Anatomy and Physiology - Muscles
Introduction- 650 muscles in body (40% body weight)
Functions:
A. Voluntary movement including speech and breathing
B. In addition to external motion of the arms and legs, the muscular system also moves things inside the
body( Internal motion includes the movement of the digestive system, the cardiovascular system, and the
respiratory system)
C. Posture
D. Heat production
* Different types of muscles allow for both external and internal movement.
II. Overview
Excitability-capacity to generate electrical impulses
Contractility- capacity to shorten in length
A. Muscle is a general term for all contractile tissue
B. The contractile property of muscle tissue allows it to:
1. Become short and thick in response to a nerve impulse
2. Relax once the nerve impulse is removed
C. This alternating contraction and relaxation causes movement
III. 3 Types of muscles
1. Skeletal muscle
Origin- attachment to stationary end of muscle. (Ceps)
Belly- thicker , middle region of muscle
Insertion- attachment end of muscle(tail)
Attaches to the skeleton
Tendons – Fibrous tissues that attach skeletal muscle to bones (attach to periosteum of bone)
• Aponeurosis – a broad sheet of connective tissue that attaches certain muscles to bones and soft
tissues
Tendon of orgins:
Called the “ceps”
Attach to less movable structures (biceps, triceps, quadriceps)
Tendon of insertion:
The tail of the muscle
Attachment to the more moveable structure
ii. Ligaments attach bone to bone
b. Is under conscious control (is voluntary muscle)
Anatomy and Physiology - Muscles
c. Composed of fibers with a striped appearance (therefore called striated muscle)
Functions: Performs external movements of the body (running, lifting, etc.)
Maintains body posture
Helps with heat generation
Fascia of muscleA. Epimysium – fibrous connective tissue sheath that encloses the entire belly of the muscle
B. Perimysium- loose connective tissue sheath that surrounds only a bundle (fascile) of muscle fibers
C. Endomysium-loose connective tissue sheath that surrounds each individual muscle fiber.
Blood supply and nerve supply (innervation) of muscle:
A. blood vessels and nerve fibers in the connective tissue fascia of the muscle branch to the individual
muscle fibers
B. Innervation of muscle fibers –
1. Proprioceptors- sensory neurons that supply muscles
2. Somatic neurons- motor neurons that permit voluntary excitation of skeletal muscle fibers. Each
somatic motor neuron innervates (supplies) several hundred skeletal muscle fibers (called a microunit)
2. Smooth muscle
Found within internal organs, blood vessels, and airways (also called visceral muscle)
Is not under conscious control (is involuntary muscle)
Anatomy and Physiology - Muscles
Does not have a striped appearance
Functions include:
The internal movement of food in the digestive organs (peristalsis)
Facilitating blood distribution by changing the diameter of blood vessels (vasoconstriction and
vasodilation)
Facilitating the movement of air by changing the diameter of the airways found in the lungs
3. Cardiac
Found only in the heart (makes up the heart walls)
Is not under conscious control (is involuntary)
Is striated
Contraction of cardiac muscle causes your heart to beat
Clinical Application – Muscle tone
Normally, all muscles exhibit muscle tone (tonus), which is the partial contraction of a muscle with
resistance to stretching
Increased muscle tone (hypertrophy) – seen in athletes
Loss of muscle tone (atrophy) is seen in patients who do not use their muscles
a. Atrophied muscle tissue may become flaccid (soft and flabby)
b. Examples of situations where atrophy may develop:
i. In a bedridden patient
ii. In a patient who’s arm or leg has been in a cast for several weeks
c. One reason hospitalized patients are encouraged to get out of bed ASAP is to prevent atrophy
While skeletal muscle can regenerate from damage, extensive damage results in scarring
