GEP (Life Structure) Week 2 Flashcards
Identify the anatomical areas of the foot in the image
The bones of the ankle and foot are important in supporting the weight of the body and providing attachment sites for the muscles of the lower leg and foot:
They can be divided into three groups:
Tarsals:
Talus, superiorly (which makes up the ankle joint)
Calcaneus, which is basically the ‘heel’ and lies under the talus
Navicular, meaning ‘little ship’ in Latin because it looks like a boat
Cuboid, cuboidal in shape
3x cuneiforms, which are wedge-shaped
5x metatarsals, connected distally to the tarsals with the tarsometatarsal joints
Phalanges
second to fifth toes have proximal, middle and distal phalanges
the big toe only has proximal and distal phalanges
Identify the anatomical locations in the image
The ankle (or talocrural) joint is a hinge-type synovial joint, which enables dorsiflexion and plantarflexion of the foot.
The distal tibia and fibula are bound together by strong ligaments, which make a bracket-shaped socket.
The talus fits nicely into this socket and enables movements:
Dorsiflexion: the broad anterior part of the talus is held in the socket, which makes the joint more stable.
Plantar flexion: the narrow posterior part of the talus is in the socket, so the joint is less stable.
What are the ligaments of the ankle
There are two main sets of ligaments that support the ankle:
Medial (or deltoid) ligament:
Originates from the medial malleolus (a bony prominence on the distal tibia).
Consists of four ligaments, which fan out from the malleolus, attaching to the talus, calcaneus and navicular bones.
Main action is to resist over-eversion of the foot.
This ligament is STRONG and less likely to be damaged.
Lateral ligament:
Originates from the lateral malleolus (a bony prominence on the distal fibula).
Main action is to resist over-inversion of the foot.
WEAK ligament.
Comprised of three ligaments:
Most important is the anterior talofibular ligament (ATFL), which spans between the lateral malleolus and lateral aspect of the talus.
This is most likely to be damaged in an ankle sprain or twisted ankle, as it is weaker than the deltoid and also sprains usually result from excessive inversion to a plantarflexed foot (and ATFL resists over-inversion).
Name these areas of common ankle injuries
Twisted ankle from excessive inversion
Calcaneofibular ligament (lateral side) may also be damaged alongside ATFL
Fractures to the medial or lateral malleoli or distal fibula from a strong force
Pott’s fracture can involve all of these from forced eversion of the foot.
What are the movements and Planes Recap
What are the superficial muscles of posterior compartment: what innervates it, and the vascular supply
Superficial
Gastrocnemius
Soleus
Plantaris
Actions:
plantar flexion at ankle joint, flexion at knee joint
Innervation:
Tibial nerve (branch of sciatic)
Blood supply:
Posterior tibial artery
Superficial compartment includes 3 muscles:
Gastrocnemius, which has two heads (lateral and medial) and makes up the calf shape of the leg - the heads combine to form a single muscle belly. Action: plantarflexion at the ankle joint and flexion at the knee joint.
Soleus is the muscle underneath the Gastrocnemius (gets it’s name as it looks like a flat fish). Action: plantarflexion of foot at ankle joint.
Muscles converge distally to form the calcaneal tendon (aka Achilles tendon) - if damaged, unable to plantarflex foot.
Plantaris is a small muscle (absent in 10% of the population). Action: contributes to the plantarflexion
What are the Deep muscles of posterior compartment: what innervates it, and the vascular supply
Deep
Popliteus → lateral rotation of femur to unlock knee
Flexor digitorum longus → flexion of lateral four toes
Flexor hallucis longus → flexion of big toe
Tibialis posterior → inversion and plantarflexion of foot
Innervation:
Tibial nerve (branch of sciatic)
Blood supply:
Posterior tibial artery
-Popliteus forms the base of the popliteal fossa behind the knee. Action: unlocks the knee joint by laterally rotating femur around the tibia
-Flexor digitorum longus, Action: flexion of the lateral four toes
-Flexor hallucis longus, Action: flexion of the big toe
-Tibialis posterior, Action: inversion and plantarflexion of the foot and contributes to the medial arch.
What are the muscles of Lateral compartment: what innervates it, and the vascular supply
-Fibularis longus
-Fibularis brevis
Actions:
Eversion of foot
Innervation:
Superficial fibular (or peroneal) nerve
Blood supply:
Fibular artery
Fibularis longus is larger and more superficial. Action: eversion and plantarflexion and supports lateral arches of foot, tendon attaches into base of the 1st metatarsal.
Fibularis brevis is deeper and shorter, tendon attaches to the base of 5th metatarsal.
