Anatomy of the Skeletal System Flashcards
What is the skeletal system comprised of?
Bone and cartilage
What are some of the key features of the skeletal system?
Serves both structural and physiological purposes
Made up of many different types of bones
What are the two major anatomical subdivisions of the skeletal system and what is included in each division?
Axial Skeleton:
Skull
Vertebrae
Ribs
Sternum
Appendicular Skeleton:
Bones of upper and lower limbs
What are some key features of cartilage?
Multiple different types
Semi rigid but flexible
Composed of chondrocytes that produce extracellular matrix
Generally avascular and has no nerve supply
What are some of the functions of cartilage?
Provides a smooth surface for bones to articulate at joints
Acts as a shock absorber
Enables the growth and development of long bones
What is the term used to describe the growth and development of long bones?
Endochondral ossification
What do bones consist of?
Calcified extracellular matrix
What doe bone cells include?
Osteocytes (surrounded by bone matrix)
Osteoblasts (bone forming cells)
Osteoclasts (bone resorbing cells)
What are the two types of bone and how can they be differentiated?
Compact bone:
Dense bone
Outer shell of all bones
Surrounds spongy bone
Trabecular (or spongy or cancellous) bone:
Found inside bones
Which bones have a periosteum and what is this term?
All bones
An outer fibrous covering
What is inside the trabecular bone?
Medullary cavity
What can the trabecular bone allow?
Allows bones to compress and allows the blood vessels to run through the bone
What are the names of the different classifications of bones and what are examples of these?
Long bone: femur
Short bone: carpal
Flat bone: frontal
Irregular bone: vertebrae
Sesamoid bone: patella
What is the main physical feature of long bones?
Greater in width than in length
What are some other key physical features of long bones?
Long shaft
Cylindrical cross-section
Usually expanded at either end (epiphyses)
Mainly compact bone with spongy bone at the ends
What are some examples of long bones?
Humerus
Phalanges (finger/toe bones)
What is the main physical feature of short bones?
Equal in width and in length
What are some other key features of short bones?
Composed of mainly spongy bone surrounded by thin layer of compact bone
Allow small movements when articulated together
Spherical
What are some examples of short bones?
Wrist (carpal) bones
Ankle (tarsal) bones
How are long and short bones defined?
Relative to their width and length
Long/short defines their shape not their size as some long bones can be smaller than short bones
Where can flat bones mostly be found?
Mostly around organs like the brain
What are the key physical features of flat bones?
Smooth and thin
Don’t have to be laid out flat
What is the structure of flat bones?
Layer of trabecular bone between two layers of compact bone
What are the main functions of flat bones?
Protect soft internal structures
Provide attachment for muscles
What are some examples of flat bones?
Bones of the skull and the sternum
What are the key features of irregular bones?
Elaborate in shape
Cannot be classified into any of the other categories
What are some examples of irregular bones?
Vertebrae
Many found in the face
Are there many sesamoid bones in the body?
No
Where are sesamoid bones located?
Form within tendons of some muscles as the tendons pass over joints
Size and distribution vary
Why is there variation in the size and distribution of sesamoid bones?
Some sesamoid bones are present in most people, other smaller ones are variable and can develop throughout life
What are some examples of sesamoid bones?
Patella (knee cap)
Pisiform (carpal bones)
What are vertebrae?
Irregular bones that can be divided into 5 groups
What are the groups that the vertebrae can be divided into and how many vertebrae are in each group?
Cervical: 7
Thoracic: 12
Lumbar: 5
Sacral (sacrum): 5
Coccygeal: 3-5 w/ coccyx
How can the vertebrae be differentiated?
Cervical have transverse foramina (passageways for vertebral artery, vein and sympathetic nerves can pass through)
Thoracic have extra articulations for ribs (“branches”/ indent points)
Lumbar have neither special feature but have a large body (kidney shaped body which is a little thicker in the front than the back)
What are the sacrum and coccyx?
Two sets of vertebrae
What is the sacrum?
Five vertebrae fused together
What is the coccyx?
Vestigial tail, often fused, made of 3-5 increasingly rudimentary vertebrae
What is a joint?
Where one bone articulates with another
What are the two basic classifications of joints?
Functional
Structural
What is the functional classification based on?
A range of motion
What are the different types of functional joints and what are some examples of their location?
Synarthrosis: fixed, does not provide any movement (skull)
Amphiarthrosis: slightly moveable (ribs and sternum)
Diarthrosis: freely moveable (hips, shoulders, knees, etc.)
What is the structural classification of joints based on?
The intervening type of tissue
What are the different types of structural joints?
Fibrous: connected by dense connective tissue, no joint cavity
(Growth plates of long bones –> fuse in late teens/early adulthood)
Cartilaginous: connected by hyaline cartilage, no joint cavity
Synovial: have a synovial, fluid filled cavity that surrounds the articulating bones
What are some examples of where fibrous joints can be located within the body?
Structures of the skull
Membranous connections between bones
Gomphosis (tooth in bony sockets)
What are some examples of cartilaginous joints in the body?
Ribs to sternum
Intervertebral discs
Growth plates of long bones
What is the mobility of synovial joints and what are examples of them?
Freely moveable, wide range of movement (diarthrosis)
Most joints of the limbs
What are the features that all synovial joints have?
Articular cartilage
Synovial/joint cavity
Joint capsule
Ligaments
