apk exam 2 Flashcards
1
Q
skeletal system
A
made of bones, cartilages, and joints
2
Q
cartilage
A
- is connective tissue
- 3 types: hyaline, elastic, fibrocartilage (remember CHEF)
- abundant extracellular matrix: gel-like, fibers
- predominant cell type = chondrocytes
3
Q
hyaline cartilage
A
- aka articulate cartilage
- end of long bones
- growth plates within bones
- costal cartilage
- respiratory structures
- embryonic skeleton
4
Q
elastic cartilage
A
- epiglottis
- outer ear/pinna
- abundant elastic fiber in matrix
5
Q
fibrocartilage
A
- pubic symphysis
- menisci in the knee joint
- intervertebral discs
6
Q
perichondrium
A
- 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
7
Q
functions of obones
A
- support
- protection
- mvmnt
- mineral storage
- hemopoiesis
- E storage
- metabolism
8
Q
bone classIfications
A
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)
9
Q
sesamoid bone
A
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)
10
Q
bone tissue
A
- compact; found on the outside; denser outer layer
- spongey aka trabecular bone: internal
11
Q
gross anatomical features of a typical long bone
A
- 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)
12
Q
epiphyseal line
A
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
13
Q
epiphysis
A
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
14
Q
diaphysis
A
- 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
15
Q
gross anatomy of short, flat, and irregular bones
A
- dont have medullary cavities
- outside: periosteum, compact
- inside: endosteum, spongy bone
16
Q
periosteum
A
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
17
Q
osteoblast
A
immature bone cells which secrete the matrix tht will eventually become calcified bone
18
Q
osteoclasts
A
breaks down bone
19
Q
endosteum
A
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
20
Q
bone markings
A
- the surface of a bone reflects the stresses applies to specific locations
- projections
- joint surfaces
- depressions and openings
21
Q
microscopic anatomy of compact bone
A
- 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)
22
Q
concentric lamellae
A
- look like tree rings outside of the osteons
- calcified extracellular matrix tht is part of the osteon
23
Q
osteon
A
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
24
Q
circumferential lamellae
A
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
25
perforating (volkmann's) canal
different from central canal
- runs PERPENDICULAR to the central canal to connect b/w different osteons
26
canaliculi
tunnels tht run within the concentric lamellae
- osteocytes use the tunnels to reach other osteocytes - communicate with others and transfer nutrients
27
interstitial lamellae
the calcified extracellular matrix tht is NOT part of the osteon but is essentially filling in the gaps between the osteons
28
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
29
microscopic anatomy of spongy bone
1. trabecula = little beam; refers to the network structure
2. 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
30
ossification/osteogenesis
process by which bone forms
- 2 types of osteogenesis: intramembranous and endochondral
- bone formation occurs in 4 situations:
1. formation of bone in an embryo
2. growth of bones until adulthood
3. remodeling of bone throughout life
4. repair of fractures
(REAR - remodel, embryo, adulthood, repair; to rear is also to raise/grow, as in livestock)
31
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
32
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
33
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
34
how do bones get LONGER?
