Long Bone Anatomy Diaphysis: Shaft of the bone – Made of compact bone Epiphysis: Ends of the bone – Made mostly of spongy bone – There is a little compact.

Long Bone Anatomy

Diaphysis: Shaft of the bone– Made of compact bone

Epiphysis: Ends of the bone– Made mostly of spongy bone– There is a little compact bone on the outer surface

Articular Cartilage: cap of hyaline cartilage on each epiphysis which articulates with the next bone

Medullary canal: contains fat Periosteum: thin layer like an onion-skin that wraps around the bone. It is

anchored to the bone by fibers called Sharpie’s fibers. Nutrient foramen is in the shaft to allow passage for nutrient artery to the

bone.

Long Bones Contain Spongy and Compact Bone.

Compact Bone Anatomy

Compact bone is organized into cylinders called osteons.

The functional unit of compact bone is the osteon. It is the functional unit because all of the osteon’s functions occur within the osteon.

Compact Bone

Osteon (cylinders)

Osteon Anatomy

Osteoblasts are immature bone cells. They first arrive through the nutrient artery in the embryo

bone when it is still made out of cartilage. Osteoblast cells are shaped like stars. They align

themselves in concentric circles, as though they are holding hands. One ring of osteoblasts form a large circle, then the next ring inside is smaller, with a smaller ring inside that, and so on. The rings they form are called lamellae (from the word “laminate”, which means to lay on top of something. The rings lay on top of each other).

Compact Bone Lamella (rings)

Osteoblasts mature into osteocytes

The osteoblasts start to secrete hydroxyapatite (calcium and phosphate, which is bone) outside of themselves.

When they do this, they become trapped in the cave that they have made out of bone.

They are now called osteocytes (mature bone cell).

They cave they are trapped in is called a lacunae.

Compact Bone

Osteocytes (mature bone cells) trapped

in their lacunae (caves)

Osteon Anatomy

Each osteocyte is star shaped, so they seem to have arms and legs. These appendages also are trapped in the bone cave, so they form little canals.

These canals that hold their arms and legs are called canaliculi (little canals).

Canaliculi are needed to allow for diffusion of nutrients and wastes between the osteoblasts.

Canaliculi (little canals) hold the arms and legs of the osteocytes

Osteon Blood Supply

The nutrient artery, which entered the shaft of the bone, branches out and one branch runs through the center of each osteon.

The canal in the center of each osteon which contains the artery is called the Haversian canal, or central canal.

The blood supply needs to connect to the adjacent osteons, so there is a transverse canal, called Volkmann’s canal, or the perforating canal.

Haversian (central) canal

Volkmann’s (perforating) canal

Spongy Bone: Epiphysis

Instead of osteons, spongy bone has trabeculae (open spongy network which allows blood vessels to pass)

Bone Cells

Osteoblast (makes bone) Osteocyte (mature bone cell) Osteoclast (reabsorbs bone)

Tendons and Ligaments

Tendons attach muscle to bone. Tendons are not muscle tissue; they are connective tissue.

Ligaments attach bone to bone. Tendons and ligaments are both made from dense

regular connective tissue. An aponeurosis is a modified tendon that flares out

and attaches into connective tissue instead of bone. There is one that attaches the frontalis muscle (raises eyebrows) to the skull. Another one is in the palm of the hand.

Tendon: dense reg. CT

Terms to Know

Osteon: functional unit of compact bone. hydroxyapatite The crystalline structure of calcium and phosphate

that make up bone matrix lamellae The circular and concentric layers of collagen fibers lacunae The pockets or cavities in which the cells are trapped Haversian (or central) canal The large channels containing a blood

vessel which run longitudinally down the center of each unit canaliculi The “tiny channels” which run transversely through the

layers of bone and allow for diffusion of nutrients and wastes to the cells

perforating canal: connects one Haversian canal to another osteocytes The mature bone cells which are trapped in the matrix and

help to maintain it Osteoblasts: bone cells that lay down new bone Osteoclasts: bone cells that reabsorb bone

Terms to Know

Periosteum (secured to the bone by Sharpey’s fibers) Sharpey’s fibers (anchor the outer wrapping to the bony

matrix below it) Articular Cartilage (cap around long bone) Epiphysis (ends of long bones) Diaphysis (shaft of long bone) Medullary Cavity (hollow area inside long bone) Spongy Bone (contains trabeculae instead of osteons and

lamellae) Trabeculae (web-like formation, like a sponge) Tendon (attaches muscle to bone) Ligament (attaches bone-to-bone) Aponeurosis (modified tendon)

Cartilage and Bone

Structure and Function

Bone Characteristics

Vascular (has own blood supply) Regenerates well (because it is vascular) Contains hydroxyapatite (calcium and

phosphate) Forms mostly after birth Is not flexible

Formation of Endochondral (Embryonic) Bone

In the embryo, hyaline cartilage develops in the general shape of the future bone.

