Terminology - Landmarks - Skeletal System

• 1. Person stands erect.
• 2. Feet parallel, flat on the floor.
• 3. Arms are at the sides of the body. 
• 4. Palms forward.

Prone.

Supine.

• Medial - nearer to the midline. 
• LAteral - further (away) from the midline,towards the sides. 
• Bilateral - both sides. 
• Unilateral - one side. 
• IpSilateral - on the same side. 
• Contralateral - on the opposite side. 
• Proximal - nearer to the 'attachment'. 
• Distal - further from the 'attachment'.

• Cranial - head/towards the head. 
• Caudal - tail/towards the tail. 
• Anterior/Ventral - nearer the front. 
• Posterior/Dorsal - Nearer the back. 
• Superior - Towards the top. 
• Inferior - Towards the bottom. 
• Superficial - Closer to the skin/surface. 
• Deep - further under the skin. 

• 1. Coronal/Frontal Plane - vertical plane that divides the anterior (front) and posterior (back) parts of the body.  
• 2. Sagittal - vertical plane that divides the left and right parts of the body. 
• 3. Transverse - horizontal plane that divides the superior (top) and inferior (bottom) parts of the body.

206. 

• 1. Haemopoiesis - formation and development of blood cells. 
• 2. Mineral haemopoiesis (mostly calcium and phosphate). 
• 3. Support framework for the body.
• 4. Forms boundaries (skull). 
• 5. Attachment for muscles and tendons. 
• 6. Permits movement (joints). 
• 7. Triglyceride storage (yellow bone marrow).

[Osteo] = bone 

• Osteogenic Cells are unspecialised stem cells. 
• They are the only bone cell to undergo division, which produces Osteoblasts.

• Osteoblasts are bone building cells. 
• They surround themselves with extracellular matrix and become trapped in their secretions and become osteocytes.

• Osteocytes are mature bones cells. 
• They maintain daily metabolism of bone, such as nutrient/waste exchange.

Osteoclasts are huge cells derived from fusion of as many monocytes(white blood cells).

It is when Osteoclasts break down the tissue in bones.

Compact bone is tightly-packed, contains few spaces and is strong.

An Oeston is a structural unit of compact bone.

• 1. Central canal - contains blood vessels and nerves. 
• 2. Lamellae - calcified extracellular matrix containing minerals and collagen. 
• 3. Lacunae - between lamellae, are small spaces called lacunae that contain osteocytes. 
• 4. Canaliculi - interconnected canals that provides a route for nutrients/waste.

• 1. Does not contain osteons - instead it consists of thin columns called trabeculae.
• 2. Small spaces between trabeculae help make bone lighter and can be filled with bone marrow. 
• 3. Spongy bone is always covered with a layer of compact bone.

Bone contains an extracellular matrix that surrounds separated cells.

Calcium Phosphate. 

• 1. A bone that has a greater length than width.
• 2. Contains a shaft=diaphysis and 2 heads=epiphyses. 
• 3. Mostly compact bone in diaphysis and spongy bone in epiphysis.

They are separated by the epiphyseal plate.

• The epiphyseal plate is a layer of hyaline (thin glass-like) cartilage.
• This allows the diaphysis to grow in length.

• Thin outer compact bone covered by hyaline cartilage. 
• Inner spongy bone with red marrow.

• Diaphysis are the tubular shaft part of the long bone. 
• The outer compact bone is covered by periosteum. 
• Central, medullary(bone marrow cavity) contains red/yellow bone marrow.

Peri = surrounding Osteon = bone 

Periosteum is a dense layer of vascular connective tissue that surround the external bone surface.

• 1.Outer fibrous layer - protects bone. 
• 2. Inner layer - mostly of osteoblasts and osteoclasts for growth and repair.
• 3. Serves as attachment for ligaments and tendons.

Endo =outside

Endosteum is a thin layer of vascular connective tissue that surrounds the internal medullary (bone marrow cavity) cavity.

• 1. Short bones - curved shaped.
• 2. Irregular bones - complex shapes. 
• 3. Flat bone - 2 plates of compact bone.
• 4. Sesamoid bone - e.g. patella(knee). 
• 5. Long bones - e.g femur(thigh).

• Periosteum
• Compact Bone
• Spongy Bone - containing red bone marrow.

