SKELETALSYSTEM

Bone & Tissue

Axial Skeleton

Appendicular Skeleton

Articulations

Bone Physiology• Types of Bone :

1. Long – when length is greater than width, arms and legs, act as levers pulled by muscles

2. Short – about equal length, width, and thickness but irregularly shaped, wrist and ankle, limited movement, completely covered in ligament

3. Flat – actually thin or curved more often than flat, ribs, scapula, sternum, and cranium, muscle attachment or protection

4. Irregular – don’t neatly fit into any other category, facial and hip bones, vertebrae

5. Sesamoid – small bones embedded in certain tendons that pass over a joint (knee or wrist) , patella and pisiform carpal

6. Accessory – mostly in the feet, some in the skull (sutural bones), form when developing bones don’t fuse completely,

Gross Anatomy of Long Bones• Diaphysis – tubular shaft• Epiphysis – round end• Epiphyseal growth plate• Marrow :

– Yellow mostly adipose– Red hemopoeisis (Blood

cell creation)• Endosteum – lines the

trabeculae (• Periosteum – lines the

outside of compact bone

Compact/Spongy Bone Tissue• Haversian system

– Osteon (entire section)

• Lamellae- rings• Central canal-

contains blood vessels

• Perforating canal• Lacunae- hole

containing bone cell• Canaliculi- tiny canal• Cancellous bone

(trabeculae- bands or columns of connective tissue

Bone Cells (define)• Osteogenic (osteoprogenitor) – stem cell, highly mitotic, found deep in

the periosteum and endosteum layers.• Osteoblast – “b” stands for build, these pump calcium and phosphate in

and out of bone matrix• Osteocyte – main cell of fully developed bone, live in the lacuna and

extend out through the canaliculi into the matrix, develop from osteoblast, maintain the bone homeostasis

• Osteoclast – “c” stands for clear, these clear or remove calcium from the matrix, develop from white blood cells

• Bone-lining cells – regulate mineral salts movement in and out of adult bones

Bone Growth- OSSIFICATION!!!• Longitudinal-

epiphyseal growth plate

• Diameter and fracture healing- periosteum

• Modeling- formation of new bone layers on the exterior and simultaneous removal of bone from the interior layer

• Remodeling- strengthening bones under more stress and lightening bones under less stress

Physiological Functions• Calcium – enzyme function, membrane permeability, muscle

contraction, nerve impulses, blood clotting, bone formation

• Phosphate – acid / base balance

• Blood Cells – hemopoietic tissue, red bone marrow is the site of the body’s main blood cell production

• Effects of hormones & nutrition – PTH (parathyroid hormone) and CT(calcitonin) impact bone formation

• Effects of aging – old = loss the ability to use calcium- WHAT then is the DESTINY of the bones????

Axial Skeleton

• Skull:– Sutures– Fontanels –

soft spot on top of infant head

– Bones:

1. Frontal

2. Parietal

3. Occipital

4. Temporal

5. Sphenoid

6. Ethmoid

• Facial bones:

1. Mandible

2. Maxilla

3. Nasal

4. Zygomatic

• Other skull bones:

1. Hyoid- connects to tongue

EAR BONES

2. Incus

3. Malleus

4. Stapes

• Vertebral Column:1. Cervical, neck (C1-C7)-

a) Atlas – C1 (#6) yes motion

b) Axis – C2 (#7) no motion

c) 3-6 are typical

d) Vertebra prominins – C7

2. Thoracic, chest (T1-T12) –articulate with ribs

3. Lumbar, back (L1-L5)- largest, strongest, back muscles attach

4. Sacrum (5 fused vertebrae)-give strength and stability to pelvis

5. Coccyx (4 fused vertebrae)-vestige of embryonic tail

Typical Vertebrae• Functions:

1. Body

2. Vertebral arch:a) Pedicles

b) Laminae- the curve of the arch

(houses the spinal cord!)

a) Vertebral foramen

3. Vertebral processes:a) Spinous process

b) Transverse process

c) Articular processes (superior & inferior)

4. Intervertebral disk- fibrocartilage = flexible support

5. Primary curve – thoracic and sacral curves appear before birth

6. Secondary curve – cervical and lumbar curves after birth

The Thorax:1. 12 thoracic vertebrae

( posterior)

