BIO 102 Skeletal System HANDOUT 1 SKELETAL SYSTEM rev 12-12 Bone or Osseous Tissue –consists...

BIO 102 Skeletal System HANDOUT

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SKELETAL SYSTEM rev 12-12

• Bone or Osseous Tissue– consists primarily of nonliving extracellular

crystals of calcium minerals which make the bone hard

– contains several types of living bone cells, nerves, and blood vessels

– Is classified as a connective tissue


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Bones perform 5 important functions:• support-provides a hard framework that supports

the body, attaches the skeletal muscles and cradles the body’s organs

• movement-supports muscles to allow us to move• protection-because they are hard and surround

our internal organs, they protect our organs • formation of blood cells within the marrow cavity

• mineral storage-bones store minerals that are important to body metabolism and function


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Bones can be classified into 4 categories based on shape

• Long--bones of the limbs and fingers– are longer than they are wide– consist of a hollow, cylindrical shaft called the

diaphysis and– an enlarged knob at each end called the

epiphysis– An internal marrow space or cavity


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• Short--bones of the wrists – are approximately as wide as they are long

• Flat--including the cranial bones, sternum and ribs– are thin, flattened and sometimes curved, with a small

amount of spongy bone between 2 layers of compact bone

• Irregular--hip bones and vertebrae• include a variety of shapes that don’t fit into the

other categories


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• All bones contain 2 types of osseous tissue– a solid, compact tissue which forms the

external layer of bone– a spongy tissue with trabeculae


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• Periosteum covers the outer surface of all bones

• is a tough connective tissue consisting of 2 layers • the outermost layer is dense irregular connective

tissue– is richly supplied with nerve fibers, lymphatic

vessels and blood vessels which enter the bone through openings called nutrient foramen


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– provides insertion or anchoring points for the tendons and ligaments

– contains specialized bone forming cells– if the end of a long bone forms a movable joint,

the joint surface is covered by a thin layer of articular or hyaline cartilage that reduces friction, cushions the bone ends during joint movement, and absorbs mechanical stress


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• The internal part of the bone surface is covered by endosteum (a delicate connective tissue membrane)– this covers the trabeculae in the marrow

cavities of the spongy bone– lines the canals that pass through compact bone– contains osteoblasts (bone forming cells),

osteoclasts (bone resorption cells), and osteocytes (bone cells)


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Long bones

• Compact bone forms the external layer • central cavity of the shaft of long bones is called

the medullary cavity– this cavity is filled with red marrow in children

(for RBC production), and with yellow bone marrow in adults• yellow marrow is primarily fat which can be

utilized for energy• Compact bone consists of calcium phosphate laid

in a pattern around the central cavity


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• Structural Unit of Compact bone is the– Osteon (or Haversian system) this forms a

pattern of hollow tubes like the growth rings of a tree trunk


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• Parts of the Haversian system:– each ring of bone tissue in the hollow tube is

called a lamellae – Haversian or Central canal: middle cavity in

a Haversian system. Contains the blood vessels and nerve fibers

– lacunae: found at the junctions of the lamellae and is filled with bone cells called osteocytes


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• canaliculi: thin canals in bone tissue which connect the lacunae to each other and to the central canal– provide a path for nutrients to travel to the osteocytes

and for wastes to be removed

• Volkmann’s canals lie at right angles to the long axis of the bone and connect the blood and nerve supply of the periosteum to those in the central canals and the medullary cavity– this allows all osteocytes to get nutrients even

though they aren’t near a blood vessel


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Spongy bone

– Is found inside the epiphysis• spongy bone is less dense than compact bone

allowing the bones to be light but strong– this helps the bone to withstand mechanical stress

• spongy bone is a honeycomb of hard, strong pieces called trabeculae

– helps the bone to resist mechanical stress

– the open spaces of the trabeculae are filled with red or yellow bone marrow

• blood cell formation (hemopoiesis) takes place in the spongy bone


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– Contains the epiphyseal plate: line of cartilage where bone lengthening takes place in childhood

• When bone length growth is completed, the epiphyseal plate becomes ossified (hardened) and leaves an epiphyseal line


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SKELETAL SYSTEM

• Skeleton – provides support– protects internal organs– produces blood cells– stores minerals (calcium and phosphorus)– stores energy– Permits movement via muscle attachments– Provides levers to make movement easier


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Skeletal system contains 3 types of connective tissue

• bone--hard elements of the skeleton

• ligaments--dense fibrous connective tissue that binds the bones to each other

• cartilage--specialized connective tissue consisting primarily of fibers of collagen and elastic in a gel-like fluid called ground substance

Knuckle CrackingThe snapping sound is made by the rush of synovial fluid from one area of the joint to another as the joint is forcefully pulled apart. Research shows that:

• this should not cause an increase in osteoarthritis,

•that people who crack their knuckles eventually have decreased grip and hand function.

