anatomy unit 2 lecture objective notes

Unit II - The Skeletal System Overview

• Objectives and Study Guide:

  • Familiarize with all diseases/disorders related to the skeletal system.

Functions of the Skeletal System

• Support the body.

• Protect vital organs.

• Facilitate movement by serving as levers.

• Store minerals (calcium and phosphorus).

• Produce blood cells (hematopoiesis).

Classification of Bones by Shape

• Long Bones: Example - femur

• Short Bones: Example - carpals

• Flat Bones: Example - scapula

• Irregular Bones: Example - vertebrae

• Sesamoid Bones: Example - patella

Gross Features of Long Bones

• Types of Bone Tissue:

  • Compact Bone: dense outer layer; supports and protects.

  • Spongy Bone: porous inner layer; contains red bone marrow.

  • Articular Cartilage: covers joint surfaces for smooth movement.

  • Periosteum: protective outer membrane.

  • Endosteum: internal lining of the medullary cavity.

  • Medullary Cavity: central cavity containing yellow marrow.

  • Yellow Marrow: fat storage.

  • Red Marrow: site of blood cell production.

  • Epiphysis: end of the bone; contains spongy bone;

  • Diaphysis: central shaft of the bone;

  • Metaphysis: site of growth; contains epiphyseal plate in growing bones.

  • Epiphyseal Line: remnant of the growth plate in adults.

  • Nutrient Foramen: openings for blood vessels.

Anatomy and Physiology of Bone Tissue

• Osteon: structural unit of compact bone.

• Calcified Matrix: rigid extracellular matrix that provides strength.

• Central (Haversian) Canal: central channel for blood vessels and nerves.

• Perforating (Volkmann) Canal: channels connecting blood supply of periosteum to those in the Haversian canals.

• Osteocytes: mature bone cells that maintain bone tissue.

• Canaliculi: small channels that connect lacunae.

• Osteoblasts: cells that build bone.

• Concentric Lamellae: layered structure around Haversian canals.

• Osteoclasts: cells that break down bone tissue.

• Osteogenic (Osteoprogenitor) Cells: stem cells for bone formation.

• Lacuna: small cavities where osteocytes reside.

• Bone Lining Cells: flat cells on bone surfaces.

• Trabeculae: supporting strands in spongy bone.

• Mesenchymal Cells: stem cells that can differentiate into osteoblasts.

Bone Markings Definitions

• Process: any bony prominence.

• Spine: a sharp, slender projection.

• Condyle: rounded end of a bone.

• Epicondyle: projection above a condyle.

• Tubercle: small rounded projection.

• Tuberosity: larger, roughened projection.

• Trochanter: large, blunt projection (only on femur).

• Trochlea: a smooth, grooved articular process.

• Crest: a narrow ridge of bone.

• Line: a less prominent ridge.

• Head: a bony expansion carried on a narrow neck.

• Neck: constriction below the head.

• Fossa: shallow depression.

• Facet: smooth, flat surface; joint surface.

• Fissure: narrow, slit-like opening.

• Foramen: round or oval opening.

• Meatus (Canal): canal-like passageway.

• Sinus: cavity within a bone.

• Groove/Sulcus: furrow along a bone that accommodates a vessel, nerve, or tendon.

• Ramus: arm-like bar of bone.

• Notch: indentation at the edge of a structure.

Bone Formation Processes

• Endochondral Bone Formation: process where bones develop from hyaline cartilage (e.g., long bones).

• Intramembranous Bone Formation: process where bone develops from fibrous membranes (e.g., flat bones).

• Types of Growth:

  • Interstitial Growth: growth from within due to division of cells.

  • Appositional Growth: growth in width from the outside.

• Exercise’s Role: stimulates bone density and strength.

Bone Growth at Epiphyseal Plate

• Bone growth occurs at the epiphyseal plate which is in the long bone's growth region, facilitating elongation.

• Human Growth Hormone: promotes growth of cartilage and bone.

• Estrogen and Testosterone: influence growth plate activity and closure.

• Glands: Pituitary gland (GH), Ovaries (estrogen), and Testes (testosterone).

Bone Remodeling Process

• Remodeling: continuous cycle of bone formation and resorption.

• Calcitonin: hormone that lowers blood calcium levels; produced by the thyroid gland.

• Parathyroid Hormone: hormone that increases blood calcium levels; produced by parathyroid glands.

Compact vs. Spongy Bone

• Compact Bone: dense layer providing strength and support.

• Spongy Bone: lightweight, contains trabeculae and red marrow for blood cell production.

Axial Skeleton Identification

• Includes bones of the skull, vertebral column, and ribs.

  • Skull Sutures:

    • Sagittal Suture: between left and right parietal bones.

    • Coronal Suture: between frontal and parietal bones.

    • Lambdoidal Suture: between parietal and occipital bones.

    • Squamous Suture: between temporal and parietal bones.

Appendicular Skeleton Identification

• Includes upper and lower limbs, girdles connecting limbs to axial skeleton.

• Distinctions between arm/forearm and thigh/leg.

Types of Fractures

• Open Fracture: bone pierces skin.

• Closed Fracture: no puncture in skin.

• Incomplete Fracture: bone not completely broken.

• Complete Fracture: bone fully fractured.

• Spiral Fracture: bone twisted apart.

• Displaced Fracture: ends of bone not aligned.

• Nondisplaced Fracture: ends of bone still aligned.

Bone (Fracture) Repair Process

• Steps include inflammation, soft callus formation, hard callus formation, and bone remodeling.

Skeleton Overview

• Recognize components of skull, vertebral column, and ribs (axial and appendicular skeleton).

• Skull Bones: classified as cranial (protecting the brain) versus facial (forming the face).

• Vertebral Structure: differentiates between cervical, thoracic, and lumbar vertebrae.

• Ribs Count: 12 pairs of ribs.

Pelvic Differences

• Understand differences between male and female pelvis.

• Distinction between true and false pelvis.

Sinuses of the Skull

• Sinus Function: lighten the skull, resonating sound, warming/humidifying air.

• Types:

  • Frontal Sinuses: located in the forehead region.

  • Sphenoidal Sinuses: located behind the nose.

  • Maxillary Sinuses: located in the cheek area.

  • Ethmoidal Air Cells: small cavities located between the nose and the eyes.