the skeletal system
Post on 24-Feb-2016
21 Views
Preview:
DESCRIPTION
TRANSCRIPT
The Skeletal System Organs – bones, joints, cartilage,
ligaments
FunctionsA. Support – hard framework that supports
and anchors all soft organs of the body – Ex. Legs act as pillars to support trunk, rib cage supports thorax wall
B. Protection – skull protects brain, ribs protect heart/lungs, zygomatic arch protect the eye
C. Movement – skeletal muscles, attached to bone by tendons, used the bones as levers to move the body and it’s parts; arrangement of bones and the design of joints determine the types of movement possible
Functions (con’t)D. Storage
Fat stored in the internal cavities Bone matrix stores minerals (Ca+2) –
“deposits” and “withdrawals” of minerals to and from bones goes on almost continuously
E. Blood cell formation (hemopoiesis) Carried on in red bone marrow; hemopoietic
tissue – Fig. 6-5 Hemopoietic tissue is found in the ends of
long bones Transformed to yellow bone marrow, an inactive
fatty tissue, as person ages
Classification of BonesA. Classified according to shapeB. Contain different proportions of
1. Compact bone (smooth & homogeneous)
2. Spongy (cancellous) bone – spaces & trabeculae (beams)
Classification of BonesC. Long bones
1. Longer than they are wide
2. Consists of a shaft plus two ends 3. Primarily compact bone; but may contain
substantial amounts of
spongy bone
Classification of BonesD. Short bones
1. Roughly cube-like – ex. Wrist/ankle 2. Mostly spongy bone; compact bone only
provides a thin surface
Classification of BonesE. Flat Bone
1. Thin, flattened and usually a bit curved –
sternum, ribs, most skull bones2. Two roughly parallel compact bone
surfaces with a layer of spongy bone between
Classification of BonesF. Irregular bones – some skull, hip,
vertebrae1. Fit none of the preceding classes2. Complex shapes3. Mainly spongy bone enclosed by thin layers
of compact bone
G. Sesamoid bones –a special type of short bone
embedded within a tendon; ex. - patella
Bone Structure – 2 levelsA. Gross Anatomy – What you can see with the naked eye - Fig. 6-1B. Microscopic Anatomy – Fig. 6-2, 6.3
Gross AnatomyLong Bone – most have the same basic structure
1. diaphysis (shaft) – hollow tube of hard compact bone2. medullary cavity – hollow area; contains yellow bone marrow3. epiphyses – bone end or extremities; usually more expanded
than diaphysis; thin layer of compact bone forms exterior;interior spongy bone filled with red bone marrow4. epiphyseal line/plate – remnant of cartilage present at junction of diaphysis & epiphyses in young bones; growthare that allows bones to lengthen5. articular cartilage – found where long bones articulate (join);cushions the bone ends and absorbs stress during joint movement6. periosteum – outer surface of diaphysis; richly supplied withnerve fivbers, lymphatic vessels, and blood vessels which entervia nutrient canals7. endosteum – fibrous membrane that lines medullary cavity
Gross Anatomy
Microscopic AnatomyCompact bone – Fig. 6-2, 6-3
1. Haversian system – structural unit; circular 7 tubelike;composed of calcified matrix arranged in multiple
layers (one inside the other – like an onion)2. osteocytes (bone cells) – regulate the removal of calcium from
bone matrix
Osteocyte (within lacuna)
Microscopic AnatomySpongy bone
1. Trabeculae – structural unit2. Osteocytes – only a few cell layers thick; no Haversian system3. Nutrients reach osteocytes by diffusion
Microscopic AnatomyCartilage – Fig. 6-4
1. Fibers embedded in gel (not calcified matrix)2. Chondrocytes (cartilage cells)3. Cartilage contains no blood vessels; nutrients diffuse
through matrix4. Function
a. supports & reinforcesb. cushioning propertiesc. resists compressive stress (articular
cartilage)
Microscopic Anatomy
Bone Development(osteogensis) – Fig. 6-5
A. Intramembranous ossification – flat bones form from fibrous membrane – ex. Skull, clavicle, ribs
B. Endochondral ossification – bone formation from hyaline cartilage structures; most bones form this way;
osteoblasts – bone forming cellsosteoclasts – bone reabsorbing cells
Endochondral Ossifcation – Fig.
Cartilage model is the starting point
Endochondral Ossifcation – Fig.
Formation of a bone collar around the shaft of the hyaline cartilage model
Endochondral Ossifcation – Fig.
Cartilage matrix calcifies; chondrocytes die
Endochondral Ossifcation – Fig.
Invasion of internal cavities by periosteal bud and spongy bone formation (3 mo. embryo)
Endochondral Ossifcation – Fig.
