Lab 7 Terms and Lesson Flashcards
Where do the muscles of the thigh generally insert?
Extend from one or more bones of the pelvis to insert on the femur
What is the location and action of the Ilioposoas: Iliacus and Psoas Major?
- Muscles of the anterior hip. The iliacus originates on the ilium and psoas major originates on the lower vertebrae. both muscles insert on the proximal femur
- Both muscles act to flex the thigh
What is the location and action of the piriformis?
- Deep muscle of the gluteal region. Originates on the anterior sacrum and inserts on the greater trochanter of the femur
- Laterally rotates and abducts the thigh
What is the location and action of the tensor fascia latae?
- Muscle of the lateral hip and thigh that originates on the iliac crest and inserts on the proximal lateral tibia via the iliotibial tract
- Flexes and abducts the thigh
What is the location and action of the gluteus maximus?
- Large superficial muscle of the posterior hip that originates on the ilium and sacru, and inserts on the gluteal tuberosity of the femur
- Extends and laterally rotates the thigh
What is the location and action of the gluteus medius?
- Deep to the gluteus maximus, the gluteus medius originates on the posterior ilium and inserts on the greater trochanter of the femur
- Abducts and medially rotates the thigh
What is the location and action of the gluteus minimus?
- Deep to the gluteus medius, the gluteus minimus originates on the posterior ilium and inserts on the greater trochanter of the femur
- Abducts and medially rotates the thigh
What is the location and action of the gracilis?
- Muscle of the medial thigh that originates on the pubis and inserts on the medial surface of the proximal tibia
- Adducts the thigh and flexes the leg
What is the location and action of the adductor magnus?
- A deep adductor muscle that originates on the ischium and pubis and inserts on the linea aspera of the femur
- Adducts and medially rotates the thigh
What is the location and action of the adductor longus?
- Originates on the pubis and inserts on the linea aspera of the femur
- Adducts, flexes, and medially rotates the thigh
What is the location and action of the adductor brevis?
- Originates on the pubis and inserts on the linea aspera of the femur
- Adducts, medially rotates and flexes the thigh
What are the four muscles that form the Quadriceps femoris group?
- Rectus femoris
- Vastus lateralis
- Vastus medialis
- Vastus intermediua
What is the location and action of the rectus femoris?
- Part of quadriceps femoris
- Muscle of the anterior thigh that originates on the anterior ilium and inserts on the tibial tuberosity vie the patellar ligament
- Flexes the thigh and extends the leg
What is the location and action of the vastus lateralis?
- Part of the quadriceps femoris
- Originates on the proximal femur and inserts on the tibial tuberosity
- Extends the leg
What is the location and action of the vastus medialis?
- Part of the quadriceps femoris
- Originates on the linea aspera of the femur and inserts on the tibial tuberosity
- Extends the leg
What is the location and action of the vastus intermedius?
- Part of the quadriceps femoris
- Originates on the anterior and lateral surfaces of the body of the femur and inserts on the tibial tuberosity
- Extends the leg
What is the location and action of the sartorius?
- Called the “tailo’s muscle” the sartorius is the longest muscle in the body. It originates on the ilium and inserts on the medial body of the tibia
- Flexes the leg, and flexes and laterally rotates the thigh
What are the three muscles in the hamstring group?
- Biceps femoris
- Semimembranosus
- Semitendinosus
What is the location and action of the biceps femoris?
- Part of the hamstrings group
- Lateral muscle of the posterior thigh. Its twp heads originate on the ischial tuberosity and linea aspera of the femur and inserts on the head of the fibula and lateral condyle of the tibia
- Flexes the leg and extends the thigh
What is the location and action of the semimembranosus?
- Part of the hamstring group
- Medial and deep muscle of the hamstrings group that originates on the ischial tuberosity and inserts on the medial concyle of the tibia
- Flexes the leg and extends the thigh
What is the location and action of the semitendinosus?
- Part of the hamstrings group
- Medial and superficial muscle of the hamstrings group that originates on the ischial tuberosity and inserts on the medial side of the body of the tibia
- Flexes the leg and extends the thigh
What are the two muscles of the triceps surae group?
-Gastrocnemius and soleus
What is the location and action of the gastrocnemius?
- Part of the triceps surae group
- Muscle of the posterior leg. Its two heads originate on the distal posterior femur and insert on the calcaneus vis the achilles tendon
- Plantar flexes the foot and flexes the leg
What is the location and action of the soleus?
- Part of the triceps surae group
- Deep to the gastrocnemius, this muscle originates on the head of the fibula and proximal medial tibia and inserts on the calcaneus via the achilles tendon
- Plantar flexes the foot
What is the location and action of the tibialis anterior?
