In terms of muscles, this is the basic unit as it can be extremely thin and extremely long.
This is a group of fibers surrounded by perimysium.
This is composed of several fascicles, surrounded by epimysium and is widest at its belly.
Connective Tissue Sheaths
These are loose connective tissue with reticular fibers (net-like collagen pieces)
The innermost layer of connective tissue.
This surrounds a fascicle.
This surrounds the outermost layer.
This tends to have dense regular connective tissue and is a synonym for epimysium.
This is the less mobile bone, generally the more proximal bone.
This is the more mobile bone, generally the more distal bone.
These attach directly to the bone.
These tend to be long and rather elastic, and the connective tissue sheaths extend past the muscle. Due to this, they can cross very mobile joints and end up being stronger and more durable.
A type of indirect attachment, but is a slightly narrow strip.
This is much more sheet-like than a tendon.
These are very strong ligaments that form a cuff/bracelet around insertion tendons to prevent them from pulling away form the joint surface.
These are two muscles working together, with the one working the most called a prime mover.
These work oppositely
Concerned with posture.
Long central tendon and feathers off from that, thus the fasciculi are arranged in a feather-like pattern, these end having shorter muscle fibers and are quite strong.
This feathers off to one side.
This feathers off to both sides
This looks like a fan.
The fasciculi are parallel to the muscle's long axis and run along the entire length of the muscle, thus allowing them to contract over great distances, albeit with low amount of strength.
This is similar to parallel, but has a wider, belly, thus they can contract with more force.
Broad origin, but narrow insertion.
Circular arrangement of fasciculi, thus can close and open. These tend to surround body openings.
Location Names - Structural
Hallucis: Big Toe
Location Names - Relative
Lateral, Medial, Intermediate
Maximus, Minimus, Longus, Brevis
Rectus: Parallel to bone
Origin and Insertion
Number of Origins (Heads)
cep (head), biceps, triceps, etc.
Extensors, Flexors, Abductors, Adductors
Connective Tissue that comes together to form the Illiotibial Tract
very broad layer of connective tissue.
Helps tendons stay against the body, etc.
Anterior part helps with forward movement, posterior side helps with stabilization and moving backwards. There are also medial muscles and adductor muscles.
There is the anterior extensor, the posterior flexor, and lateral muscles... though I think we skipped this.
Central Nervous System
This consists of the brain and spinal cord and is the integrating and command center of the nervous system.
Peripheral Nervous System
This is the nervous system minus the central nervous system, and contains spinal nerves, which carry impulses to and fro the spinal cord, and cranial nerves, which carry impusles to and from the brain.
Sensory (Afferent) Division
Division of the Peripheral Nervous System that consists of nerves that carry messages to the CNS. This division keeps the CNS constantly informed of events going on both inside and outside the body.
Motor (Efferent) Division
This division of the Peripheral Nervous System that transmits impulses from the CNS to the effector organs (muscles and glands). These effect (or bring about) a motor response.
Somatic Nervous System
This is composed of muscles under voluntary control that conduct impulses from the CNS to skeletal muscles.
Autonomic Nervous System
This is the involuntary nervous system and regulates the activities of smooth muscles, cardiac muscles, and glands (both endo- and exo-).
This works in opposition to our parasympathetic nervous system, and acts as our "fight-or-flight" response system.
This works in opposition to the Sympathetic Division and conserves energy and calms us down.
These nerves of the PNS attach to the brain.
These nerves of the PNS attach to the spinal cord
Classifying Nerves - according to neuron types
Classifying Nerves - According to Target Region of Body
Afferent Sensory Nerves
-somatic (body) and visceral (internal)
-somatic and autonomic
General Nerve Anatomy
There are individual axons surrounded my myelin sheaths, which act as insulators to speed up the signal.
Axons and Myelin sheaths are surrounded by endoneurium.
Fascicles, bundles of axons, are surrounded by perineurium.
Lastly, that nerve, or bundle of fascicles, is surrounded by epineurium.
Spinal nerves that are afferent neurons.
Spinal efferent neurons, and are more anterior.
Dorsal Root Ganglions
Cell bodies of afferent neurons.
Spinal Nerve - Anatomy
These nerves are paired, seeing as we have a bilateral body, but post-ganglion these nerves are mixed nerves.
These nerves actually branch out into rami and contain a nerve plexus, which is basically a hub of nerves
Spinal Nerve Rami
Sends to the dorsal roots.
Sends to the ventral roots.
Nerve Plexus - Structure
These are interwoven group of nerves and each plexus forms several spinal cord segments. These travel to several muscles and the original nerve divides, then joins parts of other nerves to form a new nerve.
Nerve Plexus - Purpose
Nerves emerging from the plexus contain input from several spinal nerves, thus nerves from a variety of regions. Also, muscles receive input from several layers of the spinal cord, thus being a protective measure so that we don't lose all control if one nerve is hurt.
