Muscles and duchenne muscular dystrophy Flashcards
also anatomy of lower leg and foot
What is dorsiflexion
Angling the foot up
What is plantar flexion
Angling the foot down
What are the three superficial posterior leg muscles
gastrocnemius, soleus, plantaris
What are the three deep posterior leg muscles
tibialis posterior, flexor digitorum longus, flexor hallucis longus
What are 4 anterior leg muscles
tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius
what are the two lateral leg muscles
fibularis longus, fibularis brevis
what is the name of the true ankle joint
talocrural joint
what is the name of the subtalar joint
talocalcaneal
functions of the talocrural joint
dorsi and plantarflexion
functions of the subtalar joint
eversion and inversion
common insertion of superficial posterior leg muscles
calcaneal tuberosity via calcaneal tendon
common innervation of superficial posterior leg muscles
tibial nerve (S1-S2)
common action of superficial posterior leg muscles
plantar flexion of ankle joint
common innervation of posterior deep leg muscles
tibial nerve (L4-S3)
common action of posterior deep leg muscles
inversion and weak plantar flexion
common innervation of anterior leg muscles
deep fibular nerve (L4-S1)
common action of anterior leg muscles
dorsiflexion
distal attachment of fibularis longus
attaches medially
common innervation of lateral leg muscles
superficial fibular nerve (L5-S2)
common action of lateral leg muscles
eversion and weak plantarflexion
what are the 3 muscular compartments of the ankle retinacula
flexor, extensor and fibular
what are the 4 named parts of the medial (deltoid) ligament of the ankle
tibiocalcaneal part
tibionavicular part
posterior tibiotalar part
anterior tibiotalar part
what are the 3 named parts of the lateral ligament of the ankle
anterior talofibular
calcaneofibular
posterior talofibular
functions of the food arches
provide shock absorption and act as springboards
what are the 3 foot arches
medial longitudinal
lateral longitudinal
transverse
what provides passive support of the foot arches
bones and ligaments
what provides dynamic support of the foot arches
muscles and tendons
innervation of the anterior/flexor compartment of the thigh
femoral nerve
innervation of the posterior/extensor compartment of the thigh
sciatic nerve
innervation of the medial/adductor compartment of the thigh
obturator nerve
innervation of the anterior/extensor compartment of the leg
deep fibular nerve
innervation of the posterior/flexor compartment of the leg
tibial nerve
innervation of the lateral/evertor compartment of the leg
superficial fibular
nerve roots of the lateral cutaneous nerve of the thigh
L2-3
nerve roots of the super fibular nerve
L4-S5
nerve roots of the deep fibular nerve
L4-S2
nerve roots of the common fibular nerve
L4-S2
nerve roots of the tibial nerve
L4-S3
nerve roots of the nerve to obturator internus
L5-S2
nerve roots of the sciatic nerve
L4-S3
nerve roots of the inferior gluteal nerve
L5-S2
nerve roots of the nerve to quadratus femoris
L4-S1
nerve roots of the superior gluteal nerve
L4-S1
nerve roots of the saphenous nerve
L3-4
nerve roots of the femoral nerve
L2-L4
nerve roots of the obturator nerve
L2-4
nerve roots of the nerve to piriformis
S1-2
nerve roots of the posterior cutaneous nerve of the thigh
S1-3
What is the symbol for a male on a pedigree
Sqaure
What is the symbol for a female on a pedigree
Circle
What is the symbol for someone deceased on a pedigree
(subsequent circle or square) with a line through it diagonally
What is the symbol for affected on a pedigree
Coloured in
What is the symbol for a carrier on a pedigree
half coloured in
What is the symbol for a female carrier (x linked recessive) on a pedigree
small black dot in the middle of a circle
what is “proband” on a pedigree
an arrow pointing to the individual who brought the genetic disease into light
ie, a child with down’s syndrome
what is a consultand on a pedigree
the individual enquiring about the pedigree/being genetically tested
represented by the letter C on the chart
What is the symbol for a consanguineous relationship on a pedigree
two lines between two individuals
What is the symbol for a divorce on a pedigree
diagonal line through the marriage line
What is the symbol for a pregnancy on a pedigree
a diamond
What is the symbol for a miscarriage on a pedigree
a small black dot
What is the symbol for identical twins on a pedigree
a line between the triangle of twins
What is the symbol for non-identical twins on a pedigree
both children stemming from one point to form a triangle
what is a simple genetic pattern of inheritance
the ones we learned in school
chromosomal
autosomal recessive/dominant
x linked recessive
x linked dominant
y linked
what is a complex genetic pattern of inheritance
multiple genes + environmental factors (part genetic or multifactorial)
multiple genes +/- chromosomal abnormalities
(cumulative genetic)
what is ‘knight’s move’ on a pedigree
two males related through an unaffected female
(only males affected) - x linked recessive, female has extra X chromosome to protect her
What are myofibrils mad eup of
repeating units called sarcomeres
what is a muscle fibre made of
a bundle of myofibrils
what is a fascicle made of
a bundle of muscle fibres
usually 10-12
covered by perimysium
what is the epimysium
connective tissue surrounding the entire muscle
what is the perimysium
connective tissue surrounding the bundles of muscle fibres
what is the endomysium
connective tissue surrounding individual muscle fibres
where are the capillaries in muscles
between and surrounding individual myofibers
separated from myofibers by the interstitial space
what is the sarcolemma
membrane that covers a muscle fiber
describe the shape of a myofibril
repeating unit of sarcomeres
responsible for muscle contraction
rod shaped organelles
what is a sarcomere
basic unit of muscle
generates force and contracts
made up of thick and thin protein filaments giving muscle its striped appearance
what are the thick filaments
mysoin
what are the thin filaments
actin
function of the z disc
anchors thick and thin filaments to elastic filaments
function of M line
transverse structure that marks the centre of sarcomere and links myosin.