involves 2 steps:
1. cartilage growth on the epiphysis side of the epiphyseal plate
2. 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
35
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
36
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
37
how to identify osteoclasts
they have ruffled borders which increases SA to maximize release of hcl and degradation enzymes
- has multiple nuclei
38
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
39
structural classification of joints
- based on 2 criteria:
1. presence/absence of a synovial cavity
2. type of CT binding bones together
- 3 classes:
1. fibrous joints
2. cartilaginous joints
3. synovial joints
(tip: FIBing CAn be a SIN)
40
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
1. planar/plane/gliding joint
2. hinge
3. pivot
4. condyle
5. saddle
6. ball and socket
41
fibrous joints
- not going to have synovial cavity
- bones held together by dense collagen fibers (ligaments)
- 3 examples;
1. suture
2. syndesmosis
3. gomphosis
42
cartilaginous joints
bones held juntos by cartilage; no synovial cavity
1. synchondroses
2. symphyses
tip: symphonies in sync
43
functional classification of joints
relates to the type & degree of movement allowed @ the joint
- 3 classes;
1. synarthroses - immovable joints
2. amphiarthroses - slightly movable joints
3. diarthroses - freely movable joints
44
interosseus membrane
b/w ulna and radius is an example of a syndesmosis
- collagen fibers
- DOES NOT INCLUDE THE PROXIMAL RADIOULNAR JOINT
45
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
46
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
47
gomphosis
- fibrous joint
- peg-in-socket fibrous joint. periodontal ligaments. bone to tooth; holds tooth in socket
- immobile
48
synchondroses
bones united by hyaline cartilage
- synarthrosis
- ex: epiphyseal plate = temporary synchondrosis
- ex: joint b/w 1st rib and sternum (immovable joint)
49
symphyses
bones united by fibrocartilage; occur midline of the body
- amphiarthrosis
- ex: intervertebral discs and pubic symphysis
50
components of synovial joints
1. ligament: dense regular ct proper
2. joint cavity/synovial cavity with synovial fluid (lubricates and provides nutrients)
3. articular cartilage - hyaline
4. articular capsule/joint capsule
* made of 2 layers: tough outer layer = fibrous layer; deeper layer = synovial membrane
5. periosteum
tip: LIke ASAP
51
synovial capsule
- sleeve-like capsule tht encloses the synovial cavity
- has 2 layers:
1. fibrous layer:
* continuous with the periosteum
* dense irregular ct proper
* strengthens the joint
2. synovial membrane;
* covers any bony surface inside the joint capsule not covered by hyaline cartilage
* loose CT
* secretes synovial fluid
52
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
53
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
54
reinforcing ligaments of synovial joints
- band-like ligaments tht strengthen the joint
- 3 types:
1. capsular
2. extracapsular
3. intracapsular
55
capsular ligament
thickened band in the joint capsule
- thickened areas of the fibrous layer of the capsule
- ex: glenohumeral ligaments
56
extracapsular ligament
outside the joint capsule
- ex: medial and lateral collateral ligaments
57
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)
58
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
59
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
60
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
61
types of synovial joints
categorized based on the shape of the articulating bones
1. planar/gliding
2. hinge
3. pivot
4. condyloid
5. saddle
6. ball and socket
62
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
63
gliding movements
synovial joints
- sliding flat surfaces of 2 bones across e/o
64
angular movements
1. flexion
2. extension
3. abduction
4. adduction
5. circumduction
65
flexion
decreasing the angle b/w 2 bones
- type of angular movement @ synovial joint
66
extension
increasing the angle b/w bones from a flexed position BACK TO THE ANATOMIC POSITION
- type of angular movement @ synovial joint
67
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
68
adduction
move limb TOWARDS body midline
tip: think of it like ADDING something to ur body
69
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
70
rotational movements at synovial joints
turning a bone around the longitudinal axis
- COMPLETE ROTATION
1. medial rotation
2. lateral rotation
71
medial rotation
rotate towards medial plane
72