Foramen of the Vertebra
Where nerves are coming from.
Holes in the side of the vertebrae.
Numbering Vertebrae and Spinal Nerves - Cervical
7 Cervical Vertebrae: C1-C7
8 Pairs of Cervical Nerves: C1-C8
Numbering Vertebrae and Spinal Nerves - Thoracic
12 Thoracic Vertebrae: T1-T12
Articulating with ribs.
12 Pairs of Thoracic Nerves: T1-T12
Thoracic vertebrae is more from side to side.
Numbering Vertebrae and Spinal Nerves - Lumbar
5 Lumbar Vertebrae: L1-L5
5 Pairs of Lumbar Nerves: L1-L5
Numbering Vertebrae and Spinal Nerves - Sacrum
5 Fused Vertebrae
5 Pairs of Sacral Nerves: S1-S5
Numbering Vertebrae and Spinal Nerves - Coccyx
4 Fused Vertebrae
1 Very Tiny Pair of Coccygeal Nerves, C0
"Borrowed" Muscles from Lower Trunk
Innervation is supplied by the lumbar plexus, and they act at the hip/thigh and/or knee/leg joints, they tend to pull muscles into the leg.
A rigid bar that moves on a fixed point when a force is applied to it.
The fixed point that a lever pivots on.
The applied force when dealing with a lever.
The resistance to the applied force when dealing with a lever, generally what one is trying to lift.
What is the purpose of levers?
To transform some effort into the movement of some load, and this can be in terms of strength, as in moving a heavy load, or can in be in terms of speed, as in moving something quickly.
This is a power lever and can output a lot of strength with a little input. It requires a longer distance between effort and fulcrum and short distance between fulcrum and load. Like a car jack.
This is a speed lever, and more force is applied to the lever than is produced by the lever. This requires a shorter distance between effort and fulcrum and a longer distance between fulcrum and load, like a shovel. This does, however, generally have a greater range of motion.
First-Class Levers : Definition
This is when the lever is set up as:
Load --- Fulcrum --- Effort
It can have mechanical disadvantage or mechanical advantage.
Example: Seesaws and Scissors
First-Class Levers - Mechanical Advantage
This is when the fulcrum is closer to the load. For example:
Effort : posterior neck muscles
Fulcrum: Occipital condyles/atals
Load: Entire skull
First-Class Levers - Mechanical Disadvantage
This is when the fulcrum is closer to the effort.
Effort: Triceps brachii
Fulcrum: Elbow, in this case the humerus and ulna.
Second-Class Levers - Definition
This is when the lever is set up as:
Fulcrum --- Load --- Effort
The movement allowed by this is stricter, but generally stronger. Also, this is only mechanical advantage, by definition.
Example: Wheelbarrow, or standing on tip-toe.
Fulcrum: Ball of foot
Load: The entire body
Effort: Calcaneal/Achilles Tendon
This is when the lever is set up as:
Load --- Effort --- Fulcrum
This movement is much freer, but not very strong and is mainly good at speed.
Example: Tweezers, or the biceps brachii
Effort: Biceps Brachii
Fulcrum: Elbow, again the humerus and ulna.
Adductors - Overview
This entire group is meant for adducting your leg, and is innervated by the obturator nerve. They are useful for riding a horse, etc. and if you stretch this area it is a "pulled groin"
Hamstrings - Overview
These are located on the posterior thigh and extend the hip and flex the knee equally well. They also limit simultaneous full hip flexion and full knee extension, like punting a football. They consits of the biceps femoris, semimembranosus, and semitendinosis. They are also all innervated by the sciatic nerve.
Muscles of the Posterior Leg - Overview
These are all innervated by tibia nerve, also called the triceps surae.
Muscles of Anterior, Lateral Surface of Leg - Overview
These are all innervated by peroneal nerves and, in general, are extrinsic foot muscles.
Also termed responsiveness, the ability to recieve and respond to a stimulus, or the ability to respond to the environment.
The ability to shorten forcibly when adequately stimulated, and is generally an active process.
The ability to be stretched or extended, possibly even beyond resting length. This is generally a passive process.
The ability of a muscle cell to recoil and resume its resting length after being stretched. This helps prevent too much stretching.
Skeletal Muscle - Appearance
This muscle is striated, meaning striped, and is made up of very long cylinders. It is multinucleated due to being very long, and is the only exception as other cells only have one nucleus. Muscles and their corresponding motor neurons were developed together from birth and so if one is hurt the other suffers.
Skeletal Muscle - Control
This tissue is under voluntary control of the somatic nervous system, specifically motor neurons.
Skeletal Muscle - Functions
Nearly all movement of the human body comes from skeletal muscle.
Functioning almost continuously, these muscles help keep us upright.
