage

Has great tensile strength and can withstand heavy compression; found in intervertebral discs.

Osteocytes

Mature bone cells that live in lacunae and regulate calcium in the bone matrix.

Bone Matrix

The non-living component of bone, made of collagen fibers and calcium salts.

Compact Bone

The dense, solid, and strong outer layer of bone.

Spongy (Cancellous) Bone

The inner, porous layer of bone that contains red bone marrow.

Osteon (Haversian System)

The structural unit of compact bone.

Haversian Canal

The central canal in an osteon that contains blood vessels and nerves.

Canaliculi

Microscopic canals that connect lacunae, allowing osteocytes to communicate.

Perforating (Volkmann's) Canals

Canals that run at right angles to the bone shaft, connecting the interior to the external surface.

Long Bones

Bones that are longer than they are wide; act as levers.

Short Bones

Roughly cube-shaped bones.

Flat Bones

Thin, flattened, and often curved bones.

Irregular Bones

Bones with complex shapes.

Diaphysis

The shaft of a long bone.

Epiphysis

The end of a long bone.

Medullary Cavity

The hollow cavity within the diaphysis that contains yellow bone marrow.

Articular Cartilage

Hyaline cartilage that covers the epiphyses where bones form joints.

Periosteum

The fibrous connective tissue membrane covering the outer surface of bone.

Red Bone Marrow

Hemopoietic tissue; found in the spongy bone of adults.

Endosteum

The membrane that lines the medullary cavity.

Ossification

The process of bone formation.

Intramembranous Ossification

Process where bone develops from a fibrous membrane; forms flat bones of the skull.

Endochondral Ossification

Process where bone forms by replacing a hyaline cartilage model; forms most bones of the body.

Epiphyseal Plate (Growth Plate)

A plate of hyaline cartilage where long bones grow in length.

Closure of the Epiphyseal Plate

The replacement of cartilage by bone, stopping bone lengthening.

Osteoblasts

Bone-forming cells that secrete bone matrix.

Osteoclasts

Bone-resorbing cells that break down bone matrix.

Key Nutrients for Bone

Calcium, phosphorus, and protein; Vitamin D; Vitamins A & C.

Hormones for Bone Growth

Growth Hormone, Thyroxine, Sex Hormones.

Hormones for Calcium Homeostasis

Parathyroid Hormone increases blood calcium; Calcitonin decreases blood calcium.

Weight-Bearing Exercise

Stress that stimulates bones to thicken and strengthen.

Osteoporosis

A disease where bone resorption outpaces deposition.

Rickets/Osteomalacia

Disorders of poor bone mineralization, leading to soft, weak bones.

Cranial Bones

The 8 bones that enclose and protect the brain.

Sutures

Immovable fibrous joints between cranial bones.

Foramen Magnum

The large opening in the occipital bone for the spinal cord.

Sella Turcica

A depression in the sphenoid bone that holds the pituitary gland.

Fontanels

Fibrous membranes between fetal skull bones that allow compression during birth.

Facial Bones

The 14 bones that form the face.

Mandible

The only movable skull bone; the lower jaw.

Paranasal Sinuses

Air-filled cavities in skull bones that lighten the skull and provide voice resonance.

Vertebral Column Functions

Protects the spinal cord, supports the head and trunk.

Regions of the Spine

Cervical, Thoracic, Lumbar, Sacrum, Coccyx.

Atlas (C1)

The first cervical vertebra; supports the skull and allows a "yes" motion.

Axis (C2)

The second cervical vertebra; allows the head to pivot "no".

Abnormal Spinal Curves

Scoliosis, Kyphosis, Lordosis.

Sternum Parts

Manubrium, Body, Xiphoid Process.

Rib Types

True Ribs, False Ribs, Floating Ribs.

Pectoral Girdle

Consists of the scapula and clavicle.

Scapula

Shoulder blade; features the glenoid fossa.

Clavicle

Collar bone; acts as a brace for the scapula.

Humerus

Bone of the upper arm.

Head of Humerus

Fits into the glenoid fossa to form the shoulder joint.

Deltoid Tuberosity

Roughened area on the humerus for the deltoid muscle.

Distal Humerus Landmarks

Trochlea, Capitulum, Medial & Lateral Epicondyles.

Ulna

Medial bone of the forearm; features the olecranon process.

Radius

Lateral bone of the forearm; the head rotates during pronation/supination.

Carpals

The 8 small bones of the wrist.

Metacarpals

The 5 bones of the palm.

Phalanges

The bones of the fingers.

Pelvic Girdle

Consists of the two hip bones and the sacrum.

Hip Bone Parts

Ilium, Ischium, Pubis.

Acetabulum

The deep socket in the hip bone that receives the head of the femur.

Female vs. Male Pelvis

The female pelvis is wider with a broader pubic angle.

Femur

The thigh bone; the longest and strongest bone in the body.

Greater & Lesser Trochanters

Large projections on the proximal femur for muscle attachment.

Patella

The kneecap; a sesamoid bone.

Tibia

The shin bone; the major weight-bearing bone of the lower leg.

Medial Malleolus

The medial "ankle bone" formed by the tibia.

Fibula

The thin, non-weight-bearing bone of the lower leg.

Lateral Malleolus

The lateral "ankle bone" formed by the fibula.

Tarsals

The 7 bones of the ankle.

Metatarsals

The 5 bones of the foot.

Foot Arches

Longitudinal and transverse arches that provide spring.

Joint (Articulation)

A site where two or more bones meet.

Structural Classification

Fibrous, Cartilaginous, Synovial.

Functional Classification

Synarthrosis, Amphiarthrosis, Diarthrosis.

Synovial Joint Characteristics

Have a joint cavity, articular cartilage, and an articular capsule.

Synovial Membrane

The inner lining of the joint capsule that secretes synovial fluid.

Bursae

Fluid-filled sacs that cushion and reduce friction.

Types of Synovial Joints

Plane, Hinge, Pivot, Condyloid, Saddle, Ball-and-Socket.

Joint Movements

Flexion, Extension, Abduction, Adduction, Rotation, Circumduction, Pronation, Supination.

Temporomandibular Joint (TMJ)

The joint between the mandible and temporal bone.

Shoulder (Glenohumeral) Joint

A ball-and-socket joint with the greatest range of motion.

Hip Joint

A very stable ball-and-socket joint.

Knee Joint

The largest and most complex joint; a modified hinge joint.

Sprain

The stretching or tearing of ligaments.