S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
1
Muscular System Laboratory Guide
Dissection of the Muscles: See pages 229-230 in the Lab Manual
1. Remove the fascia and subdermal fat covering the skeletal muscles.
2. observe that there is a thin, but tough, sheet of fascia that covers the
surface of the muscles
3. separate the muscle from each other by slitting this fascia
4. Notice that by pulling on the muscles, you can better visualize the direction
the muscle fibers are running in (the fibers of a single muscle are
generally oriented in only 1 direction).
5. use a probe & forceps to pick-off the fascia & separate the muscles from
each other
6. do not cut, tear, or remove muscles (unless instructed)
Clean-up at the end of each Lab Period:
1. throw all extraneous tissues & newspaper in the large trash cans
2. make sure your cat is sufficiently moist with formalin preservative
3. wash the dissection tray with water at the sink
4. wash-down the lab table with the soap solution so that it is clean
Note: If your cat specimen is pregnant or lactating, the mammary glands will
appear as a pair of large, glandular masses along the ventral sides of
the abdomen and thorax under the skin. They should be removed with
the skin.
1
Muscular System Laboratory Guide (Marieb 6th ed)
S. Fink
2
Muscular System Laboratory Guide
Instructions:
1. You are responsible for the names, origins, insertions, and actions of every
muscle listed in this Laboratory Guide.
2. During the lab time, you are expected to dissect the cat specimen.
3. Read and follow the procedures in Chapter 14 of your laboratory manual
(Marieb)
a. Be able to identify all required muscles on any cat.
b. Be able to also identify these required muscles in a human.
4. You should also refer to the drawings in Chapters 11 in your textbook
(Marieb)
Muscles to Find:
1. Trapezius (p. 209; & p. 234)
-- this large muscle of the back consists of 3 portions: the clavotrapezius,
spinotrapezius, and acromiotrapezius
-- in the cat these 3 portions may be dissected apart; in man they have
essentially fused together
ORIGIN: (occipital bone and spinous processes of the) thoracic vertebrae
INSERTION: the clavicle, and the spine & acromion processes of the scapula
ACTION: elevates the shoulders & (as when you "shrug your shoulders"),
adducts the shoulders ("retracts" the shoulders)
[pulls the shoulders towards the midline]
Note: a "stiff" neck often is associated with this muscle
-------------------------------------------------------------------------------------------------------------2. Latissimus dorsi (p. 209; & p. 234)
ORIGIN: spinous processes of thoracic & lumbar vertebrae and sacrum;
thoraco-lumbar fascia of ilium
INSERTION: (lower portion of the intertubercular groove of) humerus
ACTION: extends, adducts and rotates the humerus medially
(viz: over-hand breast-stroke in swimming or paddling a canoe)
(antagonist of the Deltoid)
-------------------------------------------------------------------------------------------------------------2
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
3
3. Deltoid (p. 209; & p. 238)
-- this shoulder muscle also consists of 3 portions: the clavodeltoid,
acromiodeltoid, and spinodeltoid
-- in the cat these 3 portions may be dissected apart; in man they have
essentially fused together
ORIGIN: the clavicle, and the spine & acromion processes of the scapula
INSERTION: (deltoid tuberosity of the) humerus
ACTION: abducts the upper arm (antagonist of the Pectoralis major)
-------------------------------------------------------------------------------------------------------------4. Rhomboideus (p. 209; & p. 237)
-- since this muscle is located beneath the Trapezius, you should transect
("cut through") the Trapezius on one side (only!)
