Module 3 - Muscular system Flashcards
where is the pectoralis major and what does it do
it attaches to the anterior chest wall, and runs laterally over the shoulder joint and attaches to the upper humerus
when it contracts/shortens it results in adduction of the arms
what is the name of the abdominal muscle with vertical fibres
rectus abdominis (nicknamed 6 pack)
what are the 4 layers of abdominal muscles called
- rectus abdominis (vertical)
- transverse abdominis (horizontal)
- external oblique
- internal oblique
what happens when the abdominal muscles contract
compress abdominal cavity and increase pressure
what are the 2 most superficial muscles of the back
- trapezius
- latissimus dorsi
where do the superficial muscles of the back join medially
spinous process of the vertebrae
the trapezius muscle has 3 fibre directions. What are they and what are their actions
superior (scapula up to cervical spine/head) - elevate scapula
horizontal (scapula to upper thoracic spine) - retract the scapula
inferior (scapula down to lower thoracic spine) - depress the scapula
what muscles work to keep the spine upright/erect
erector spinae
what are the 3 muscle that make up the glutes and what distinguishes them (why are they named that)
they are named by their size (which also happens to be outermost to innermost)
gluteus maximus
gluteus medius
gluteus minimus
how does the gluteus maximus cross the hip joint and consequently what is its function
it crosses posteriorly and extends the hip joint
how do the gluteus medius and gluteus minimus cross the hip joint and what is their function
they cross the hip joint laterally and abduct the hip
what are the 3 positions of muscle fibres in the deltoid, how do they cross the joint and what do they do
position: anterior - flexion of shoulder
position: middle (crosses the shoulder laterally- abduction
position: posterior - extension of the shoulder joint
which muscles are used to flex and extend the elbow and where are they found
flexion = biceps brachii - found anterior to the elbow joint
extension = triceps brachii - found posterior to the elbow joint
note: brachii translates to “of the arm”
bicep translates to “2 headed” and tricep is “3 headed”
what is the name of the group of muscles on the posterior side of the forearm and what is their role
extensors of the wrists and digits
(extend wrists and digits)
what is the name of the muscle group on the anterior side of the forearm and what is their role
flexors of the wrists and digits
(flex wrists and digits)
where are the pronators and supinators located and what do they do
supinators - on top of the radius just below the elbow - they rotate the forearm so the palms face forward in an anatomical position
pronators - just below the elbow and just above the wrist - rotate the wrist so the palm faces backwards in the anatomical position
what is the name of the group of 4 muscles on the anterior side of the thigh and what do they attach to
quadriceps - attach to the femur proximally and tibia distally (over the knee)
the 3 muscles on the posterior aspect of the thigh are known collectively as what
hamstrings
what are the names of the 3 muscles in the hamstring and what is a defining feature of each
from medial to lateral:
semimembranosus - has a flat tendon of origin (originate at ischium of pelvis)
semitendinosus - has a long tendon of insertion (to the tibia)
Biceps femoris - has 2 heads
the hamstrings cross the hip and knee posteriorly. what is their action when contracted
extension of the hip
flexion of the knee
which joint in the body has an opposite naming of flexion and extension
knee
what is the name of the muscles inside your thigh, what joint do they cross and how to they act on it
adductors of the hip
cross the hip joint medially
adduct the hip
what is the muscle on the anterior aspect of the leg, attaching to the tibia and crossing the ankle joint anteriorly and what is it’s role
- it crosses the joint obliquely and attaches to the medial side of the foot
- it is called the tibialis anterior
- it can pull the foot upwards (dorsiflexion of the ankle) or it can turn the plantar surface medially (inversion of the ankle)
what is the name of the main muscle in the calf and what does it attach to posteriorly
it is called the gastrocnemius and attaches to the calcaneus (heel bone) via the achilles tendon
what does the gastrocnemius do when contracted
plantarflexion of the foot (pointing toes)
what is the name of the muscle that closes the eyes
orbicularis oculi
what is the name of the muscle that puckers the mouth
obicularisoris
what is the name of the muscle attached to the zygomatic bone and is responsible for smiling
zygomaticus
what is the name of the muscle at the forehead, that may contract if you are surprised
frontalis
what 2 bones form the joint that moves when chewing and what is the name of the joint
the temporal bone and the mandible
the joint is the temporomandibular joint
what are the 2 muscles of mastication and where do they join
temporalis - joins the temporal bone and mandible
masseter - joins the zygomatic arch and the mandible
what is the muscle that forms the wall of the buccal cavity and what is its role