lateral rotation
rotate away from medial plane
73
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
74
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
75
hyperextension
increasing the joint angle BEYOND THE ANATOMICAL POSITION
- not the same as extension
76
pivot joint
synovial joint
- sleeve around a rod
- ex: proximal radioulnar joints, atlantoaxial joint C1 C2
- for rotation; supination (palm up) and pronation (palm down)
77
condylar joint
synovial joint
- oval articular surfaces
- flexion, extension, adduction, and abduction
- metacarpophalangeal (knuckle) joints, wrist joints
78
saddle joint
synovial joint
- articular surfaces are both concave and convex
- adduction and abduction; flexion and extension
- carpometacarpal joints of thumbs; sternoclavicular joint
79
opposition
special thumb movement where it touches the other fingers or reaches across the palms
- able to do this bc of the saddle joint
80
ball and socket joint
- synovial joint
- flexion, extension, adduction, abduction, rotation
ex: shoulder joints and hip joints
81
elevation
specialized movement; lifting a body part superiorly
- ex: mandible
82
depression
moving a body part inferiorly; specialized movement
- ex: mandible
83
protraction
specialized movement; moving a body part in the anterior direction
- ex, jutting ur jaw out
84
retraction
specialized mvnt; moving a body part in the posterir direction
- ex: moving ur jaw inwards
85
inversion
turning the sole of the foot medially
86
eversion
turning the sole of the foot laterally
87
dorsalflexion
specialized movement in ur feet
- lifting the foot so its superior surface approaches the shin (lifting ur foot up)
88
plantar flexion
depressing the foot elevating the heel
- point ur foot downwards
- specialized mvnt of the foot
89
sternoclavicular joint
synovial joint, saddle joint
- ligaments:
1. costoclavicular ligament
2. interclavicular ligament
3. anterior sternoclavicular ligament
4. posterior sternoclavicular ligament
- these ligaments make it VERY DIFFICULT TO DISLOCATE CLAVICLE FROM STERNUM
- more likely to break collarbone than to dislocate it
- can elevate, depress, protract, retract, rotate
90
glenohumeral joint
where scapula meets humerus
- is a ball and socket joint; permits lots of movement, but less stable
- coracohumeral ligament
- joint capsule + 3 weak glenohumeral ligaments
91
femorocoxal joint
head of femur + pelvic
- ball (head of femur) and socket (acetabulum) joint
- acetabular labrum deepens the socket to allow for head of femur to fit better
- synovial joint, has synovial cavity
- articular capsule present
- ligamentum teres present inside joint capsule
92
capsular ligaments of the hip (of the femorocoxal joint)
bands from the fibrous sheaths of the articular capsule
- there are 3:
1. iliofemoral ligament
2. ischiofemoral ligament
3. pubofemoral ligament
93
femorotibial joint (knee joint)
largest, most complex joint
- knee joint DOES NOT INCLUDE THE FIBULA - fibula has weight-bearing function so it's not pt of the joint
- modified hinge joint (synovial)
* main action = flexion/extension
* some med/lat rotation
- extremely strong & stable bc lots of ligaments and muscles
- shared joint space with the femoropatellar joint (knee cap) (gliding joint)
94
knee structures
1. medial condyle
2. hyaline cartilage
3. lateral condyle of femur
4. tibia
5. fibula; femur does not articulate with fibula
6. medial & lateral menisci: fibrocartilage discs that do not expand the entire width of joint
7. patella + patellar ligament, which extends from patella to tibia
8. quadriceps tendon
9. anterior cruciate ligament (ACL): intracapsular ligament; crosses over to the knee
10. posterior cruciate ligament (PCL): intracapsular lig.; starts behind @ tibia and cross synov cavity and attaches to the femur
11. tibial collateral ligament: extracapsular ligament; femur to tibia; aka MCL (medial collateral ligament)
12. fibular collateral ligament: femur to fibula; extracapsular ligament (LCL)
95
knee joint muscles and tendons
1. quadriceps femoris muscle on top of femur
2. tendon of quadriceps femoris muscle attaches to the patella
3. medial patellar retinaculum & lateral patellar retinaculum: bands of CT that reinforces the knee
96
chondromalacia patellae
97
myocyte
muscle cell, muscle fiber
98
sarcolemma
plasma membrane of the muscle fiber
99
sarcoplasm
cytoplasm of a muscle fiber
100
sarcoplasmic reticulum (SR)
ER of a muscle fiber
- stores Ca2+
- webbed structure around the individual myofibrils