Periosteum forms on the outside of the developing bone.

Osteoblasts enter through the nutrient artery and deposit bony tissue in place of disintegrating cartilage.

Two Centers of Ossification

Primary Ossification– Starts in diaphysis; turns cartilage into bone.– Then the medullary canal hollows out

Secondary Ossification– Starts in epiphysis; turns cartilage into bone– It leaves behind a growth plate (epiphyseal line)

to allow the child’s bone to grow

Types of Bones

Long Bones– Arms and legs

Sesamoid Bones– Develop inside tendons and near joints

Flat Bones– Skull bones and scapula

Irregular Bones– Vertebrae

Cartilage

What are the three types of cartilage and where in the body can each of these three types of cartilage be found?– Hyaline cartilage (most of the joints)– Fibrocartilage (vertebral discs, pubic symphysis)– Elastic cartilage (ears)

What type of cartilage does an embryonic skeleton have?– Hyaline

Cartilage Characteristics

Avascular (no blood supply) Does not regenerate well (because it is

avascular) Contains no calcium Begins conversion to bone before birth Is flexible

Joint Disorders and Joint Injuries

Structure of joints makes them prone to traumatic stress Function of joints makes them subject to friction and wear Affected by inflammatory and degenerative processes Sprains – ligaments reinforcing a joint are stretched or torn Dislocation – occurs when the bones of a joint are forced

out of alignment Torn cartilage – common injury to meniscus of knee joint

Inflammatory and Degenerative Conditions

Bursitis – inflammation of a bursa due to injury or friction Tendonitis – inflammation of a tendon sheath Arthritis – describes over 100 kinds of joint-damaging

diseases– Osteoarthritis – most common type – “wear and tear” arthritis– Rheumatoid arthritis – a chronic inflammatory disorder – Gouty arthritis (gout) – uric acid build-up causes pain in joints

Lyme disease – inflammatory disease often resulting in joint pain; Lyme disease is caused by a bacterium and is transmitted to humans by the bite of infected blacklegged ticks. Typical symptoms include fever, headache, fatigue, and skin rash. If left untreated, infection can spread to joints, the heart, and the nervous system.

Osteoporosis: loss of minerals

Figure 6.15

Normal Bone

Osteoporosis

Stages of Healing a Fracture

Figure 6.14

Blood escapes

Fibrous callous

Spongy Bone callous

Osteoclasts remove excess bone

Four Stages of Fracture Repair

Fractures

CLASSIFICATION OF FRACTURES

CLOSED– Skin is not broken– Requires cast

OPEN– Bone has broken through the skin– Increased chance of infections, which can be life-

threatening.– Requires surgery, hospitalization and IV

antibiotics

CLASSIFICATION OF FRACTURES

INCOMPLETE– Only one side of the bone is broken

Examples– Hairline (stress) fracture– Greenstick fracture

COMPLETE– Both sides of bone is broken

CLASSIFICATION OF FRACTURES

Once you have described if the fracture is open or closed, and complete or incomplete, then you describe the fracture shape:

• Stress (hairline) fracture

• Greenstick fracture

• Epiphyseal fracture

• Transverse fracture

• Oblique fracture

• Spiral fracture

• Comminuted fracture

• Avulsion fracture

• Impacted fracture

• Compression fracture

• Depression fracture

Types of Fractures

http://video.about.com/orthopedics/Fractures-1.htm

http://video.about.com/orthopedics/Fractures-2.htm

STRESS FRACTURE

STRESS FRACTURE: least serious, get tiny, almost invisible breaks. Usually from overexertion. Muscle builds up faster than bone. Six weeks into military basic training camp, see lots of stress fractures from too much new running.

Can’t see it on x-ray for three weeks. Diagnose it by placing a tuning fork on the bone, but not at the area of tenderness…the vibration travels down the shaft of the bone until it reaches the fracture site. This will be very painful if it is a stress fracture.

