1 Unit 5 Skeletal System I. Functions A. Support: > Internal framework, structure, anchors & supports soft tissue organs B. Protection: > Protects vital organs C. Movement: > Provides attach point for muscles > Bones & muscles act as levers D. Storage: > Fat, calcium, and phosphorus E. Blood Cell Formation: (hematopoiesis) > Occurs in spongy bone within red marrow cavities
19
Embed
Unit 5 Skeletal System - Badger Anatomy & Physiology · 2 II. Division of Skeletal System A. Axial Skeleton (blue) –Skull, ribs, spine –Protects organs B. Appendicular Skeleton
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Unit 5 Skeletal System
I. Functions
A. Support:> Internal framework, structure, anchors & supports soft tissue
organs
B. Protection:> Protects vital organs
C. Movement:> Provides attach point for muscles> Bones & muscles act as levers
D. Storage:> Fat, calcium, and phosphorus
E. Blood Cell Formation: (hematopoiesis)> Occurs in spongy bone within red marrow cavities
2
II. Division of Skeletal System
A. Axial Skeleton (blue)– Skull, ribs, spine– Protects organs
B. Appendicular Skeleton (pink)– Limbs & attachments– Aids in movement
A. Compact Bone: – Very dense & smooth appearance– Long diaphysis (shaft)
B. Spongy Bone: – Small porous pieces of bone– A lot of open spaces (epiphysis)
III. Classification of Bones **All bones have external layer of compact with spongy bone internally
3
IV. Shapes of Bones
A. Long Bones:– Longer than wide– Shaft with heads on both ends– Mostly compact
B. Short Bones:– Cubelike– Mostly spongy
C. Flat Bones:– Thin, flat, curved– 2 layers compact around spongy
D. Irregular Bones:– Varieties of shapes– Don't fit other categories
4
5
A. Diaphysis – Shaft of the bone, mostly compact
bone
> Periosteum: fibrous connective tissue – Covers bone
> Medullary Cavity: space inside Diaphysis– Adults: yellow marrow (fat)– Infants: red marrow (Hematopoiesis)
B. Epiphyses: – Ends of long bones (heads), mostly
spongy bone
> Articular cartilage: hyaline cartilage– Covers end of Epiphyses– Absorbs shock & reduces friction
> Epiphyseal plate: (growth plate)– Hyaline cartilage line across epiphyses
> Epiphyseal line: – Compact bone line across epiphyses– Signifies bone done growing
V. Bone Gross Anatomy (long bone)
6
VI. Bone Microscopic Anatomy
A. Cell Types:1. Osteocytes: mature bone cells found in cavities
« Connected by gap junctions
2. Osteoblasts: boneforming cells« Will convert into osteocyte
3. Osteoclasts: bonedestroying cells
VI. Bone Microscopic Anatomy cont'd
B. Haversian Systems / Osteon: complex, consisting of a central canal & matrix rings with mature bone cells
> Lacunae: tiny cavities in which mature bone cells are found
> Lamellae: calcified matrix rings– Lacunae found in between rings– In compact bone: rings of lamellae around central canal
> Central Canals: run lengthwise through bone– Carry blood vessels & nerves
> Canaliculi: tiny canals that connect lacunae together & to central canal
> Perforating (Volkmann's) Canals: canals that run at 90 degree angles through the compact bone
7
8
A. Formation (Ossification / Osteogenesis) & Growth:
1. Embryonic Development:– Skeleton composed of fibrous membranes & hyaline cartilage – Ossification begins ~67 weeks in development
« Intramembraneous Ossification» Skull flat bones & clavicles form from fibrous membranes
« Endochondral Ossification» Other bones form from hyaline cartilage
VII. Bone Formation, Growth, and Remodeling cont'd• Endochonral Ossification Steps:
a. Bone Collar forms
b. Cavitation of the hyaline cartilage (Primary Ossification Center)> Chondrocytes hypertrophy> Surrounding matrix calcifies> Chondrocytes die (nutrient diffusion inhibited)> Matrix begins to deteriorate
– Bone collar stabilizes
c. Cavities are invaded with blood vessels, red marrow, osteoblasts,osteoclasts (known as the periosteal bud)> Spongy bone development begins (by osteoblasts)
d. Medullary cavity forms & Diaphysis elongates> Osteoclasts form medullary cavity> Diaphysis elongates due to:
– Epiphyseal cartilage dividing & ossification "chases" cartilage formation along length of diaphysis
e. Ossification of Epiphyses (Secondary Ossification Center)> Similar to primary ossification (no medullary cavity)> Hyaline cartilage remaining when secondary ossification is
complete:– Articular Cartilage– Epiphyseal Plates
(will discuss this in our next section)
10
2. Growth (early adults)> Epiphyseal plates are site of long bone growth
> Steps are as follows:– New cartilage is formed on external face of epiphyseal plate
surface that is farther away from medullary cavity
– Old cartilage on internal face of epiphyseal plate closest to medullary cavity is broken down and replaced by bony matrix
– Process controlled by growth & sex hormones« ends when epiphyseal plate is converted to bone« usually occurring at the end of puberty
> growth plate maintains constant thickness:
> rate of cartilage growth balanced by replacement of bony tissue
VII. Bone Formation, Growth, and Remodeling cont'd
2. Thoracic vertebrae: (T1T12) – Larger than the cervical, articulate with ribs
3. Lumbar vertebrae: (L1L5) – Main weight bearing vertebrae
4. Sacrum: fusion of 5 vertebrae– Articulates with hip bones – Forms sacroiliac joints
5. Coccyx: fusion of 3 vertebrae (tailbone)
*Intervertebral disk made of flexible fibrocartilage
IX. Axial Skeleton cont'd
16
17
C. Thoracic Cage
1. Sternum: – Fusion of manubrium, body, xiphoid process– Articulates with first 7 pairs of ribs
2. True ribs: first 7 pairs
3. False ribs: next 5 pairs– Share articulation point– Floating ribs last 2 pairs that are not connected to
the sternum at all
IX. Axial Skeleton cont'd
18
X. Appendicular Skeleton
A. Pectoral Girdle: allows for great flexibility/movement of arms
1. Clavicle (collar bone)
2. Scapula (shoulder blade)
B. Pelvic Girdle: weight bearing / protection– Formed by 2 coxal (hip) bones – Each formed by fusion of 3 bones in the hip socket – Hip socket called acetabulum
« Ilium« Ischium« Pubis
most anterior bone"sit down" bone,
most inferior
articulates with sacrum
C. Bones of the upper limbs:1. Humerus shoulder to elbow2. Radius thumb side of forearm3. Ulna pinky side of forearm4. Hand carpals, metacarpals, phalanges