Skeletal System

Functions

support, movement, storage (calcium & phospate ions), blood cell production, protection of organs

Hematopoiesis

blood cells being made in the bone marrow

Axial

central part of human skeleton

Appendicular

bones of limbs and gridles

Girdles

bones that link appendicular to axial

Long bones

longer than wide (humerous)

Short bones

cube-shaped with spongy bone (carpals)

Flat bones

thin and curved (skull)

Sesamoid bones

round and emmbedded in a tendon (patella)

Irregular bones

do not fit in any other category (vertebrae)

Epiphysis

rounded end of a long bone; covered with articular/hyaline cartilage; proximal and distal

Diaphysis

middle, shaft; contains medullary cavity (which has yellow marrow); metaphysis in between diaphysis and epiphysis

Compact Bone

dense;organized into osteons; has calcium, phosphate, and LACUNAE (cavities); exterior of all bones; lined by periosteum (outside) and endosteum (inside); strength, protection, resistance to stress

Periosteum

it lines the outside of bone; contains dense CT, osteroblasts (cells), blood vessels, and nerves.

Spongy Bone

aka CANCELLOUS BONE; has more spaces (trabecular); reduces bone weight and houses red marrow

Trabeculae

lattice-like rods that create holes in spongy bone; provides structural support to joints; absorbs shock; gets bigger with age (weakens bone; older women)

Red Marrow

fills spaces in between trabeculae (in spongy bone); contains stem cells that differentiate into RBCs, WBCs, and, platelets

Yellow Marrow

made of adipose; stores fat as an energy reserve

Medullary Cavity

hollow interior of diaphysis; in lined by endosteum; contains yellow marrow

Epiphyseal/Growth Plate

center of (lengthwise) growth in long bones; is a layer of hyaline cartilage; grows until after adolescence (then only widens); growth, thyroid, sex hormones affect growth

3 cell types

osteocytes, osteoblasts, and osteoclasts

Osteocytes

mature osteoblasts; in lacunae

Osteoblasts

immature osteocytes; makes/builds new bone cells and matrix; in periosteum

Osteoclasts

dissolves and reshapes bone (bone-resporbing); in endosteum

Bone matrix

organic: 1/3; inorganic: 2/3 (very important)

Organic Bone Matrix

Mostly collagen - prevents breakage by giving flexibility, strength, and resistance to stretching and twisting

Inorganic Bone Matrix

Na, K, F, Ca, Mg, Hyroxyapetite, P

Structure of bone

osteons, lamellae, and lacunae

Osteons

main circular structure of bone

Lamellae

ring-like sheets of bone

Lacunae

dark, hollow cavities between lamellae; each contains one osteocyte

Canals

central, haversion, and volkmann’s

Central Canal

contains tiny blood vessels and tiny canaliculi (connects each lacunae to this blood source)

Haversion Canal

center of each osteon

Volmann’s Canal

links adjacent Haversian canals

Canaliculi

allows nutrients and wastes to move between osteocytes; keeps bone tissue alive and strong

When a Fracture Occurs

1. blood vessels damaged and hematoma forms

2. blood vessels deliver O2, nutrients, and repair cells to injury site

3. Osteoblasts (from periosteum) begin producing new bone matrix

4. Bony callus is formed and eventually remodels into normal bone tissue

Ca (inorganic matrix)

role in neuromuscular junction

P (inorganic matrix)

role in teeth formation and energy

Hyroxyapetite

makes bone hard enough to support weight and not compress

inner ear #

3

skull #

22

cranuim #

8

facial #

14

throax #

27

upper limb #

30

lower limb #

29

peliv girdle #

6

vetebral column #

33

axial #

80

appendicular #

126

shoulder girdle

2

Types of Joints

fibrous, cartilaginous, synovial

Fibrous Joints

immovable; dense CT; cranial sutures

Carliagineous Joints

limited movement; fibro or hyaline cartilage; vertebral discs

Synovial Joints

free movement; fluid-filled cavity; knee, elbow, fingers, etc.

Synovial Joints Function

minimize bone-to-bone contact (arthritis; spurs)

Parts of Synovial Joint

fibrous capsule, bursa, articular cartilage, synovial fluid, synovial membrane

Fibrous capsule

encloses synovial joint

Bursa

protective fluid-filled sac (problems can cause knee pain/soreness)

Articular Cartilage

coats ends of each bone

Synovial Fluid

seperates bones (within synovial membrane)

Synovial membrane

contains synovial fluid; cracking joint caused by stetching of membrane causing air to escape

Synovial Joint Types

pivot, hinge, saddle, ball & socket, condyloid, plane/gliding

Hinge Joint

allows single-plane movement (open, close); elbow, knee, phalanges

Ball and Socket

allows a full 360 degree range of motion; shoulder, hip

Condylar/Condyloid

allows angular movement in 2 planes; radius & carpals; metalcarpals & phalanges

Saddle

allows angular AND circular movement in 2 planes; carpal & metalcarpal at base of thumb

Gliding/Plane

allows bones to slide across each other in multiple directions; carpals & carpals, tarsals & tarsals

Pivot

allows full rotation but in a single plane; atlas & axis (top of neck), radius & ulna

Knee Joint Anatomy

ligaments for stability and menisci (type of cartilage) for shock absorption