- ends are enlarged/bulbed: this is called the terminal cisternae
101
muscle types
1. skeletal
2. smooth
3. cardiac
102
skeletal muscle
elongated, multinucleate, striated
- voluntary control
103
cardiac
striated, intercalated discs b/w cardiac cells to make sure contractions are synchronous, uninucleate
- involuntary control
104
smooth muscle
uninucleate, not striated
- involuntary control
- hollow organs of GI track, urinary bladder, stomach, esophagus - propels things through
105
all muscle tissue characteristics
1. contractility: ability to shorten & gener8 force; muscles only PULL on structure it's attached to
2.excitability: ability to respond to stimuli by producing electrical signals
3. extensibility: ability to stretch without being damaged
4. elasticity: ability to return to its original length/shape following distension; recoil back
106
functions of skeletal muscle
1. movement
2. posture and joint stabilization
3. open/close body passageways (sphincters)
4. thermogenesis; when skeletal muscle contracts (voluntary & involuntary), it gener8s heat; also prevents heat loss by contracting smooth muscle involuntarily (goosebumps & dartos muscle, which houses the scrotum)
107
CT components of skeletal muscles
1. epimysium: CT that covers the entire muscle
2. Perimyseium; wrap fascicles (a bundle of individual muscle fibers); within the fascicle, we have individual muscle fibers
3. endomysium: b/w individual muscle fibers
108
tendon
CT attachment of a skeletal muscle to a bone's periosteum
- continuous w/ all 3 CT sheaths of a muscle beyond the length of muscle fibers
- cord-like (think of the end of a tootsie roll)
109
aponeurosis
broad, flat tendon instead of cord-like shape; attaches muscle to bone or skin
110
muscular attachment to the bone
- direct attachment: the length of the CT is very short so it looks like the muscle attaches to the bone directly
- indirect attachment: tendon/CT is clearly visible in attaching muscle to bone; most common type
- origin vs insertion
111
origin
the placement/location on bone where muscle attach where the bone doesn't move when the muscle contracts
112
insertion
location where muscle attaches to a bone that will move
ex: when the brachialis contracts, it shortens, pulling on the insertion point, causing ulnar and radius to flex
113
strains vs sprains
- strains: muscle injury or tendon injury; tendon is a CT but part of the sheaths that contain muscle fibers
* might see bruising - associated with muscle
- sprain: ligament injury
114
nervous innervation of muscle
each muscle is typically innervated by 1 nerve which branches extensively within the CT sheaths
- each axon making up the nerve synapses with multiple muscle cells
115
blood supply of muscles
each muscle is typically supplied by 1 artery which branches extensively within the CT sheaths
- capillary networks within the endomysium are WAVY in resting muscle to allow for extensibility of this tissue; wavy shape allows muscles to be supplied even when they contract or relax
116
skeletal muscle fiber
striations caused by proteins
- nuclei are located peripherally so it is not going to be centralized in the muscle fiber bc there are so many diff organelles within the muscle fibers
- myocytes are cylindrical
117
striations
due to the organization of various proteins within the muscle
- myofibrils make up myofibers (myocyte); proteins within myofibrils allow contraction to happen
118
myofibrils
specialized contractile organelles WITHIN myofibers (muscle cells)
- each myofibril is composed of a series of sarcomeres
- run entire length of the muscle fiber
- myofibrils are not just actin and myosin
made of 3 types of proteins:
1. contractile proteins
2. regulatory
3. structural
119
sarcomere
basic contractile unit of muscle; make up myofibrils; segments of myofibrils
- have overlapping proteins that give striated look
- zed (Z) lines/discs: looks like zig-zag/zipper; tells u where the 2 ends of ur sarcomere are
- each sarcomere is made of myofilaments
- thin and thick filaments
120
thin filaments
extend from Z line to middle of sarcomere
made of actin (protein); each thin filament made of 2 strands of actin
- 6 thin filaments interact/surround each thick filament
121
thick filaments
darker bands extending from the center of the sarcomere
made of myosin
- ends of myosin thick filaments have heads that look like golf clubs - heads interact with thin filament to contract
122
A band of sarcomere
length of myosin filament (thick filament)