ORIGIN: (spinous processes of C-7 and upper) thoracic vertebrae
INSERTION: (medial border of the) scapula
ACTION: adducts the shoulders (pulls the shoulder towards the midline)
(synergist with Trapezius)
-------------------------------------------------------------------------------------------------------------5. Infraspinatus (p. 209)
ORIGIN: (infraspinous fossa of) scapula
INSERTION: (greater tubercle of) humerus
ACTION: rotates the upper arm laterally (antagonist of Latissimus dorsi)
-------------------------------------------------------------------------------------------------------------6. Supraspinatus (p. 209; & p. 237)
ORIGIN: (supraspinous fossa of) scapula
INSERTION: (greater tubercle of) humerus
ACTION: abducts the upper arm (synergist with the Deltoid)
-------------------------------------------------------------------------------------------------------------7. Teres major (p. 209)
ORIGIN: (inferior angle of) scapula
INSERTION: (lesser tubercle of) humerus
ACTION: extends, adducts and rotates the upper arm medially
(synergist with the Latissimus dorsi)
--------------------------------------------------------------------------------------------------------------
3
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
4
8. Splenius (capitus and cervicus) (p. 211; & p. 237)
ORIGIN: (spinous processes of C-7 and upper) thoracic vertebrae
INSERTION: occipital bone and mastoid process of temporal bone
ACTION: when the muscles on both sides contract: extends the head
upward; when only the muscle on one side contracts: rotates the
head laterally to that side (antagonist of Sternocleidomastoid)
-------------------------------------------------------------------------------------------------------------9. Serratus anterior (ventralis) (pp. 206 & 208; & p. 232)
ORIGIN: upper 9 ribs
INSERTION: (medial border of the) scapula
ACTION: rotates the scapula (shoulder) downwards towards the ribs
(also aids in forced inhalation by elevating the ribs when the
scapula is fixed in position)
-------------------------------------------------------------------------------------------------------------10. Spinalis dorsi (thoracis) (p. 211)
-- "Erector Spinae" muscle
ORIGIN: the spinous processes of the sacral vertebrae
INSERTION: the spinous processes of the cervical vertebrae
ACTION: when the muscles on both sides contract: extends (straightens)
the spine; when only the muscle on one side contracts: bends the
spine laterally to that side
-------------------------------------------------------------------------------------------------------------11. Longissimus dorsi (thoracis) (p. 211)
-- "Erector Spinae" muscle
ORIGIN: the transverse processes of the sacral vertebrae
INSERTION: the transverse processes of the cervical vertebrae of the spine
and the mastoid process of the Temporal bone
ACTION: when the muscles on both sides contract: extends (straightens)
the spine; when only the muscle on one side contracts: bends the
spine laterally to that side
-------------------------------------------------------------------------------------------------------------12. Subscapularis (p. 206)
ORIGIN: subscapular fossa of scapula
INSERTION: lesser tubercle of humerus
ACTION: rotates the humerus medially (synergist with the Latissimus dorsi
& Teres major; antagonist of the Infraspinatus)
-------------------------------------------------------------------------------------------------------------4
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
5
13. Pectoralis major (p. 206; & p. 232)
-- this fan-shaped muscle is the largest muscle of the chest
ORIGIN: clavicle and sternum
INSERTION: intertubercular groove of humerus
ACTION: adducts the upper arm (antagonist of the Deltoid) & pulls chest
upward
Pectoantebrachialis:
Xiphihumeralis:
In the cat, these two muscles are associated with
the Pectoralis major; they are absent in man.
-------------------------------------------------------------------------------------------------------------14. External Abdominal Oblique (p. 208; & p. 233)
-- note that the fibers run ventro-medially
ORIGIN: surface of lower 8 ribs
INSERTION: linea alba, pubic symphysis and iliac crests
Note: the linea alba ("white line") is a strip of fascia that runs from
the xiphoid process of the sternum to the pubic symphysis)
ACTION: flexes at the waist; compresses the abdominal organs (especially
during a "Valsalva maneuver”)
The free lower border of the External Oblique rolls-up upon itself to form the
inguinal ligament which extends from the anterior superior iliac spine to the pubic
symphysis.
