Topic 18: The Skeletal System

- there are 206 bones in the human skeleton (adult)

Skeletal anatomy
1.  Axial skeleton is the skull and trunk (80 bones, includes ear ossicles)
2.  Appendicular skeleton is the limbs and girdles (függestőövek) (126 bones)

1.  Axial skeleton

Cranium/Skull (agykoponya) are the bones of the head

Source:  http://www.rugusavay.com/information-on-skull-anatomy-and-functions/

Source:  http://www.kidport.com/reflib/science/humanbody/skeletalsystem/Skull.htm

-at the base of the occipital bone there is a large hole called the occipital foramen (öreglyuk), from which the spinal cord leaves the brain

Vertebral Column 

- formed of vertebra (in the following types and numbers) separated by cartilaginous discs (to absorb shock) 

Source:  http://teachmeanatomy.info/back/vertebral-column/

-although the vertebra do vary somewhat in shape and size between the groups, they generally all share the same basic structure

Source:  http://www.lower-back-pain-toolkit.com/lumbar-spinal-stenosis.html

- the first two cervical vertebra below the skull, the atlas and the axis, are quite different from the rest

Source:  http://legacy.owensboro.kctcs.edu/gcaplan/anat/notes/api%20notes%20h%20skeletal%20vertebrae.htm

Ribs/Thoracic Cage (mellkas)

- there are 12 pairs of ribs, all twelve are attached at the back to thoracic vertebrae

- ribs can be referred to as true ribs (pairs 1-7) when they connect directly to the sternum (szegycsont)

- false ribs (pairs 8-12) are connected to the sternum only via costal cartilage or not at all.  Pairs 11 and 12 are not connected at all and are thus referred to as floating ribs.

Source:http://www.edoctoronline.com/medical-atlas.asp?c=4&id=22092

The ribs in red are "true" ribs, while the green and blue ones are "false" ribs.  The blue ribs are "floating" ribs
Source:  http://en.wikipedia.org/wiki/Rib_cage

2.  Appendicular Skeleton

Pectoral Girdle (vállöv) - scapula (shoulderblade - lapockacsont) and clavicle (collarbone - kulcscsont)

Arm - humerus (felkarcsont), ulna (singcsont) and radius (orsócsont), carpals (form the wrist - kéztőcsontok), metacarpals (form the palm of the hand - kézközépcsontok), phalanges (ujjpercek)

Source:  http://www.rci.rutgers.edu/~uzwiak/AnatPhys/APFallLect10.html

Pelvic Girdle (medenceöv) - made up of numerous bones that are fused together

Source:  http://www.studyblue.com/notes/note/n/appendicular-skeleton-lower-extremities/deck/2699280

Leg:  femur (combcsont), patella (kneecap - terdkalács), tibia (sípscont) and fibula (szárkapocscsont), tarsals (form the ankle - lábtőcsonok), metatarsals (form the body of the foot - lábközépcsontok) and phalanges (toes - ujjpercek)

Source:  http://www.web-books.com/eLibrary/Medicine/Physiology/Skeletal/Divisions.htm

Bone Structure and Growth

Long or shaft bones: 

- the shaft of the bone is formed by compact bone tissue

- the outer surface is covered by the periosteum (csonthártya), which is dense connective tissue with vessels and nerves to protect and repair bone tissue

- protuberances (dudorok) can be found on the bone surface for muscle attachment

- the shaft of the bone is hollow and filled with yellow bone marrow, which is primarily adipose tissue in adults, but can revert to red marrow in case of life-threatening blood loss.

-the head of the bone is formed of spongy bone tissue, which is interspersed with red bone marrow, which produces red and white blood cells.  The bone network in spongy bone is capable of reorganizing if stress and strain on the bone changes.

- the head of the bone is covered with a protective layer of cartilage

- growth in length of a long bone occurs at both ends (at the epiphyseal plate), growth in width occurs beneath the periosteum.  

Source:  http://mmaarriiaa0.tripod.com/id6.html

-other bones types are short bones (eg. carpals),  flat bones (eg. scapula), irregular bones (eg. vertebra) and sesamoid bones (eg. patella)

Joints/articulations (ízületek/összeköttetések)
- 3 kinds:  fixed (fibrous), semi-movable (cartilaginous), movable (synovial)

1.  Fixed (fibrous)
- the cranium contains multiple fixed joints, the points where 2 bones meet are called sutures

2.  Semi-movable (cartilaginous)
- the joint has some ability to move, for example bending or twisting, but it is limited motion.  A good example are the joints between vertebra

3.  Movable (synovial)
- these joints have free movement.  There are multiple kinds of joints
a. pivot joints (forgóízület): one bone rotates around the "pivot" of the other bone allowing side to side, up and down motion, eg. atlas and axis at base of skull, radius and ulna as hand turns inward or outward
b. hinge joints (hengerízület):  movement only in one plane, like a door opening and closing.  eg. elbow, knee
c.  gliding joints (tojásízület):  limited motion in all directions as bones slide past each other eg. wrist
d.  ball and socket joints (gömbízület):  allow for rotation eg. shoulder, hip 

Source:  http://www.tooloop.com/skeletal-system-types-of-joints/skeletal-system-types-of-joints/

Ligaments (ízületiszalag)

- they are like tough elastic bands

-made of dense connective tissue

- connect bone to bone

Of the various joints, the semi-movable and movable joints contain cartilage to reduce friction between the bones.  The movable joints also often have bursa (ízüetitok), which are small sacs filled with synovial fluid (consistency of egg-whites), that help to cushion and absorb shock.