• Red bone marrow - red blood cells, platelets, most white blood cells are created here.
• Yellow bone marrow - contains fat cells, some white blood cells are created here.

The natural process of bone formation.

• During foetal development.
• During growth.
• Throughout life.
• Repair.

• 1. Intramembranous ossification - bone growth at embryo & foetus stage. All flat bones i.e. skull. 
• 2. Endochondral ossification - bone growth from 2 months onwards. cartilage is broken down as ossification proceeds.

• Long bones growth in length = interstitial growth.
• All other bones growth in thickness = appositional growth.

• Epiphyseal Plate - a layer of hyaline cartilage in the epiphyses where bones cells are produced.
• ⬇︎
• Osteoblasts - move in to ossify the matrix to form bone. 
• ⬇︎
• Early 20's epiphyseal plate completely ossifies to leve a thin epiphyseal line. Bone can no longer grow.

The fractured bone may be shorter than normal once adult bone formation is reached.

Osteoclasts resorb old bone that lines the medullary cavity, while osteoblasts, via intramembranous ossification, produce new bone tissue beneath the periosteum.

Hormones affect bone growth and remodelling by altering the ratio of osteoblast to osteoclast activity.

• 1. Growth hormone - stimulate osteoblasts(bone-forming cells). 
• 2. Thyroid hormone - promotes osteoblasts.
• 3. Cortisol(stress hormone) & steroid medications - Promotes osteoclasts (breaking down of bone cells).

• 1. Testosterone & Oestrogen - Promotes osteoblasts. 
• 2. Calcitonin(lowers blood calcium) - Promotes osteoblasts. 
• 3. Parathyroid hormone(increases blood calcium) - Promotes osteoclasts.

Bone is made up 99% calcium. Blood calcium levels have to be tightly controlled to ensure proper blood clotting, nerve and muscle function. 

Osteoclasts break down bone and release calcium into the blood. This is referred to as hypocalcemia.

Hypo =low 

An increased osteoblast activity takes calcium back into the bone. This is referred to as hypercalcemia. 

Hyper =high

Calcium exchange is regulated by the parathyroid glands and the thyroid gland.

• 1. Parathyroid gland. 
• 2. Increases blood calcium levels. 
• 3. a. Increases osteoclast activity
• b. increased renal(kidney related) calcium absorption. 
• c. increases calcitriol (active form of vitamin d). 

• 1. Thyroid gland. 
• 2. Decreases blood calcium levels. 
• 3. a. Inhibits osteoclasts. 
• b. Promotes osteoblasts.

• 1. Vitamin D facilities calcium absorption.
• 2. Crucial for healthy bones.

• 1. Low sun exposure. 
• 2. Reduced dietary absorption. 
• 3. Reduced ability to produce an active form of vitamin D through liver, kidneys and skin.

Magnesium.

• 1. Bones can become stronger in response to mechanical stress e.g. pull of skeletal muscle.
• 2. Mechanical stress leads to increased mineral deposition and increased production of collagen fibres.  
• 3. Mechanical stress is important for ensuring bone formation occurs more quickly than bone resorption.

The axial skeleton is the 'central skeleton' and consists of 80 bones.

• 1. Skull
• 2. Inner ear ossicles.
• 3. Throat hyoid bone. 
• 4. Chest (thoracic cage).
• 5. Vertebral column.

• The Skull forms the cranium and face and encapsulates the brain. 
• The skull bones are joined with fibrous joints called sutures.

Sinuses are spaces within the skull.

• 1. Communicate with nasal cavity. 
• 2. Give resonance to the voice. 
• 3. Lighten bones of face and cranium.

• There are 33 vertebrae. The upper 24 are articulating and separated from each other by intervertebral discs.
• The lower nine are fused in adults, five in the sacrum and four in the coccyx.

• Cervical (7) C1-C7
• Thoracic (12) T1-T12
• Lumbar (5) L1-L5 
• Sacrum (5 in human embryo) Fuse together once born. 
• Coccyx (4 in human embryo) Fuse together once born.

• 1.Protection. 
• 2. Support.
• 3. Axis.
• 4. Movement.

There are 24 intervertebral discs which make up 1/3 of the length of spinal column.

• Intervertebral discs are composed of an annulus fibrosus and a nucleus pulposus.
• 1. Annulus Fibrosus - strong radial tire–like structure made up of lamellaeThe annulus fibrosus encloses the nucleus pulposus.
• 2. Nucleus Pulposus - gel-like pad that absorbs shock.