•Joint damage may be caused by long term chronic ligament inflammation with subsequent pain

Related research found that knuckle crackers are also more likely to bite their fingernails, smoke, and drink alcohol


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The Skeleton is organized into the• Axial skeleton and the Appendicular skeleton• Axial skeleton

– forms the long axis of the body which supports the head, neck and trunk

– consists of the – skull, **bones of the ear– vertebral column, **hyoid bone (in the throat)– ribs and – sternum

Appendicular skeleton• bones which help get us from place to place

(locomotion) and enable us to manipulate our environment

**these bones are also parts of the axial skeleton


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• The Skull includes the bones of the face, the cranial bones and the jaws

• Frontal bone (forehead)

• Parietal bones (behind the frontal bone, on the top rear part of the skull)

• Occipital bone (forms the back of the skull)

near the base of this bone is an opening called the foramen magnum. This is where the vertebral column connects to the skull and the spinal cord enters the skull to communicate with the brain


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• Occipital condyles--2 rounded bumps at the base of the skull which pivot on the 1st vertebrae (as in nodding the head to say “yes”)

• Temporal bones (on the lateral [left and right side] of the skull under the parietal bone)

– each temporal bone has an opening into the ear canal which allows sound to travel to the eardrum

• Sphenoid bone which forms the back of the eye sockets

• Ethmoid bone which helps support the nose and part of the eye socket


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• Facial bones and jaws-comprise the front of the skull

– zygomatic bones form the cheeks and the outer part of the eye sockets

– nasal bones (including the ethmoid) underlie only the upper bridge of the nose (the rest of the nose is made up of cartilage and other connective tissue)

– lacrimal bones are the inner part of the eye sockets

» each is pierced by a tiny opening through which the tear ducts drain


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– maxillary bones form part of the eye sockets, anchors the upper row of teeth, and forms part of the upper palate

» upper, immovable, jaw bone is called the maxilla

– Mandible or lower jaw anchors the lower teeth

• Hyoid bone: not really part of the skull; lies inferiorly to the mandible in the anterior neck

– is the only bone in the body which doesn’t articulate with another bone


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• Ear bones– present in the middle ear and move when air

vibrations bend the eardrum inward» called the malleus (hammer), incus (anvil)

and stapes (stirrup)

• Several of the cranial and facial bones contain air spaces which form the sinuses and make the skull lighter

• Vertebral column or spine– supports the head, protects the spinal cord and serves as

the attachment for each of our arms and legs and the body’s muscles


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– Is a column of 33 vertebrae (irregular bones) which extends from the skull to the pelvis

– is classified into 5 anatomical regions• cervical (neck)-7 vertebrae• thoracic (chest or thorax)- 12 vertebrae• lumbar (lower back)-5 vertebrae• sacral (sacrum/upper pelvic region)- 5

vertebrae which have fused• coccygeal (coccyx or tailbone)- 4 fused

vertebrae


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– The first cervical vertebrae is called the Atlas• it articulates with the occipital condyles

– The second cervical vertebrae is called the Axis• you need to know these names

– vertebrae share 2 points of contact called articulations

• The spinal cord passes through a canal between the articulations

– vertebral bodies are separated from each other by intervertebral disks which serve as shock absorbers and permit a limited amount of movement and flexibility


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• Ribs and sternum (breastbone)– Sternum is actually 3 fused bones– protect the chest cavity– we have 12 pairs of ribs

• the upper 7 pairs, called “true” ribs, • “False ribs:

– pairs 8-10 are joined to the 7th rib by cartilage and are thus indirectly attached to the sternum

• Floating ribs: pairs 11 and 12: don’t attach to the sternum at all.