Muscle Tone greatly influences Joint Stability.
Skeletal muscle accounts for about 40% of body mass, and when healthy can generate three to four times heat when needed. Hence shivering.
Cardiac Muscle - Appearance
This tissue is also striated, but the fibers are much shorter and are linked at "intercollated disks" by desmosomes.
Cardiac Muscle - Control
This is involuntary, and even generates its own beat.
Cardiac Muscle - Function
Moving blood and maintaining blood pressure.
Smooth Muscle - Appearance
This is non-striated, hence being "smooth", is spindle-shaped, and one has one nucleus.
Smooth Muscle - Control
This is under involuntary control and is controlled by the nervous system and hormones.
Muscle Fibers - General
These muscle cells are derived from myoblasts, have a sarcolemma, which is just a plasma membrane for muscle cells, and is surrounded by endomysium, which is CT around each fiver.
Where a neuron meets its target
This is like a bus terminal and belongs to the neuron. It is the widened base of a motor neuron's axon and has vesicles containing the neurotransmitter called acetycholine.
This is the space between the pre-synaptic terminal and the motor endplate in a neuromuscular junction. ACh is released from the pre-synaptic terminal and diffuses across the cleft. When ACh delivers its message, AChE, Acetycholine Esterase, breaks down ACh.
This is a specialized region of the sarcolemma, and contains many folds to increase surface area for recieving ACh. It also contains many transmembrane protein receptors for recieveing ACh.
Muscle Cell Organelle Specializations
First off, muscle fibers are multi-nucleate, and the sarcolemma's contain Transverse Tubules. These folds in the Sarcolemma help speed along an Action Potential. Lastly, there is the Sarcoplasmic Reticulum, which contains high levels of Calcium which can released with an electric signal.
Sarcomere - Overview
The sarcomere is the functional unit of skeletal muscle.
This thick filament contains a rod-like tail attached by a hinge to two globular heads. These forms bundles of myosin, which looks like an olive tree branch thing.
This thin filament looks like a string of beads. Tropomyosin strands coil around actin to give it some stiffness and stability. Troponin also is associated with actin and is a globular protein that tends to bind with Calcium.
Myosin filaments tend to block light, and so light bands are actin and dark bands are myosin. At the end of each sarcomere is a z line, or z disc, which basically acts as an anchor.
Purpose of Arches
Our weight is support by arches because they can hold much more weight than normal, weight ends up being correctly distributed to out metatarsals and calcaneus, and due to the shape of the arch we obtain a little energy boost when walking due to the shock absoprtion properites of the arches in our feet.
Maintenance of Arches
These help maintain the founding shape of the arch.
Generally you shouldn't really only on these, but when a bunch are put together they can be quite durable.
This also helps keep the shape as the long tends of the extrinsic foot muscles help keep tension on the arch.
Loss of arches
This results in flatter feet which results to less efficient walking, pain, and possibly more damage in the future. This can be genetic, or can come from long periods of immobile standing, running on hard surfaces without arch support, obesity, or improper shoes.
Medial Longitudinal Arch
The Talus is the keystone for this arch, and generally it helps us put weight on the calcaneus and first three metatarsals. Maintenance depends primarily on ligaments and two muscles.
This helps pull up the inside of the arch since its tendon goes under the lateral malleolus to the first metatarsal.
Flexor Hallucis Longus:
This pulls on the big toe and thus helps keep the arch together.
Lateral Longitudinal Arch
This arch has the cuboid as its keystone and helps put weight on the calcaneus and fifth metatarsal. Maintenance of this arch primarily depends on ligaments and the fibularis longus, which goes behind the lateral malleolus and pulls up the arch like a sling.
This arch depends on the bones forming nice structures and uses the other arches as pillars for support. Maintenance depends on bone articulations and the fibularis longus, which also helps keep the transverse arch up.
M.C.D.W. - Starting Conditions
Both legs need to be on the ground.
M.C.D.W. - Stepping Forward with the Right Leg - Actions of the Left Leg
This leg is now the weight-bearing leg.
Muscles: Gluteus Minimus and Gluteus Medius.
Purpose: Swing leg around the other so that our legs don't bump into each other.
Hip Medial Rotation
Muscles: Gluteus Minimus and Gluteus Medius
Purpose: This helps keep the left leg a bit more central to help on balance.
M.C.D.W. - Stepping Forward with the Right Leg - Actions of the Right Leg - Pushing Off
Plantar Flextion of the Right Foot
Muscles: Soleus and Gastrocnemius.
Purpose: Pushing body forward, propeling.
Hip Extension of Right Limb
Purpose: Moving, putting the force forward for movement.
Slight Knee Flexion
By the hamstrings, right after pushing off, to prevent toes from dragging.