- Anterior muscle of the leg that originates on the lateral condyle of the tibia and inserts on the first metatarsal and cuneiform (one of the tarsals)
- Dorsiflexes and inverts the foot
What is the location and action of the tibialis posterior?
- Deep to the soleus, the tibialis posterior originates on the superior portion of the posterior tibia and fibula and inserts medially on the inferior surface of several tarsals and metatarsals
- Inverts and plantar flexes the foot
What is the location and action of the Fibularis (Peroneus) longus
- Lateral muscle of the leg that originates on the lateral condyle of the tibia and head of the fibula and inserts on the first metatarsal and cuneiform
- Everts and plantar flexes the foot
What is the location and action of the fibularis (proneus) brevis?
- Later muscle of the leg that originates on the body of the fibula and inserts on the fifth metatarsal
- Everts and plantar flexes the foot
What is the location and action of the extensor digitorum longus?
- Anterior muscle of the leg. Originates on the lateral condyle of the tibia and anterior surface of the fibula and inserts on the middle and distal phalanges of digits II-V
- Dorsiflexes the foot and extends digits II-V
What is the location and action of the flexor digitorum longus?
- Deep posterior muscle of leg. Originates on the middle third of th posterior surface of the tibia and inserts on the distal phalanges of digits II-V
- Plantar flexes foot and flexes digits II-V
What is the location and action of the flexor halliucis longus?
- Deep posterior muscle of the leg. Originates on the inferiro two thirds of the posterior portion of the fibula and inserts on the distal phalanx of the great toe
- Plantar flexes foot and flexes the great toe/hallux
Identify the following on the picture:
- Synaptic cleft
- Myofibril
- Sarcolemma
- Synaptic end bulb
- Endomysium
- Motor end plate (folded sarcolemma)
Identify the following on the model:
- Sarcoplasmic reticulum
- Synaptic end bulb
- Nucleus of schwann cell
- Axon of motor neuron
- Sarcomere
- Triad
- Vesicle
- Synaptic cleft
- Nucleus of muscle fiber (cell)
- Sarcolemma
- Terminal cistern
- Transverse (T) tubule
What does a triad consist of?
2 Terminal cisterna + 1 T Tubule
What does a motor neuron do?
Stimulates contraction
What does a motor unit consist of?
One motor neuron + all skeletal muscle fibers innervated by it
What are the branches divided from an axon of a motor neuron called?
Axon terminals
What do axon terminals do?
These branches have synaptic end bulbs that form the NMJ (Neuromuscular junction) with skeletal muscle
What are the four anatomical structures of the NMJ that we need to know?
- Synaptic end bulb
- Synaptic vesicles
- Acetylcholine
- Motor end plate
What are the five steps of NMJ excitation?
- Action potential arrives at the synaptic end bilb and causes openin of voltage gated Ca2+ channels
- Synaptic vesicles containing the neurotransmitter acetylcholine (ACh) undergo exocytosis
- ACh is released into the synaptic cleft and binds to ACh receptors on the motor end plate
- ACh receptors open and allow Na+ to enter the muscle fiber, generating an action potential on the sarcolemma
- ACh is broken down to acetate and choline by acetylcholine esteracse (AChE)
What are the 5 excitation-contraction coupling steps?
- Action potential runs along the sarcolemma, continues into T-tubules
- Triggers release of Ca2+ from the sarcoplasmic reticulum
- Ca2+ diffuses into saroplasm and myofibrils
- Ca2+ binds to troponin on the thin filament -> myosin binding site on actin gets exposed
- Crossbridges form -> tension is generated (starts contraction)
What is myasthenia gravis?
- Weakness and rapid fatogue of muscles that are under voluntary control
- Why?
- It is an autoimmune condition where antibodies attack muscle receptors that control voluntary muscles
- Drawing pathophysiology representations of someone with and without myasthenia gravis
- There are receptor blocking particles (antibodies) that dont let normal neurotransmitters attach to the receptors
What are different types of myasthenia gravis?
- Congenital: genetic defect inherited by both parents
- Changes in genes, even gene encoding acetylcholine receptor
- Ocular
- Generalized
- Transient Neonatal: infants born to mothers that have myasthenia gravis trend to get symptoms after the first 48 hrs of birth
- Juvenile
What are the causes of myasthenia gravis?
- Antibodies are blocking receptors for acetylcholine, which does now allow for muscle contraction
What are the risk factors of myasthenia gravis?
- Women between the ages of 20 and 40
- Men older than 60
- Family history
- Gets worse with things like stress and fatigue
- No other known risk factors
What are symptoms of myasthenia gravis?
- Eye muscles
- Drooping of the eyelids
- Double vision
- Face and throat muscles
- Difficulty swallowing, making certain facial expressions, etc
- Neck and limb muscles
- Arms are most common to be affected the worst
What is the diagnosis for myasthenia gravis?