-------------------------------------------------------------------------------------------------------------15. Internal Abdominal Oblique (p. 208; & p. 233)
-- note that the fibers run ventro-lateraly
ORIGIN: thoraco-lumbar fascia on back, inguinal ligaments, and iliac crests
INSERTION: linea alba and surface of lower ribs
ACTION: flexes at the waist; compresses the abdominal organs (especially
during a "Valsalva maneuver”)
-------------------------------------------------------------------------------------------------------------16. Transversus Abdominus (p. 208; & p. 233)
-- a deep muscle that lies directly over the parietal peritoneum of the
abdominal cavity; note that the fibers run transversely
ORIGIN: thoraco-lumbar fascia on back, iliac crests, and inguinal ligaments
INSERTION: xiphoid process of the sternum, linea alba, and pubic symphysis
ACTION: flexes at the waist; compresses the abdominal organs (especially
during a "Valsalva maneuver”)
5
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
6
-------------------------------------------------------------------------------------------------------------17. Rectus Abdominus (p. 208; & p. 233)
-- note that this muscle is located beneath the linea alba, enclosed within a
thick, broad fascia sheath (aponeurosis)
ORIGIN: pubic symphysis & pubic bones
INSERTION: xiphoid process of the sternum
ACTION: flexes at the waist; compresses the abdominal organs (especially
during a "Valsalva maneuver”)
-------------------------------------------------------------------------------------------------------------18. Sternocleidomastoid (pp. 204 & 206; & p. 231)
-- in the cat, this muscle appears as two muscles: the sternomastoid and
the cleidomastoid
ORIGIN: sternum and clavicle
INSERTION: mastoid process of the Temporal bone
ACTION: when the muscles on both sides contract: flexes at the neck;
when the muscle on one side contracts: bends the neck laterally
to that side
[Accessory Nerve; XII]
-------------------------------------------------------------------------------------------------------------19. Mylohyoid (p. 204; & p. 231)
-- a "suprahyoid" muscle
ORIGIN: the mandible
INSERTION: the hyoid bone
ACTION: elevates the hyoid bone and the base of the tongue
when swallowing
[Trigeminal Nerve; V]
-------------------------------------------------------------------------------------------------------------20. External Intercostal Muscles (p. 207)
-- note that the fibers run ventro-medially just like the External Oblique fibers
ORIGIN: lower border of each rib
INSERTION: upper border of next lower rib
ACTION: elevates the rib cage and thus enlarges the thoracic cavity
(as when inhaling)
--------------------------------------------------------------------------------------------------------------
6
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
7
21. Internal Intercostal Muscles (p. 207)
-- note that the fibers run ventro-laterally just like the Internal Oblique fibers
ORIGIN: upper border of each rib
INSERTION: lower border of next upper rib
ACTION: lowers the rib cage and thus decreases the thoracic cavity
(as when forcefully exhaling)
-------------------------------------------------------------------------------------------------------------22. Triceps brachii (p. 213; & p. 238)
-- this muscle is broader in the cat than it is in man
-- you should identify all 3 heads on the cat: long, lateral and medial heads
ORIGIN: long head: scapula
lateral & medial heads: posterior surface of the humerus
INSERTION: olecranon process of the ulna (elbow)
ACTION: extends the forearm (antagonist of the Biceps brachii & Brachialis)
[Radial Nerve]
-------------------------------------------------------------------------------------------------------------23. Brachialis (p. 213; & p. 238)
-- on the cat, the Brachialis begins at about the same point where the
Biceps brachii ends
ORIGIN: distal half of anterior surface of the humerus
INSERTION: coronoid process of the ulna
ACTION: flexes the forearm (synergist with the Biceps brachii)
[Musculocutaneous Nerve]
-------------------------------------------------------------------------------------------------------------24. Brachioradialis (p. 216; & p. 238)
-- on the cat, the Brachioradialis begins at about the same point where the
Brachialis ends
ORIGIN: distal half of the humerus
INSERTION: styloid process of the radius
ACTION: flexes the forearm (synergist with the Biceps brachii and Brachialis)
[Radial Nerve]
--------------------------------------------------------------------------------------------------------------
7
Muscular System Laboratory Guide (Marieb 6th ed)
S. Fink