As the primary ossification enlarges, osteoclasts break down spongy bone & form medullary cavity
Ossification of epiphyses- development of secondary ossification centers in epiphyses;
cartilage begins to become bone- when complete cartilage remains only at epiphyseal surfaces
(articlular cartilage) and at the epiphyseal plate
Endochondral Ossifcation – Fig. 6-5
Bone growth continues during infancy & youth- long bones lengthen at epiphyseal plate- long bones thicken by a process called appositional growth (inside breaks down at a
slower rate than exterior builds up)- some facial bones (nose, mandible) grow
throughout life
Endochondral Ossifcation – Fig. 6-5
The Skeleton – 206 bones
Axial skeleton – forms long axis of body & includes the bones of the skull, vertebral column, and rib cage
Appendicular skeleton – bones of upper and lower extremeties and girdles (shoulder/hip)
The Axial Skeleton – 80 bonesA. Skull – body’s most complex bony
structure – Fig. 6-81. Cranial bones (8)
a. site of attachment of head muscles
b. enclose & protect brain & organs of hearing & equilibrium
Cranial Bones (red highlight)
The Axial Skeleton – 80 bones2. Facial bones (14)
a. form framework of faceb. hold eyes in an anterior positionc. provide cavities for the organs of
taste & smell and openings for the
passage of air & food
d. secure teethe. anchor the facial muscles of
expression
Facial Bones (black & nasal concha)
The Axial Skeleton – 80 bones3. Middle ear bones (6) – used in sense of
hearing
The Axial Skeleton – 80 bones4. Sutures – interlocking joints of skull
bones
The Axial Skeleton – 80 bonesB. Vertebral column – 26 irregular bones
that form a flexible curved rod that supports the body trunk1. Provides attachment points for ribs &
muscles of back2. Division of spine – curvature increases
strength, resilience & flexibility of spine,
making it function like a spring rather than
a rod
Vertebral Column
The Axial Skeleton – 80 bonesC. Thorax – 12 pairs of ribs (both male &
female),sternum, thoracic vertebrae, costal cartilage1. Forms protective cage around thoracic organs2. Supports shoulder girdles & upper limbs3. Provides attachment points for the muscles
of the back, chest, & shoulders4. Intercostal spaces – occupied by inter-
costal muscles which elevate & depress
during breathing
Rib Cage
The Appendicular Skeleton 126 bones
A. Adapted to carry out movementB. Pectoral (shoulder) girdle – clavicle,
scapulaC. Arm/hand – humerus, radius, ulna,
carpals, metacarpals, phalangesD. Pelvic girdle – coxal bones (ilium,
ischium, pubic)E. Leg/feet – femur, tibia, fibula, patella,
tarsals, metatarsals, phalanges
The Appendicular Skeleton Pectoral Girdle
The Appendicular Skeleton Arm/hand
The Appendicular Skeleton Pelvic Girdle
The Appendicular SkeletonLeg/feet
Male & Female Skeletal Differences
A. Most male skeletons are larger (no great functional importance)
B. Structural difference in pelvis1. Male - narrower2. Female – structured to cradle baby; broader, shallower,lighter, rounder
C. Pelvic brim1. Male – basically heart shaped2. Female – wider, oval from side to side
D. Coccyx1. Male – narrow, longer; less movable; curves ventrally2. Female – wider, shorter; more movable; straighter
Male & Female Skeletal Differences
Male & Female Skeletal Differences
Articulations (joints)
Two different ways to classifyStructural classification – based on material that
bindsfibrouscartilaginoussynovial
Functional classification – based on amount of movement
Articulations Synarthroses – immovable joints; fibrous
connective tissue grows between the articulating bones; - ex. Sutures of cranial bones
Articulations Amphiarthroses – slightly moveable; cartilage or
fibrous tissue connects articulating bones – ex. Symphysis pubis, ligaments, fibrous membrane between radius & ulna
Articulations Diarthroses – allow considerable movement; Fig. 6-20, 6-21,
Table 6-71. Ball & socket
a. shoulder & hip jointsb. this type of joint permits the widest range of motion
Articulations Diarthroses – allow considerable movement; Fig. 6-20,
6-21, Table 6-72. Hinge joints
a. elbow & knee, fingers, toesb. movement in 2 directions – flexion (bending), extension (straightening)
Articulations Diarthroses – allow considerable movement; Fig. 6-20, 6-21,
Table 6-73. Pivot joint
a. small projections of one bone pivots in an arch of anotherb. C2 (axis) projection pivots in arch of C1 (atlas); allows rotation of the head
Articulations Diarthroses – allow considerable movement; Fig.
6-20, 6-21, Table 6-7 4. Saddle Joint – only 1 pair
a. between metacarpal bone of thumb & carpal bone of the wristb. produces great mobility (opposable thumb);
flex & extend Abduct – moving away from midline Adduct – moving toward midline Circumduct - circle
Articulations Diarthroses – allow considerable movement; Fig.
6-20, 6-21, Table 6-75. Gliding – flat surfaces
a. least movable of all diarthrotic joints
b. joint between vertebrae or between
& carpal/tarsal bones
Articulations Diarthroses – allow considerable movement; Fig.
6-20, 6-21, Table 6-76. Condyloid joints (ellipsoid)
a. condyle fits into an elliptical socket
b. ex. – distal end of radius & carpal
bones or femur & tibia
top related