- Neurological examination
- Ice pack test: places an ice pacl on droopy eyelid for 2 minutes
- Edrophonium test: edrophonium chloride may show a sudden, but temporary improvement in muscle strength
- Blood analysis: looking for abnormal antibodies
- Repetitive nerve stimulation
- EMG
- CT Scan or MRI
- Pulmonary function tests
What are treatments for myasthenia gravis?
- Cholinesterase inhibitors
- Corticosteroids
- Immunosuppressants
- Intravenous immunoglobulin
- Surgery to remove thymus gland or thymoma
- Video-assisted thymectomy versus robot-assisted thymectomy
What are complications with myasthenia gravis?
- Myasthenia crisis: muscles that control breathing are not strong enough to work anymore
- Thymus tumores = thymomas
- More likely to have underactive or overactive thyroid
- More likely to have autoimmune diseases, such as rheumatoid arthritis
What are misconceptions and fun facts about myasthenia gravis?
- Autoimmune myasthenia gravis affects approximately 14-40 people out of every 100,000 people in the US
- myasthenia gravis is sometimes ranked on a grading scale
- Grade 0-5 with grade 0 being asymptomatic and grade 5 being so severe that a tube is required to assist with breathing
What is some prevention for myasthenia gravis?
- There is no cure
- Treatment can help alleviate symptoms, such as muscle weakness, droopiness of eyelids, chewing, etctera…
In myasthenia gravis, antibodies interfere with muscle receptors that would normally bind to the neurotransmitter called what?
Acetycholine
What is the cause of congenital myasthenia gravis as compared to the other types?
Genetic defect that is inherited by both parents, rather than an autoimmune disease
What are 2 different thymectomy procedures for treatment?
Video-assisted and robot-assisted
What age will most men get myasthenia gravis? What about women?
Men = over 60
Women = 20-40
What are the 2 main symptoms associated with ocular myasthenia gravis?
Eyelid drooping and double vision
What is electromyograohy (EMG)? and how does it work?
EMG is the technique used to monitor the electrical activity of muscle cells. By using electrodes, it is possible to detect the change in electrical charge caused by the current (ion) flow associated with muscle cell excitation
Define motor unit
A motor neuron and all of the muscle fibers it innervates
What are the three types of motor units?
Small - slow oxydative fiber types
Medium - Fast oxidative glycolytic fiber types
Large - fast glycolytic fiber types
What is the role of the nervous system in force production?
- Nervous system can increase the amount of force a muscle produces through 2 methods
- Increases the rate at which you activate the motor units (Temporal summation)
- Increases stimulation frequency = temporal summation
- Recruit or activate more motor units (spatial summation)
- Increase motor unit recruitment = spatial summation
What is isotonic contraction?
Tension is constant while muscle length changes
What is isometric contraction?
No change in muscle length but there is tension development
What are three types of contractions?
- Ramp contraction
- Maximal voluntary contraction MVC
- Submaximal contraction
***All 3 are isometric contractions
What are the expected results for ramp contraction?
- Force increased over time
- EMG amplitude increased over time
- Sense of effort increased over time
What is the physiology behind ramp concentration?
- More and more motor units are recruited gradually in order to increase the force produced by the muscle
- The amplitude of the EMG will increase gradually as more and more motor units are recruited and the force will also increase until max force
What are expected results of maximal voluntary contraction?
- Force decreased over time
- EMG amplitude decreased over time
- Sense of effort increased over time
What is the physiology behind maximal voluntary contraction?
- All motor units are recruited at the beginning of the test but start to drop off (deactivate) due to fatigue
- As force declines, surface EMG declines in amplitude because more and more motor units are fatiguing and dropping out of EMG recording
What are expected results of submaximal contraction?
- Force at onset and middle of the test stayed at about 50% max
- Force at end of test decreased
- EMG amplitude increased from onset to middle, then decreased from middle to end of test
- Sense of effort increased over time
What is the physiology behind submaximal contraction?
- A submaximal # of motor units are recruited
- As they begin to fatigue, more motor units are recruited to take thie place. EMG amp increases until all motor units are activated
- Force up to this point is not changed. However, more motor units are active in order to sustain submax force
- When all motor units are recruited any subsequent fatigue will lead to a decline in EMG amp
Discuss muscle fatigue
- Not completely understoof
- Progressive increase in the effort required to maintain a desired force, and a progressive inability to maintain this force in sustained or repetitive contractions
- Endurance athletes may become depleted of glycogen stores
- For short duration high intensity exercise could be caused by a decline in pH vis accumulation of lactic acid. Product of anaerobic metabolism