8
25. Extensor carpi radialis (longus & brevis)
(p. 215; & p. 238)
ORIGIN: lateral epicondyle of the humerus
INSERTION: metacarpal bone
ACTION: extends and abducts the wrist
[Radial Nerve]
-------------------------------------------------------------------------------------------------------------26. Extensor digitorum (communis) (p. 215; & p. 238)
ORIGIN: lateral epicondyle of the humerus
INSERTION: phalanges
ACTION: extends the fingers
[Radial Nerve]
-------------------------------------------------------------------------------------------------------------27. Extensor carpi ulnaris (p. 215; & p. 238)
ORIGIN: lateral epicondyle of the humerus
INSERTION: metacarpal bone
ACTION: extends and adducts the wrist
[Radial Nerve]
-------------------------------------------------------------------------------------------------------------28. Biceps brachii (p. 206; & p.238)
-- this muscle is broader in the cat than it is in man
ORIGIN: short head: coracoid process of the scapula
long head: glenoid fossa of the scapula
INSERTION: radial tuberosity of the radius
ACTION: flexes the forearm (synergist with the Brachialis)
supinates the forearm (antagonist of the Pronator teres)
[Musculocutaneous Nerve]
-------------------------------------------------------------------------------------------------------------29. Pronator teres (p. 215; & p. 238)
ORIGIN: medial epicondyle of the humerus
INSERTION: shaft of the radius
ACTION: pronates the forearm (antagonist of the Biceps brachii)
[Median Nerve]
--------------------------------------------------------------------------------------------------------------
8
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
9
30. Flexor carpi radialis (p. 215; & p. 238)
ORIGIN: medial epicondyle of the humerus
INSERTION: metacarpal bone
ACTION: flexes and abducts the wrist
[Median Nerve]
-------------------------------------------------------------------------------------------------------------31. Palmaris longus (p. 215; & p. 238)
ORIGIN: medial epicondyle of the humerus
INSERTION: metacarpal bone
ACTION: flexes the wrist
[Median Nerve]
32. Flexor carpi ulnaris (p. 215; & p. 238)
ORIGIN: medial epicondyle of the humerus
INSERTION: metacarpal bone
ACTION: flexes & adducts the wrist
[Median Nerve]
--------------------------------------------------------------------------------------------------------------
9
Muscular System Laboratory Guide (Marieb 6th ed)
S. Fink
10
33. Sartorius (p. 219; & p. 243)
-- a strap-like muscle ("tailor's muscle"); it is the longest muscle in the body,
although it is not very strong
ORIGIN: anterior superior iliac spine
INSERTION: proximal end of the tibia
ACTION: this muscle pulls the entire thigh up towards the hip; thus it
flexes the thigh like the anterior muscles of the thigh
(viz: the Iliopsoas & Tensor Fascia Lata)
[Femoral Nerve]
==============================================================
The Anterior-Extensor Muscle Group of the Leg
34. Quadriceps femoris (p. 219; & p. 243)
-- the Quadriceps femoris actually consists of 4 separate muscles that all insert
onto the tibial tuberosity via the patellar tendon
-- the Quadriceps comprises the "Anterior Extensor" muscle group of the thigh
[-- each of the 4 muscles is innervated by branches of the Femoral Nerve]
a. Rectus femoris (p. 219; & p. 243)
-- located on the mid-portion of the thigh
-- Note: because the Rectus femoris does not separate well from the
Vastus medialis, bisect the Rectus femoris on one side to see the
Vastus intermedius
ORIGIN: anterior inferior iliac spine
INSERTION: tibial tuberosity via patellar tendon
ACTION: extends the leg at the knee
[Femoral Nerve]
-------------------------------------------------------------------------------------------------------------b. Vastus lateralis (p. 219; & p. 243)
-- it is commonly used by diabetics for IM injections of insulin
ORIGIN: linea aspera of the femur
INSERTION: tibial tuberosity via patellar tendon
ACTION: extends the leg at the knee
[Femoral Nerve]
--------------------------------------------------------------------------------------------------------------
10
Muscular System Laboratory Guide (Marieb 6th ed)
S. Fink
11
c. Vastus intermedius (p. 219; & p. 243)
-- located beneath the Rectus femoris, on the antero-medial aspect of
the thigh
-- Note: because the Rectus femoris does not separate well from the
Vastus medialis, bisect the Rectus femoris on one side to see the
Vastus intermedius
ORIGIN: shaft of the femur
INSERTION: tibial tuberosity via patellar tendon
ACTION: extends the leg at the knee
[Femoral Nerve]