Pathology Connection – myopathy, strains, and tears
1. Myopathy- A general term for muscle disease or disorder
Anatomy and Physiology - Muscles
Causes can include: Injury, Genetics, Nervous system disorders, Medication, Cellular abnormalities
Symptoms: Weakness, Cramping, Stiffness, Spasm
Treatment depends on the cause
2. Strains and tears
Cause: Strains are caused by overstretching the tendons or muscles
Severity of injury can range from mild to severe
• Mild - pulled muscle (a slight overstretch of the muscle)
• Severe - complete muscle tear or complete tendon rupture
Injuries can be acute or chronic
• Acute – usually resulting from trauma
• Chronic – usually resulting from overuse or disease
Signs and symptoms – vary depending on severity of injury
Mild strain (no tear of muscle or tendon fibers) – mild pain and possibly stiffness
Moderate strain (some tearing of muscle or tendon fibers) – more intense pain, bruising, obvious
weakness
Severe strain (complete tear of muscle or tendon) – severe pain, swelling, extensive bruising, and often
Complete loss of movement
Diagnosis: Medical history, Physical examination, Imaging (MRI, X-ray, ultrasound)
Treatment – varies with severity of injury
Strains
• In the first 72 hours: PRICE therapy
- Protection
- Rest
- Ice
- Compression
- Elevation
• After the first 72 hours
- Gradual increase in activity and/or physical therapy
- Application of heat
• Pain relievers (like acetaminophen or ibuprofen)
**Strains are often slow to heal
Tears – treated surgically at the time of diagnosis
• Skeletal muscle and dense regular connective tissue have only moderate ability to repair themselves
Tendinitis/Tendinosis
Cause:
A degenerative disease leading to breakdown and scarring of tendons
Appears to be caused by the failure of tendons to repair themselves after injury
Commonly seen related to overuse/repetitive motion or untreated acute injuries
Risk factors
Some tendons are more prone to tendinosis:
- Rotator cuff
- Achilles tendon
- Tibialis posterior tendon
- Tendons of lateral elbow
Anatomy and Physiology - Muscles
Other risk factors : Age, Gender, Skeletal anatomy, Types of occupational equipment used, Systemic
disease (like diabetes mellitus, because of poor wound healing)
b. Signs and symptoms include pain, tenderness, and stiffness
c. Treatment: PRICE
Physical therapy
Steroids (short term only)
Lasers
Ultrasound and extracorporeal shock wave therapy
Surgery is a last resort
** Unfortunately, treatments are not very effective, and prognosis is not as good as for acute tendon
injuries
Shin Splints
A common inflammatory injury of the lower leg extensor muscles and surrounding tissues
Related to running
Can be treated with rest, reduction of exercise intensity, ice, anti-inflammatory medication, and
modification of footwear.
Amazing Body Facts
a. Muscles make up almost half the weight of the entire body
b. The size of your muscles depends on how much you use them and how big you are
c. The little muscles around the eye can contract 100,000 times a day
d. Individual muscle cells can be up to 12 inches (30 cm) in length
e. At about age 40, the number and diameter of muscle fibers begin to decrease
By age 80, 50% of the muscle mass may be lost
Exercise helps to decrease this loss
Muscle tears – sometimes they are beneficial
When you exercise a muscle group, it develops small tears
The healing process leads to increased muscle growth and mass
Process works best if you give the muscle group a rest after exercise
Anatomy and Physiology - Muscles
Major skeletal muscle groups/ skeletal muscles of specific regions
Facial skeletal muscles
Muscle
Location
Function
a. Orbicularis oculi
Encircles eye
Closes eyelid
b. Masseter
Jaw or mandible
Closes jaw
c. Sternocleidomastoid From sternum (breast bone) Flexes neck forward and rotates head
and clavicle (collar bone) to
temporal bone (lower sides of skull)
