Anatomy Unit 4 - Skeletal System

4 Types of Bones

Long bones, Short bones, Flat bones, Irregular bones

Long bones

• Greater in length than width

• Slightly curved

• Majority is compact bone (very hard)

Examples of Long Bones

Humorous, Radius, Ulna, Femur, Tibia, Fibula

Short Bones

• Typically cube-ish

• Equal in length and with

Examples of short bones

Carpals and tarsals

Flat bones

• Typically thin

• 2 flat plates of compact bone and spongy bone in the middle (Think of a bone sandwich)

Examples of flat bones

Ishcium

Irregular Bones

Complex/unique shape

Examples of irregular bones

Mandible, vertebrae, ischium

Axial Skeleton

• Made up of 80 bones

• Includes skull, vertebrae, and everything directly attached to it

Purpose of the skull

Protection for the brain

Sinuses

Holes in the skull

Mandible

Only movable bone in the skull

Sutures

Immovable joints between parts of the skull

Fontanels

Soft spots in the skull, in babies

Cranium

8 bones in this part of the skull

Frontal bones

Forehead, 1 of 3 strongest bones of the bone

3 Smallest Bones in the body

1. Incus

2. Malleus

3. Stapes

Foramen Magnum

Hole that spinal cord passes through

Amount of vertebrae in an adult

26

Function of vertebrae

Protection of the spinal cord, provided support and flexibility

Invertebral Disks

Cartilage in between the vertebrae

Scoliosis

Vertebral column is rotates, spine is curved

Lordosis

Lumbar vertebrae is tilted forward

Kyphosis

Hunchback, commonly in thoracic or cervical

Sternum

Chest bone that protects your heart, arguably one of the strongest bones in the body

Costals

Pprotect your lungs, heart, liver, and other internal organs

Costal cartilage

Connects your ribs to the sternum, makes it flexible

True ribs

1st set, directly connected to the sternum

False ribs

Share a cartilage, do not connect to the sternum

Floating Ribs

(11&12), They have no cartilage. Protects your adrenal gland (that sit on top of kidney)

Appendicular Skeleton

Made up of 126 bones - Appendages

Differences between male and female skeletons

• Females have a wider pelvis while males have a taller pelvis

• Males have more bone density because they’re heavier

• Males have thicker joints

• Male hyoid bone is more pronounced because of the larynx

• In the a female, the coccyx is more straight and on the male it’s more curved

• Pelvic area is more curved in female and heart-shaped in males

Osteology

Study of bones

Why are bones lightweight

They’re full of bone marrow

6 Functions of Bone

Support, movement, protection, red blood cells production, energy storage, mineral homeostasis

Parts of a long bone

• Metaphysis/Epiphyseal Disk/Line/Plate/Growth Plate

• Epiphysis

• Articular cartilage

• Medullary cavity

• Periosteum

Epiphyseal Disk

Where long bone growth takes place, also known as:

• Metaphysis

• Epiphyseal Line

• Epiphyseal Plate

• Growth Plate

Epiphysis

End of the long bone, consists of spongy bone

Articular Cartilage

Good shock absorber, lines the surface of joints in long bones

Medullary cavity

Middle of the long bone, filled with yellow bone marrow

Periosteum

Skin/outer covering of long bones, where the bone grows in width

Fibrous layer of the periosteum

Outer layer, very dense, irregular connective tissue, nerves located here

Osteogenic layer of the periosteum

Next to the actual bone tissue

What are bones made of?

25% Water, 25% Protein, Minerals, Collagen

Crystalization

Process where minerals in the bones harden

Ossification

Formation of a bone

Intramembranous Ossification

In babies, bone forms from within the bone and spreads out across already laid down cartilage. The bones grow together and create a suture

Endochondral Ossification

Bone grows into growth plates, hyaline cartilage set out

Interstitial growth

When bones grow in length

Appositional growth

When bones grow in thickness

Types of bone cells

Osteoprogenitors, Osteoblasts, Osteocytes, Osteoclasts

Osteoprogenitors

• First/Stem cells of bones

• Undergo mitosis

• On the surface of bone, right under the skin

Osteoblasts

• Cells that actually form bone material

• Secrete collagen, proteins, mineral salts

• Isolate themselves (Paint themselves into a corner)

• Lost the ability of mitosis

Osteocytes

• Come from osteoblasts

• Also cannot perform mitosis

• Can perform all other cell functions

Osteoclasts

• Destroy bone tissue

• Resorption

• Important for bone damage, when bone tissue gets damaged it needs to be discarded

Types of bone tissue

Compact bone, spongy bone

Compact bone

• Hard stuff

• Effective for support and protection

• Located in mostly the diaphysis and outside epiphysis

Spongy bone

• Found in epiphysis of long bones and middle/center of flat bones

• Filled with red bone marrow that make red blood cells

Long Bone Growth

• Hyaline

• Growth Plates:

1. Zone of resting cartilage (conder means cartilage)

• Condersytes - Cartilage cells

2. Zone of proliferation cartilage

3. Zone of hypertrophic/maturing cartilage

4. Zone of calcified cartilage (Hardening)

• Can also be called crystallization or mineralification

• Only place where long bone growth takes place

• Clavicles

Examples of minerals in bone

• Tricalcium phosphate

• Calcium carbonate aka Limestone

• Magnesium hydroxide

Haversian system

• 50% mineral salts

• Gets nutrients through the central canal

Concentric lamella

• Layers of crystallized bone around compact bone that share the same center point

Lacunae

Little spaces inside of the concentric lamella

Canaliculi

(blood vessels) transport nutrients

Central Canal

Main vessel blood vessel travels through bone

Wolff’s Law

A bone grows or remodels in repose to the forces or demands placed upon it

Types of bone fractures

• Nondisplaced Fracture

• Displaced Fracture

• Complete

• Incomplete

• Linear

• Transverse

• Compound (open)

• Simple (closed)

Common Types of Bone Fractures

• Comminuted - Bone fragments, (Community - comminuted)

• Spiral - Ragged break when bone is excessively twisted

• Depressed - Broken bone portion presses inward

• Compression - Bone is crushed

• Stress Fracture - Microfracture

Stages in Healing a Bone Fracture

1. Hematoma Formation

• Torn blood vessels hemorrhage which causes bone cells to rush and cause bruising

2. Formation of the Callus

3. Bony Callus formation

4. Bone remodeling

   1. Aids wolf's law, bone grows thicker as it responds to stress