Intro to Muscular System/Axial Musculature Flashcards
How are muscles like Russian dolls?
Muscles are made up of fascicles, which are made up of fibres. The fibers are inside of the fascicles, which are inside of the muscles.
What is the epimysium?
The muscle’s epithelial layer
What is the perimysium?
The fascicle’s epithelial layer
What is the endomysium?
The fiber’s epithelial layer
What makes up a fibre?
Myofibrils (like spaghetti strands)
What does the sarcoplasmic reticulum do?
Stores Ca2+ for muscle contraction
What is a sarcomere?
The basic unit of muscle contraction
What are the boundaries of a sarcomere?
The Z-lines
What is the centre of a sarcomere?
The M-line
What are myocin and actin and what do they do?
Myocin is a thick filament and actin is a thin filament. They interdigitate (go in between one another).
What does the H-band contain?
Myocin only (thick filaments) – think: H-band is MYocin
What does the I-band contain?
Actin only (thin filaments) – think: “I” is a thin letter
What does the A-band contain?
Both myocin (thick) and actin (thin) filaments.
During contraction, the H-band _______, the I-band ______ and the A-band _______. (increases/stays the same/decreases)
H-band decreases
I-band decreases
A-band stays the same
Which line do the myocin heads tilt toward?
The M-line
What is the importance of motor units?
They control the intensity of nerve stimulation and muscle tension
What color are slow fibers? What color are fast fibers?
Slow are red, fast are white.
Are slow or fast fibers more powerful?
Fast
Which type of fibers (slow or fast) uses aerobic metabolism to generate ATP?
Slow
Which type of fibers (slow or fast) uses anaerobic glycosis to generate ATP?
Fast
Does aerobic metabolism or anaerobic glycosis require oxygen?
Aerobic metabolism
If a runner had an enlarged soleus muscle in their leg, would they be a long distance runner or a sprinter? Would they have more slow or fast fibers?
They would be a long distance runner. They would have more slow fibers.
If a runner had an enlarged gastrocnemius muscle in their leg, would they be a long distance runner or a sprinter? Would they have more slow or fast fibers?
They would be a sprinter. They would have more fast fibers.
Do slow or fast fibers fatigue more rapidly?
Fast
What is the most common muscle type?
Parallel muscles
During the contraction of parallel spindle muscles, the muscle gets ______ and the belly gets ______.
Shorter, wider.
Do parallel or convergent muscles exert more force?
Parallel
What is the name of the fan-shaped muscle type?
Convergent muscles
Where would you find a circular muscle?
Around an opening, aka. any sphincter.
What is the name of the muscle type shaped like a bird feather?
Pennate muscles
What do the fascicles in a pennate muscle strike at an oblique angle?
A tendon
What is the benefit of pennate muscles?
It packs more fibers into a small space than parallel muscles, creating more force.
What is the difference between a unipennate, bipennate and multipennate muscle?
Unipennate = fibers only on one side of the tendon Bipennate = fibers on both sides of the tendon Multipennate = tendon branches within the muscle
During an action, what is the agonist muscle?
The prime mover, whose contraction produces movement.
During an action, what is the synergist muscle?
It assists the prime mover (agonist) in performing the movement.
During an action, what is the antagonist muscle?
It opposes the movement of the prime mover (agonist) in order to counterbalance its movement.
What is a class 1 lever and what are the benefits and drawbacks?
The fulcrum is in between the weight and the force, increasing range and speed. The drawback is that it requires an immense amount of force.
What is a class 2 lever and what are the benefits and drawbacks?
The weight is in between the fulcrum and the force, which produces a lot of force. The drawback is that the range is small and slow.
What is a class 3 lever and what are the benefits and drawbacks?
The force is in between the fulcrum and the weight, giving it a high range and speed. The drawback is that the higher the range and speed, the smaller the force.
What is the most common class of lever in the body?
Class 3
What is an example in the body of a class 1 lever?
The neck is the fulcrum, the head is the weight and the neck muscles are the force.
Which cranial nerves are the extraocular muscles innervated by?
3, 4 and 6
CN III, IV and VI - Oculomotor, Trochlear and Abducens
Which cranial nerve is the mastication muscles innervated by?
