Category Archives: The Skeletal System

Lecture 27 – Bones – Lower Extremities – Femur, Tibia, and Fibula


Femur – Larger and heavier than other bones.  Proximally, there is a greater and a lesser trochanter.  (Muscles attach to the greater trochanter.)

Distally, you will find the lateral and medial epicondyles.  The neck of the femur is the most frequent and common site of fracture, especially in older people.  The patella, kneecap is between the condyles.  The patella is sesamoid, or shaped like a sesame seed.  The tendon of the quad surrounds the patella.  In other words, the patella is housed in the tendon of quadricepts femoris.  Its job is to stabilize the knee joint.

The epiphyseal plate is where bones grow.  This bone growth ceases by age 21.  X-rays can assist in identifying age.

The tibia is the weight bearing bone of the lower extremity (medial).  It is triangular shaped.  You can feel the apex of the triangle of the tibia through the skin.  There is no muscle on it.  It is only covered with periosteum, that is filled with nerve fibers.  Do you remember the mischievous children who would kick someone in the shins?  Ouch!

The tibia articulates on the proximal end with the femur and the fibula.  The tibia articulates distally with the ankle bone (talus) and fibula.  The fibula is thin and slender.  (I have shared the silly joke before.  We once had a childcare provider named Fibiola.  She loved my youngest child and held him for hours.  She spoke Portuguese and we did not.  It was hilarious.  She was adorable and came highly recommended by her English-speaking relatives.  We just smiled, drew pictures, and spoke body language.  Needless to say, I will never forget her.  The point is, she was tall and thin, like the fibula.)  Use any mental picture you can use to honestly pass the test.

The protrusion, or medial aspect of the distal tibia, which is the medial malleolus, or hammer.

To Review:

Fibula – long, thin and lateral – not weight bearing, muscle attachments, only.

Proximal articulation – tibia; distally it articulates with the talus.

The lateral malleolus is usually larger and is part of the leg.  Many people think it is part of the ankle.

Tarsal bones (7) true ankle bones

2 largest –        calcaneus – heel bone- the Achilles tendon attaches to it

talus

Metatarsals – sole of the foot – 5

1st is the largest and is weight bearing

The 5th is frequently fractured – the dancer’s fracture – 5th metatarsal

Phalanges – Big toe has 2, just like the thumb.  All others have three.

We should be able to cover my final thoughts on bones in two more sessions.  We will make some brief comments of joints, cartilage, and bone formation.  As promised, we will do an extensive survey of blood before going on to some popular muscles.  Do well with this information.

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Lecture 26 – Skeletal System – Pelvic Girdle


I have one final thought about the ulna.  Distally, we find the styloid process for the wrist bones.  (Also called carpal bones; remember, the carpals can carry. This is alliteration from elementary English class.)

The carpus consists of 2 rows of 4 bones in each row.

Metacarpals – Palm – 5 bones.  The heads of the metacarpals are called knuckles.

Phalanges – 3 in fingers and 2 in each thumb.

Pelvic girdle – Pelvis means “basin” and basins carry objects!  This is a simple concept.  The pelvis consists of 3 bones, the ilium, the ischium, and the pubic bone.  All come together at the acetabulum, which means vinegar cup.  The vinegar cup or acetabulum receives the head of the femur.

Ilium

The anterior iliac spine is important for attaching ligaments.

The sacroiliac joint sometimes loosens with age and can produce intense pain.

The ischium is posterior and inferior.  We sit on our ischial tuberosities.  The obturator foramen receives blood vessels and nerves.  The outer part of the foramen is covered with connective tissue.

The pubic bone is the most anterior pelvic bone.  The two pubic bones meet in the middle at the pubic symphysis.  Symphysis means together.  (Think about a musical symphony where many instruments are played together to provide one beautiful sound.  I am sure that you recall my method for learning, which is to utilize any honest techniques to assist your memory.)  Fibrocartilage is located at the pubic symphysis.  This joint loosens during childbirth to allow for the passage of the baby.  Sometimes expectant mothers experience wobbly hips late in the pregnancy, thereby needing to rise from a sitting position slowly.  Sometimes women experience pain at this joint during pregnancy.  The body is highly capable of carrying out its natural functions.

The loosening of the pubic symphysis accounts for one of the distinct differences between women and men.  The male pelvis is narrower, heavier, and deeper.  The pelvis of a woman is wider.  Do well with this information.