***See facial Muscle work sheet.
Anterior and posterior trunk skeletal muscles
Muscle
Location
Function
a. Pectoralis major
Chest
Flexes the chest area
b. Intercostals
Between ribs
Lifts and lowers the ribs to assist breathing
c. Diaphragm
Floor of thoracic cavity
Primary muscle of normal breathing
Diaphram a unique muscle that is under both voluntary and involuntary control:
• You do not need to think every time you breathe
• However, you can voluntarily change the way your breathe
Skeletal muscles of the arm and shoulder
Muscle
Location
a. Biceps brachii
Anterior upper arm
b. Triceps brachii
Posterior upper arm
c. Deltoid
Shoulder
Function
Flexes arm (flexes elbow)
Extends arm (extends elbow)
Moves arms (at the shoulder); also an IM injection site
Skeletal muscles of the legs
Muscle
Location
a. Gluteus maximus
Buttocks
b. Quadriceps
Anterior portion of thigh
c. Vastus lateralis
Upper outer thigh
(part of quadriceps)
d. Hamstrings
Posterior portion of thigh
e. Tibialis anterior
Front of lower leg
f. Gastrocnemius
Main muscle of calf
Function
Abducts and rotates thigh; IM injection site
Extends lower leg (extends knee)
Extends knee
Flexes lower leg (flexes knee)
Dorsiflexes foot
Flexes foot (plantarflexes foot)
Anatomy and Physiology - Muscles
Learning Hint – Muscle names
Muscles can be named by several criteria
1.Muscle location Example – Biceps brachii; brachii = arm
2.Number of origins Example – Biceps brachii; biceps = two heads
3.Action Example – Adductor longus; adducts the thigh
4.Size- Example - Gluteus maximus; maximus = biggest
5. Location of attachments Example – brachioradialis; radialis refers to the radius
6. Shape Example – Deltoid is a triangular muscle; delta =triangle
7. Combination- Example – Pectoralis major; pectoral = shoulder,major = big
Pathology Connection – Fibromyalgia syndrome
Myalgia – pain or tenderness in a muscle
Fibromyalgia syndrome – a chronic pain syndrome
Characterized by:
Pain of three months duration
Bilateral tenderness
Fatigue
Sleep disorders
Depression
Anxiety
Exercise intolerance
Epidemiology – more common in women
Cause – unknown
There does not seem to be any inflammation involved
May be caused by hyperactive stress response
May also be caused by sensory or neurological problem leading to increased sensitivity to pain
Diagnosis
Pain in 11 of 18 designated tender points for fibromyalgia
Treatment
There is no definitive treatment
Symptoms can be managed with antidepressants, antiepileptics, exercise, and/or pain relievers
However, symptom management is often inadequate at relieving pain completely
Skeletal muscle movement
Contraction and relaxation
a. Movement of the body is the result of contraction (shortening) of certain muscles while there is
relaxation of others
b. Primary mover (or agonist) – the chief muscle causing a movement
As the muscle contracts, it pulls the bone, causing movement
Most muscles attach to at least two bones
One bone is stationary, and one bone moves with muscle contraction
• Point of origin – the end of the muscle that is attached to the stationary bone
• Point of insertion – the muscle end attached to the moving bone
c. Synergistic muscles assist the primary mover
d. Antagonist muscles cause movement in the opposite direction of the agonist
e. All movement is a result of contraction of primary movers and relaxation of opposing muscles
Anatomy and Physiology - Muscles
Movement terminology
a. Rotation describes circular movement that occurs around an axis Ex. – turning head from left to right
b. Abduction means to move away from the midline of the body
c. Adduction is a movement toward the midline
d. Extension means increasing the angle between two bones connected at a joint
The muscle that straightens a joint is called the extensor muscle
e. Flexion is the opposite of extension, decreasing the angle between two bones
The muscle that bends the joint is called the flexor muscle
***Actions of a Skeletal Muscle:
Extensor - increases the angle at a joint
Flexor - decreases the angle at a joint
Abductor - moves limb away from the midline of the body
Adductor - moves limb toward midline of the body
Levator - moves insertion upward
Depressor - moves insertion downward
Rotator - rotates a bone along its axis
Sphincter - constricts an opening
Abnormal muscle movement
Ataxia – a condition of irregular muscle movement and lack of muscle coordination
Movement at the cellular level
Muscle cells
1. Muscle is made of elongated cells called muscle fibers
2. Each muscle fiber contains several subunits called myofibrils
Internal anatomy of a muscle cell
1. Muscle cells contain structures called sarcomeres
a. Sarcomeres are the functional contractile units of each cell
2. Each sarcomere has two types of threadlike structures called thick and thin myofilaments
a. Thick myofilaments are made up of the protein myosin
b. Thin myofilaments are made up of the protein actin
3. The sarcomere has the actin and myosin filaments arranged in repeating units
a. These repeating units are separated from each other by dark bands called Z lines, which give the
striated appearance to skeletal muscle
Muscle contraction
Anatomy and Physiology - Muscles
1. Muscle cell contraction occurs when the two types of myofilaments slide toward each other
a. This shortens each sarcomere, and therefore the entire muscle
2. The sliding of these filaments is made possible by the formation of temporary connections (called
crossbridges) between actin and myosin
a. Once these connections are made, myosin “heads” rotate and pull the actin towards the center of the
sarcomere
3. When the muscle cell relaxes, the filaments return to their resting or relaxed position
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Z lines are places where actin filaments are anchored and define the limits of the sarcomere
I bands are lighter bands where actin fibres do not overlap with myosin
A bands are darker bands where myosin filaments are located
M lines are the sites where myosin filaments are anchored
During contraction, actin filaments slide along the myosin filaments. This involves accessory proteins and the
expenditure of energy. As a result of the sliding action, the sarcomere is shortened (Z lines move closer and I
bands shorten).
