Anatomy - Skeletal

Skeletal System

The body system composed of bones and cartilage.

Functions of Bones

The critical roles that bones play in the human body, including support, movement, protection, blood cell production, and mineral and fat storage.

Classes of Bones

The categorization of bones based on their shape and structure, including long bones, short bones, flat bones, irregular bones, and sesamoid bones.

Bone Formation and Development

The process by which bones are formed and grow.

Bone Repair

The process by which bones heal themselves after a fracture.

Effect of Exercise, Nutrition, and Hormones on Bone Tissue

The impact of physical activity, diet, and hormonal balance on the health and strength of bones.

Imbalance of Calcium and Bone Tissue

The consequences of an abnormal level of calcium in the body on bone health.

Support, Movement, and Protection

The functions of bones in providing structural support, facilitating movement, and protecting internal organs.

Levers and Joints

The mechanical roles of bones as levers and joints as fulcrums in facilitating movement.

Long Bones

Bones that are cylindrical in shape and longer than they are wide, found in the arms, legs, fingers, and toes.

Short Bones

Bones that are cube-like in shape and approximately equal in length, width, and thickness, found in the wrists and ankles.

Flat Bones

Bones that are thin and often curved, serving as points of attachment for muscles and protecting internal organs.

Sesamoid Bones

Small, round bones that form in tendons and protect them from compressive forces, commonly found in the feet, hands, and knees.

Diaphysis

The tubular shaft of a long bone.

Epiphysis

The wider section at each end of a long bone, filled with spongy bone.

Medullary Cavity

The hollow region in the diaphysis of a long bone, filled with yellow marrow.

Endosteum

The delicate membranous lining of the medullary cavity where bone growth, repair, and remodeling occur.

Periosteum

The fibrous membrane covering the outer surface of bones, containing blood vessels, nerves, and lymphatic vessels.

Head

Prominent rounded surface, example:Head of femur

Facet

Flat surface, example:Vertebrae

Condyle

Rounded surface, example:Occipital condyles

Projections

Raised markings, example:Spinous process of the vertebrae

Protuberance

Protruding, example:Chin

Process

Prominent feature, example:Transverse process of vertebra

Spine

Sharp process, example:Ischial spine

Tubercle

Small, rounded process, example:Tubercle of humerus

Tuberosity

Rough surface, example:Deltoid tuberosity

Line

Slight, elongated ridge, example:Temporal lines of the parietal bones

Fossa

Elongated basin, example:Mandibular fossa

Fovea

Small pit, example:Fovea capitis on the head of the femur

Sulcus

Groove, example:Sigmoid sulcus of the temporal bones

Canal

Passage in bone, example:Auditory canal

Fissure

Slit through bone, example:Auricular fissure

Foramen

Hole through bone, example:Foramen magnum in the occipital bone

Meatus

Opening into canal, example:External auditory meatus

Sinus

Air-filled space in bone, example:Nasal sinus

Compact bone

Denser, stronger type of bone tissue

Spongy bone

Also known as cancellous bone, contains osteocytes in a lattice-like network of matrix spikes called trabeculae

Osteogenic cells

Develop into osteoblasts, found in deep layers of the periosteum and marrow cells

Osteoblasts

Responsible for bone formation, found in growing portions of bone

Osteocytes

Entrapped in the bone matrix, found on bone surfaces and at sites of old, injured, or unneeded bone

Osteoclasts

Responsible for bone resorption

Hydroxyapatite

Crystals formed by the combination of calcium phosphate and calcium carbonate, gives bones their hardness and strength

Periosteum

Outer fibrous layer of bone

Endosteum

Inner osteogenic layer of bone

Medullary cavity

Cavity within the diaphysis of long bones, contains bone marrow

Nutrient foramen

Opening through which blood vessels and nerves enter the bone

Epiphyseal plate

Cartilaginous plate at the ends of long bones, responsible for longitudinal bone growth

Fracture

A broken bone

Closed reduction

Manipulation and setting of a broken bone without surgery

Open reduction

Surgery required to expose and reset a broken bone

Types of fractures

Closed, open, transverse, spiral, comminuted, impacted, greenstick, oblique

Transverse Fracture

A type of fracture that occurs straight across the long axis of the bone.