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Appendicular skeleton• bones which help get us from place to place (locomotion)

and enable us to manipulate our environment

– includes the:– Pectoral or Shoulder Girdle is a supportive

frame for the upper limbs• consists of the clavicles and scapulas

– Arms (the humerus, ulna, radius, carpals [wrist bones], the palm [metacarpal bones], and the fingers [the phalanges])


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– The Pelvic or Hip Girdle consists of the 2 pelvic (hip) bones and the sacrum and coccyx of the vertebral column

• they meet in front at the pubic symphysis where cartilage joins the 2 bones

• primary purpose is to support the weight of the upper body against the force of gravity

• in adult women, the pelvic girdle is

– broader and shallower than in men and

– the pelvic opening is wider/rounder--to allow for childbirth

– the sacrum is flatter


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– The leg bones:• Femur (thigh)

• Patella (knee cap)

• Tibia (lower leg)

• Fibula (lower leg)

• Tarsals (ankle joint)

• Metatarsals (foot)

• Phalanges (toes)


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Mature Bone Remodeling and Repair

• Changes in shape, size, strength:– Dependent on diet, exercise, age

• Bone cells regulated by hormones:– Parathyroid hormone (PTH): removes calcium

from bone– The thyroid hormone Calcitonin adds calcium to

bone

• Repair: hematoma and callus formation


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• Joints or Articulations– are sites where 2 or more bones meet– give our skeleton mobility– hold the skeleton together– are the weakest parts of the skeleton

• Ligaments (connective tissues) and tendons (muscular tissue) stabilize each joint


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• Joint types– freely movable or synovial --bones are separated by a

thin fluid filled synovial cavity which secretes synovial fluid as a lubricant

• Synovial membrane lines the interior surfaces of the joint.

• Hyaline cartilage lines the articulating surfaces of the bones

Types of synovial joints:• Ball and socket--the ball end of one bone fits into

the socket of another bone: shoulder and hip joints• Hinge joint —allows movement in one plane

– Knee and elbow joints


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• Slightly Movable or Cartilaginous --has no synovial cavity and permit only slight movement (this type joint is mainly found in the axial skeleton)

– has a pad of fibrocartilage between 2 bones• Pubic Symphysis (is only moveable during

childbirth)

• intervertebral discs

• sacroiliac

• joint connecting the lower ribs to the sternum


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• Immovable or Fibrous Joints – flat bones in a baby’s skull

• at birth these bones are separated by space filled with fibrous connective tissue. These “soft spots” are called fontanels

– allow the baby’s head to squeeze through the birth canal

– allow for brain growth and development


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Diseases and Disorders of the Skeletal System

• Sprains: stretched or torn ligaments or muscular injury– Partially torn ligaments will repair themselves but take

a long time due to poor vascularization

– Completely torn ligaments require surgery to repair

• Cartilage injuries usually due to overuse– Require surgery to remove damaged cartilage

• Bone dislocation: occurs when bones are forced out of alignment– Subluxation is a partial dislocation

• Bursitis: inflammation of the part of the joint which contains the synovial fluid– Falling on your knees, repeated leaning on your elbows

• Inject with anti-inflammatory drugs

• Remove some excess fluid by needle aspiration to relieve pressure in the joint

• Tendinitis: inflammation of the tendon sheath– Typically caused by overuse

• Arthritis: inflammation of joints– Rheumatoid Arthritis

– Osteoarthritis= Degenerative Joint Disease (DJD)


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Rheumatoid Arthritis• Thought to be an autoimmune disease that causes chronic

joint inflammation as well as inflammation of tissue around the joints

– Inflammation in other body organs

• ? Genetic cause, environmental, viral, bacterial

• Exacerbations and remissions

• Chronic inflammation leads to destruction of cartilage, bone and ligamentsjoint deformity

• Symptoms: fatigue, energy loss, decreased appetite, low-grade fever, muscle and joint aches and stiffness (worse in mornings)


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Treatment: ---REST

– reduce joint inflammation and pain

– Patient education to maximize joint function

– Prevent joint destruction and deformity

• Medications:– Aspirin and corticosteroids, NSAIDs (non-steroidal

anti-inflammatory drugs), to decrease pain and inflammation

• No known cure


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Osteoarthritis

Most common form of arthritis

•Characterized by the breakdown of cartilage and can also damage ligaments and muscles

•Causes changes in joint structure and joint capsule thickening that leads to stiffness, aching and pain

•Causes: obesity, joint injury, repetitive stress to a joint


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Homeostatic Imbalances• Rickets

– Bones of children are inadequately mineralized causing softened, weakened bones

– Bowed legs and deformities of the pelvis, skull, and rib cage are common

– Caused by insufficient calcium in the diet, or by vitamin D deficiency


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Homeostatic Imbalances

• Osteomalacia (in adults)– Bones are inadequately mineralized causing

softened, weakened bones– Main symptom is pain when weight is put on

the affected bone– Caused by insufficient calcium in the diet, or by

vitamin D deficiency


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Homeostatic Imbalances• Osteoporosis