Pathology Connection – Muscular dystrophy (MD)
Duchenne’s muscular dystrophy
A genetic, incurable myopathy
Caused by an error in the dystrophin protein gene
Dystrophin’s function is to hold muscle fibers together during contraction
Without functional dystrophin, muscle fibers degenerate
All types of muscle are affected (smooth, cardiac, and skeletal)
Carried on the X-chromosome, so it is seen much more often in boys
Symptoms:
Muscle weakness
As disease progresses, more muscle fibers disappear. Muscle becomes progressively weaker, scarred,
and filled with fatty deposits
Smooth muscle and cardiac abnormalities often develop as well
Disease course:
A progressive disease
Usually diagnosed around age 4
By age 10, usually child is wheelchair bound
Average life span is 17 years
Death is usually due to respiratory or cardiac failure
Diagnosis:
Physical examination, including evaluation for gait abnormality and pseudohypertrophy of the calves
Biochemical tests for muscle enzymes
Anatomy and Physiology - Muscles
Genetic testing
Electromyogram:
• A test where the muscle group is stimulated with an electrical impulse
• The impulse triggers a muscle contraction, and the strength of contraction is measured
Treatment
There is no effective treatment for DMD, so focus is on symptom management, assistive devices, and
palliative care
Physical therapy is not used, because it increases the breakdown of muscle fibers
There are some experimental treatments under investigation
* Current research is focusing on increasing muscle repair to keep pace with muscle damage
Becker’s muscular dystrophy
A milder form of MD
Has a later onset; usually diagnosed in 20s or 30s
Leads to debilitating myopathy, but progresses more slowly
Neuromuscular system:
1. Contraction of skeletal muscle requires the coordination of both the muscular and nervous systems
2. Initiation of a skeletal muscular contraction requires an impulse from a motor neuron of the nervous
system
a. This impulse causes the neuron to release a chemical called acetylcholine
b. The acetylcholine binds to receptors on the muscle cell called ligand gated sodium channels
i. Binding of acetylcholine causes these sodium channels to open
ii. Sodium flows into the muscle cell, causing intracellular calcium to be released
iii. Once calcium is released, the muscle contracts
3. This all occurs at the neuromuscular junction – the place where a nerve cell touches a muscle cell
4. After the nerve cell has finished sending its signal, acetylcholine must be removed from the
neuromuscular junction
a. Acetylcholinesterase – the enzyme that cleans up acetylcholine
ATP and calcium
1. Energy is needed for contraction and relaxation; this energy comes from ATP (adenosine triphosphate),
which helps the myosin heads form and break the crossbridges with actin
2. Calcium is needed to help actin, myosin, and ATP interact with each other
a. During muscle relaxation, calcium is stored away from the actin and myosin in the sarcoplasmic
reticulum (SR)
b. During muscle contraction, calcium is released from the SR
i. The released calcium causes actin, myosin, and ATP to interact, resulting in muscle contraction;
ii. When calcium returns to the SR, the crossbridge attachments are broken and the muscle relaxes
3. Sequence of muscle contraction (including calcium and ATP)
a. The nervous system tells a muscle to contract by releasing acetylcholine
b. Acetylcholine binds to the muscle cell, causing sodium channels to open
c. Sodium ions flow into the muscle cell, causing the cell to become excited
d. This causes calcium to be released from the SR
e. The calcium, now free in the cytoplasm, helps myosin form cross-bridges with actin
f. ATP helps myosin heads repeatedly pivot, let go, and reattach to the actin
g. This causes the actin filaments to slide along the myosin filaments
h. The sarcomere shortens, and therefore shortens the muscle (muscle contraction)
i. When the contraction is done, the calcium is pumped back into the SR
ii. The muscle relaxes & Calcium is returned to storage for the next contraction.