What are the muscles of Anterior compartment: what innervates it, and the vascular supply
-Tibialis anterior
-Extensor digitorum longus
-Extensor hallucis longus
-Fibularis tertius
Actions:
Dorsiflexion and inversion of foot
Innervation:
Deep fibular nerve (L4-S1)
Blood supply:
Anterior tibial artery
What are th muscles of the foot
not a question
Overiew of the leg muscles
Hallucis = big toe
Digitorum = lateral four toes
Flexor = anterior compartment
Extensor = posterior compartment
What is the arterial supply of the lower limb
What is the venous supply of the lower limb
Most follow arteries
Great (or long) saphenous vein passes anterior to medial malleolus at the ankle → drains into femoral vein
Small saphenous vein passes posterior to the lateral malleolus → drains into popliteal vein → femoral vein
Most veins run alongside the arteries apart from the saphenous superficial veins
Great (or long) saphenous vein
drains dorsal venous arch of the foot and dorsal vein of the big toe → wraps up the medial side of leg, passing anteriorly to the medial malleolus at the ankle, and posteriorly to the medial condyle at the knees as it ascends → eventually drains into the femoral vein just below the inguinal ligament.
can be harvested and used in a coronary artery bypass
Small saphenous vein
drains dorsal arch of foot and the dorsal vein of the little toe → wraps up the posterior side of the leg, passing posteriorly to the lateral malleolus of the ankle → at the level of the knee, passes between the two heads of the gastrocnemius muscle and empties into the popliteal vein in the popliteal fossa (which then drains into the femoral vein).
What is the nerve supply of the lower limb
Sciatic nerve (L4-S3) splits into
Tibial nerve (supplies posterior compartment) → medial plantar and lateral plantar nerves (supplies muscles in sole of foot)
Common fibular (peroneal) nerve → deep fibular (peroneal) nerve (supplies anterior compartment) and superficial fibular (peroneal) nerve (supplies lateral compartment)
What are the dermatones and cutaneous innervation
dermatome is an area of skin supplied by one spinal nerve root
cutaneous innervation refers to areas of skin supplied by one peripheral nerve (which may originate from multiple nerve roots)
What are the cutaneous nerves of the lower leg
Femoral nerve (L2-L4)
Saphenous nerve (anteromedial aspect of the leg and foot)
Sciatic nerve (L4-S3)
Superficial fibular nerve (anterolateral aspect of the leg and dorsum of foot)
Sural nerve (posterolateral aspect of the leg and foot)
Deep fibular nerve (space between 1st and 2nd toes on dorsum of foot)
Medial calcaneal nerve (medial aspect of the heel)
What are the common peroneal nerve injury
Common peroneal nerve wraps around the head of the fibula
Damaged by:
-fracture of the fibula
-use of a tight plaster cast
Presentation:
-Unable to dorsiflex → foot drop
-Weakness of eversion
-Stepping gait
-Loss of sensation over the dorsum of the foot, and lateral side of leg
Tibialis anterior as example
when dorsiflexing the foot, its attachment at the lateral condyle of the tibia stays still, therefore, is the origin
the attachment at the 1st metatarsal moves, so is the insertion.
Give an overview of cardiac muslce
Location: wall of the heart
Control: involuntary
Regulation: ANS and hormones
Features of fibres:
-Branched
-Uninucleated
-Striated
-Intercalated discs between cells
Give an overview of smooth muscle
Location: walls of hollow internal organs (blood vessels, respiratory tract, digestive system etc)
Control: involuntary
Regulation: ANS and hormones
Features of fibres:
-Branched
-Uninucleated
-Non-striated (smooth)
-Cells are tapered at each end (spindle-shaped)
give an overview of skeletal muscle
Location: attached to bones (skeleton)
Control: voluntary
Regulation: CNS and PNS
Features of fibres:
Multinucleated
Striated
Long and cylindrical cells
What are the features of skeletal muscle
Origin: attachment on the more immovable bone
Insertion: attachment on the more flexible bone
Agonist: muscle/s that produces most of the force at a joint
Synergist: muscle/s that help the agonist
Antagonist: muscle/s that oppose the action of the agonist
Fixator: muscle/s that prevent a bone from moving
Not a question
Overview of different types of muscles
Label these anatomical areas of the muslce
What is Muscle
‘Mysiums’ separate the muscle:
Epimysium wraps around the whole muscle.
Perimysium wraps around the fascicle.
Endomysium wraps around the muscle fibre.
Muscle fibres contain lots of mitochondria and myofibrils.
Myofibrils are bundles of connected protein filaments.
Myofibrils can be divided into sarcomeres, which are the functional units of muscle.
There are 2 filaments: thick myosin and thin actin.
These filaments move relative to each other to generate movement.
A fascicle is a collection of muscle fibres - muscles are made up of many bundles of fascicles.
What is the sarcomere and its components
A single sarcomere is between the Z-discs.
Z-discs anchor the thin actin filaments.
Myosin is also attached to the Z-disc by an elastic filament (less important).
A-band = myosin.
Dark band under microscope.
I-band = actin
Light band under microscope.
