ANP Bones Notes

Superior

Above

Inferior

Below

Lateral

Away from the Midline

Medial

Toward the midline

Proximal

Towards the body (Refers to arms and legs)

Distal

Away from the body (Refers to arms and legs) 

Anterior

Front

Posterior

Back

Fossa

Shallow Indent

Foramen

A hole that nerve Travels through

Crest

A sharp Ridge of Bone

Tuberosity/Tubercle

• A Bulge of bone that attaches to ligaments/tendons 

Notch

A small indent in the bone

Condyle

The ends of a joint that meets with another bone

Epicondyle

A small bump (Epi = above)

Process

A bar of bone that extends from the main bone

Spine

A sharp point of bone

Facet

Flat surface on the bone that articulates with another

Ligaments

They hold bones to other bones

Tendons

They hold bones to muscles

How many ribs do humans have

Humans have 24 ribs total, with 12 on each side of the body.

True Ribs

(1–7) Connect directly to the sternum.

false ribs

(8–10)  Connect indirectly to the sternum via costal cartilage of rib 7.

Floating ribs

(11–12) Floating ribs that are not connected to the sternum at all.

Cervical Vertebrae

All have a transverse foramen. C3–C6 have a bifurcated spinous process.

Thoracic Vertebrae

Connect to ribs; have costal facets on transverse processes and superior/inferior demi facets on the body.

Lumbar Vertebrae

Physically larger and thicker, with broad spinous processes and no transverse foramen or costal/demi facets.

Bones classified by shape

How are Bones categorized

Long bones

Examples: Femur, humerus.

Short bones

Examples: Carpals, tarsals.

Flat bones

Examples: Parietal, frontal, ribs, sternum.

Irregular bones

Bones with multiple shapes, e.g., vertebrae and os coxa.

Sesamoid bones

Shaped like sesame seeds; patella is the largest.

Axial skeleton

Includes skull, hyoid, ribs, sternum, and vertebrae.

Appendicular skeleton

Includes shoulders, scapula/clavicle, arms/hands, os coxa, legs/feet.

Osteoprogenitor cells

Stem cells that give rise to osteoblasts.

Osteoblasts

Immature bone cells that give rise to osteocytes.

Osteocytes

Mature bone cells in lacuna; maintain calcium matrix.

Osteoclasts

Bone cells from red bone marrow that break down bone.

Recap bone cells process

Osteoprogenitor → Osteoblasts → Osteocytes.
Red marrow stem cells → Osteoclasts.

Open fracture

Bone has broken through the skin.

Compound fracture

Bone is broken cleanly in two.

Open compound fracture

Bone broken in two and pierced through the skin.

Greenstick fracture

Bone is partially broken; fragments still connect both sides.

Pott fracture

Broken ankle (medial or lateral malleolus).

Colles fracture

Broken wrist at distal end of radius/ulna.

Impact fracture

The proximal end of the bone is driven into the medullary cavity of the distal end.

Comminuted fracture

Bone splinters into fragments that must be removed.

Spiral fracture

Bone twists and breaks in corkscrew pattern.

Break process: hematoma

• Thrombin activates fibrinogen to become fibrin 

Break process: soft callus

Soft callus forms (chondrocytes make collagen), osteoblasts build bone (osteocytes form matrix), bony callus forms, then osteoclasts remodel and smooth it.

.Break process: bony callus

Osteoblasts form osteocytes → bone matrix → overproduce bony callus

Break process: remodeling

Osteoclasts smooth and reshape the healed bone.

Hox clusters

Four clusters (A, B, C, D), each with 13 genes, dictate the embryo’s body plan.

Bones is as life goes on

• During Embryogenesis, the Baby has a mostly cartilage skeleton. As the baby grows, the cartilage is slowly replaced with calcified bone. Through childhood the skeleton becomes more calcified, until adulthood where the epiphyseal plate transitions into the epiphyseal plate transitions into the epiphyseal line. 

Epiphyseal plate

This is a collection of cartilage at the ends of bones, allowing the bones to grow in length. The types of cartilage are resting, hypertrophic, and proliferating.