• Sternum. 
• Ribs (12 pairs).

They are called 'floating ribs' because they are only attached to the vertebrae.

• There are 126 bones in the appendicular skeleton. 
• Their main functions are;
• 1. Body movement
• 2. Protects organs of digestion, excretion and reproduction.

• 1. Shoulder Girdle. 
• 2. Arm.
• 3. Hand.
• 4. Pelvic Girdle. 
• 5. Leg.
• 6. Foot.

• 1. Clavicle (collar bone). 
• 2. Scapula (shoulder blade).
• 3. Humerus (funny bone).
• 4. Ulna (elbow)
• 5. Radius (arm bone).
• 6. Carpals (wrist bones).
• 7. Metacarpals ([meta=after/along], hand bones).
• 8. Phalanges (finger/toe bones). 

• 1. Hip Bones. 
• 2. Sacrum.
• 3. Coccyx. 

• 1. Femur - (thigh bone) longest and strongest bone in the body. 
• 2. Tibia (shin bone). 
• 3. Fibular (lower leg bone). 
• 4. Tarsals (anke bones). 
• 5. Metatarsals ([meta=after/along], foot bones).
• 6. Phalanges (toe/finger bones). 

• The muscle's points of attachment to bones or other muscles are designated as origin or insertion. 
• 1. The part of the muscle that does move is is called the origin. 
• 2. The part of the muscle that does move is called insertion.

Tendons. 

Attachments bridge one or more joints so that muscle contraction produces movement of these joints. 

187.

• 1. Connected by dense connective tissue.
• 2. Limited movement.

E.g. Suture, like those between skull bones.

• 1. Limited to no movement. 
• 2. Connected by hyaline cartilage or fibrocartilage. 

e.g intervertebral discs, epiphyseal growth plate. 

• 1. Free movement. 
• 2. Covered by a layer of hyaline cartilage called articular cartilage that reduces shock/friction. 
• 3. Covered by articular capsule which unites articulating bones. 
• 4. Contains synovial fluid. 

e.g. ‘ball and socket’ (shoulder & hip) & hinge (elbow & knee).

Bursae are sac-like structures that are strategically located to reduce friction.

A tendon sheath is a layer of synovial membrane around a tendon. 

Increase or decrease in the angle between bones.

• 1. Flexion - Decrease in angle (usually saggital plane)
• 2. Extension - Increase in angle (usually saggital plane)
• 3. Hyperextension - Extension beyond anatomical position
• 4. Rotation - movement around its longitudinal axis. In the limbs it can be medial
• (towards the midline) or lateral (away from the midline)
• 5. Lateral flexion - Movement of trunk away from the midline
• 6. Abduction – Movement away from Midline
• 7. Adduction – Movement towards Midline
• 8. Circumduction – Circular - flexion, abduction, extension, hyperextension,
• adduction in succession.

• Joint hypermobility means that some or all of a person's joints have an unusually large range of movement. 
• This can cause dislocations.

Occur at specific joint:

• 1. Elevation - Superior movement (up)
• 2. Depression - Inferior movement (down)
• 3. Protraction - Anterior movement in transverse plane (forward).
• 4. Retraction - Posterior movement in transverse plane (backward)
• 5. Inversion – Medial movement of sole (turn in).
• 6. Eversion – Lateral movement of sole (turn out).
• 7. Dorsiflexion – Bending foot up.
• 8. Plantar flexion – Bending foot down.
• 9. Supination – Movement of forearm to turn the palm up.
• 10. Pronation – Movement of forearm to turn the palm posteriorly.
• 11. Opposition – Movement of thumb across palm to touch fingertips.

A fracture is any break in a bone. 

Causes included trauma, low bone density, Vitamin D deficiency. 

• 1. Complete - completely separated. 
• 2. Incomplete - remains intact/simple fracture. 
• 3. Linear - along bone length.
• 4. Transverse - dissects across bone.
• 5. Compound - protrudes through skin. 
• 6. Simple - does not protrude skin.

• 1. Haematoma & Inflammation.
• 2. Fibrocartilaginous Callus Formation.
• 3. Bony Callus Formation.
• 4. Bone Remodelling.