Anatomy and Physiology - Muscles
Amazing Body Facts - Rigor mortis
1. When a body dies, stored calcium cannot be pumped back into the sarcoplasmic reticulum
a. Excess calcium remains in the muscles throughout the body and causes muscle fibers to shorten and
stiffen
2. When a body dies, ATP can no longer be produced
a. Without ATP, the actin-myosin cross-bridges cannot be broken
3. Together, the excess calcium and lack of ATP result in stiffening of the entire body. This stiffening is
called rigor mortis.
. Pathology Connection – Myasthenia gravis and tetanus
Myasthenia gravis
An autoimmune disorder where the immune system attacks and destroys a large number of acetylcholine
receptors at the neuromuscular junction
Signs and symptoms:
i. When motor neurons release acetylcholine, the muscle cell cannot respond
ii. This results in muscle weakness, which characteristically worsens with activity and improves with rest
iii. The eye muscles are typically affected first, though some patients initially experience difficulty chewing,
swallowing or talking
Course of disease:
A progressive disease
Course varies widely from person to person
Epidemiology: Most common in women under 40 and men over 50
Diagnosis
Characteristic fluctuating weakness
Blood tests for acetylcholine receptor antibodies
Electromyography
Treatment
Acetylcholinesterase inhibitors
• Slows the breakdown of acetylcholine
• Allow increased activity of acetylcholine
Corticosteroids
Immunosuppressant drugs
Plasma exchange
Tetanus (also known as “lock jaw”)
Caused by an untreated bacterial wound infection
The bacteria responsible is Clostridium tetani, which lives in the soil
This bacteria produces a toxin that causes the disease b. Signs and symptoms
Muscle spasms (involuntary, sudden and violent muscle contractions)
In tetanus, major muscle spasms may be triggered by minor stimuli (like loud noises, turning on a light)
ii. Rigid paralysis
iii. Stiffness
iv. Pain
Course of disease
Symptoms usually begin in the jaw
Symptoms progress over time
Eventually, the diaphragm may become paralyzed
Treatment
Cleaning of the wound
Injection of IV tetanus anti-toxin
Sedation
Anatomy and Physiology - Muscles
Ventilator support
Pain management
Recovery takes several weeks, and many patients have long term problems
Prevention is possible through vaccination
Initial tetanus series given in childhood
Booster shots given every 10 years to adults
Smooth muscle (Visceral muscle)
Found in:
The organs (except for the heart)
The blood vessels
The bronchial airways
Function – helps with internal body processes
1. Smooth muscle in the blood vessels – affects blood pressure
* When the vessels get larger in diameter (vasodilate), there is less resistance to flow and blood pressure drops
*When smooth muscle contracts, the vessels get smaller in diameter (vasoconstrict), resulting in increased blood pressure
2. Smooth muscle in the airways – affects breathing in asthmatics
*During an asthma attack, smooth muscle in the airways constricts. It becomes difficult to get air in and out of the lungs.
And the patient begins to wheeze
3. Other smooth muscles - sphincters
* Sphincter – a donut-shaped muscle that can act like a doorway (opening and closing)
* Found in several parts of the digestive system (as well as other places in the body) Rectum, pyloric in stomach.
Smooth muscles are involuntary muscles and don’t contract as rapidly as skeletal muscles, which
contract 50 times faster
Smooth muscle receives a smaller blood supply than skeletal muscle, resulting in poorer repair of injured
tissue
Cardiac muscle
Cardiac muscle creates the walls of the heart
Contraction forces blood from the heart, causing it to circulate through the blood vessels in the body
Cardiac muscle is involuntary
Cardiac muscle fibers are shorter and receive a richer supply of blood than any other muscle in the body
Cardiac muscle fibers are connected by intercalated disks
1. Because of this connection, when one fiber contracts so do the adjacent fibers
2. This creates a domino effect; the wave of motion squeezes blood out very efficiently
Cardiac muscle does not repair itself after damage
1. If damage occurs, it leads to scarring
2. Scar tissue doesn’t contract like normal tissue because it is rigid
3. If the scar tissue is extensive enough, it can decrease cardiac output, leading to disability and/or death
Muscular fuel