buccinator - no movement in mastication but compresses the cheeks
what are the 3 layers of connective tissue in a muscle and what do they surround
epimysium - surrounds the whole muscle (fascicles and blood vessels and nerves)
perimysium - surrounds each muscle fascicle
endomysium - surrounds each muscle cell
what muscles have striations
skeletal muscles and cardiac muscles
which muscle type is multinucleated
skeletal
what shape are the nuclei in muscle cells
round in cardiac muscle and elongated in skeletal muscle and smooth muscle
describe the shape of each muscle cell
cardiac - branched cylinders
skeletal - cylindrical
smooth - spindle-shaped
where are the nuclei in different muscle cells found
cardiac and smooth - central
skeletal - peripheral
what are t tubules and why are they important
t tubules are projections of the sarcolemma into the cell
when the action potential travels along the cell it moves along the t tubule which brings it closer to the sarcoplasmic reticulum
what is the role of Ca++ in muscle contraction
Action potential triggers the sarcoplasmic reticulum to release Ca++
The Ca++ then binds to the troponin which moves the tropomyosin out the way of the active site so the actin and myosin can bind
what is excitation-contraction coupling
the process from an action potential on a muscle surface to the interaction of actin and myosin
what 3 proteins for the thin myofilament
actin, troponin, tropomyosin
what are the 7 functions of the muscular system
- MOVEMENT of the body
- maintain POSTURE
- RESPIRATION
- production of BODY HEAT
- COMMUNICATION
- CONSTRICTION of organs/vessels
- CONTRACTION of heart
M-P-R-BH- C-C-C
what are 4 general properties of muscles
- excitability (respond to stimulus)
- contractility
- extensibility (stretch)
- elasticity (recoil)
how does connective tissue surrounding muscle help with movement
the CT connects the muscle to the tendon to the bone so that a muscle contraction can move the bones
what does the prefix sarco mean
muscle cell
what are terminal cisternae
enlarged sarcoplasmic reticulum located either side of the t tubule
what is the I band and what runs up the center of it
- it is the light band
- it is the area with only actin (thin filament)
- up the middle is the z line which is the attachment point for actin
what is the A band and what runs up the middle of it
- the A band is the dark band
- it is the length of the thick filament myosin
- up the middle of it is the H zone (where there is no actin, only myosin)
- and the line up the middle of the H zone is the m line
- the m line is the middle and is the attachment point for the myosin
describe how ATP is used by myosin
myosin head rests at 45º
ATP attaches to the head and is converted to ADP + P and the head reaches 90º
ADP + P are removed and the head returns to 45º
what are G and F actin
G actin (globular) are linked together to form 2 strands of F actin (fibrin)
what changes within the sarcomere in a contracted muscle
- A band remains the same
- I band shortens
- H zone disappears
what happens in a muscle cell when the action potential stops
- sarcoplasmic reticulum takes back Ca++
- troponin changes back
- tropomyosin covers active site
- no more actin myosin interaction
what happens when tension is >=< load
if tension > load then muscle contracts and movement occurs
if tension = load muscle contracts isometrically (just holding position)
if tension<load muscle contracts eccentrically (tension maintain but muscle lengthens eg. controlled release)
describe a motor unit
- motor neurons only go to a few cells in a muscle
- this unit may contain hundreds or thousands of muscle cells
- ## nerve impulse travelling down that neuron will only cause the cells in it’s unit to contract
what 2 ways can we increase tension in a muscle
summation - increase frequency of impulse (number of nerve impulses coming down the neuron)
recruitment - add another motor unit - causing more cells to contract
how do muscle that require fine control/precision differ from muscles that require more power/less precision in terms of their motor units
fine control muscles = smaller number of muscle cells in each motor unit but many motor units
power muscles = large number of muscle cells in each unit and less units
how are muslce cells in a motor unit positioned and how are motor units used within a muscle
- muscle cells in a motor unit are spread around the muscle so an impulse can trigger a weak contraction of the whole muscle
- motor units contract asynchronously (different units contract at different times) - to avoid fatigue
what are the 3 ways a muscle can attach to a bone
- via a tendon
- an aponeurosis (thin sheet of connective tissue)
- directly to the periosteum of the bone
what are the different lines of pull a muscle can have
circular eg around mouth
unipennate ( attach to one side of the tendon)
parallel ( fibres are parallel to muscle)
convergent ( single attachment point and fans out) eg pectoralis major
bipennate (fibres on 2 sides of a tendon)
multipennate eg deltoid
what 5 factors influence the naming of muscles
- shape
- number of heads
- direction of fibres
- region/attachment
- action