 

 

 

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Lecture 22 – The Vertebral Column (Atlas and Adontoid Process)


We have discussed the hyoid bone before.  It is unique in that is has no bony attachments and is only connected by muscles and ligaments.  It is a u-shaped bone in the anterior portion of the neck.  It is inferior to the mandible and superior to the larynx.  Some people may casually call it the Adam’s apple.

The vertebral column has 33 bones:

7          cervical (neck)

12        thoracic

5          lumbar

5          sacral – immovable

4          coccygeal – immovable  (The sacrum and coccyx are fused.)

From the posterior angle, the spine looks like a column, while laterally it looks like a curve.  From superior to inferior, the curves are as follows:

Cervical curve

Thoracic curve

Lumbar curve

Sacral curve (also called the pelvic curve)

Coccygeal curve

Thoracic vertebrae have processes called ribs.  Thoracic vertebrae also have large spines, which are longer than the adjacent vertebra.  The lumbar vertebrae have the largest bodies because they are weight-bearing.

During a laminectomy, a surgeon will cut through the lamina to perform a tumor.  The thoracic area is a common site for spinal tumors.

C1 – 1st cervical vertebra – also called the atlas.  (The globe holds the world, which is round.  Keep it light-hearted with a silly hint!)  Likewise, the altas holds the skull.  Atlas articulates with the occipital bone and C2.  The occipital bone is immediately superior to the atlas.  The 1st cervical vertebra is a just a ring with no body.  C2 looks slightly different because it has a tooth-like process.  (Adontoid process)  The body of the first is fused to the body of the second, and fits like a puzzle.  C1 and C2’s fusion allows us to turn our heads laterally.

Intervertebral discs or just ‘discs’, as commonly called, are between the vertebrae to cushion them.  The shape of a disc is similar to a donut.  They are composed of rings of fibrocartilage.  The exterior is called annulus fibrosis, and the interior is called nucleus pulposis.  The nucleus pulposis is a soft, gelatinous center.  As a kid, I used to think that a slipped disc actually slipped out of place, creating a bone on bone situation.  In reality, the nucleus of the disc is leaking.  It involves a lot more than the implication that the whole disc slipped out of place.  This condition is exceedingly painful because many nerves are involved.  With degenerative disc disease, the discs take turns slipping.

Now, brace yourself for some really silly business!  I insist on drawing and writing pieces of information the old-fashioned way.  In the next few lectures, I will upload some crude drawings from my many years of notes.  Believe it or not, these drawings still help me to remember the most minute details.  I am excited about providing you with a great laugh!

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Lecture 21 – Bone Density


What is a Bone Density Test?  What do the numbers mean?

A bone mineral density test (BMD) is the best way to determine your bone health.  The test can identify osteoporosis, measure your response to osteoporosis treatment, and determine your risk for broken bones.  The most widely used BMD test is a dual-energy x-ray absorptiometry, or DXA test.  It is painless and is similar to having an x-ray.  The test measures bone density at your hip and spine.

A DXA test measures your bone mineral density and compares it to that of your established norm to give you a score.  Although no bone density is 100 % accurate, the DXA test is the single most important predictor of whether a person will have a fracture in the future.

Your DXA test results are compared to the ideal or peak mineral density of a 30-year-old adult, and you are given a T-score.  A score of 0 means your BMD is equal to the norm for a healthy young adult.  Differences between your BMD and that of the healthy young adult norm are measured in units called standard deviations.  (SD’s)  The more standard deviations below zero, indicated as negative numbers, the lower the BMD and the higher the risk of fracture.

A T-score between +1 and -1 is considered normal or healthy.  A T-score between -1 and -2.5 indicates that you have low bone mass, although not low enough to be diagnosed with osteoporosis.  A T-score of -2.5 or lower indicates that you have osteoporosis.  In conclusion, the greater the number the more severe the osteoporosis.

World Health Organization Standards

Normal

Bone density is within 1 SD (+1 or −1) of the young adult mean.

Low bone mass

Bone density is between 1 and 2.5 SD below the young adult mean
(−1 to −2.5 SD).

Osteoporosis

Bone density is 2.5 SD or more below the young adult mean
(−2.5 SD or lower).

Severe (established) osteoporosis

Bone density is more than 2.5 SD below the young adult mean, and there have been one or more osteoporotic fractures.

 

Bone mineral density is sometimes to that of a typical individual whose age is matched to yours.  The comparison gives you a Z-score.  Because a low BMD level is common among older adults, comparisons with the BMD of a typical individual whose age is matched to yours can be misleading.  The diagnosis of osteoporosis or low bone mass is based on your T-score.  However, a Z-score can be useful for determining whether an underlying disease or condition is causing bone loss.