123
H zone of sarcomere
area with only thick myosin filament - no overlap with thin filament
124
I band of sarcomere
region with only thin filament
125
M line of sarcomere
series of proteins that run down middle of sarcomere ; region with only thick myosin filament, no overlap with thin filament
126
elastic/titin filaments
large proteins; look like coiled springs; allows sarcomeres to stretch by uncoiling and recoil
- anchor myosin in place
tip: Titin sounds like Titan, Ariel's dad = sea = ships = ANCHORing ships -> titin anchors myosin
also Titan, the moon, is far from earth, it would be a stretch to get there -> titin = stretch
127
contraction and filament movement
- thin filaments are pulled in towards the M line of sarcomere
- sliding motion
128
contractile proteins
also make up myofibrils
- actin myofilaments
- myosin myofilaments
129
regulatory proteins
make up myofibrils
- troponin
- tropomyosin
determine whether or not the actin and myosin filaments can interact
- actin has myosin binding sites
- tropomyosin lays on top of myosin binding sites -> can block myosin heads from attaching to binding sites
- troponin is attached to tropomyosin NOT actin - when Ca2+ released from sarcoplasmic reticulum, it binds to troponin -> causes conformational change -> causes tropomyosin to lift off of binding sites -> now contraction can occur bc myosin heads can bind to actin
130
structural proteins
make up myofibrils
- titin (inside sarcomere)
- dystrophin (@ ends of the myofibril)
- titin: allows for elastic recoil of sarcomere -> prevents damage to muscle fibers when it gets stretched; anchors myosin thick filaments
- dystrophin: anchor myofilament to the sarcolemma
131
myofilaments
- 2 actin strands twist to form helix -> produces a thin filament
- hundreds of myosin make up thick filament
- myosin heads reach towards actin and pull in
- power stroke = myosin heads pulling in actin -> forces sarcomere to shorten/contract
132
t-tubules
transverse tubules
- tunneling in the of sarcolemma/invagination of sarcolemma
- associated with the sarcoplasmic reticulum
133
triad
"oreo": t-tubule = cream part; 2 cookies = terminal cisternae of the SR
134
sliding filament mechanism of contraction
myosin heads attach to myosin binding sites on actin and undergoes power stroke, pulling actin towards the M line
- it looks like the thick and thin filaments are sliding over e/o & incr amt of overlap b/w the 2
- contraction increases overlap of filaments, but THE LENGTH OF THE FILAMENTS NEVER CHANGE
135
change in appearance with contraction
- relaxed:
* I band is large & light in color
- contract:
* I band is smaller
* A band stays the same size bc length of myosin filaments stay the same
* H zone decreases in size bc filaments are pulled in
* space b/w Z lines decreases bc sarcomere is shortened
136
nervous innervation of skeletal muscle
1 named nerve tht extends through the muscle and branches out
- motor unit: motor neuron + all the muscle fibers it is innervating; specific type of neuron which controls multiple muscle cells/fibers
- motor neuron: sends directions to the muscle fiber to contract
- motor unit allows for recruitment
- neuron does not touch physically touch muscle fiber -> communicates via neuromuscular junction
137
motor unit recruitment
neuron sends a signal down to 1 nerve that can control various motor units depending on the action
- either send to a motor unit that controls a large number of muscle fibers to perform a large action or a small motor unit that controls a small amount of muscle fibers to perform a small action
138
neuromuscular junction (NMJ)
interface b/w neuron and muscle fiber
- 3 main components:
1. axon terminal: end of neuron; aka terminal bouton; receives signal that is coming down the entire neuron -> ca2+ channels open so ca2+ moves into the axon terminal from the extracellular fluid
* this signals the synaptic vesicles -> migrate to end of axon terminal -> exocytosis to release acetylcholine (neurotransmitter) into synaptic cleft
- enzymes in synaptic cleft break down ACh so we dont have sustained contractions
2. junctional folds of the sarcolemma: incr SA to pack in acetylcholine receptors to absorb acetylcholine
* motor end plate = where receptors are in the junctional folds; area tht dips down
3. synaptic cleft: space b/w the ends of the neuron/AXON TERMINAL and the sarcolemma of muscle cell
- neuron not directly connected to muscle
