Laboratory Exercise 6
Skeletal Muscle Cells and Their Packaging into Muscles
I.
1. From the inside out, name the three types of connective tissue wrappings of a skeletal
muscle.
• The three types of connective tissue wrappings of a skeletal muscle are
Endomysium Perimysium, and Epimysium
2. Why are the connective tissue wrappings of skeletal muscle important? (Give at least three
reasons).
• The importance of the connective tissue wrappings of skeletal muscle are to
support, connect, and strengthen the muscles.
II. On the following figure, label endomysium, perimysium, epimysium, and fascicle.
Bone Perimysium
Blood Vessel
Endomysium
Tendon Muscle Fiber (cell)
Epimysium Fascicle
3. Use the items in the key to correctly identify the structures described below.
Key: fiber sarcolemma sarcoplasm
myofibril sarcomere tendon
myofilament
sarcomere 1. contractile unit of muscle
fiber 2. a muscle cells
sarcolemma 3. plasma membrane of the muscle fiber
myofibril 4. a long filamentous organelle with a banded appearance found within muscle
cells
myofibril 5. actin- or myosin-containing structure
tendon 6. cord of collagen fibers that attaches a muscle to a bone
Classification of Skeletal Muscles
III. Several criteria were given for the naming of muscles. Match the muscle names
(column B) to the criteria (column A). Note that more than one muscle may fit the
criterion in some cases.
Column A Column B
Flexor digitorum
superficialis 1. action of the muscle abdominis transversus
Deltoid 2. shape of the muscle Biceps brachii
Pectoralis major
3. location of the origin and/or Deltoid
insertion of the muscle Erector spinae
Biceps brachii 4. number of origins external intercostals
Erector spinae 5. location of the muscle relative to a bone Flexor digitorum superficialis
or body region Pectoralis major
Rectus abdominis 6. direction in which the muscle fibers run relative
To some imaginary line
Rectus abdominis
Pectoralis major 7. relative size of the muscle
III. When muscles are discussed relative to the way they interact with other muscles, the
terms shown below are often used. Define each term.
Antagonist:
• • As muscles contract, the antagonist works. Reverses a prime mover 's
intervention and/or opposes it. In muscle function, antagonists perform two
essential roles: (1) preserving the location of the body or leg, such as keeping the
arm out or standing erect; and (2) regulating rapid movement, such as shadow
boxing without landing a punch or the ability to monitor the motion of a limb.
Fixator:
The fixator acts as a stabilizer during the passage of some portion of one part of
the body. It helps the muscle of the agonist to function efficiently by stabilizing the
root of the muscle of the agonist so that the latter can tug against the bone without
rising, achieving an effective contraction.
Prime mover (agonist):
• When the muscles contract, the prime mover (agonist) performs.
Synergist:
• The synergist serves on moveable joints in which movement is produced in
conjunction with another muscle. Synergistic muscles help neutralize external
motion from the agonists (muscles) to ensure that within the target plane of
motion, the force produced works.
V. Muscles of the Head and Neck
a. Using choices from the list at the right, correctly identify the muscles provided with leader
lines on the diagram.
Buccinator frontalis masseter
Platysma occipitalis orbicularis oculi
orbicularis orris zygomaticus
Frontalis
Occipitalis
Orbicularis oculi
Zygomaticus
Buccinator
Masseter
Orbicularis oris
Platysma
b. Using the terms provided above, identify the muscles described next.
Zygomaticus 1. used to grin
Buccinator 2. muscle used during whistling
Orbicularis Oculi 3. used in blinking and squinting
Platysma 4. its contraction makes the “sad clown” face (pulls the corners of the
mouth downward)
Frontalis 5. raises your eyebrows for a questioning expression
Orbicularis Oris 6. your “kisser”
Masseter 7. allows you to “bite” that carrot stick
Platysma 8. tenses skin of the neck during shaving
Muscles of the Trunk and Upper Limb
a. Using choices from the key, identify the major muscles described next:
Key:
biceps brachii deltoid erector spinae
extensor carpi radialis extensor carpi ulnar is intercostal
extensor digitorum superficialis external oblique flexor carpi radialis
internal oblique latissimus dorsi pectoralis major
rectus abdominis transversus abdominis trapezius
triceps brachii
Rectus Abdominis 1. a major spine flexor
Latissimus Dorsi 2. prime mover for pulling the arm posteriorly
Triceps Brachii 3. elbow extender
Internal Oblique, Transversus Abdominis 4. help form the abdominal girdle (four pairs of muscles)
External Oblique, Rectus Abdominis
Extensor Carpi Ulnaris 5. extends and adducts wrist
Deltoid 6. allows you to raise your arm laterally
Pectoralis Major, Latissimus Dorsi 7. shoulder adductors (two muscles)
Biceps Brachii 8. flexes elbow; supinates the forearm
Intercostal 9. small muscles between the ribs
Trapezius 10. extends the head
Erector spinae 11. extends the spine
Extensor Carpi Ulnaris 12. extends and abducts the wrist
Muscles of the Lower Limb
I. Use the key terms to respond to the descriptions below. (Some terms may be used more than
once.)
Keys:
adductor group biceps femoris extensor digitorum longus
fibularis (peroneus) muscles gastrocnemius gluteus maximus
rectus femoris semimembranosus semitendinosus
tibialis anterior tibialis posterior vastus muscles
Fibulas(peroneus) muscles 1. lateral compartment muscle that plantar flexes and
everts the ankle
Gluteus Maximus 2. forms the buttock
Gastrocnemius 3. a prime mover of ankle plantar flexion
Tibialis Anterior 4. a prime mover of ankle dorsiflexion
Vastus Muscles 5. allow you to grip a horse’s back with your thighs
Semimembranosus, Semitendinosus 6. muscles that insert into the tibial tuberosity (two
choices)
Rectus Femoris, Vastus Muscles 7. muscles that extend thigh and flex knee (two muscles
Tibialis Posterior 8. prime mover of inversion of the foot
Tibialis Anterior 9. prime mover of dorsiflexion of the foot
Gluteus Maximus 10. adduct the thigh, as when standing at attention
Extensor Digitorum Longus 11. extends the toes
Semimembranosus 12. extends knee and flexes thigh
Gluteus Maximus 13. used to extend the hip when climbing stairs
Gastrocnemius 14. prime movers of plantar flexion (two muscles) of the
foot
Muscle Recognition
a. Identify the lettered muscles in the diagram of the human anterior superficial musculature by
matching each letter with one of the following muscle names:
t 1. orbicularis orris v 2. pectoralis major
x 3. external oblique u 4. sternocleidomastoid
g 5. biceps brachii e 6. deltoid
l 7. vastus lateralis q 8. frontalis
k 9. rectus femoris w 10. rectus abdominis
aa 11. Sartorius c 12. platysma
I 13. flexor carpi radialis r 14. orbicularis oculi
cc 15. Gastrocnemius b 16. masseter
d 17. Trapezius p 18. tibialis anterior
bb 19. Adductors m 20. vastus medialis
z 21. transversus abdominis n 22. fibularis longus
j 23. Iliopsoas a 24. Temporalis
s 25. Zygomaticus f 26. triceps brachii
h 27. Brachialis o 28. extensor digitorum longus
y 29. internal oblique dd 30. soleus
q.
a. r.
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b. t.
c. u.
d.
e. v.
f.
g.
h
w.
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y.
i.
z.
j.
aa.
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k.
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