Stress Fracture, 3 weeks later

GREENSTICK FRACTURE

GREENSTICK FRACTURE: most common in children; like breaking a green twig, it’s not completely broken. It breaks on one side but bends on the other. Bones in children are not fully mineralized.

Table 6.1

Epiphyseal Fracture

EPIPHYSEAL FRACTURE The growth plate in the bone of a child is called the

epiphyseal growth plate. That area is weaker than bone, so the whole thing can be broken through during an injury.

It is very serious because the bone may grow crooked thereafter. May need repeated surgeries to straighten the bone as it grows.

TRANSVERSE FRACTURE•Bone breaks completely through, right to left, in the transverse plane

OBLIQUE FRACTURE•Bone breaks completely through, from upper to lower, in an oblique plane

SPIRAL FRACTURE: Bone was twisted, such as in skiing or rollerblading.

COMMINUTED: The most serious; bone shatters into many small pieces. Bone graft might be needed.

AVULSION FRACTURE

– A piece of bone is broken off by the sudden, strong contraction of muscle.

– Common sports injury– Often seen with “groin muscle injury”

Avulsion Fracture

The person twisted their ankle and a tendon pulled off a piece of the bone.

IMPACTED FRACTURE

IMPACTED FRACTURE:

Pressure was exerted on both ends of the SAME bone.

The bone is crushed

Often seen in femur after falling from a height.

Impacted fracture of the

femur• The person fell

from a height, and the head of the femur jammed into the neck of the femur.

COMPRESSION FRACTURE

COMPRESSION FRACTURE

TWO bones are forced together

Bone is crushed.

Example would be two vertebrae being crushed together from a fall from a height.

People with osteoporosis (loss of bone minerals) often get this type of fracture spontaneously.

Table 6.1

DEPRESSION FRACTURE

DEPRESSION FRACTURE

Bone is pressed inward

Often seen in skull fracture from blunt object

Depression Fracture

PATHOLOGICAL FRACTURES

PATHOLOGICAL FRACTURE:

When the bone breaks first, then the patient falls. This is especially common in the hip bone of someone with osteoporosis.

ARTHRITIS

OSTEOARTHRITIS RHEUMATOID ARTHRITIS GOUTY ARTHRITIS (GOUT)

OSTEOARTHRITIS

• OSTEOARTHRITIS: more common the older you get.

• The articular cartilage begins to break down, and bone spurs start to grow. The surface is no longer smooth, and movement now causes pain.

• It is also known as “wear and tear” arthritis. • This is the most common disorder of joints. • Can be mild to severe, needing joint replacement.

These people can actually predict the weather, since the synovial fluid is under pressure. As air pressure changes, fluid expands and hurts more.

Artificial Hip Joint

RHEUMATOID ARTHRITIS

RHEUMATOID ARTHRITIS: not a disease of old age. It’s an autoimmune disease where body attacks and destroys the cartilage in synovial joints. It is not known for spur formation, unlike osteoarthritis.

They swell and become unusable, causing knarled hands and feet. Usually need joint replacements, but that will only last about 15 years. First replacement in 60 years old is ok, but in a 30 year old, eventually bone degrades and can no longer take the stem of the implant.

It does NOT make many bone spurs; it is degenerative in nature.

Rheumatoid Arthritis

GOUTY ARTHRITIS (GOUT)

Gout is caused by a genetic error in the metabolism of uric acid. An gouty episode is triggered by eating too much red meat or protein.

The breakdown product of proteins is urea, which leads to uric acid crystals in the cooler areas of the body, especially the MPJ’s (metatarsal-phalangeal joints) of the base of the big toes. The crystals poke the cartilage like needles.

Gout is not known for spur formation, unlike osteoarthritisWas more common years ago when people ate nothing but

meat. The crystals cause the joint to swell up.

OTHER BONE DISORDERS

• Osteomalacia (“malformed bones”) is a genetic malformation of the bones. The epiphyseal plates are particularly affected.

• Rickets is a type of osteomalacia that is NOT genetic; it is caused by lack of vitamin D. Like all types of osteomalacia, rickets also particularly affect the epiphyseal plates.

OTHER BONE DISORDERS

Osteomalacia (genetic) Rickets (not genetic)

OTHER BONE DISORDERS

Osteomyelitis is an infection of bone.