– Group of diseases in which bone reabsorption outpaces bone deposit• Excessive loss of calcium and also collagen

fibers from bone– Spongy bone of the spine is most vulnerable– Occurs most often in postmenopausal women– Bones become so fragile that sneezing or

stepping off a curb can cause fractures


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Osteoporosis: Treatment

• Calcium and vitamin D supplements• Increased weight-bearing exercise• Hormone (estrogen) replacement therapy (HRT)

slows bone loss• Natural progesterone cream prompts new bone

growth• Statins increase bone mineral density


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Paget’s Disease• Characterized by excessive bone breakdown with

new bone formation – Initially have excessive bone resorption (osteoclastic

phase) followed by a reactive phase of excessive, abnormal bone formation (osteoblastic phase)

• Pagetic bone is chaotic, fragile and weak and tends to have reduced mineralization

• Usually localized in the skull, spine, pelvis, femur, • Unknown cause (possibly viral)• Treatment includes the drugs Didronate and

Fosamax


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Bone Fractures (Breaks)

• Bone fractures are classified by:– The position of the bone ends after fracture– The completeness of the break– The orientation of the bone to the long axis– Whether or not the bones ends penetrate the

skin


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Types of Bone Fractures

• Nondisplaced – bone ends retain their normal position

• Displaced – bone ends are out of normal alignment

• Complete – bone is broken all the way through• Incomplete – bone is not broken all the way

through


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Types of Bone Fractures

• Compound (open) – bone ends penetrate the skin• Simple (closed) – bone ends do not penetrate the

skin• Comminuted – bone breaks into three or more

pieces; common in the elderly• Oblique - a fracture which goes at an angle to the

axis


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Common Types of Fractures

• Epiphyseal – epiphysis separates from diaphysis along epiphyseal plate; occurs where cartilage cells are dying

• Greenstick – incomplete fracture where one side of the bone breaks and the other side bends; common in children

Spine Curvature Disorders

•Lordosis. Also called “swayback”, the spine curves significantly inward at the lower back.

•Kyphosis. characterized by an abnormally rounded upper back, also called “humpback or hunchback”

•Scoliosis. sideways curve to the spine. The curve is often S-shaped or C-shaped.


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Causes•Osteoporosis•Obesity•Inflammation of the disc space between the bones of the spine most often caused by infection•Abnormal vertebrae development in utero (congenital kyphosis)•Poor posture or slouching (postural kyphosis)•Arthritis•Osteoporosis•Spina bifida: the spinal column of the fetus does not close completely •Spine infections•Spine tumors•Genetic


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• Idiopathic (80%).

• Neuromuscular conditions (15%) include cerebral palsy, spina bifida and poliomyelitis.

• Metabolic problems

• Crush fracture from trauma, osteoporosis, tuberculosis or malignancy.


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http://www.patient.co.uk/search.asp?searchterm=CEREBRAL+PALSY

http://www.patient.co.uk/search.asp?searchterm=MYCOBACTERIUM+TUBERCULOSIS

Symptoms: vary depending on the type and severity of curvature•Appearing swayback•Having a large gap between the lower back and the floor when lying on your back on a hard surface that doesn’t change when you bend forward•Back pain and discomfort•Problems moving certain ways•head appears to bend forward •Hump or curve to the upper back


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• Fatigue in back or legs

• Uneven shoulder blades with one being higher than the other

• An uneven waist or hip

• Leaning toward one side

• clothing seems longer on one side than on the other.

• when looking in a mirror the height of the hips and shoulders appears uneven.


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Treatment•determined based on the severity and type of spinal curvature disorder•Medication to relieve pain and swelling•Exercise to increase muscle strength and flexibility•Wearing a back brace•Weight loss•Surgery•Observation. If there is a slight curve your doctor may choose to check your back every four to six months to see if the curve gets worse.•Bracing. A back brace is often prescribed for kids and adolescents who are still growing to prevent the curve from getting worse.


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Types of surgery

•Spinal instrumentation. Instruments such as hooks, rods, and wire are attached to the spine to realign the bones of the spine and keep them secure following spinal fusion.

•Artificial disc replacement. Degenerated discs in the spine are replaced with artificial ones.


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http://www.webmd.com/back-pain/spinal-fusion-for-scoliosis

Complications•Distortion of the spinal column may cause restriction of the chest with impairment of lung function•Compression of abdominal contents can occur•Severe deformity may impinge on the spinal cord and cause paraplegia


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BIO 102 Skeletal System HANDOUT 1 SKELETAL SYSTEM rev 12-12 Bone or Osseous Tissue –consists...

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Transcript of BIO 102 Skeletal System HANDOUT 1 SKELETAL SYSTEM rev 12-12 Bone or Osseous Tissue –consists...