Oblique Fracture

A type of fracture that occurs at an angle that is not 90 degrees.

Spiral Fracture

A type of fracture where bone segments are pulled apart as a result of a twisting motion.

Comminuted Fracture

A type of fracture where several breaks result in many small pieces between two large segments.

Impacted Fracture

A type of fracture where one fragment is driven into the other, usually as a result of compression.

Greenstick Fracture

A partial fracture in which only one side of the bone is broken.

Open (or compound) Fracture

A fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection.

Closed (or simple) Fracture

A fracture in which the skin remains intact.

Fracture Hematoma

The formation of a blood clot at the site of a bone fracture.

Callus

A mass of tissue that forms at the site of a fracture during the healing process.

Trabecular Bone

A type of bone tissue that forms the internal framework of bone.

Vitamin D

A nutrient that is essential for calcium absorption and bone health.

Calcium

A mineral that is needed to make calcium phosphate and calcium carbonate, which form the hydroxyapatite crystals that give bone its hardness.

Vitamin K

A nutrient that supports bone mineralization and may have a synergistic effect with vitamin D.

Magnesium

A mineral that is a structural component of bone.

Fluoride

A mineral that is a structural component of bone.

Omega-3 Fatty Acids

Nutrients that reduce inflammation that may interfere with osteoblast function.

Osteoporosis

A disease characterized by a decrease in bone mass that occurs when the rate of bone resorption exceeds the rate of bone formation.

Growth Hormone

A hormone that increases the length of long bones, enhances mineralization, and improves bone density.

Thyroxine

A hormone that stimulates bone growth and promotes the synthesis of bone matrix.

Sex Hormones

Hormones that promote osteoblastic activity and production of bone matrix, responsible for adolescent growth spurt, and promote the conversion of epiphyseal plate to epiphyseal line.

Calcitriol

A hormone that stimulates the absorption of calcium and phosphate from the digestive tract.

Parathyroid Hormone

A hormone that stimulates osteoclast proliferation and resorption of bone, promotes reabsorption of calcium by kidney tubules, and indirectly increases calcium absorption by the small intestine.

Calcitonin

A hormone that inhibits osteoclast activity and stimulates calcium uptake by bones.

Axial Skeleton

The part of the skeleton that forms the vertical, central axis of the body and includes all bones of the head, neck, chest, and back.

Appendicular Skeleton

The part of the skeleton that includes all bones of the upper and lower limbs, plus the bones that attach each limb to the axial skeleton.

Cranial Portion

The part of the skull that houses and protects the brain.

Facial Portion

The part of the skull that forms the face.

Pectoral (Shoulder) Girdle

The bones that connect the upper limbs to the axial skeleton.

Thoracic Cage

The bony structure that protects the heart and lungs.

Upper Limb

The bones of the arm, forearm, and hand.

Vertebral Column

The series of bones that make up the spine.

Pelvic Girdle

The bones that connect the lower limbs to the axial skeleton.

Lower Limb

The bones of the thigh, leg, and foot.

Skull

The bony structure that forms the head.

Temporal Bone

A bone of the skull that houses the middle and inner ear structures.

Maxilla

A bone of the skull that forms the upper jaw.

Zygomatic Bone

A bone of the skull that forms the cheekbone.

Mandible

The lower jawbone.

Frontal Bone

A bone of the skull that forms the forehead.

Parietal Bone

A bone of the skull that forms the sides and roof of the cranium.

Occipital Bone

A bone of the skull that forms the back of the head.

Sphenoid Bone

A bone of the skull that forms part of the base of the skull and the sides of the eye sockets.

Ethmoid Bone

A bone of the skull that forms part of the nasal cavity and the eye sockets.

Lacrimal Bone

A bone of the skull that forms part of the eye socket and the tear ducts.

Nasal Bone

A bone of the skull that forms the bridge of the nose.

Vomer Bone

A bone of the skull that forms part of the nasal septum.

Inferior Nasal Concha

A bone of the skull that forms part of the nasal cavity.