5-3.
CN V3 - Trigeminal
Which cranial nerve is the facial expression muscles innervated by?
7
CN VII - Facial
Which cranial nerve is the pharyngeal muscles innervated by?
10
CN X - Vagus
Which cranial nerve is the tongue muscles innervated by?
12
CN XII - Hypoglossal
Which cranial nerve is the neck muscles innervated by?
Neck muscles are innervated by the cervical nerves
Which extraocular muscles are NOT innervated by CN III? Which CNs are they innervated by?
The lateral rectus - VI (6)
The superior oblique - IV (4)
When looking up, which 2 muscles do you use?
Superior rectus and inferior oblique
When looking down, which 2 muscles do you use?
Inferior rectus and superior oblique
How would you determine if a patient had a CN VI or CN IV palsy?
You would ask them to look left an right, and if they had difficulty looking right it would be damage in the lateral rectus, making it a CN VI palsy. If they had difficulty looking left it would be damage in the superior oblique, making it a CN IV palsy.
What do the temporalis and masseter muscles do?
They open and close the mouth (for chewing)
What do the lateral and medial pterygoid muscles in the jaw do?
Lateral: depresses the mandible and grinds food
Medial: elevates the mandible to chew
What does the orbicularis oculi muscle of the face do?
It closes the eyes
What does the orbicularis oris muscle of the face do?
It purses the lips
What does the platysma muscle of the face do?
It tenses the skin of the neck
What does the frontaris muscle of the face do?
It wrinkles the forehead and raises the eyebrows
What does the buccinator muscle of the face do?
It tenses the cheeks for sucking
How do you get Bell’s palsy?
By damaging the facial nerve (CN VII)
What do the tensor & levator veli palatini muscles of the throat do?
They tense and elevate the soft palate
What does the superior, middle and inferior constrictors of the throat do?
They constrict different sections of the pharynx
What are the four muscles of the tongue?
Palatoglossus
Styloglossus
Hyoglossus
Genioglossus
What does the hyoid bone do?
It supports the tongue
What does the mylohyoid muscle in the throat do?
It tenses the floor of the mouth for swallowing
What does the digastric muscle in the throat do?
It depresses the mandible to open the mouth wide
What is the correct order of these events during swallowing?
- Contraction of tensor and levator veli palatini muscles
- Contraction of mylohyoid and tongue muscles
- Sequential contraction from the top of constrictor muscles
- Elevation of larynx by many muscles
2, 1, 4, 3
What does the sternocleidomastoid muscle in the throat do?
It turns the head in the opposite direction of contraction
What do the infrahyoid muscles in the throat do?
They pull down the hyoid bone
What do the longus capitis and longus colli muscles do?
They flex the neck
What do the scalene muscles do?
They flex the neck and head, and elevate the ribs.
What does the transversospinal group of muscles do?
It allows vertebrae to flex & extend and does fine movement adjustments
If you sprain the zygapophyseal joints in your back, what might happen?
You might have acute back pain
What 3 muscles make up the erector spinae and what do they do?
Longissimus, Spinalus and Iliocostalis
They extend the back
What do the intercostal muscles do?
They contract to elevate the ribs during inhalation
What do the rectus abdominis muscles do?
They are trunk flexors
How many layers of abdominal muscles are there? What are they?
3 - External abdominal oblique, internal abdominal oblique and transverse abdominis
What is the inferior vena cava?
A vessel that carries blood
What is the largest artery that carries blood to the lower body?
The aorta
What are the right and left crura?
The tendinous structures that come up from the legs
What is innervated by the phrenic nerve? Which nerves make up the phrenic nerve?
The diaphragm. C3, C4 and C5
Does the diaphragm contract during inhalation or exhalation?
Inhalation
Where are the coccygeus and levator ani muscles?
In the pelvic floor
Is the external urethral sphincter larger in males or females? Why?
It’s larger in males to accommodate for ejaculate
What are the Ischiocavernosus and Bulbospongiosus
muscles and what happens when they contract?
They are perineal muscles. Contraction increases blood flow into the erectile tissues of the genitalia.