What is the filament sliding theory
RELAXED:
M-line = middle of the sarcomere
H-zone = area between end of actin filaments (only contains myosin).
CONTRACTED:
On contraction…
I-band gets shorter
H-zone gets shorter
A-band stays the same
Z-disc and M-line get closer together, but stay the same size
How does muscle contractions occur
Contraction starts from the neuromuscular junction (NMJ)…
NMJ = synapse between LMN and skeletal muscle fibre.
Action potential arriving at synapse causes influx of calcium into synapse.
This causes release of neurotransmitter.
For skeletal muscle contraction, this is acetylcholine.
Postsynaptic membrane has nicotinic receptors (nAchR).
Binding of Ach to nAchR allows for influx of sodium.
This causes an action potential in the sarcolemma (surrounding the muscle fibre).
Describe process whereby an action potential triggers a skeletal muscle fibre to contract
- AP travels along the sarcolemma, and down the T-tubules → depolarisation.
- Depolarisation causes opening of voltage-gated L-type Calcium channels, allowing calcium to enter the cell.
- Calcium-influx activates ryanodine receptors on sarcoplasmic reticulum → intracellular calcium store.
- Makes calcium concentration in cell very high.
- Calcium binds to troponin-c, which moves tropomyosin off the myosin-binding site on actin.
- Binding of myosin head to actin forms cross-bridge.
- Binding allows myosin to pull actin, shortening the sarcomere → muscle contraction.
- Muscle contraction happens simultaneously.
Describe process whereby an action potential triggers a skeletal muscle fibre to contract
To relax the muscle, calcium is pumped back into the SR by the sarco/endoplasmic reticulum calcium-ATPase.
How does myosin move actin
ATP binding causes myosin-head to detach from actin.
If there is no ATP, muscle cannot relax if already contracted → theory on cramp?
What is a the Motor Unit
Skeletal muscle is innervated by α-motor neurons.
Motor unit = single α-motor neuron and the individual muscle fibres it innervates.
Single muscle fibre only innervated by one neuron.
But each α-motor neuron can innervate many fibres.
The more fibres innervated by one neuron, the stronger the contraction, but the less fine the control.
Precise movements (eyes, fingers etc) have a low amount of muscle fibres for each neuron.
Large movements (legs etc) have large amount of muscle fibres for each neuron.
What are the types of muscle contraction
Concentric
Muscle shortens
Muscle force is greater than resistance
Eccentric
Muscle lengthens
Muscle force is less than resistance
Muscles stretches
Isometric
Muscle stays same length
Muscle force is equal to resistance
How is energy utilisatied by the body and muscle
Working muscles need: Oxygen + Energy
Need to remove: Carbon Dioxide + Lactate
ATP is essential for many processes in exercise, including muscle contraction.
-Only ever enough free ATP in muscles for 1-2 seconds of movement.
-ATP must be generated by other means:
1)Creatine Phosphate (CP)
2)Glycolysis
3)Oxidative Phosphorylation
-Fat + protein sources of ATP in long-term exercise/starvation.
What is considered short duration and prolonged exercise
What is creatinine phosphate and its function
Fastest way for muscles to make ATP.
At rest, excess ATP is used to make CP.
Creatine kinase moves phosphate group from CP to ADP → ATP.
Done without Oxygen.
Only enough CP for 10/15 seconds.
Used in first seconds of intense exercise.
Hydrogen ions strongly inhibit creatine kinase
Give an overview of glycolosis
Uses glucose to produce energy without oxygen (anaerobic).
Fast; used after CP used up.
Produces 4 ATP for 1 molecule of Glucose but 2 ATP is used breaking down glucose = Net 2 ATP.
1 molecule of Glucose also makes 2x Lactic Acid.
Lactic acid forms lactate and hydrogen ion.
What is oxidative Phoshorylation
Supplies ATP for light/moderate exercise, but is dependent on Oxygen.
-Produces ~35 molecules of ATP per glucose (compared to the net 2 in glycolysis) → much more efficient.
-Pyruvate (from glycolysis) gets converted into Acetyl-CoA, which enters the Krebs cycle.
-Krebs cycle produces NADH and FADH which go into the Electron Transport Chain
-NADH and FADH help pump hydrogen ions into intermembrane space of mitochondria → travel down ATP-Synthase to make lots of ATP.
Pyruvate can also be made from fat and protein metabolism.
Fat = very slow, resting metabolism or long term exercise.
Protein = muscles ‘eating’ themselves to move → starvation.
How are different substrate broken down and utilised
What are the 2 different types of muslce fibres
There are 2 main types of muscle fibres:
Type 1 (slow-twitch)
Aerobic; use Ox Phos so require lots of oxygen.
Have lots of mitochondria and myoglobin → makes them red.
Endurance.
Type 2 (fast-twitch)
Mainly anaerobic, but Type 2A has some aerobic activity.
Not much mitochondria and myoglobin → makes them white.
Sprinting/resistance training.
