Skeletal System

Axial Division

Bones in longitudinal axis: skull, rib cage, vertebral column, pelvis

Appendicular Division

Bones of the limbs and girdles

Girdles

Ring of bone for attachments: shoulder and hip

Cartilage and Other tissue division

Cartilage, tendons, and ligaments

Three Divisions of the Skeletal System

Axial, Appendicular, Cartilage and Other tissues

Tendons

Connect bone to muscle

Ligaments

Connect bone to bone

Bones and Cartilage matrix

protein and ground substance

Classifications by Composition

Compact and Cancellous

Compact Bone

Dense; homogeneous throughout

Cancellous Bone

small, needle like pieces of bone; a lot of space in between (AKA spongy bone)

Type (shape and Size)

Long, short, flat, and irregular

Long Bone

Longer than wide; mostly compact

Long Bone example

bones of the limbs (except carpals, tarsals, and patella)

Short Bones

Cube-like; mostly cancellous

Short bones examples

carpals, tarsals, patella

Flat bones

Thin, sheet-like; mostly curved; cancellous sandwiched between 2 sheets of compact

Flat bones examples

ex: skullbone, ribs, sternum

Irregular bones

bones that do not fit into category 1-3

Irregular bones examples

vertebrae, pelvis

Skeletal System Function

1. Support

2. Protection

3. Movement

4. Storage

5. Hematopoesis

Skeletal System Storage

Yellow marrow stores fat, bones store calcium phosphate

Blood cells are produced in _______

red marrow

Medullary Cavity

found in diaphysis; contains yellow marrow (in babies contains red marrow)

Yellow marrow

fat cells; found in diaphysis

Red Marrow

blood forming; in babies located in diaphysis, in adults located in epiphysis

2 Membranes of the Bone

Periosteum and Endosteum

“peri”

around

“endo”

within

Periosteum

membrane covering outside of bone

Endosteum

membrane lining medullary cavity

Osteon

aka Haversion System; single bone cell

Haversian Canal

blood vessels/nerves run through

Lamellae

Concentric rings of bone

Lacunae

tiny spaces where osteocytes

Canaliculi

tiny canals that connect lamellae

3 types of bone cells

Osteoblast, osteocyte, osteoclast

Osteoblast

form bone cells

Osteocyte

mature bone cells

Osteoclasts

break down bone cells

2 Categories of Bone Markings

Projections and Depressions/Openings

2 categories of Projections

Muscle/Ligament Attachment and Forms a Joint

2 categories of Depressions/Openings

Passages for blood vessels/nerves and other

Muscle and Ligament Attachment Projections

1. Tuberosity

2. Crest

3. Process

4. Trochanter

5. Epichondyle

6. Tubercle

7. Spine

Projections that Form a Joint

Head, facet, and condyle

Openings that are passages for bv/nerves

Fissures, Foramens

Other Depressions

meatus, sinus, fossa

Tuberosity

large and rounded; may have a rough surface which allows for better attachment/ grip for muscles and ligaments

Tuberosity examples

Ischial tuberosity (on pelvis) and medical malleolus (tibia) + lateral malleolus (fibula)

Crest

Narrow, bony ridge; usually prominent

Crest example

iliac crest, brow ridges

Process

Any prominence that “juts out”

Process examples

Styloid process (inferior skull), spinous process (posterior) and transverse process (vertebrae)

Trochanter

Only found in the femur; Irregular shape with a blunt end

Tubercle

smaller tuberosity; small and rounded

Tubercle example

Abductor tubercle; greater/lesser tubercle of the humerus

Spine

Sharp, slender piece of bone

Spine example

ischial spine; scapular spine

Epichondyle

above chondyle, raised area for muscle attachment

Epichondyle example

medial epichondyle of femur

Head

wider, expanded part of the top of the bone, carried on a narrow neck

Facet

Smooth, nearly flat surface, serves as an articulation point

Facet example

facet of inferior articular process (vertebrae)

Condlye

Rounded area where 2 bones come together

Condyle example

mandible connects to maxilla

Fissure

Narrow, slit-like opening

Fissure example

Orbital fissure

Foramen

Round, oval opening

Foramen example

Foramen magnum

Meatus

Canal or tunnel through bone

Meatus example

external auditory meatus

Sinus

Air filled cavity lined with mucous membrane

Mucous membrane

produced by goblet cells

4 sinus cavities

frontal, ethmoidal, sphenordal, and maxillary

Sinus Cavity functions

make the skull lighter and act as resonating chambers for sound

Fossa

Shallow indentation in bone that serves as an articulation surface

Fossa Example

mandibular fossa (mandible (condyle) articulates with maxilla)

Comminuted Fracture

Bone breaks into large fragments (at least 3) often seen in people with osteoporosis

Osteoporosis

bone loses calcium and becomes brittle

Compression

Occur in vertebrae (anteriorly)

Depression Fracture

Bones break inwards, often seen in the skull

Impacted/ buckle fracture

ends of two bones are forced into each other or bone breaks in the middle and pieces are forced into each other

Typically occurs when trying to break a fall

Spiral Fracture

Occurs when there is a twisting motion applied; jagged edges; typically seen in sports injuries

Greenstick Fracture

Bone breaks incompletely (like a live branch); most often seen in children because their bones are still flexible + made from cartilage models

Transverse Fractures

Bone breaks evenly across

Longitudinal

Bone breaks lengthwise

Segmented

Bone breaks in at least two pieces creating bone segments

2 classifications of fractures

Closed and Open

Closed Fracture

aka simple fracture; bone does NOT break the skin

Open fracture

aka compound fracture; bone DOES break the skin; 2 tissues are broken (bone and skin)

How do we fix it?

1. Take an x-ray

2. If bone is misaligned, Dr. manipulates it back into place

3. severe break or compound fracture, may require surgery and require pins, slates, or screws

Bone Repair step 1

Bone Breaks

Bone repair step 2

Vessels break and bleed

Bone Repair Step 3

Hematoma forms (clot) and bone cells start to die

Bone Repair Step 4

Fibroblasts (make collagen) enter the clot and form new tissue (fibrocartilage callus)

Bone Repair Step 5

Osteoclasts remove dead and damaged bone cells then osteoblasts enter and deposit new bone (bony callus)

Bone repair step 6

Bone remodeling takes several weeks to be complete

Three Considerations of Bone Repair

1. Keep the area immobilized

2. 4-6 weeks typically for bone to heal

3. Area of break is stronger than adjacent areas

Why is area of bone stronger than adjacent areas?

• “Zone” is made up of new bone

• While healing, new mechanical stresses develop (from immobilization) and new bone gets remodeled to those stresses

Joint definition

A place where 2 bones come together