Low Bone Mass Versus Osteoporosis

The information provided by a BMD can help your doctor decide which prevention or treatment options are right for you.  If you have low bone mass that is not low enough to be diagnosed as osteoporosis, this is referred as osteopenia.  Low bone mass can be caused by many factors such as:

heredity,

the development of less-than-optimal peak bone mass in your youth,

a medical condition or medication to treat such a condition that negatively affects bone, or

abnormally accelerated bone loss.

Everyone who has low bone mass will not develop osteoporosis, but everyone with low bone mass is at a higher risk for the disease and the resulting fractures.

A person with low bone mass can take steps to slow down bone loss and prevent osteoporosis in the future.  Physicians will encourage healthy habits, such as eating foods that are rich in calcium and vitamin D.  Weight-bearing exercises, such as walking, jogging, or dancing will help increase strength.  In some cases doctors may recommend medication to prevent osteoporosis.  These medications may slow or reverse bone loss.  Future BMD tests will be necessary to check the progress.

The U.S. Preventative Services Task recommends that women age 65 and older should be screened routinely for osteoporosis.  This task force also recommends that routine screening begin at age 60 for women who are at increased risk for osteoporotic fractures.  A panel convened by the National Institutes of Health in 2000 recommended that bone density testing be considered in people taking glucocorticoids medications for two months or more.  This also holds for people with other conditions that place them at high risk for an osteoporosis-related fracture.

The panel did not find enough scientific evidence upon which to base universal recommendations about when all men and women should receive a BMD test.  Each person is analyzed on a case by case basis.

For more information you may contact the Centers for Disease Control and Prevention’s National Center for Health Statistics

3311 Toledo Road

Hyattsville, MD 20782

800-232-4636

 

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Lecture 16 – Survey of Bones (Continued)


What happens after a fracture?

  1. Sever bleeding; a clot forms at the site of the fracture.
  2. Periosteum – surrounding the bone is made of connective tissue cells for fibroblasts that form osteoblasts.  Osteoblasts are bone-forming cells that form fragments of bone within the clot.  The fragment plus the clot equals a CALUS.  The formation of a calus is an essential step in repairing a bone.
  3. Osteoblast formation of periosteum forms bone between the two fragmented ends.  This is called a collar.

Types of Joints

The science of joints is called arthrology.

  1. Fibrous Joints – A small amount of connective tissue between bones.  Example:  Sutures and bones of the calvarium (skull).
  2. Cartilagenous – Fibrocartilage between bones.  Example:  vertebrae –( intervertebral discs); pubic symphysis (between two pubic bones).
  3. Synovial Joints – syn – with; ovial – egg whites in natural state, not the yolk.  Example:  Humerus, which articulates with glenoid fossa; femur with acetabulum, which means vinegar cup.
  4. Hinge joints – Example: elbows.  These joints increase and decrease the angle of the arm.  Make a muscle like Popeye, the sailor man.  Then relax and straighten arm out to the side.  Hing joints are also found in the knee.
  5. Ball and socket joints-  A synovial joint, such as the shoulder or hip joint, in which a spherical knob or knoblike part of one bone fits into a cavity or socket of another.  Some degree of rotary motion is possible in every direction. Also called enarthrosis.

 Characteristics of a Synovial Joint

  1. Articular cartilage
  2. Synovial membrane produces synovial fluid
  3. Heavy connective tissue and joint capsule for stability and protection.  (I have difficulty watching baseball players slide into home plate!  That is stressful to the joints of the knee.  A little bit of learning is truly a dangerous thing, as Pope Alexander said.)
  4. Bursa cushion the joints by reducing friction caused by the surrounding muscles.  Not all synovial joints bursa; Bursa are found in knees and shoulders.
  5. Head and depression joints.  Examples:  Humerus and glenoid cavity; femur and acetabulum.
  6. Pivot joint – Example: radius with head pivot around the ulna.  This is why the anatomical position is important.  Palms must be forward in order for the ulna to be medial to the body.  If you have your palms facing backwards, the radius and ulna will pivot and change positions!
  7. Saddle joint – 1st metacarpal has a convex surface.

Joint Movement

  1. Flexion – biceps – decreasing in angle.
  2. Extension – increasing in angle
  3. Adduction – toward the midline (Adducter)
  4. Abducter – away from the midline.  For example, the deltoid muscle takes the arm away from the body.
  5. Circumduction – circular motion.

