Anatomy & Physiology Module 2: Muscle System

skeletal muscle

• striated

• voluntary control

• long cylindrical fibres

• multinucleate

• strength of contraction varies, rapid, fatigable

cardiac muscle

• striated

• involuntary control

• branched fibres intercalated disks

• uninucleate or binucleate

• only in heart

smooth muscle

• no striations

• involuntary control

• fusiform fibres

• uninucleate

• continuous slow sustained contraction

characteristics of skeletal muscle tissue

• excitability

• contractility

• extensibility

• elasticity

functions of skeletal muscle tissue

• produce movement-locomotion and manipulation

• maintain posture- continuous tiny adjustments to counteract gravity

• stabilise joints

• generate heat with contraction- helps maintain normal body temp

organ

composed of skeletal muscle fibres, blood vessels, nerves, connective tissue

endomysium

surrounds individual muscle fibre

perimysium

surrounds each fascicle or bundle of muscle fibres

epimysium

surrounds whole muscle

origin

attached to the less moveable bone

insertion

• attached to the more moveable bone

• during contraction, the point of insertion moves closer to the origin

• direct attachment to bone- epimysium is fused to periosteum

• indirect attachment to bone- connective tissue covering extends beyond muscle and becomes tendon

muscle name

• shape

• size

• location

• direction

• number of origins

• muscle action

flexion

reduce angle between bones

extension

increase angle between bones

rotation

turning on the axis(medial, lateral)

adduction

ADD together, back to midline

abduction

moving away from the midline

pronation/supination

forearm

dorsiflexion/plantarflexion

ankle

inversion/eversion

ankle

myology

when describing actions. always state the joint and the movement occurring across it

ex:elbow flexion, knee extension

agonist

muscle that preforms the action (the agony)

prime mover

the agonist most responsible for the movement

antagonist

muscle whose action opposes the agonist action

synergist

muscles that work together to preform the same task

fixator

synergist contracting to stabilize a joint

facial expression muscles

insert into the skin

• orbicularis oculi

• zygomaticus major

• risorius

• orbicularis oris

mastication muscles

• buccinator

• temporalis

• masseter

duchenne smile

genuine smile

• contracts zygomaticus major

• includes orbicularis oculi

non-duchenne smile

social medial smile

• contracts zygomaticus major

muscles of the neck

• sternocleidomastoid

• scalene muscles

• splenius capitis

anterior muscles from the hip superiorly are___

flexors

anterior muscles from the hip inferiorly are ___

extensors

key roles of thorax muscles

• to stabilize and move vertebral column

• to stabilize and move scapula

• to assist respiration

• to move upper limb at shoulder joint

key roles of the abdominal muscles

• to stabilize and move vertebral column

• to move lower limb at hip joint

deep muscles of the posterior trunk

erector spinae

• prime movers of trunk extension

• spinalis: along spinous process, most medial column

• longissimus: along transverse process, middle column, longest and thickest

• iliocostalis: most lateral column, ilium to ribs

Quadratus lumborum

• both are in opposite compartment & antagonists to the abdomical muscle

deep stabilizers of posterior trunk

• span single intervertebral joint only

• synergists in extension and rotation of the trunk to the opposite side

• stabilising role

• rotatores

• mutifidus

superficial muscles

agonist for shoulder and arm movement

origin:axial skeleton

insertion: appendicular skeleton

• trapezius

• latissimus dorsi

muscles of the anterior abdomen

prime movers of flexion of vertebral column antagonists to erector spinae

4 paired muscles:

• external oblique

• hands in pockets

• rectus abdominis

• sit ups

• internal oblique

• perpendicular to EO

• transversus abdominis

• deep corset

core stabilizers

anteriorly

• trunk flexors

posteriorly

• trunk extensors

superiorly

• diaphragm

inferiorly

• pelvic diaphragm

muscles of respiration

inhalation: active

• diaphragm flattens

• external intercostals

forced inhalation

• scalenes

• sternocleidomastoid

• levator scapulae

exhalation: passive

• diaphragm and external intercostal muscles relax

• rib cage descends

• lungs recoil due to elasticity

forced exhalation: active

• external obliques

• transversus abdominis

• internal intercostals

muscles of the pelvic floor

levator ani

• pubococcygeus

• iliococcygeus

• coccyges