A. Muscles, like all tissue, need fuel (in the form of nutrients) and oxygen to survive and function
B. The body stores glycogen in the muscle; when needed, glycogen is converted to glucose, which
releases energy
C. Muscles with very high demands also store fat and use it as energy
D. Muscle blood supply and color
1. Higher demand muscles have a rich blood supply to carry much needed oxygen
a. These muscles are needed for endurance (like long distance running)
b. The rich blood supply gives them a darker color
2. Muscle with fewer heavy demands needs only a small supply of blood
a. These muscles do not have much endurance
Anatomy and Physiology - Muscles
b. They have lighter color (due to their smaller blood supply)
Example – Light meat and dark meat in chicken
a. Since chickens do not fly, the breast and wing are not heavily used; these areas contain white meat
b. Legs endure constant use; they contain dark meat
Muscles and body temperature
1. Not only do muscles produce movement, they also help maintain posture, stabilize joints, and produce
heat
2. Producing heat is important in maintaining body temperature
3. As the energy-rich ATP is used for muscle contraction, three fourths of the energy escapes as heat
4. This process helps to maintain body temperature by generating heat when muscles are used
a. When you exercise, your temperature rises
b. If you become too cold, your body uses muscle contractions to generate heat (through shivering)
Applied Science – Botulism
Botulism is a potentially deadly disease resulting from food poisoning with the Clostridium botulinum
bacteria
The bacteria produce a toxin that paralyzes muscle
Science can utilize botulinum toxins for medical and cosmetic treatment
Small amounts of botulinus toxin are injected into facial muscles to stop previously untreatable facial
twitching by paralyzing the muscles
Toxin also is used to treat wrinkles without surgery; known as Botox injections
Diseases and Conditions of the Muscular System
Strains (tears)
Etiology – Acute injury or chronic overuse or disease
Signs and Symptoms – Varies with severity, pain, stiffness,bruising, weakness, loss of function
Diagnostic Tests – Examination, radiologic studies, patient history
Treatments – Acute injury: depends on severity, PRICE, pain relievers, heat, PT, surgery.
Chronic: PRICE, PT, anti-inflammatory drugs, lasers, ultrasound, shock waves
Tendinitis
1. Etiology – Acute injury or chronic overuse or disease
2. Signs and Symptoms – Varies with severity, pain, stiffness, bruising, weakness, loss of function
3. Diagnostic tests – Examination, radiologic studies, patient history
4. Treatments – Acute injury: depends on severity, PRICE, pain relievers, heat, PT, surgery. Chronic: PRICE,
PT, anti-inflammatory drugs, lasers, ultrasound, shock waves
Shin splints
1. Etiology – Repetitive lower body exercise such as running.
Can be due to faulty foot mechanics or footwear
2. Signs and symptoms – Pain in the tibia region
3. Diagnostic tests – Patient history and physical exam
4. Treatments – Ice packs, anti-inflammatory medications, decrease the intensity of exercise and avoid hills
and hard surfaces, modify footwear
Cramps/Spasms
1. Etiology – Can be result of prolonged physical activity, excessive fluid/electrolyte loss, menstruation
2. Signs and symptoms – Sudden, severe involuntary muscle contraction
3. Diagnostic tests – Patient history and physical exam. Blood work for electrolyte levels
4. Treatments – Rest from specific task, rehydration, passive stretching, dietary electrolyte replacement
Anatomy and Physiology - Muscles
Fibromyalgia Syndrome
Etiology – Unknown, but may be neurological
Signs and Symptoms – Chronic pain, bilateral tenderness, fatigue, sleep disorders, depression, exercise
intolerance
Diagnostic tests – Location of pain confined to “tender points”
Treatments – Symptom management, not very effective, some helped by antidepressants, exercise, pain
relievers, antiepileptics
Duchenne muscular dystrophy (MD)
Etiology – Genetic defect in muscle protein, causes disintegration of muscle fibers
Signs/ symptoms – Muscle weakness in early stages, later, significant progressive muscle weakness including
skeletal, cardiac and smooth muscles
Diagnostic tests – Physical exam, biochemical and genetic tests, Electromyogram (EMG), muscle biopsy
Treatments – No real treatment, disease is invariably fatal in adolescence or young adulthood.