-------------------------------------------------------------------------------------------------------------d. Vastus medialis (internus) (p. 219; & p. 243)
ORIGIN: linea aspera of the femur
INSERTION: tibial tuberosity via patellar tendon
ACTION: extends the leg at the knee
[Femoral Nerve]
==============================================================
35. Iliopsoas (Psoas major and Iliacus) (p. 219; & p. 243)
-- the Psoas major and Iliacus are often represented by a single muscle:
the Iliopsoas
ORIGIN: lumbar vertebrae & anterior surface of the ilium
INSERTION: lesser trochanter of the femur
ACTION: flexes and rotates the thigh laterally
(when the thigh is fixed in place, the Iliopsoas flexes the spine
as a prevertebral muscle)
[Femoral Nerve]
==============================================================
11
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
12
36. The Medial-Adductor Muscle Group of the Leg
-- this group consists of 4 separate muscles located on the medial aspect of
the thigh
[-- each of the 4 muscles is innervated by branches of the Obturator Nerve]
a. Gracilis (p. 219; & p. 243)
-- this appears as a very broad muscle in the cat, that almost "crosses"
with the Sartorius muscle
ORIGIN: pubic symphysis
INSERTION: proximal end of the tibia
ACTION: adducts the thigh; flexes the leg at the knee; (viz: gripping
your thighs into the sides of a horse while horse-back riding)
[Obturator Nerve]
-------------------------------------------------------------------------------------------------------------b. Adductor magnus (femoris) (p. 219; & p. 243)
-- this muscle is located just underneath the Gracilis
-- this muscle is represented as 2 separate muscles in man:
the Adductor brevis and Adductor magnus
ORIGIN: pubic bone
INSERTION: linea aspera of the femur
ACTION: adducts the thigh; flexes the leg at the knee (viz: gripping your
thighs into the sides of a horse while horse-back riding)
[Obturator Nerve]
-------------------------------------------------------------------------------------------------------------c. Adductor longus (p. 219; & p. 243)
-- this muscle is located just superior to the Adductor femoris
ORIGIN: pubic bone
INSERTION: linea aspera of the femur
ACTION: adducts the thigh; flexes the leg at the knee (viz: gripping your
thighs into the sides of a horse while horse-back riding)
[Obturator Nerve]
--------------------------------------------------------------------------------------------------------------
12
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
13
d. Pectineus (adductor) (p. 219; & p. 243)
-- this muscle is located just superior to the Adductor longus
ORIGIN: pubic bone
INSERTION: femur
ACTION: adducts the thigh; flexes the leg at the knee (viz: gripping your
thighs into the sides of a horse while horse-back riding)
[Obturator Nerve]
==============================================================
37. The Posterior-Flexor ("Hamstring") Muscle Group of the Leg
-- this group consists of 3 separate muscles located on the posterior aspect of
the thigh
-- the Hamstring muscle group acts as the antagonist of the Quadriceps
femoris muscle group
[-- each of the 3 muscles is innervated by branches of the Sciatic Nerve]
a. Biceps femoris (p. 221; & p. 240)
-- this muscle is broader in the cat than in man
ORIGIN: short head: linea aspera of the femur
long head: ischial tuberosity
INSERTION: proximal end of the tibia
ACTION: flexes the leg at the knee (antagonist of the
Quadriceps femoris) and extends the thigh
[Sciatic Nerve]
-------------------------------------------------------------------------------------------------------------b. Semitendinosus (p. 221; & p. 240)
-- this muscle is broader in the cat than in man
ORIGIN: ischial tuberosity
INSERTION: proximal end of the tibia
ACTION: flexes the leg at the knee (antagonist of the
Quadriceps femoris) and extends the thigh
[Sciatic Nerve]
--------------------------------------------------------------------------------------------------------------
13
Muscular System Laboratory Guide (Marieb 6th ed)
S. Fink
14
c. Semimembranosus (p. 221; & p. 240)
ORIGIN: ischial tuberosity
INSERTION: proximal end of the tibia
ACTION: flexes the leg at the knee (antagonist of the
Quadriceps femoris) and extends the thigh
[Sciatic Nerve]
==============================================================
Fascia of the Thigh ("fascia lata") (p. 221; & p. 240)
The fascia lata ("broad fascia") is continuous with the thoraco-lumbar and external
abdominal fascia. The fascia lata attaches proximally to the pelvic bones and the
inguinal ligament. It attaches distally with the fascia of the leg, and laterally to the
lateral condyle of the tibia (as the “iliotibial tract”).