- electrical signal move across surface of sarcolemma and then down the t-tubules until it reaches the terminal cisternae of the SR -> causes Ca2+ to be released -> bind to troponin -> tropomyosin leaves binding site -> myosin head can bind to actin and pull it to contract
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skeletal muscle fiber types
muscles have many fiber types, but some fiber types are more prevalent in certain types of muscles
1. Type I muscle fiber
2. Type IIa
3. Type IIb/IIx
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type I muscle fiber
slow oxidative (so)
- have high myoglobin content - red color
- slow contraction
- ATP production: aerobic; needs o2 to make atp
- resists fatigue; does not tire out easily
- small fiber diameter
- maintains posture and used for endurance activities
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type IIa muscle fiber
fast ox-glycolytic (fog)
- high amt of myoglobin content - pink color
- fast contraction
- atp production: aerobic & anaerobic
- moderate fatigue resistance
- intermediate fiber diameter
- for walking and sprinting
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type IIb/IIx muscle fiber
fast-glycolytic (fg)
- low amt of myoglobin content -
- fast contraction
- does not need o2 to make atp
- low fatigue resistance; tire quickly
- white color (low myoglobin)
- large fiber diameter
- for rapid and intense movement for short duration; ex SPRINTING
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myoglobin
protein in skeletal muscle tht is responsible for transporting o2 in ur muscles
- gives red appearance to rare steak tht looks like blood
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how many voluntarily controlled muscles do u have?
700
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fascicular arrangement of muscles
fascicles are bundles of fibers within a skeletal muscle surrounded by perimysium
- they are arranged differently in various muscles
- fascicle arrangement reflects function:
* longer fibers -> gr8r range of motion
* more fibers -> gr8r strength
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fascicles and muscle shapes
strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles
1. fusiform
2. parallel
3. convergent
4. unipennate
5. bipennate
6. multipennate
7. circular
2.
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fusiform muscle shape
belly tapers at the ends to the tendons
ex: biceps brachialis
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parallel muscle shape
fascicles arranged parallel; doesn't taper; run longitudinally
ex: rectus abdominis
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convergent muscle shape
broad muscle (origin) that tapers to a tendon (insertion)
- dorito-shaped
- pectoralis major
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unipennate muscle shape
fascicle is coming at angle to the tendon
- the fibers come @ 1 angle
- palmar interosseous; extensor digitorum longus (EDL)
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bipennate muscle shape
fibers run @ 2 angles coming in towards the tendon
- ex: rectus femoris
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multipennate muscle shape
fascicular arrangement comes in towards the tendon @ multiple angles;
- ex: deltoid; deltoid is not a convergent muscle bc multiple muscles run through the muscle itself & fascicles run obliquely towards the tendons
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circular muscle shape
- fascicles arranged in concentric rings
- always found around external body openings (sphincters)
ex: orbicularis oculi, also orbicularis oris (muscle around ur mouth)
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pennate muscles
short fascicles tht attach obliquely to a tendon that runs the length of the muscle
- "penna" = feather
- uni, bi, or multi-
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parallel muscle
fascicles run parallel to the long axis of the muscle
- fusiform - more bulged in the center b4 tapering @ both ends
- straplike: flatter; ex: sartorius muscle
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lever systems
describes the relationship b/w bone and muscle
- load: what are we trying to move; ex: moving a hand or holding an external weight
- lever: bone
- fulcrum: pivot point where the movement is occuring
- effort: muscle
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2nd class lever system
load in the middle, fulcrum and effort on opposite sides
- ex: when u tip toe.