M.C.D.W. - Stepping Forward with the Right Leg - Actions of the Right Leg - Moving the Right Leg Forward
1. Stabilization of the Pelvis
Muscles: Gluteus Minimus and Gluteus Medius
Purpose: Not dropping down.
2. Hip Flexion
Purpose: Allow for some movement.
3. Leg Extension
Muscles: Quadriceps Femoris
Purpose: Have a straight knee when moving forward.
4. Foot Dorsiflexion
Muscles: Tibialis Anterior
Purpose: Land on calcaneus, thus less stressful.
Definition of Membrane Potential
A Membrane Potential is simply the voltage across a membrane, with outside the cell relatively being defined as 0mV. This voltage, however, is generated by ion movement across the membrane, with cations coming in causing a positive current and cations leaving causing a negative current.
This is the "normal" membrane potential, when the cell is not active, or when we are not stimulating it. Typically, this is around -70mV, meaning the cell is primarily losing cations.
An Action Potential is a rapid electric signal that involves a temporary reversal of the membrane potential, meaning cations suddenly come in the cell. Action Potential can also propagate, or travel, down the axon.
Motor Neuron : Stimulation
First, an action potential is initiated by neuron cell body, and then the action potential moves down the axon, a process called propagation, moving towards the axon terminal.
Motor Neuron - AP and neurotransmitter release
The action potential triggers neurotransmitter release from the pre-synaptic terminal, especially acetycholine, which causes the vesicles holding Ach to exocytote Ach into the synaptic cleft.
Motor End Plate Events
Ach first binds to Ach receptors, which causes cations to rish in. Specifically, this Actiin Potential is initiated in the sarcolemma, but it then travels down Transverse Tubules (T Tubules), causing sacroplasmic reticulum to release calcium.
This is simply a terms used to describe how an action potential (excitation) can cause contraction. Calcium is by far the key link in this, however, as when calcium is release from the sarcoplasmic reticulum it binds to troponin, a little protein on actin, and continues this process of contraction.
End of Contraction - Acetycholine
When the Action Potential has passed, Ach is no longer release as it is no longer needed, and thus AchE is released to break down the remaining Ach. This recycling process is called reuptake.
End of Contraction - Calcium
This process is a reversible reaction, as when the action potential is finished calcium is released from troponin and then moved back into the sarcoplasmic reticulum. Thus, this basically resets everything.
All or Nothing Contraction
There are no partial contractions.
This is an autoimmune disease that attaches Ach receptors, and even though we constantly replace receptors this makes it so that we simply cannot replace fast enough. The main symptom is muscle weakness (like not being able to fully open your eye) . The treatment for this would be AchE inhibitors to block the reuptake process
Tetanus (a.k.a. lockjaw)
This is caused by a bacterial infection that is generally caught when in muddy, rusty areas. This releases an Ach receptor agonist, which acts like Ach, thus causing permanent constant contraction. This often results in death as the diaphragm can never relax, thus they suffocate to death.
This is a poison from South-American frogs that works as an Ach receptor antagonist, meaning it prevents Ach from acting. When this happens, muscles cannot contract and thus results in a limp paralysis, and often death since the diaphragm cannot contract.
Paralysis of pectoralis minor
Paralysis, as scapula is not held against the body, and thus a "winged scapula", and cannot elevate the arm.
Sliding Filament Mechanism
There is no breaking down, simply filaments sliding against each other.
Filaments: Relaxed State
In the sarcoplasmic reticulum, absent from the cytoplasm.
Each head is in an "energized" state, being attached to ADP + P, but the energy simply has not been used yet and most heads are not attached to actin.
The actin filaments are just chilling there.
Lying over the myosin's binding spots, so myosin cannot bind to actin.
Lying next to tropomyosin.
1. Calcium is released from the sarcoplasmic reticulum into the cytoplasm and binfs to troponin, which changes troponin's shape.
2. Troponin "nudges" tropomyosin into the actin grooves, thus uncovering the myosin binding sites.
3. The energized myosin heads thus bind to the actin and perform a "power stroke" that pulls actin toward the center of the sarcomere.
4. ADP is released from the heads and a new ATP takes it place, coming from the mitochondria, which is quickly broken down into ADP + P, but which allows the myosin to detach from the actin filament, perform a "recovery stroke", and be ready to contract again.
5. If calcium is still present this process simply repeats.
Each period of contraction involves multiple attach/power stroke/detach/recovery stroke periods, and it simply needs Calcium and ATP, but we only run out of ATP when dead, hence rigor mortis.
Appearance of Sarcomere
Ultimately, there will be a bigger overlap in filaments, the distance between z lines will decrease, the width of the light band will decrease, and the width of the dark band will remain the same.
Rotator Cuff Muscles
These form a cuff around the humerus, thus unless they are balance concerning muscle tone this can dislocate the shoulder.