True or False (if false, change the bolded portion to make it true):
Skeletal muscle cells are under involuntary control.
False, they are voluntary
True or False (if false, change the bolded portion to make it true): Endomysium binds skeletal muscle fascicles together to form individual skeletal muscles.
FALSE: endomysium binds skeletal muscle fibers together to form skeletal muscle fascicles.
True or False (if false, change the bolded portion to make it true):
The direction of pull exerted on a muscle tendon changes as the number of active motor units increases.
FALSE: the amount of force (or contractile force) exerted on a muscle tendon changes as the number of active motor units increases.
True or False (if false, change the bolded portion to make it true):
The collagen fibers of the tendon of origin of semitendinosus are oriented medial to lateral.
FALSE: the collagen fibers of the tendon of origin of semitendonsus are oriented proximal to distal. This is because the collagen fibers of a tendon are oriented parallel to the primary direction of pull (see Lecture 11, slide 19). Since Semitendinosus is oriented proximal to distal and is a hip extensor, the fibers will primarily experience proximal to distal tensile forces and hence be oriented proximal to distal.
Pick one muscle located in the anterior compartment of the leg and provide two of its functions and one reason that it can perform each function.
answers will vary:
Tibialis anterior:
-dorsiflex the foot b/c it passes anterior to the ankle joint
-invert the foot b/c it passes on the anterior medial side of the foot and inserts into the plantar medial surface
Extensor hallucis longus:-extends the 1st pedal digit (BE SURE TO SPECIFY WHETHER IT ACTS ON A PEDAL OR MANUAL DIGIT!) b/c it passes the joints of the 1st digit along the dorsal surface of the foot
-dorsiflex the foot b/c it passes anterior to the ankle joint
Extensor digitorum longus:-Dorsiflex the foot b/c it passes anterior to the ankle joint
-Extends pedal digits 2-5 (BE SURE TO SPECIFY WHICH DIGITS IT ACTS ON) b/c it passes the joints of digits 2-5 along the dorsal surface of the foot
Identify the muscles shown in this picture:
A: Semitendinosus
B: Long head of biceps femoris
Identify the muscles and osteological features shown in this image:
A: Psoas major muscle
B: greater trochanter
C: Ischium
D: Ilacus muscle
Provide the following information for parallel muscles:
A) one physical characteristic
B) one functional characteristic
C) one example
A) parallel muscle fibers, fibers of equal length, relatively fewer fibers compared with pennate muscles
B) fatigue resistant, relatively low contractile force
C) gracilis, adductor longus, adductor brevis, suprahyoid muscles, infrahyoid muscles...
Provide one functional advantage and one functional disadvantage of convergent muscles.
Advantage: they can perform multiple functions b/c convergent muscles are arranged into distinct sections, which exert pulls in different directions on the tendon of insertion.
Disadvantage: when the full muscle contracts, the overall contractile force is lower b/c the fibers pull on the tendon of insertion in different directions.
Which muscle has a higher degree of fine motor control and why:
A) a muscle with 5 muscle fibers in each motor unit
B) a muscle with 25 muscle fibers in each motor unit
A has a higher degree of motor control because the fewer fibers that are grouped into each motor unit, the more precise the degree of motor control. Think of it as trying to write with a pencil the size of a baseball bat versus a normal sized pencil: the normal sized pencil is smaller and easier to control.
True or False (if false, change the bolded portion to make it true):
During contraction, muscle insertions are usually pulled toward the origin.
TRUE
Design a (made up) muscle:
Give the origin, insertion and path (i.e., joints passed and orientation of the muscle to the joint) of a muscle that can flex the leg at the knee
dorsiflex the foot at the ankle
evert the foot at the ankle
Origin: posterior aspect of both femoral condyles
Insertion: plantar lateral surface of the foot
Path:
passes posterior to the knee joint
wraps around to the anterior leg midway down the leg and passes anterior to the ankle joint
Wraps around to the plantar surface of the foot on the lateral side and inserts onto the lateral cuneiform.
Design a (made up) muscle:
Give the origin, insertion and path (i.e., joints passed and orientation of the muscle to the joint) of a muscle that can Flex the thigh at the hip Internally rotate the thigh at the hip Flex the leg at the knee
Origin: Superior pubic ramus (Anterior aspect of the pelvis)
Insertion: posterior aspect of tibial plateau/posterior medial tibial condyle
Path:Passes anterior to the hip jointTravels along the medial side of the thigh
Wraps around the medial side of the knee to the posterior medial tibial condyle
True or False (if false, change the bolded portion to make it true):
The short head of biceps femoris is a synergist semimembranosus for extension of the thigh at the hip.
FALSE: the long head of biceps femoris (or gluteus maximus or semitendinosus) is a synergist semimembranosus for extension of the thigh at the hip.
True or False (if false, change the bolded portion to make it true):
The short head of biceps femoris is a synergist to the long head of biceps femoris for flexion of the leg at the knee.
TRUE
True or False (if false, change the bolded portion to make it true):
Muscles that are synergists of each other can perform the same action.
TRUE
True or False (if false, change the bolded portion to make it true):
Muscles that are synergists of each other have to perform ALL of the same actions.
FALSE: muscles are synergists for a particular function. For example, flexor carpi ulnaris and extensor carpi ulnaris are synergists of each other for adduction, but antagonists of each other for palmarflexion and dorsiflesion.