4 ways muscle is affected in DMD
Muscle damage
Muscle inflammation
Atrophy and Hypertrophy
Fibre replacement
What form of inheritance is DMD
X-linked recessive inheritance
50% of male offspring will be affected
50% of female offspring will be carriers
describe DMD progression
Sequential, Non-linear and irreversible
what is the median age for motor milestone
the age at which half of children acquire a certain skill
what is the limit age for motor milestone
the age by which 97% of children have achieved a certain skill
clinical features of DMD between birth to 18 months
No concerns during pregnancy or at birth
delayed motor milestones might be reported
not independently walking by 18 months
clinical features of DMD between age 2-3
enlarged calf muscles
frequent falls
tiredness/fatigability
delayed motor milestones
learning difficulties
clinical features of dmd between age 3-4
difficulties in running and climbing stairs
struggle to get up from floor (Gower’s maneuver)
frequent falls
struggling to jump
persistent tip-toe walking
what is positive gowers sign
when lying in supine position the child must turn over and walk their hands to their feet in order to get up
what is the mnemonic to aid DMD diagnosis
M - motor milestone delay
U - unusual gait
S - speech delay
C - creatine kinase asap
L - leads to
E - early diagnosis DMD
how is creatine kinase affected in DMD
it leaks out of muscle if there is damage
treatment options for DMD
no cure
steroid therapy to dampen down muscle inflammation
- prednisolone, deflazacort
what causes DMD
Defect in the dystrophin gene
Any mutations that disrupt the reading frame or point mutations that generate a premature stop codon disrupts the dystrophin protein translation, leading to DMD
function of atalauren
enables ribosome read through of premature stop coding to allow protein synthesis to occur as normal
What is compartment syndrome
when the pressure within a muscle compartment is so high that blood perfusion is no longer possible
- no blood flow = muscle death
possible causes of compartment syndrome
- fracture
- crush injury
- revascularisation
- fluid infusion
- arterial rupture
- snake bite
5 P’s (signs) of vascular injury
(limb ischaemia)
Pain
pulselessness
pallor
paresthesia
perishing cold
describe pain of compartment syndrome
out with expectation
massive analgesic use
on passive movement of muscle in compartment - unbearable pain
examination of compartment syndrome in lower limb
wiggling big toe
measuring pressure
how to fix compartment syndrome
slice open the skin and fascia overlying the entire length of the compartment to relieve the pressure
skin sometimes cannot then be closed so a skin graft is often needed
what are the three types of motor units in human muscle
Type 1 - Slow contracting - Oxidative
Type 2a - Intermediate - Mixed
Type 2b/x - Fast contracting - Glycolytic
summarise energy sources at max effort
ATP stores and Phosphocreatine deplete in a few seconds
Anaerobic glycolysis can contribute for a few minutes; Type 2b fibres
Aerobic metabolism dominates after 3-5 minutes; Type 2a and Type 1 fibres
what are the two forms of fatigue
peripheral and central
describe peripheral fatigue
within muscle fibres
failure of excitation-contraction coupling
failure of force generation at cross bridges
failure of ATP generation by depletion of energy stores
describe central fatigue
within the nervous system
loss of excitability of motor cortex
reflex inputs from ‘metabo-receptors’ in muscle