Bodies are meant to be in motion.  A sedentary lifestyle causes obesity and other illnesses, especially diabetes mellitus.  Get some form of exercise every day.  Enjoy your day.

 

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Lecture 14 – Skeletal System (Cont’d)


Let’s begin with a bit of mathematical trivia.  Do you know how the search engine Google came up with its name?  Googol is the mathematical term for a 1 followed by 100 zeros.  This term was coined by Milton Sirotta, nephew of American mathematician Edward Kasner.  The term was popularized in the book “Mathematics and the Imagination” by Kasner and James Newman.  Google’s usage of the term reflects the company’s goal of organizing incredible amounts of information on the Internet.  (As organized as the information is, it cannot all be accurate.  Know the credentials of your sources.)  So, a googol of something is a very large quantity, sort of like a gazillion dollars.  You must be very comfortable with numbers in order to enjoy this career.  Learn the language of math.  Once you know the definitions, math becomes much more simplistic.

Maxilla – upper jaw (keystone of the face)

What is a keystone?  Or a cornerstone?  Keystone and cornerstone are used metaphorically to describe a course of action or a unit upon which all others rest.  If the keystone is removed, the entire structure will collapse.  In the Bible, Jesus is described as the cornerstone of spiritual life; all who place trust in him will never be put to shame.  Pennsylvania is considered the Keystone State, as Philadelphia was the capital of the United States before Washington, D.C.  All of the major players lived in Philly in the 1700’s, such as Washington, Jefferson, Franklin, etc.  Pennsylvania was the place of the signing of the declaration of Independence, the home of Betsy Ross, and the liberty bell.  If one was to remove PA from America, the entire historical structure would collapse.What would happen to cheese steaks, hot pretzels, and water ice, if Pennsylvania was obliterated from the earth?   Historically and spiritually, we can identify with a keystone; even if history and religion are not your favorite academic subjects.

Why is the maxilla called the keystone of the face?  All facial bones touch the maxilla, except the mandible.  There are 2 parts to the maxilla.  It has a protusion called the zygomatic process.  The maxilla has a role in forming the roof of the mouth; the anterior roof of the mouth is formed by the maxilla.

Nasal bones – 2 bones form the bridge.  We have a special place for our glasses to sit!

2 – inferior conchae – the –ae makes it plural.  This is the inferior lateral nasal cavity.

1 – vomer – on the medial nasal cavity (commonly called the septum)

Lacrimal bones – 2 of them, also, on the medial portion of the orbit.  (inferior medial orbit)

(Note: Lacrimal glands are responsible for tear formation.  It is OKAY to cry!  That means your lacrimal ducts work!)

Zygomatic bones – Form the middle aspect of the cheek bone.

Let’s review.  The whole cheek is made up of 3 bones –

Zygomatic process of the maxilla

Zygomatic bone

Zygomatic process of the temporal bone

Palatine bones – 2 of them will form the posterior portion of the hard palate (posterior roof of mouth)

Hard palate – Anteriorly – formed by the maxillary bone

Posteriorly – formed by the palatine bone

The mandible forms the only movable joint of the skull.  It is called the keystone of the lower jaw.  I am happy that this joint moves, as most of us love food.  I work very hard and treat myself to a small piece of chocolate every evening.  My motto:  “Chocolate solves everything.”  The statement is grossly incorrect, but that is my silly comforter.  Chocolate does not really solve everything, but the rewarding feeling gives me the boost I need to strategize through my problems.

By now you know that I have devoted my life to a couple of causes that have touched my heart, so to speak.  I am passionate about domestic violence prevention and women’s health.  Being self-sufficient is a great way to end domestic violence.  Many women return to violent situations because the abuser is the financial support system.  This is why I advocate for women to study hard, work diligently, and save for emergencies.  In my lectures on the nose and jaws, I jokingly say that one purpose of these body structures is to provide a nice living for cosmetic surgeons and ENT teams.  My humor can be dry and sarcastic at times.  I feel that sometimes we have to be shamed into doing the right thing.  Although we have excellent surgeons who have superior training, we should not remain in violent relationships of any sort.  It is my duty to constantly air this commercial.  Repetition works.  Pass the information on to others who need to hear my commercial.  As much as I extol the virtues of my dark chocolate comfort food, even chocolate cannot heal the physical and emotional wounds from an abuse.  Protect your body and your mind.  It is the only body that you have.  Make solid and safe choices.  Choices can be life-making or life-taking.  Do well with this new information!

 

 

 

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