Symptom
Management and palliative care. Some experimental treatments in development
Mitochondrial myopathy
Etiology – Defect in ATP production in mitochondria
Signs and symptoms – Progressive muscle weakness, often accompanied by hearing loss, diabetes mellitus,
heart problems, nervous system disorders and other biochemical abnormalities
Diagnostic tests – Genetic tests, biochemical tests, EMG, muscle biopsy (for ragged red fibers)
Treatments – No consensus on treatment, some drugs can decrease symptoms but nothing can stop
progression
Myasthenia gravis
Etiology – Autoimmune attack at neuromuscular junction
Signs /symptoms – Progressive, fluctuating muscle weakness, often starting with facial or eye muscles
Diagnostic tests – Blood tests, EMG
Treatments – Steroids, immunosuppressant drugs, plasma exchange, acetylcholinesterase inhibitors
Tetanus (Lock jaw)
Etiology – Bacterial infection; Clostridium tetani
Signs and symptoms – Progressive descending muscle spasm, paralysis, stiffness and pain, esp. jaw
Diagnostic tests – Physical exam, lab tests to rule out other disorders, history of wound
Treatments – Wound hygiene, tetanus antitoxin, sedation, ventilator support, pain management
Pharmacology Corner – Skeletal muscle drugs
Non-steroidal anti-inflammatory drugs (NSAIDs)
Relieve inflammation, but do not have the negative side effects of steroids
Examples – ibuprofen (Advil), naproxen (Aleve)
Pain medications
Aspirin
Acetaminophen (Tylenol)
Muscle relaxants
Help muscles rest in order to heal themselves
Help relieve musculoskeletal spasms
Examples – Flexeril, Parafon Forte
Paralytic medications
Used in situations where paralysis is desired (like during surgery)
Cut off communications between the brain and the muscles
Examples – succinylcholine (Anectine), pancuronium (Pauvulon)
Must be closely monitored, because too much medicine can cause the heart or breathing to stop
Do not affect consciousness or relieve pain; therefore in surgery, they must always be given with sedative/pain
relieving drugs
Anatomy and Physiology - Muscles
Facial Muscle Worksheet
Muscle
Location
Function
Origin
Insertion
Anatomy and Physiology - Muscles
Facial muscles
Oribicularis Oculi
Nasalis
Zygomatic Minor
Masseter
Zygomatic Major
Temporalis
Buccinator
Levator Labii Superior
Oribcularis Oris
Levator Anguli Oris
Anatomy and Physiology - Muscles
Platysma
Depressor Anguli Oris
Mentalis
Depressor Labii Inferioris
Occipitalis
Aponeurosis tendon
Sternocleidomastoid
Frontalis
Anatomy and Physiology - Muscles
Frontalis & Occipitalis raises eyebrows and wrinkles to forehead
Frontalis attached by a tendon Aponeurosis to occipitalis
Temporalis over temporal bone assists with chewing and wiggling ears.
Orbicularis oculi (circular muscle around eye / ocular- closes eyelid, winking, blinking
Orbicularis oris (circular muscle /oral )pucker lips
Zygomaticus (major and minor) attachment to zygomatic bone and insertion to corner of lips; Smiling
Buccinator (under zygomaticus muscles) sucking, blowing, fish face, keeps food against teeth,& whistling.
Masseter (masticating food) assists chewing
Sternocleidomastoid neck muscle attach to (insertion site) mastoid process to clavicle and sternum – shake head no or
back and forth
Platysma- allows head to move forward
Trapezius hyperextends neck
Levator Labii Superior raises lip (Elvis look)
Levator Anguli Oris works with zygomatic muscles (synergists) to smile
Frown:
Depressor Labii Inferioris depresses lower lip pouting /frowning
Depressor Anguli Oris main muscle of frowning
Mentalis deeply perplexed face (chin)
Procerus muscle in-between eyes wrinkle skin in between eyes
Anatomy and Physiology - Muscles
Leg muscles:
The largest muscle masses in the leg are present in the thigh and the calf.
The muscles that make up the quadriceps are the strongest and leanest of all muscles in the body. These four muscles at the
front of the thigh are the major extensors (help to extend the leg straight) of the knee. They are:
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Vastus lateralis: On the outside of the thigh, this is the largest of the quadriceps. It extends from the top of the
femur to the kneecap, or patella.
Vastus medialis: This teardrop-shaped muscle of the inner thigh attaches along the femur and down to the inner
border of the kneecap.
Vastus intermedius: Between the vastus medialis and the vastus lateralis at the front of the femur, it is the deepest
of the quadriceps muscles.
Rectus femoris: This muscle attaches to the kneecap. Of the quadriceps muscles, it has the least affect on flexion of
the knee.
The hamstrings are three muscles at the back of the thigh that affect hip and knee movement. They begin under the gluteus
maximus behind the hipbone and attach to the tibia at the knee. They are:
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Biceps femoris: This long muscle flexes the knee. It begins in the thigh area and extends to the head of the fibula
near the knee.
