Transcript Skeletal system

Skeletal system
Skeleton
• Axial Skeleton
• Support and protect
organs of the head,
neck, and trunk
• Skull
• Vertebral Column
• Thoracic cage
• Appendicular
Skeleton
• Bones of limbs
• Bones that anchor
limbs to axial skeleton
• Pectoral Girdle
• Pelvic girdle
Functions
• 1. Support
– A hard framework that supports the weight of
the body and cradles its soft organs
Functions
• 2. Protection
– Skull forms a protective case for the brain
– Vertebrae surround spinal cord
– Rib cage protect the organs of the thorax
Functions
• 3. Movement
– Skeletal muscles attach to the bones by
tendons and use the bones as levers to move
the body and its parts.
– The arrangement of bones and the structure
of the joints determine the types of movement
that are possible
Functions
• 4. Mineral Storage
– Reservoir for minerals, especially calcium and
phosphate
– Stored minerals are released into the
bloodstream as ions for distribution to all parts
of the body as needed.
– If body needs more, osteoclasts break down
bone to release Ca into blood
– Osteoporosis: disorder caused by excessive
loss of bone volume and mineral content
*Bones easily fractured
*Most common in light skinned females
after menopause
*Risk increases if decrease calcium
intake, decrease exercise, and
decrease estrogen
*May be prevented if dietary intake of
800mg Ca before age 35, regular
excercise
Functions
• 5. Blood-cell formation
– Bones contain red and yellow bone marrow in the
cavity of long bones, spongy bone, osteonic canals of
compact bone.
– In adults red marrow is found in spongy bone of ribs,
sternum, vertebrae, pelvis and epiphyses of humerus
and femur
– Red marrow makes the blood cells (red, white, and
platelets), and yellow marrow is a site of fat storage,
with little or no role in blood-cell formation
– With increase age, red marrow is replaced by yellow
marrow.
Classification of Bones
• The shape of each bone fills a particular
need
• Bones are classified by their shape as
long, short, flat or irregular
1. Long Bones
• Long bones are longer than they are wide
• Most bones in the limbs are long bones
• named for elongated shape, not for overall
size
2. Short Bones
• Roughly cube shaped
• Ex. Bones of wrist
• Sesamoid bones are a special type of
short bone that forms within a tendon
(patella)
3. Flat Bones
• Flat bones are thin, flattened, and usually
curved.
• Ex. Skull, ribs, sternum, and scapula
4. Irregular Bones
• Various shapes that don’t fit into previous
categories
• Ex. Vertebrae and hip bones
Gross Anatomy of Bones
• Compact bone: almost every bone of the
skeleton has a dense outer layer that looks
smooth and solid to the naked eye. This
external layer is compact bone.
Composes the wall of the diaphysis
• Internal to this is spongy bone (cancellous
bone) a honeycomb of small needle like or flat
pieces called trabeculae (little beams)
Open spaces between the trabeculae are
filled with red or yellow bone marrow
Found in epiphysis, lightweight
Structure of a Typical Long
Bone
A. The tubular diaphysis or shaft forms the long axis of
a long bone
B. The epiphyses are the ends of bones
C. Periosteum- covering of the bone, made of fibrous
c.t.; place of attachment for ligaments and tendons,
helps repair bone tissue
D. Medullary cavity- hollow chamber in the diaphysis;
lined by the endosteum, filled with marrow (marrow
cavity)
Bone Structure
• Matrix is dense and mostly calcium phosphate
with some collagen fibers
• -contains bones cells within pockets (lacunae)
• 1. Osteocytes- mature bone cells which recycle
calcium in the matrix and repair damaged bone
• 2. osteoblasts- cells actively depositing bone
matrix
• 3. osteoclasts- cells actively removing bone
matrix
• Functional Unit of Bone is the Osteon.
– Osteocytes are arranged in concentric layers
(lamellae) around a central canal which
contains one or more blood vessels
• Narrow passageways (canaliculi) extend
between the lacunae and blood vessels to
form a network for exchange of nutrients,
gases, and wastes
Bone Development and Growth
• During development cartilage is replaced by
bone (ossification)
• 2 types:
– Intramembranous ossification
• Occurs in the deeper layers of the dermis (fibrous
connective tissue)
• Some skull bones, mandible, clavicle
Endochondral ossification
– Most bones form this way
– Within cartilage
– 1. cavities form within the cartilage
– 2. blood vessels grow around the edges
– 3. cartilage cells convert to osteoblasts & a layer of
bone forms around the shaft
Endochondral ossification
– 4. blood vessels penetrate the central region &
osteoblasts start producing spongy bone
– 5. remodeling forms the marrow cavity & bone of
the shaft becomes thicker & the cartilage near the
epiphysis is replaced by bone
Increasing the length of bone
• 1. Osteoblasts from the diaphysis continually
invade the cartilage of the epiphyses & ossify
• 2. new cartilage is continually added to the
epiphyses. This region is the epiphyseal
plate. This causes the bone to lengthen.
