apk exam 2 Flashcards
skeletal system
made of bones, cartilages, and joints
cartilage
- is connective tissue
- 3 types: hyaline, elastic, fibrocartilage (remember CHEF)
- abundant extracellular matrix: gel-like, fibers
- predominant cell type = chondrocytes
hyaline cartilage
- aka articulate cartilage
- end of long bones
- growth plates within bones
- costal cartilage
- respiratory structures
- embryonic skeleton
elastic cartilage
- epiglottis
- outer ear/pinna
- abundant elastic fiber in matrix
fibrocartilage
- pubic symphysis
- menisci in the knee joint
- intervertebral discs
perichondrium
- tissue around the cartilage; resists outward expansion when cartilage is under pressure; growth and repair. of cartilage
- made of dense irregular CT
- ex: around the epiglottis
functions of obones
- support
- protection
- mvmnt
- mineral storage
- hemopoiesis
- E storage
- metabolism
bone classIfications
BASED ON SHAPE, NOT SIZE
- long bone (ex: humerus, metacarpals)
- short bone (ex: talus): more cube-like, no elongated shaft
- sesamoid bone
- flat bone: flat or curved (sternum, scapula, ribs)
- irregular bone (vertebra)
sesamoid bone
type of short bone sesame seed shape
- patella, base of big toe
- derived from the tendon
- acts to alter direction when we have movement @ a certain joint like a pulley)
bone tissue
- compact; found on the outside; denser outer layer
- spongey aka trabecular bone: internal
gross anatomical features of a typical long bone
- long shaft, 2 distinct ends
- proximal epiphysis (end of the bone closest to ur joints)
- metaphysis: junction b/w the epiphysis and the diaphysis; has the epiphyseal line within this region
- diaphysis = shaft
- distal epiphysis (end of the bone farthest away from ur joints)
- articular cartilage: made of hyaline cartilage; @ edge of bone where bone meets joint; reduces friction
- compact bone; most superficial layer of the shaft and the epiphysis
- spongy bone inside; red bone marrow inside spongy bone; hemopoiesis
- periosteum: membrane around the bone; not the same as perichondrium
- medullary cavity: along the shaft; yellow bone marrow (fatty)
epiphyseal line
the epiphyseal line is this calcified area where ur growth plate used to be
- wheneevr u see the line, it is indicator tht u are looking at an adult bone
epiphysis
end part of a long bone
- interior: spongy bone
- exterior: compact
- veins and arteries running along spongy and compact bone
- articular cartilage: indicates tht ur looking at the epiphysis and not the diaphysis
diaphysis
- medullary cavity
- endosteum: membrane lining interior of the bone
- yellow bone marrow
- compact bone, dont really see spongy bone
- periosteum
- vascularization - pierce through periosteum and into the bone
- collagen fiber bundles - attach periosteum to the most outer surface of the bone
gross anatomy of short, flat, and irregular bones
- dont have medullary cavities
- outside: periosteum, compact
- inside: endosteum, spongy bone
periosteum
thick membrane tht covers the EXTERNAL bone surface
- not present @ sites covered by articular cartilage
- 2 layers:
1. superficial layer = dense irregular CT
- deep layer: osteogenic (both osteoblasts and osteoclasts present)
- sharpey’s fibers (aka perforating collagen fiber bundles) attach the periosteum to the bone tissue
osteoblast
immature bone cells which secrete the matrix tht will eventually become calcified bone
osteoclasts
breaks down bone
endosteum
thin, osteogenic membrane tht covers/lines the INTERNAL bone surfaces - BOTH osteoblasts and osteoclasts are present
- locations:
•central canal of osteons (specific to compact bone)
•covering all spongy bone trabeculae
a. medullary cavity
b. epiphyses of long bones
c. inside short, irregular, and flat bones
bone markings
- the surface of a bone reflects the stresses applies to specific locations
- projections
- joint surfaces
- depressions and openings
microscopic anatomy of compact bone
- osteon
- concentric lamellae
- circumferential lamellae
- endosteum: lines bony canals and covering trabeculae
- perforating (volkmann’s) canal
- Sharpey’s fibers aka perforating collagen fiber bundles
tip: C COVES (like sea coves)
concentric lamellae
- look like tree rings outside of the osteons
- calcified extracellular matrix tht is part of the osteon
osteon
aka Haversian system; made of multiple components - one of them is the central canal or the haversian itself; blood vessels and nerves inside the canal
circumferential lamellae
different from concentric lamellae
- go around entire circumference of the bone
- longitudinal columns; miniature weight-bearing pillars
- there is abundant extracellular matrix b/w cells
- nerve, vein, artery found inside canal
- concentric lamellar around central canal
- lacunae present with osteocytes inside
- canaliculi
perforating (volkmann’s) canal
different from central canal
- runs PERPENDICULAR to the central canal to connect b/w different osteons
canaliculi
tunnels tht run within the concentric lamellae
- osteocytes use the tunnels to reach other osteocytes - communicate with others and transfer nutrients
interstitial lamellae
the calcified extracellular matrix tht is NOT part of the osteon but is essentially filling in the gaps between the osteons
