cartilage, bones, joints

Connective tissue composition

Cells + Ground substance + Protein Fibers

Connective Tissue Function

Connects various tissues and organs, providing structural support and integration.

Cartilage composition

Cells + Matrix

Cartilage

Semi-rigid connective tissue that is weaker than bone but more flexible and resilient

Avascular

Cartilage nutrients absorbed through diffusion

Chondroblasts

produce matrix of cartilage

Chondrocytes

after being encased in the matrix produced/secreted; occupies lacunae

3 types of cartilage

hyaline, elastic, and fibrocartilage

Cartilage Functions

[1] Support tissues, [2] Gliding surface, [3] Model for bone formation

Hyaline Cartilage

Provides support and flexibility; found in the trachea and at the ends of long bones.

Fibrocartilage

Tough and flexible; found in intervertebral discs, providing shock absorption.

Elastic Cartilage

Contains elastic fibers; found in the ear, providing shape and support.

Cartilage Growth

Simultaneous during embryonic period but more appositional after cartilage becomes mature

Interstitial Growth

Within the cartilage

Appositional Growth

Along the periphery/edge

Bone

Osseous tissue; hard and dense connective tissue providing structural integrity; rigid

Human Bones

206

Bone Function

[1] Support, movement, & protection, [2] Minerals, energy, & hematopoiesis

Bone Categories

Based on shapes

Long Bones

Cylindrical, long > wide

Hu, U, R

Humerus, Ulna, Radius

Fe, Ti, Fi

Femur, Tibia, Fibula

Short Bones

Cube-like; length = width = thickness; stability & support

CaTar

Carpals, Tarsals

Flat Bones

Thin and curved; points of attachment; internal organ protection

Feel Special, Flat bones

Sternum, Scapulae, Ribs, Cranial bones

Irregular Bones

no defined shape; support, protection

FaVer

Facial Bones, Vertebrae, Irregular Bones

Sesamoid

small & round

Gross Anatomy of Long Bones

APEEEMDME

Diaphysis

tubular shaft between proximal and distal ends; walls are compact bone

Medullary cavity

hollow region within diaphysis (contains yellow marrow)

Epiphysis

the proximal and distal ends; spongy bone (contains red marrow)

Metaphysis

connection between diaphysis and epiphysis; contains epiphyseal plate/growth plate

Epiphyseal plate

hyaline cartilage in early life; stops growing in early adulthood

Epiphyseal line

former epiphyseal plate that becomes osseous tissue after cessation of growth

Endosteum

site of bone growth, repair, and remodeling

Periosteum

contains blood vessels, nerves, and lymphatic vessels that nourish the bone; attachment for tendons and ligaments; covers most of bone

Articular Cartilage

covering of bone at epiphyses (joints); reduces friction and shock absorber

Gross Anatomy of Flat Bones

Outer Compact Bone + Inner Spongy Bone

Articulation

joins bone surfaces; conform to one another; where 2 bones meet

Projection

projects/protrudes above surface of bone; attachment points of tendons and ligaments; raised markings

Hole

opening/groove allowing passage of nerves and blood vessels; depressions

Bone Cells & Tissues

Small number of cells + matrix of collagen fibers (where inorganic salt crystals adhere)

Salt Crystals

Ca phosphate x Ca carbonate = Hydroxyapatite

Hydroxyapatite

hardness & strength

Collagen fibers

flexibility

Osteogenic Cells

Undifferentiated cells with high mitotic activity, capable of becoming osteoblasts.

Osteoblasts

Cells responsible for bone formation, found in the periosteum and endosteum, synthesizing collagen and calcium salts.

Osteocytes

Mature bone cells that maintain bone tissue, located in lacuna, and communicate through canaliculi.

Osteoclasts

Cells that resorb bone tissue, originating from macrophages and monocytes, for bone remodeling and repair.

Compact Bone

dense; withstands compressive forces; found under periosteum and in diaphysis; support and protection

Compact Bone Parts

Osteon/Haversian System, Lamellae, Central/Haversian Canal, Perforating/Volkmann's Canal, Lacunae, Nutrient Foramina

Spongy/Cancellous Bone

supports shifts in weight distribution

Trabeculae

lattice-like network containing lacunae, osteocytes, red marrow

Bone Formation

Starts with ossification at 6th-7th week of embryonic life

2 Pathways of Ossification

Intramembranous & Endochondral

Bone formation template

Cartilage

Bone formation framework

flexible, semi-solid matrix by chondroblasts and consists of hyaluronic acid, chondroitin sulfate, collagen fibers, and water

Chondrocytes

enclosed chondroblasts

Intramembranous Ossification

Formation of bone directly from mesenchymal tissue, primarily for flat bones.

Endochondral Ossification

Replacement of hyaline cartilage, cartilage is not a template, takes longer, and for long bones and bones at base of skull.

Epiphyseal Plate

layer of hyaline cartilage

Epiphyseal side

Side where cartilage is formed

Diaphyseal side

Side where cartilage is ossified

Four Zones of Activity

Bone Length Growth = 1R, 2P, 3M, 4C

Reserve Zone

No growth happens

Proliferative Zone

High mitotic activity; longitudinal growth

Zone of Maturation & Hypertrophy

Older and larger chondrocytes; longitudinal growth

Zone of Calcified Matrix

Chondrocytes are dead

Epiphyseal Line

When chondrocytes cease proliferation.

Bone Diameter Growth

via Appositional Growth

Appositional Growth

Involves the resorption of old bone by osteoclasts and the production of new bone by osteoblasts, increasing bone diameter; modeling

Remodeling

Resorption and production of new bone done on the same surface; usually due to injury and exercise

Joint

each connected to at least one other bone

Hyoid

joint not connected to any other bone

More stable joint

Less movement

Joint Classifications

Functional and Structural

Functional Classification of Joints

SAD

UBM

Uniaxial, Biaxial, Multiaxial; Diarthrosis

Diarthrosis

Freely movable; mostly in appendicular skeleton; synovial

Uniaxial Diarthrosis

Single plane (elbow)

Biaxial Diarthrosis

2 planes (metacarpophalangeal joint)

Multiaxial Diarthrosis

3 planes (shoulder & hip joints)

Amphiarthrosis

Slightly movable; summation of movements allow for greater range of movement

Synarthrosis

Immovable joints, such as sutures in the skull

Structural Classifications of Joints

Fibrous, Cartilaginous, Synovial

Fibrous Joint

united by fibrous connective tissue; most stable

Narrow Fibrous Joint

sutures in the skull; synarthrosis

Syndesmosis Fibrous Joint

wide gap connected by a ligament/interosseous membrane; amphiarthrosis

Gomphosis Fibrous Joint

tooth root to socket; synarthrosis

Cartilaginous Joints

joined by hyaline or fibrocartilage

Synchondrosis Cartilaginous Joint

joined by hyaline cartilage; synarthrosis

Symphysis Cartilaginous Joint

joined by fibrocartilage; amphiarthrosis

Synovial Joints

Characterized by a joint cavity, no direct connection; diarthrosis

PH College Students Poor Brains

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

Pivot Synovial Joint

rounded bone enclosed within a ring; uniaxial

Atlantoaxial joint

C1 & C2; side-to-side movement; pivot

Proximal radioulnar joint

rotation of radius; pivot

Hinge Synovial Joint

convex end + concave end; uniaxial; bending & straightening