Increasing the length of bone
• 3. at puberty, the onset of hormones
stimulates bone growth. Osteoblasts produce
bone faster than the cartilage can keep up.
The epiphyseal plate narrows and
disappears. The epiphyseal line is all that
remains. THE BONE STOPS GROWING
Axial Skeleton
• Bones of the skull, thoracic cage, & vertebral
column
The skull (22 bones)
Cranium
•
•
•
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Occipital bone: posterior & inferior surfaces
Frontal bone: forms forehead & roof orbits
Parietal bones (2): superior & lateral surfaces
Temporal bones (2): lateral & inferior
Sphenoid bone: extends from one side, behind the eyes,
and to the other side
• Ethmoid bone: forms part of the orbital wall, floor of
cranium, roof of nasal cavity, & nasal septum
Face
• Maxillae (2): forms upper jaw
• Palatine bones (2): form posterior of hard palate (roof of
mouth)
• Nasal bones (2): extend from bridge of nose to nares
• Vomer: inferior portion of nasal septum
• Inferior nasal conchae (2): scroll like bone in nasal cavity
• Zygomatic bones (2): Cheek bones
• Lacrimal bones (2): smallest; in the medial portion of
each orbit
• Mandible: lower jaw
Vertebral Column (26 bones)
• Vertebrae (24)
– Cervical vertebrae (7)
• Neck; C1-C7
• Sacrum
– 5 bones fused into 1
• Thoracic (12) vertebrae
– Midback; articulates
with the ribs; T1--T12
– Lumbar (5) vertebrae
» Lowerback; L1L5
Coccyx
4 bones fused into 1
Vertebra anatomy
• 1. body-supports weight
• 2. vertebral foramen- opening for spinal cord
• 3. transverse process- site of muscle
attachment; may articulate with ribs.
• 4. spinous process- posterior projection (what
you feel)
• 5. superior & inferior articular processes where
vertebrae articulate with one another
• Intervertebral discs- discs of fibrocartilage which
help absorb shock
Thoracic Cage
• Ribs (costae) 12 pairs
– 1-7 Vertebrosternal (true) ribs connected to
vertebrae & sternum
– 8-12 (false ribs)
• 8-10 Vertebrochondral ribs connected to vertebrae,
ribs fused together to connect to sternum
• 11-12 vertebral ribs (floating ribs) connected to
vertebrae only
• Sternum (breast bone)
– Manubrium-articulates with clavicles & 1st ribs
– Body- ribs attach here
– Xiphoid process- diaphragm and abdominal
muscle attach here
Appendicular Skeleton
• 126 bones
• 1. Pectoral girdle (shoulder girdle)
– Connect arms to trunk of body
– A. clavicle (2) (collarbone) s-shaped bones;
articulate with manubrium of sternum
– B. scapula (2) (shoulder blade) triangular
bones; articulate with the humerus
• 2. humerus (2)
– Extends from the scapula to the elbow
• 3. Ulna (2)
– Bone of forearm (medial)
– Forms the point of the elbow
• 4. Radius (2)
– Bone of forearm (lateral)
• 5. Carpals (16)
– Bones of the wrist (capitate, hamate, lunate,
pisiform, scaphoid, trapezium, trapezoid,
triqetrum)
• 6. Metacarpals (10)
– Bones of the hand
• 7. phalanges (56)
– Bones of the fingers, thumbs, and toes
– 2bones in each thumb and great toe
• 8. Pelvic girdle
– Connect the legs to the axial skeleton
– A. coxa (2) (hip bone) a fusion of 3 bones
• 1. ilium- large flared bones
• 2. ischium- inferior & posterior; the body weight is
on this when seated
• 3. pubis- inferior & anterior; the two pubic bones
articulate at the pubic symphysis (a pad of
fibrocartilage
• b. differences between male and female
pelvis
– 1. women- enlarged pelvic outlet; less
curvature of the sacrum & coccyx; low pelvis;
pubic arch greater than 100°
– 2. men- opposite of above; pubic arch 90° or
less
• 9. femur (2)
– Bones of thigh
– Longest and heaviest bones of the body
• 10. Patella (2)
– Bones of the knee
• 11.tibia (2)
– Large medial bone of the lower leg (shin)
• 12. fibula (2)
• Slender lateral bone of the lower leg
• 13. tarsals (14)
– Bones of the ankle
• A. talus -2nd largest foot bone; articulates with the
tibia
• B. calcaneus- heel bone; largest bone of the foot
• 14. metatarsals (10)
– Bones of feet
JOINTS: WHERE TWO
BONES MEET
• JOINTS, OR PLACES WHERE TWO
BONES COME TOGETHER, PERMIT
THE BONES TO MOVE WITHOUT
DAMAGING EACH OTHER.
• Joints are responsible for keeping bones
far enough apart so they do not rub
against each other as they move. At the
same time, joints hold the bones in place.