* effort is exerted by calf muscles pulling upward on the heel
* joints of the ball of the foot = fulcrum
* the weight of the body = load
- think of this as someone lifting the handle of a wheelbarrow
LOAD IS ALWAYS IN THE MIDDLE
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1st-class lever system
think of it as a see-saw; fulcrum in the middle & on either side of the fulcrum, u have a load on one side and the effort on the other
* ex: this lever system raises ur head off ur chest- the posterior neck muscles provide the effort; the atlanto-occipital joint = fulcrum; weight to be lifted = facial skeleton
FULCRUM IS ALWAYS IN THE MIDDLE
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3rd-class lever system
most common
- DO NOT CONFUSE WITH 1ST CLASS; examine the INSERTION
- the insertion will go b4 the fulcrum, so the EFFORT is actually in the middle instead of the fulcrum
- ex: ur arm curling a dumbbell
* flexing the forearm by the biceps brachii muscle; effort exerted on the proximal radius of the forearm; fulcrum = elbow joint; load = hand & distal end of the forearm
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muscle actions and interactions
- a muscle tht crosses a joint, it acts at that joint
- muscles pull, not push
- muscles tht produce opposite actions lie on opposite sides of a joint
* agonist/prime mover
* antagonist
- the roles switch depending on the action
* flexing arm: biceps = agonist, triceps = antagonist
* extending arm: triceps agonist, biceps antagonist
- if the same action occurs at the same joints with the same muscles being used, the lever class will still be the same (ex: flexing and extending ur arm in the frontal plane vs horizontal)
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agonist
prime mover; contracts to cause an action
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antagonist
stretches and yields to the effects of the agonist
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synergist
helper muscle, not primary muscle; acts to assist an agonist in 1 of 2 ways:
- add extra force
- reducing undesirable movements
* canceling out unwanted movements
a) making a fist
b) muscles with multiple actions @ a joint
* ex of a specific type of synergist: fixators: fix a bone in place
a) scapulae fixators during arm movements; keep shoulders fixed so u can just move ur arm
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naming skeletal muscles
- muscles named according to several descriptors:
1. location
2. shape
3. relative size
4. fascicle arrangement
5. location of attachments
6. number of origins
7. action
- oftentimes, multiple criteria are used to name a muscle
ex: extensor carpi radialis longus
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action can be inferred by position of muscle as it crosses a joint: anterior and posterior
1. muscle tht crosses on the ANTERIOR side of a joint = flexion
ex: pectoralis major
2. muscle tht crosses on the POSTERIOR side of a joint = extension
ex: latissimus dorsi
- these don't apply to knee and ankle bc the lower limb is rotated during development
* the muscles tht cross these joints posteriorly = flexion, and anteriorly = extensiom
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action can be inferred by position of muscle as it crosses a joint: lateral and medial
1. muscle tht crosses on the lateral side of a joint = abduction
ex: deltoid
2. muscle that crosses on medial side of a joint = adduction
ex: teres major (antagonist of deltoid)
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muscle compartments of the limbs
- fascial compartments grp muscles of similar origin & function
- most compartments are innervated by a single nerve
1. upper limb compartments
2. lower limb compartments
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upper limb muscle compartments
- anterior/posterior brachial
- anterior/posterior antebrachial
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lower limb muscle compartments
-anterior/posterior/medial thigh
- anterior/posterior/lateral leg
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anterior brachial compartment
- coracobrachialis & brachialis
- biceps brachii
- actions @ the shoulder/elbow: flexion (elbow) & adduction of the arm (shoulder)
- innervation: musculocutaneous nerve
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posterior brachial compartment
trceps brachii
- different origins:
* medial head: posterior shaft
* lateral: post shaft
* long: infraglenoid tubercle
- insertion: olecranon process of ulna
- elbow extension; assists in shoulder adduction
