Skeletal system - general knowledge Flashcards
How many bones are in the human body?
approximately 206
Functional divisions of the skeletal system?
- axial: bones of head neck and trunk
- appendicular: bones of extremities/limbs
What is included in the axial skeleton?
- Skull
- hyoid bone
- vertebrae
- ribs
- sternum
- sacrum
What is included in the appendicular skeleton?
- pectoral girdle
- upper extremities
- lower extremities
- pelvic girdle
Skeleton is composed of….
cartilage and bones
What is cartilage and what is its function?
avascular connective tissue that offers flexibility to the skeleton
How does cartilage obtain nutrients?
by diffusion because it is avascular
What is articular cartilage?
cartilage that covers articulating surfaces of bones that participate in synovial joints, providing a smooth, low friction surface for movement
What is bone tissue?
living, hard, connective tissue that makes up most of the skeleton
Functions of bones?
- support
- protection
- mechanical movement
- storage of salts
- continuous supply of blood cells
What is periosteum?
fibrous connective tissue that covers bones, except when cartilage is present, and provides attachment surface for tendons and ligaments
What is perichondrium?
fibrous connective tissue that covers cartilage
Types of bone?
compact and spongy
Describe compact bone
thin layer of bone that surrounds spongy bone
-found in greater amounts near the shafts of weight-bearing bones
Describe spongy bone
- central compartment of bones
- composed of large and numerous spaces
- contains trabeculae
- sometimes replaced or combined with medullary cavities
What are medullary cavities?
yellow (fatty) or red (blood cell and platelet forming) bone marrow
Bones are classified by what shapes?
- long
- short
- flat
- irregular
- sesamoid
Define long bones
tubular and long such as humerus and femur
Define short bones
cuboidal and only found in ankle and wrist
Define flat bones
flat and usually serve protective function such as the bones of the skull
Define irregular bones
are not long, short or flat such as bones of the face
Define sesamoid bones
develop in the tendons and protect them from wear and change the angle of tendons as the pass to attachments
What is the significance of bone markings?
they appear wherever tendons, ligaments or fascia are attached, wherever arteries lie adjacent to or enter bones or in relation to passage of a tendon
Parts of a bone
diaphysis, epiphyses, epiphyseal plate and epiphyseal line
Define diaphysis
shaft of the bone where growth develops
Define epiphysis (plural epiphyses)
end of a bone
Define epiphyseal plate
cartilaginous plates between epiphyses and diaphysis of bones that prevent fusion during long bone growth
Define Epiphyseal line
seam formed during fusion of diaphysis and epiphyses
What are the 3 types of joints?
- fibrous
- cartilaginous
- synovial
Define a fibrous joint
- united by fibrous tissue
- movement dependent on length of fibers uniting articulating bones
Types of fibrous joints
- sutures (synarthrosis)
- syndesmosis
- dentoalveolar syndesmosis (gomphosis or socket)
What are suture joints?
a type of fibrous joint that interlocks along a wavy line or overlaps
ex: skull
What are syndesmosis joints?
a type of fibrous joint that is united with a sheet of fibrous tissue (ligament or fibrous membrane)
ex: interosseous membrane that joins radius and ulna
What are dentoalveolar syndesmosis?
a type a fibrous joint between a pig-like process and socket articulation
ex: tooth root and alveolar process of jaw
Types of cartilaginous joints?
- primary cartilaginous joints (synchondroses)
- secondary cartilaginous joints (symphyses)
Define cartilaginous joints
a joint that is united by hyaline cartilage or fibrocartilage
What is a primary cartilaginous joint?
- a type of cartilaginous joint that is united by hyaline cartilage.
- permits growth and slight bending during development
- usually temporary and eventually fuse and calcify
What is a secondary cartilaginous joint?
- a type of cartilaginous joint that is united by fibrocartilage ex: intervertebral discs and pubic symphysis
- it is strong and slightly moveable
- provides shock absorption, strength and flexibility
Define synovial joint
-most common type of cartilaginous joint that is united by joint capsule that encloses articular cavity. It provides free movement between the two bones it connects and is reinforced by accessory ligaments or thickening of the joint capsule
Describe joint capsule structure
outer fibrous layer that is lined by inner serous synovial membrane
What is a joint cavity?
a potential space in a synovial joint that contains small amount of lubricating synovial fluid
What is the function of the synovial membrane and where is it located?
it functions to secrete synovial fluid into the joint cavity and it lines the outer fibrous layer of the joint capsule
What is articular cartilage?
it covers articulating surfaces of bones
What are the 6 types of synovial joints?
- plane
- hinge
- saddle
- condyloid
- ball and socket
- pivot
Define a plane joint
a type of synovial joint that allows gliding movements along plane of articulation
ex: acromioclavicular joint (acromium:clavicle joint)
Define a hinge joint
a type of synovial joint that allows flexion/extension only in sagittal plane around a single transverse axis. Usually reinforced laterally by collateral ligaments
ex: elbow joint
Define a saddle joint
a type of synovial joint that allows abduction/adduction as well as flexion/extension around 2 axes that are perpendicular to each other: sagittal and frontal
ex: carpometacarpal joint of the thumb
Define a condyloid joint
a type of synovial joint that allows abduction/adduction as well as flexion/extension but movement in the sagittal plane is more free
ex: metacarpophalangeal or radiocarpal joints
Define ball and socket joint
a type of synovial joint that allows movement in multiple planes: abduction/adduction, flexion/extension, medial rectus/lateral rectus, circumduction
ex: hip or shoulder joint
Define a pivot joint
a type of synovial joint that allows for rotation around a central axis
ex: median atlantoaxial joint (C1 rotates around the dens of C2)
Hilton’s law states…
nerves supplying a joint also supply the muscles moving the joint and the skin covering their distal attachments
Describe origin, location and function of articular arteries supplying joints
-arise from vessels around the joint, are located in the joint capsule and often form communication networks to ensure blood supply/distribution
What does anastomose mean?
to communicate through cross-connection or adjacent channels
What are periarticular anastomoses?
networks of arteries that communicate and ensure blood supply/distribution to an area
Describe location and function of articular veins supplying joints
communication veins that accompany arteries (venue comitantes)
Describe origin of articular nerves supplying joints
most are branches of nerves supplying muscles that move the joint except distally (hands and feet) they are branches of the cutaneous nerves supplying overlying skin
Describe the function of articular nerves supplying joints
they transmit sensory impulses that contribute to sense of proprioception
What is proprioception?
awareness of movement and position of parts of the body
Distribution of nerve fibers in a joint
- few in synovial membranes making then insensitive
- numerous in fibrous layer of joint capsule and accessory ligaments, making injuries to these very painful