• THE CLASSIFICATION OF JOINTS IS BASED
ON THE AMOUNT OF MOVEMENT POSSIBLE:
•
A. SYNARTHROSIS IS AN IMMOVABLE
JOINT; THEY ARE OFTEN CALLED FIXED
JOINTS, AND ALLOW NO MOVEMENT
BETWEEN BONES. These joints are
interlocked and held together by Connective
Tissue, or they are fused together. The places
where the bones of the SKULL meet
(SUTURES) are examples of immovable joints.
•
B. AMPHIARTHROSIS IS A SLIGHTLY
MOVABLE JOINT. (SEMI MOVABLE
JOINTS) These joints permit a small
amount of movement. These bones are
farther apart from each other than
immovable joint bones. The joints between
the two bones of the lower leg (TIBIA and
FIBULA) and the joints of the vertebrae
are examples of slightly movable joints.
• C. DIARTHROSIS IS A FREELY
MOVABLE JOINT. MOST OF THE
JOINTS OF THE BODY ARE FREELY
MOVABLE JOINTS.
• In Synovial Joints, the ends of the bones
are covered with a layer of Cartilage that
provides a smooth surface at the joint.
• The joints are also surrounded by a
Fibrous Joint Capsule that helps hold the
bones together and at the same time
allows for movement.
Fibrous Joint Capsule
• One of the layers of the joint capsule may
thicken to form ligaments.
• ligaments are attached to the membranes
that surround bones and hold bones
together and in place.
• The synovial memberane of the joint
capsule produces synovial fluid, which
forms a thin lubricating film over the
surface of a joint and protects the ends of
bones from friction.
• In some freely movable joints, small pockets of
synovial fluid called bursae form. Bursae
reduce the friction between the bones of a joint
and also acts as a tiny shock absorber.
• If a joint is injured, too much fluid moves into the
bursa, causing it to swell and become painful, a
condition called BURSITIS.
• 9. A more serious disorder that affects the
joints is ARTHRITIS or INFLAMMATION
OF THE JOINT. There are Two Forms of
Arthritis that affect joints.
•
A. RHEUMATOID ARTHRITIS develops when the Immune System
begins to attack the body. The joints
become inflamed, swollen, stiff, and
deformed.
•
B. OSTEOARTHRITIS - a
Degenerative Joint Disease (DJD) in
which the cartilage covering the surface of
bones becomes thinner and rougher. As
a result, bone surfaces rub against each
other, causing severe discomfort.
• Synovial Joints are grouped according to the
shapes of surfaces of the adjacent bones.
•
• A. BALL AND SOCKET JOINT - Permits
circular movement - the widest range of
movement. THE SHOULDER Joint, which
enables you to move your arm up, down,
forward and backward, as well as to rotate it in a
complete circle.
•
B. HINGE JOINT - Permits a back-and-forth
motion. The Knee enables your leg to flex and
extend. The Elbow, which allows you to move
your forearm forward and backward.
•
C. PIVOT JOINT - Permits rotation of one
bone around another. The elbow enables your
hand to turn over. It also allows you to turn your
head from side to side.
•
D. GLIDING JOINT - Permits a sliding
motion of one bone over another. Found at the
ends of the collarbones, between wrist bones,
and between anklebones.
•
E. SADDLE JOINT - Permits movement in
two planes. This type of joint is found at the
base of the thumb.
•
F. CONDYLOID JOINT - Allows for a hinge
type movement in two directions. The joints
that connect fingers with the palm and toes with
the soles of feet are examples.
Types of movement and
examples (with muscles)
flexion- move lower leg toward upper
extension- straightening the leg
hyperextension- increasing the angle past normal
abduction- moving leg away from body
adduction- movong leg toward the body
rotation- around its axis
supination- rotation of arm to palm-up position
pronation- palm down
circumduction- swinging arms in circles
inversion- turning foot so sole is inward
eversion- sole is out
Elevation and depression- raising body part up
or down
• Dorsiflexion-flexion of ankle elevation of sole
(stand on heels)
• Plantar flexion- extend ankle elevate heel (stand
on tip toes
• Protraction moving forward (thrusting chin
forward)
• Retraction- moving a part backward (pulling chin
back)
• Opposition-touching the thumb to the little finger
• Gliding- bones glide past each other (carpals,
tarsals, vertebrae)
Types of bone breaks
Simple (Closed)- skin is not pierced
Compound (Open)- skin is pierced
Complete- bone is broken in half
Incomplete- not broken through
Linear-parallel to the long axis
Transverse- perpendicular to the bone’s long
axis
Compression- bone is crushed
Greenstick- incomplete break on outer arc (the way a
green twig breaks)
Comminuted- broken into several pieces (3+)
Spiral- twisted (common sports fracture)
Epiphyseal- epiphysis separates from the diaphysis
along the epipyseal plate
Depressed- broken bone portion pressed inward (typical in
skull fracture)
Fracture repair (189p)
Hematoma- blood clot in space between edges
of break
Fibrocartilage callus- begins tissue repair
Bony callus- osteoblasts produce trabeculae
(structural support) of spongy bone and
replace fibrocartilage
Remodeling- osteoblasts build new compact bone,
osteoclasts build new medullary cavity