Semimembranosus: This long muscle extends from the pelvis to the tibia. It extends the thigh, flexes the knee, and
helps rotate the tibia.
Semitendinosus: This muscle also extends the thigh and flexes the knee.
The calf muscles are pivotal to movement of the ankle, foot, and toes. Some of the major muscles of the calf include:
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Gastrocnemius (calf muscle): One of the large muscles of the leg, it connects to the heel. It flexes and extends the
foot, ankle, and knee.
Soleus: This muscle extends from the back of the knee to the heel. It is important in walking and standing.
Plantaris: This small, thin muscle is absent in about 10 percent of people. The gastrocnemius muscle supersedes its
function.
Possibly the most important tendon in terms of mobility is the Achilles tendon. This important tendon in the back of the
calf and ankle connects the plantaris, gastrocnemius, and soleus muscles to the heel bone. It stores the elastic energy needed
for running, jumping, and other physical activity.
Anatomy and Physiology - Muscles
Anatomy and Physiology - Muscles
Anatomy and Physiology - Muscles
Arm Muscles:
The arm’s curved shape comes from its major exterior muscles. These bulky muscles also give the arm its strength.
The muscles of the arm that can be seen easily on the surface include:
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Biceps: This large muscle of the upper arm is formally known as the biceps brachii muscle, and rests on top of the
humerus bone. It rotates the forearm and also flexes the elbow.
Triceps: This large muscle in the back of the upper arm helps straighten the arm. It is formally known as the triceps
brachii muscle.
Brachioradialis: This muscle, located at the top of the forearm near the elbow, helps rotate the forearm both
outwardly and inwardly. It also flexes the forearm at the elbow.
Extensor carpi radialis longus: This muscle next to the brachioradialis is one of five major muscles that help to
move the wrist in multiple directions. When you clench your fist, this muscle bulges out from the skin.
Deltoid: Although technically part of the shoulder, the deltoid muscle controls the majority of the shoulder’s
movements and thus enables the arm to have increased range of motion.
These muscles work together to move the forearm. The biceps is the agonist, and it inserts on the radius. Contraction of the biceps flexes
the arm, moving it toward the humerus and shoulder. The triceps does the opposite. It's the antagonist, and it inserts on the ulna.
Contraction of the triceps brings the arm back down, extending it away from the humerus.
Strength training exercises are common ways to increase the size and overall strength of the major muscles in the arms.
Common exercises to build up arm muscles include curls, presses, pushdowns, and extensions using weights.
Pain can occur anywhere in the arm. The most common cause of arm pain is overexertion of a muscle or injury to it.
Twisting, pulling, or falling are common ways muscles in the arms become painful. Although repetitive injuries affect the
deep muscles more often, pulled muscles from lifting something too heavy or overexerting can also create pain and soreness,
but this usually subsides in a few days.
Arm muscle pain can usually be easily treated with resting the affected muscle and icing, elevating, and compressing the
area.
Anatomy and Physiology - Muscles
The deltoid is this muscle here, right at the shoulder joint. You could say that this is the muscle that gives your shoulder
that rounded shape that it has. It stabilizes and moves the shoulder and arm. The deltoid is the main abductor muscle of the
shoulder, meaning it moves the arm away from the center of the body.
The deltoid has three origin points along the scapula and the clavicle - these bones here. The origin points are stable and do
not move, unlike the insertion point of the muscle, here, which moves the humerus bone of the upper arm.
The antagonist (or opposing muscle) to the deltoid is the pectoralis major. This muscle is located on the upper chest area
and is kind of fan-like in shape. Similar to the deltoid, the pectoralis major has multiple origin points, but just one insertion
point. The origin points are here, along the clavicle, sternum and abdomen, while the insertion point is here, on the
humerus.
Muscles that support the deltoid and
pectoralis major
So you can see, together the deltoid and pectoralis major work to move the upper arm because both have insertion points
on the humerus. And, as you may have guessed, since the pectoralis major is the opposite of the deltoid, its function is to
adduct the arm, moving it closer to the center of the body.
Both of these muscles are aided by other muscles around the shoulder, like the pectoralis minor, latissimus dorsi and the
teres muscles, helping them raise, lower and rotate the arm.
The pectoralis major and deltoid muscles