- innervation: radial nerve
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posterior brachial compartment continued
anconeus
- origin: lateral epicondyle of humerus
**tip: ALE (anconeus lateral epicondyle)
- insertion: olecranon process of ulna
tip: IOP
- protonation (palm up to palm down)
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anterior antebrachial compartment
- 3 layers: superficial, intermediate, deep
- flexion of wrist and fingers
- innervation: median nerve (innervates the rest od the digits) and ulnar nerve (only innervates the pinky finger and half of the ring finger)
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posterior antebrachial compartment
- multiple layers: superficial and deep
- extensors; extend wrist and fingers
- innervation: radial nerve
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anterior thigh compartment
quadriceps femoris
- different origins:
* rectus femoris: AIIS
* vastus lateralis: gr8r trochanter, intertrochanteric line, linea aspera
* vastus medialis: linea aspera, intertrochanteric line
* vastus intermedius: anterolateral, proximal femoral shaft
- common insertion @ patella & tibial tuberosity
- flex hip & knee extension
- innervation: femoral nerve
- sartorius muscle: origin = ASIS; i: proximal tibia
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posterior thigh compartment
hamstrings: biceps femoris, semitendinosus, semimembranosus
- biceps femoris
* o: ischial tuberosity, linea aspera
* i: head of fibula and lateral condyle of tibia
- semitendinosus:
* o: ischial tuberosity
* i: medial, upper tibial shaft
- semimembranosus:
* o: ischial tuberosity
* i: medial condyle of tibia
- hip: extension
- knee: flexion
- innervation: tibial nerve (portion of sciatic nerve)
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medial thigh compartment
adductors
1. adductor brevis, longus, magnus, pectineus:
* o: pubis or ischium
* i: medial femur
2. gracilis:
* o: inferior pubic and ischial rami
* i: medial tibial shaft
- hip: adduction and medial rotation
- slight knee flexion
- innervation: obturator nerve
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anterior leg compartment
1. tibialis anterior
- dorsiflexion
- inversion of the foot
2. extensor hallucis longus & 3. fibularis tertius
- dorsiflexion
- extension of the big toe
4. extensor digitorum longus
- dorsiflexion and extension of the toe
- innervation: deep fibular nerve
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lateral leg component
1. fibularis longus
2. fibularis brevis
- plantarflexion of the ankle; eversion of the foot; no action @ the knee
- innervation: superficial fibular nerve
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posterior leg compartment: superifical
triceps surae
1. gastrocnemius on either side
* o: femoral condyles
* i: posterior side of the calcaneus (heel)
2. soleus: deep to the gastrocnemius
* o: superior tibia/fibula
* i: posterior side of the calcaneus
- knee flexion and plantarflexion
- innervation: tibial nerve
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posterior leg compartment: deep
1. tibialis posterior
2. flexor digitorum longus
3. popliteus
4. flexor hallucis longus
- plantarflexion; toe flexion
- innervation: tibial nerve
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case study: compartment syndrome
when a muscle swells from either trauma or overuse, pressure within the compartment containing the muscle increases
- compressed vessels -> ischemia, swelling
- compressed nerves -> pain or numbness
- in emergent cases, a fasciotomy must b performed
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if someone has anterior compartment syndrome of the leg, which nerve would be affected?
deep fibular nerve
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appositional growth of cartilage
outside growth; chondrocytes in the perichondrium secrete new matrix
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interstitial growth of cartilage
chondrocytes WITHIN the cartilage divide and secrete new matrix
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projections tht r sites of muscle and ligament attachment
1. epicondyle
2. tubercle
3. line
4. process
5. tuberosity
6. trochanter
7. crest
8. spine
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bone surfaces tht form joints
1. condyle
2. facet
3. head
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bone depressions and openings for vessels and nerves
1. fossa
2. fissure
3. notch
4. groove
5. meatus
6. sinus
tip: GROOVy SINgers FOr FISh NOT MEAT