Skull at birth

Bones are not fused, allowing childbirth and brain development.

Cartilage with age

By age 12–13, only the epiphyseal plate remains.

Fusion age

Epiphyseal plate fuses into epiphyseal line by age 21.

Resting cartilage

Stem cells that replenish proliferating cartilage.

Proliferating cartilage

Cells rapidly going through mitosis.

Hypertrophic cartilage

Cartilage transitioning into calcified bone.

Bone growth

Bones grow in length and girth.

Length growth

In the zone of proliferating cartilage, chondrocytes divide rapidly, adding new layers. The zone of hypertrophic cartilage then transitions into calcified bone. With each new layer formed, the bone gradually increases in length.

Girth growth

Endosteum broken down by osteoclasts; periosteum built up by osteoblasts.

Spongy bone

Load-bearing structure that distributes weight over larger surface area.

Trabeculae

Crossing bars of spongy bone; gaps filled with red bone marrow.

Compact bone

Withstands impact and protects organs.

Osteons

Repeating units of compact bone; contain haversian canal, canaliculi rings, and lacuna housing osteocytes.

Red bone marrow

Contains stem cells for erythrocytes, leukocytes, lymphocytes, and megakaryocytes (produce platelets).

Osteocytes do what

regulate bone formation and resorption

Yellow bone marrow

Found in medullary cavity of long bones; stores lipids.

Functions of skeletal system

Storage of calcium, support, movement, protection, and blood cell formation.

Homeostasis

Healthy/normal body conditions regulated by endocrine and nervous systems.

High blood calcium

The thyroid gland will produce calcitonin whicThe thyroid gland will produce calcitonin which activates osteoblast to build bone. Calcium goes from the blood to the bones. 

Low blood calcium

the parathyroid makes parathyroid hormones (PTH) which activates osteoclasts to break down bone. Calcium goes from the bones to the blood. 

Vitamin D

Fat-soluble vitamin derived from cholesterol via sunlight. Required for calcium incorporation into bone matrix.

Rickets

Condition caused by vitamin D deficiency. bones become flexible, and many times the femurs and tibia bend due to standing pressure. 

Osteoporosis

Dietary disorder from chronic calcium deficiency; reversible with calcium supplements.

Osteogenesis imperfecta

Rare genetic disorder affecting collagen; bones harden poorly and are brittle like chalk.

Rickets

Childhood vitamin D deficiency; bones become flexible, femurs/tibia may bend under pressure.

Cells in the body

Each cell type has unique functions/structures. All contain the genome, but only some genes are expressed.

Stem cells

Undifferentiated cells not yet fated to a type.

Totipotent stem cells

Can become any embryonic cell plus extraembryonic (placenta/umbilical cord). Fate depends on 3D orientation.

Pluripotent stem cells

Can become any embryonic cell, but not extraembryonic cells.

Multipotent stem cells

Adult stem cells (in red bone marrow); can become erythrocytes, leukocytes, lymphocytes, or megakaryocytes (platelets).

Ghost organs

Organs washed of genetic material; repopulated with patient’s adult stem cells to regrow immune-compatible organs.

1st-degree burn

Skin is red, painful, and swollen.

2nd-degree burn

Skin shows blisters, red, swollen, and painful.

3rd-degree burn

Dermal layer destroyed, including free nerve endings for pain/temp.

4th-degree burn

Burns into the hypodermal adipocyte layer.

5th-degree burn

Burns down to the muscle layer.

6th-degree burn

Burns to the bone; often fatal.

Burn patients

Main risks: dehydration and infection (skin normally prevents water loss and antigen entry).

Skin graft rejection

• Skin grafts are rejected due to donor cells holding out donor proteins on MHC1, and the T-cell not recognizing that protein as “self”. This causes the T-cell to send out cytotoxins that kill the donor cell. 

Immunosuppressive drugs

Taken 6 months to 1 year to prevent graft rejection.

UV light damage

Causes thymine dimers and DNA strand breaks.

Thymine dimers

Two thymines form a covalent bond; corrected by exonuclease and endonuclease enzymes.

Strand breaks

Break sugar-phosphate backbone of DNA; repaired by enzymes.