OTHER BONE DISORDERS

•Achondroplasia is a genetic condition where the bones don’t develop properly, especially in the epiphyseal plates, and causes a type of dwarfism.

CHONDROMALACIA

•Means a problem with the shape of a cartilage joint.•Chondromalacia patella is a condition in which the patella rubs on the femur in the knee joint, becomes scratched or deformed, causing pain. Don’t get this confused with achondroplasia, which is dwarfism!

OTHER BONE DISORDERS

Paget’s disease is more common in older persons, and may be related to a viral infection. It is characterized by excessive bone deposition.

Paget’s disease

OTHER BONE DISORDERS•ANKYLOSING SPONDYLITIS: is a disorder in which vertebrae bind strongly together to limit the flexibility of the spine.

OTHER JOINT DISORDERS

Synovitis is inflammation of the synovial tissues. May need cortisone injections.

Arthroplasty is a surgical procedure to repair or remodel a damaged joint.

Lyme disease is an inflammatory arthritis of the knee joint, caused from a bacterial infection after a tic bite.

Polydactyly (Many digits)

• The extra digit is usually a small piece of soft tissue; occasionally it contains bone without joints; rarely it may be a complete, functioning digit.

• The extra digit is most common on the ulnar (little finger) side of the hand, less common on the radial (thumb) side, and very rarely within the middle three digits.

• These are respectively known as postaxial (little finger), preaxial (thumb), and central (ring, middle, index fingers) polydactyly.

• Polydactyly can occur by itself as an autosomal dominant mutation in a single gene.

• But, it usually is one feature of a syndrome of congenital anomalies.

• 1 in every 500 live births

Polydactyly (Many digits)

Polydactyly (Many digits)

Born with two thumbs!

Syndactyly (Fused digits)

In fetal development, syndactyly is normal. At about 16 weeks of gestation, an enzyme dissolves

the tissue between the fingers and toes, and the webbing disappears.

In some fetuses, this process does not occur completely between all fingers or toes and some residual webbing remains.

Simple syndactyly can be full or partial, and is present at birth (congenital).

Syndactyly (Fused digits)

Due to an abnormal gene.

Syndactyly can be simple or complex.– In simple syndactyly, adjacent fingers or toes are joined by soft

tissue.– In complex syndactyly, the bones are fused.

Syndactyly can be complete or incomplete.– In complete syndactyly, the skin is joined all the way to the tip of

the finger– In incomplete syndactyly, the skin is only joined part of the

distance to the fingertip.

Syndactyly (Fused digits)

Syndactyly (Fused digits)

• Complex syndactyly occurs as part of a syndrome (such as Apert's syndrome) and typically involves more digits.

• Apert Syndrome is syndactyly with malformations of the skull.

Apert syndrome

Syndactyly (Fused digits)

Fenestrated syndactyly means the skin is joined for most of the digit but in a proximal area there is gap in the syndactyly with normal skin.

This type of syndactyly is found in amniotic band syndrome.

Amniotic band syndrome Congenital disorder caused by entrapment of

fetal parts (usually a limb or digits) in fibrous amniotic bands while in utero.

Polysyndactyly

End of Lecture

The rest of this PPT is not on the exam

There is a disc between each bone in the spine.The nerves exit the bone to supply

all the parts of the body.

If you choke off a nerve by twisting the bone around it, the bone starts to crush the nerve.

Just like a light with a dimmer switch; if you turn the electrical current down,

the light won’t shine as brightly. If you cut off some of the nerve supply to an organ,

the organ isn’t going to function as well.

The discs are made out of something like jelly. As long as your spine is aligned, the jelly will stay in the center.

But if the spine becomes twisted, the jelly will get pushed in the opposite direction, and the shock absorption will be lost.

If you lift a box while you are standing and twisting,

that’s when you get tears in the disc.

TEARS IN THE DISC

The fluid in the disc begins to leak out the side of the disc.

OsteoarthritisAlso Known As:

“Wear and Tear” ArthritisOr Degenerative Arthritis

Occurs when cartilage wears away, leaving raw bone to rub against raw bone.

PROPER DESK WORK STATION

Phone headset for hands-free use

Keyboard pad under your wrists

Computer at eye leveland 18-25” away from your face

The front of the chair should drop off

Adjustable seat: Feet flat to the floorOr a foot rest under the feet

Chair with good lumbar support or$10 lumbar pillow