• Blood leaks into fracture site. 
• ⬇︎
• Phagocytes breakdown damaged cells. Fibroblasts invade fracture site and lay down collagen forming a soft callus. (2-3 weeks).
• ⬇︎
• Osteoblasts replace fibrocartilage with new bone (3 months). 
• ⬇︎
• The callus is mineralised & compact bone laid down. Osteoclasts reshape the new bone. (months-years).

Improve circulation and nutrients to the bone to aid repair.

• A sprain is when trauma forces the joint to go beyond its normal range. 
• This causes stretching/tearing of ligaments.

Ligaments are bands of connective tissue that attach bone to bone. They are tougher than muscle but less flexible.

RICE - Rest, Ice, Compression, Elevation

Incomplete or partial dislocation of a joint or organ.

Complete separation of two bones at a joint.

Soft tissue damage possibly involving nerves and blood vessels.

Commonly used to visualise lungs, heart, teeth and skeletal system.

Electromagnetic Radiation. 

• An X-ray will pass through less dense matter like air, fat, muscle, but absorbed or scattered by denser materials such as bones, lungs affected by severe
• pneumonia, appearing white.

The radiation can cause cancer. 

A normal healthy spine curve will include a thoracic spine kyphosis. 

[Kyphos] - hump 

Exaggerated Kyphosis. 

A normal, healthy spinal curve will include a cervical spine and lumbar spine lordosis.

During pregnancy to support the cervical and lumbar spine.

• 1. Muscular Fatigue.
• 2. Encourages the vertebral joints to move closer causing inflammation.

A lateral 'S' shaped curve in the spine. 

People often live with a scoliosis and are asymptomatic.

Scoliosis can build up pressure on the nerves and cause spinal nerve impingement.

Chronic, progressive thinning of the bone.

It's characterised by decreased bone mineral density (BMD). 

• 1. Primary osteoporosis: Age related or idiopathic (unknown cause). 
• 2. Secondary osteoporosis: Secondary to
• another condition/medication/lifestyle.

a Dexa Scan.

• 1. T-Score (compared to young normal adult of same sex -age 30)
• 2. Z-Score <50yrs (compared to normal adult of same age, sex, height)

• 1. Increasing age. (over 30 years o age the ability o retain calcium lowers). 
• 2. Female & Post-menopausal.
• 3. Poor diet.
• 4. Drugs.
• 5. High alcohol consumption and smoking.
• 6. Genetics. 
• 7. GIT diseases - liver disease, malabsorption syndromes.
• 8. Sedentaty lifestyle - little or no physical activity. 
• 9. Endocrine problems - e.g. hyperparathyroidism, hyperthyroidism, inability to produce oestrogen.
• 10. Toxins (metals).
• 11. Low body weight. 

Asymptomatic until the bone has reached critical thinness whereby fragility fractures occur spontaneously with minor trauma.

• Pain is usually severe. 
• Pain is aggravated by increased sitting, standing or bending. 
• Rib or spinal deformities such as kyphotic posture. 
• Loss of height due to vertebral crushing and fracture.

Allopathic: Bisphosphonates (Aledronic Acid) – Inhibit osteoclast activity.

Alternative: Healthy non acidic diet.

• [Osteo] =bone [malacia] = 'softening' 
• Osteomalacia is characterised by decalcification of bone and 'softening'. 

• Rickets occurs in patients under 18 years old.
• Osteomalacia occurs in adults or adolescents. 

• Mainly caused by Vitamin D Deficiency. 
• Could also have a secondary deficiency: malabsorption disorders.

• 1. Deformed bones (bowing of legs).
• 2. Severe back pain.
• 3. Severe muscle weakness.
• 4. Fracture
• 5. In rickets: Delayed closure of fontanelles and skull softening.

[Hyper] =elevated [calc] =calcium [aemia] = in the blood


Elevated blood calcium. 

• 1. Uncontrolled release of calcium from bones e.g. tumour. 
• 2.  Hyperparathyroidism. (hyperparathyroidism, an enlargement of one or more of the parathyroid glands causes overproduction of the hormone, resulting in high levels of calcium in the blood) 

• 1. Muscle weakness. 
• 2. If high calcium is coming from the bones, bone density will be compromised and fractures may occur.

[Osteo] = bone [myelo] = marrow [itis] = inflammation

• A bacterial infection of the bone marrow resulting in necrosis(death of cells) of bone cells and hence becomes weak.