2. 12 pairs of ribs (anterior):a) 1-7 true ribs

b) 8-10 false ribs

c) 11 & 12 floating ribs

3. 12 costal cartilages

4. Sternum:a) Manubrium

b) Body

c) Xiphoid process

5. Intercostal space

Appendicular Skeleton• Upper Extremities (limbs, 64 bones):

– Pectoral Girdle (all bones X 2):1. Clavicle (collar bone) - most often broken bone• Sternoclavicular joint (medial)• Acromioclavicular joint (lateral)

2. Scapula (shoulder blade)

3. Humerous (upper arm)4. Ulna (little finger side): larger of the two, medial bone

5. Radius (thumb side): lateral bone

6. Carpal bones (8 total): a) Wrist

7. Metacarpals (5 bones):a) Palm of hand

8. Phalanges (14 bones):a) Metacarpophalangeal joint (MP joint, knuckles):

b) Thumb: I1) 2 phalanges

2) Proximal and distal interphalangeal joint (IP joint)

c) Fingers: II – IV

1) 3 phalanges per finger

2) Proximal, middle, and distal

3) Proximal interphalangeal joint (PIP joint)

4) Distal interphalangeal joint (DIP joint)

• Lower Extremities (legs, 62 bones):– Pelvic Girdle (limbs, 62 bones): Ossa coxae

1. Hip bone- really 3 (6) bones fused together, transfers weight to femur, all 3 form the ball & socket joint

a) Ilium – superior lateral prominence of hip

b) Ischium – inferior, strongest to bear weight when seated

c) Pubis – anterior, joined by the symphysis pubis

2. Femur (thigh 2) – longest, strongest, heaviest bone

3. Patella (knee cap 2) – sesamoid bone in the quadricep femoris tendon, prevents wearing across joint

4. Fibula (2)- smaller of the two bones in lower leg, adds strength to ankle

5. Tibia (shin 2)- larger of two bones in lower leg, supports body weight

6. Tarsals (ankle 14)- includes heelbone (calcaneus), raises body, forward thrust for walking and running

7. Metatarsals (sole 10)- improves stability, absorbs shock

8. Phalanges (toes 28) – provides stability

Articulations• Types of joints

A. Fibrous: lack a joint cavity, tightly joined by fibrous connective tissue, generally immovable in adults

1) Sutures – skull only

2) Syndesmoses – collagenous fibers hold two bones close together but not touching (ulna/radius – moveable, tibia/fibula – not much movement allowed)

3) Gomphoses - fibrous joint made up of a peg in a socket (teeth)

B. Cartilaginous: no joint cavity, bones united by a plate of hyaline cartilage

1) Synchondroses – permit growth not movement, temporary joint formed by the epiphyseal growth plate of long bones

2) Symphyses – fibrocartilaginous disks to absorb shock (vertebrae and pubic symphysis)

C. Synovial: articular cartilage surrounded by collaginous fibers and supported by ligaments, allow for the greatest range of motion

1) Hinge

2) Pivot

3) Condyloid

4) Gliding

5) Saddle

6) Ball and Socket

Hinge Joints• Uniaxial only• Very strong

collateral ligaments

• Permit flexion and extension

• Elbow, finger, knee, and ankle

Pivot Joints• Uniaxial

• Rotates around a central axis

• Atlantoaxial joint between the atlas and axis vertebrae and the radius/ulna articulation

• http://davisplus.fadavis.com/wilkinson/animations.cfm

Condyloid Joints• Biaxial• Metacarpophal

angeal (knuckles) joints except the thumb

• Flexion/extension, abduction/adduction, and circumduction.

Gliding Joints• Almost always

small• Flat articular

surfaces so one bone slides on another bone with minimal axis of rotation, if any

• Adjacent vertebrae, carpals, and tarsals

Saddle Joints• Multiaxial –

movement in 3 or more directions, abduction/adduction, opposition and reposition

• Opposing articular surfaces resemble saddles, both have concave and convex surfaces

• Carpometacarpal joint of thumb

Ball and Socket Joints• Multiaxial Flexion,

extension, medial (internal) rotation, lateral (external) rotation, abduction, adduction, and circumduction

• Globelike head of one bone fits into the cuplike concavity of the other

• Most freely moving joint of all, allowing movement in almost infinite number of directions

• Shoulder and hip

The Knee