collagen arrangement in the concentric lamellae
in each of the concentric lamellae, collagen fibers run in different directions allows it to resist twisting forces
- these are different from sharpey’s fibers bc they are within the bone itself
microscopic anatomy of spongy bone
- trabecula = little beam; refers to the network structure
- each trabecula is solid bone (u will find osteocytes)
•no cavities or vessels inside
• receive nutrients from capillaries in the surrounding endosteum
- red bone marrow found in the spaces
ossification/osteogenesis
process by which bone forms
- 2 types of osteogenesis: intramembranous and endochondral
- bone formation occurs in 4 situations:
- formation of bone in an embryo
- growth of bones until adulthood
- remodeling of bone throughout life
- repair of fractures
(REAR - remodel, embryo, adulthood, repair; to rear is also to raise/grow, as in livestock)
intramembranous ossification
bone forms directly within mesenchyme arranged in layers that resemble membranes
- most skull bones and the clavicles
- mesenchyme start to form woven bone which ends up being the trabeculae. then u get some calcified matrix tht forms around the trabeculae
- so, u start with mesenchyme -> spongy bone in middle -> compact bone -> periosteum on the outside
endochondral ossification
bone forms within HYALINE CARTILAGE, replacing it
- all bones from base of skull down except for the clavicles
- start with hyaline cartilage, then the diaphysis starts to calcify & the chondrocytes in this area start to die off, forming a cavity
- spongy bone formation occurs after the formation of the cavity & vascularization occurs
- the middle starts to hollow out and ossification occurs on either end of the bone
- end up with an epiphyseal plate; this little piece of cartilage allows for bone growth to occur in childhood and adolescence
- once u are an adult & stop growing, plate will calcify, so cartilage becomes bone
endochondral ossification
bone forms within HYALINE CARTILAGE, replacing it
- all bones from base of skull down except for the clavicles
- start with hyaline cartilage, then the diaphysis starts to calcify & the chondrocytes in this area start to die off, forming a cavity
- spongy bone formation occurs after the formation of the cavity & vascularization occurs
- the middle starts to hollow out and ossification occurs on either end of the bone
- end up with an epiphyseal plate; this little piece of cartilage allows for bone growth to occur in childhood and adolescence
- once u are an adult & stop growing, plate will calcify, so cartilage becomes bone
how do bones get LONGER?
involves 2 steps:
1. cartilage growth on the epiphysis side of the epiphyseal plate
- replacement of cartilage by bone on the diaphysis side
- @ adulthood, the epiphyseal plates close and bone replaces all the cartilage leaving a bony structure called the epiphyseal line
how do bones get WIDER?
osteoblasts in the periosteum add bone tissue to the circumferential lamellae
osteoclasts remove bone from the inner diaphyseal wall at about the same rate
bone resorption
taking away bone tissue
- osteoclasts secrete HCl & lysosomal enzymes
- released ions (Ca2+) enter interstitial fluid and then the blood
- collagen fibers and dead osteocytes are phagocytosed
- if u get too much bone resorption, ur bones would be brittle
how to identify osteoclasts
they have ruffled borders which increases SA to maximize release of hcl and degradation enzymes
- has multiple nuclei
joints
articulation
- the rigid elements of the skeleton meet @ sites called articulations; not all joints are bone-bone
- joints r classified structurally based on anatomical features
- joints r classified functionally based on the type & degree of movement they permit
structural classification of joints
- based on 2 criteria:
1. presence/absence of a synovial cavity
- type of CT binding bones together
- 3 classes:
1. fibrous joints
2. cartilaginous joints
3. synovial joints
(tip: FIBing CAn be a SIN)
synvovial joints
bones held juntos by ligaments, but synovial cavities present (encapsulated cavity with fluid that reduces friction)
- ALL diarthrosis/freely movable
- has ligaments that hold bones together
- most joints in the body are synovial joints
- 6 types
- planar/plane/gliding joint
- hinge
- pivot
- condyle
- saddle
- ball and socket
fibrous joints
- not going to have synovial cavity
- bones held together by dense collagen fibers (ligaments)
- 3 examples;
- suture
- syndesmosis
- gomphosis
cartilaginous joints
bones held juntos by cartilage; no synovial cavity
- synchondroses
- symphyses
tip: symphonies in sync
functional classification of joints
relates to the type & degree of movement allowed @ the joint
- 3 classes;
1. synarthroses - immovable joints
- amphiarthroses - slightly movable joints
- diarthroses - freely movable joints
interosseus membrane
b/w ulna and radius is an example of a syndesmosis
- collagen fibers
- DOES NOT INCLUDE THE PROXIMAL RADIOULNAR JOINT
suture
fibrous joint
meeting points b/w 2 cranial bones w v short interconnecting collagen fibers; jig saw puzzle
synostoses = when fibrous tissue of sutures are calcified