-------------------------------------------------------------------------------------------------------------38. Gluteus maximus (p. 221; & p. 240)
-- this posterior muscle of the hip forms much of the mass of the buttock in
man; it appears much smaller in the cat
-- the upper lateral quadrant of this muscle is a commonly used site for intramuscular (IM) injections
ORIGIN: posterior surface of the ilium and the sacrum
INSERTION: iliotibial band of the fascia lata and the shaft of the femur
ACTION: extends and rotates the thigh laterally, as when rising from a chair
or walking (antagonist of the Tensor Fascia Lata muscle)
[Gluteal Nerve]
-------------------------------------------------------------------------------------------------------------39. Gluteus medius (p. 221; & p. 240)
-- located beneath the Gluteus maximus; this muscle appears larger than the
Gluteus maximus in the cat
-- there are bursae between the tendons of insertion of each of the gluteal
muscles
ORIGIN: posterior surface of the ilium
INSERTION: greater trochanter of the femur
ACTION: abducts and rotates the thigh laterally, as when rising from a chair
(synergist with Gluteus maximus)
[Gluteal Nerve]
-------------------------------------------------------------------------------------------------------------14
Muscular System Laboratory Guide (Marieb 6th ed)
S. Fink
40. Tensor Fascia Lata
15
(p. 219; & p. 240)
ORIGIN: the iliac crests (via fascia lata)
INSERTION: the lateral condyle of the tibia (via the iliotibial band
of the fascia lata)
ACTION: abducts thigh
[Gluteal Nerve]
==============================================================
The Superficial Posterior Crural ("Calf") Plantarflexor Muscles
41. Gastrocnemius (pp. 223 & 225; & p. 241)
-- located on the postero-medial aspect of the calf
ORIGIN: 2 heads from the medial & lateral condyles of femur
INSERTION: calcaneous bone via the Achilles tendon
ACTION: plantarflexes the foot (stand on toes)
(antagonist of the Tibialis anterior)
[Tibial Nerve]
-------------------------------------------------------------------------------------------------------------42. Soleus (pp. 223 & 225; & p. 241)
ORIGIN: head of the tibia & fibula
INSERTION: calcaneous bone via the Achilles tendon
ACTION: plantarflexes the foot (stand on toes)
(synergist with the Gastrocnemius)
[Tibial Nerve]
==============================================================
43. Flexor digitorum longus (p. 225; & p. 244)
-- a deep muscle located on the postero-medial aspect of the leg
ORIGIN: tibia
INSERTION: distal phalanges
ACTION: flexes the distal toes; plantarflexes the foot
(antagonist of the Extensor digitorum longus)
[Tibial Nerve]
==============================================================
15
S. Fink
Muscular System Laboratory Guide (Marieb 6th ed)
16
The Anterior Crural Dorsiflexor Muscles
44. Tibialis anterior (p. 223; & p. 244)
-- located on the antero-lateral aspect of the leg
ORIGIN: proximal end of the tibia
INSERTION: metatarsal bone
ACTION: inverts and dorsiflexes the foot; extends the toes; (viz: prevents
stubbing of the toes as the foot swings forward in walking)
(antagonist of the Peroneus longus)
[Peroneal Nerve]
-------------------------------------------------------------------------------------------------------------45. Extensor digitorum longus (p. 223; & p. 241)
-- located on the lateral aspect of the leg
ORIGIN: tibia and fibula
INSERTION: phalanges
ACTION: extends the toes; dorsiflexes the foot
[Peroneal Nerve]
==============================================================
46. Fibularis (Peroneus) longus (p. 223; & p. 241)
-- located on the lateral aspect of the leg
ORIGIN: lateral surface of the fibula
INSERTION: metatarsal bone (via a long tendon running on the underside
of the foot)
ACTION: everts and plantarflexes the foot
(antagonist of the Tibialis anterior)
[Peroneal Nerve]
16