- immovable/synarthrosis
syndesmosis
- fibrous joint
- amphiarthrosis
(slightly mobile) OR synarthrosis
joint held juntos by ligament; fibrous tissue can vary in length but is longer than in sutures
gomphosis
- fibrous joint
- peg-in-socket fibrous joint. periodontal ligaments. bone to tooth; holds tooth in socket
- immobile
synchondroses
bones united by hyaline cartilage
- synarthrosis
- ex: epiphyseal plate = temporary synchondrosis
- ex: joint b/w 1st rib and sternum (immovable joint)
symphyses
bones united by fibrocartilage; occur midline of the body
- amphiarthrosis
- ex: intervertebral discs and pubic symphysis
components of synovial joints
- ligament: dense regular ct proper
- joint cavity/synovial cavity with synovial fluid (lubricates and provides nutrients)
- articular cartilage - hyaline
- articular capsule/joint capsule
- made of 2 layers: tough outer layer = fibrous layer; deeper layer = synovial membrane
- periosteum
tip: LIke ASAP
synovial capsule
- sleeve-like capsule tht encloses the synovial cavity
- has 2 layers:
- fibrous layer:
* continuous with the periosteum
* dense irregular ct proper
* strengthens the joint - synovial membrane;
* covers any bony surface inside the joint capsule not covered by hyaline cartilage
* loose CT
* secretes synovial fluid
synovium/synovial fluid
- viscous fluid seceted by inner synovial membrane
- similar consistency as raw egg whites
- filtrate of plasma
- located in the joint cavity and in the articular cartilages
- acts like a sponge
- weeping lubrication allows cartilage to be nourished by the fluid
- functions to:
- reduce friction b/w bones
- nourishes joint cartilages
cartilage associated with joints
articular cartilage made of hyaline cartilage
articular disc: shock absorber and makes ends of long bones a better fit; spans entire width of joint cavity; FIBROcartilage
* meniscus is DIFFERENT bc they dont span the entire width of the joint
reinforcing ligaments of synovial joints
- band-like ligaments tht strengthen the joint
- 3 types:
1. capsular
2. extracapsular
3. intracapsular
capsular ligament
thickened band in the joint capsule
- thickened areas of the fibrous layer of the capsule
- ex: glenohumeral ligaments
extracapsular ligament
outside the joint capsule
- ex: medial and lateral collateral ligaments
intracapsular ligament
inside the joint capsule; cross e/o inside the capsule
- ex: anterior and posterior cruciate ligaments
- ex: ligamentum teres (ligament of the head of the femur)
nerve and vascular supply of synovial joints
- nervous innervation: pain and postional/stretch info
- blood supply: nearby vessels send branches to ligaments and the synovial membrane
- functional redundancy of the blood supply so u dont block blood flow when u move (bc some parts will be compressed)
- allows overlapping supply of nerves and vessels
bursa
sac-like structure or round
- have synovial fluid
- elbows, knees, anywhere parts are rubbing against each other - so lots in joints
- reduce friction b/w body parts which rub against e/o
tendon sheaths
tube-like bursa that wraps around tendons
- hot dog: tendon sheath is the insulatory sheath or “bun” that wraps around the tendons; acts a cushion
- carpal tunnel area has lots of tendon sheaths
types of synovial joints
categorized based on the shape of the articulating bones
- planar/gliding
- hinge
- pivot
- condyloid
- saddle
- ball and socket
movements permitted by synovial joints
- as muscles contract, bones are moved @ the synovial joints
- the shapes of the bones @ the joints largely dictate the movements allowed
- movements are classified:
- gliding movements
- angular movements
- rotation movements
gliding movements
synovial joints
- sliding flat surfaces of 2 bones across e/o
angular movements
- flexion
- extension
- abduction
- adduction
- circumduction
flexion
decreasing the angle b/w 2 bones
- type of angular movement @ synovial joint
extension
increasing the angle b/w bones from a flexed position BACK TO THE ANATOMIC POSITION
- type of angular movement @ synovial joint
abduction
moving a limb AWAY from the body midline
tip: think of abduction as in kidnapping - take something away
- type of angular movement @ synovial joint
adduction
move limb TOWARDS body midline
tip: think of it like ADDING something to ur body
circumduction
move limb or finger so that it describes a cone in space; not complete rotate bc 1 end is fixed in place
- type of angular movement @ synovial joint
rotational movements at synovial joints
turning a bone around the longitudinal axis
- COMPLETE ROTATION
- medial rotation
- lateral rotation
medial rotation
rotate towards medial plane
lateral rotation
rotate away from medial plane
plane/planar joint
- synovial joint
- aka gliding joint
- have flat articular surfaces for smooth gliding motion
- ex: intermetacarpal and intercarpal jts; intertarsal and joints b/w vertebral articular surfaces
hinge joint
synovial joint
- 1 is cylindrical in nature and 1 will act as a trough
- allows flexion and extension
- ex: elbow joints, interphalangeal joints (upper knuckles), knee joints
hyperextension
increasing the joint angle BEYOND THE ANATOMICAL POSITION
- not the same as extension