Bio521-Labs 3-6
External Anatomy & Muscles
Before the lab, I recommend reading pages 47-50 Fishbeck & Sebas?any (2015). Make sure you
know the meanings of belly, origin and inser?on (page 67) and flexion and extension; adduc?on
and abduc?on, protrac?on and retrac?on; rota?on, prona?on and supina?on.
For the next 4 weeks you will study the external anatomy and examine the musculature of four
different animals. The muscle system is one of the most complex because it is involved in all body
movement and locomo?on. Each group of four students will be provided two lampreys, one
shark, one frog, and one cat. The first week, two students should work on the cat dissec?on
while the other pair dissects the muscles in the lamprey, frog, and the shark. For the cat, clear
away fat and connec?ve ?ssue carefully, so that individual muscles, including their origins and
inser?ons, are revealed. ASer you have iden?fied the muscles on the animal(s) that you have
been working on, you and your partner will demonstrate, or teach, those muscles to the other
pair of students in your group. They, in turn will teach you about the muscles they have dissected.
For the following weeks, you should switch specimens, so everyone has a chance to become
familiar with all four specimens. All students should carry out dissec?ons on all specimens.
Cleaning the muscles for proper iden?fica?on is ?me-consuming; by sharing the work, you have
more ?me to concentrate on learning the material.
You will become very familiar with your specimens but do remember to look carefully at others
in the room. Varia?on is the rule!
First, examine each of your specimens and learn its external anatomy. For reference, I
recommend reading the pages indicated below from Fishbeck & Sebas?any (2015):
Lamprey: pages 97-99.
Shark: pages 117-121
Frog: page 285-286
Cat: pages 399-400
ASer you have studied the external anatomy, begin dissec?ng the muscles.
“Skinning” animals prior to studying the muscles is a ?me-consuming process. For this reason,
we purchase “skinned” cats. Some?mes, cats are very moist making the cleaning of fascia and fat
challenging. If this is the case, pat your specimen with paper towels to dry it a li_le bit.
The lamprey, shark and frog need not be completely skinned. Remove a band of skin 1” - 2” wide
from one side of each animal, midway between the pectoral and pelvic regions, to reveal axial
musculature. This week, clear the skin away carefully from the pectoral region, including the
shoulder, the neck and the head of the shark and frog. Most dissec?on can be carried out with
blunt probes and forceps. Use scissors or scalpel to cut through skin but use them very sparingly.
It is very easy to destroy a muscle with a sharp scalpel!
Work through the muscles described and pictured in the lab manual, but you are only responsible
for the muscles listed below for each specimen.
Informa?on about Nasco-Guard, the preserva?ve used for some our specimens, is posted on the
front board. Do not rinse your specimens excessively unless they smell very strongly. To do so
will significantly reduce their shelf life. The company recommends no rinsing. Nasco has
developed a technique by which all but trace amounts of harmful chemicals are removed. Of
course, you s?ll don’t want to chew on a shark fin....
When storing your specimens, wrap them around a moist shroud cloth (the cat should be stored
by itself and the shark, lampreys and frog can be together), bag them in the original bag the cat
and shark came in (those are nice, strong bags), close it ?ghtly with a rubber band, and put that
bag in a black plas?c bag. This will help to control smell in the room and extend the life of the
specimens.
• Lamprey
Page 103 & Fig 14.13 from Fishbeck & Sebas?any (2015). Remove a band of skin from your
lamprey as described above.
For the external anatomy, you need to know:
Dorsal fins
Caudal fin
buccal papillae
External gill slits
Eye
Pineal organ
Lateral line system
Mouth/buccal funnel
Tongue with teeth
Nostril
Cloacal aperture
Urogenital papilla
For musculature system, you need to know:
Myomeres
Myosepta
Other structures shown in Fig. 14.14 of Fishbeck & Sebas?any (2015) will be study with the
internal anatomy.
• Shark
You need to know the ac?on or func?on of the muscles in the shark. The best way to understand
the ac?on is to work through the origins and inser?ons; the ac?on is then usually apparent. You
are not responsible for muscle origins and inser?ons in the shark for examina?on purposes,
except as noted. However, you do need to know and understand the ac?ons or func?ons.
For the external anatomy, you need to know:
Placoid scales
Rostrum
Subterminal mouth
Protrusile jaws
Teeth
Heterocercal caudal fin
Anterior dorsal fin
Posterior dorsal fin
Pectoral fin
Pelvic fin
Ampullae of Lorenzini of the lateral line
system
Nostrils
Eyes
Spiracle
Gill slits
Endolympha?c ducts
Cloaca
Claspers (only males)
Abdominal pores
For musculature system, you need to know:
Trunk and Axial Muscles:
Myomeres
F: Elevates palatoquadrate
Myosepta
F: Separates myomeres
Adductor mandibulae
F: Elevate Meckel's car?lage
Epaxial muscles (Dorsal)
Preorbitalis
F: Elevate Meckel's car?lage
Hypaxial muscles (Ventral)
Middorsal ver?cal septum
F: Separates trunk muscles into leS and
right halves
Midventral ver?cal septum
F: Separates trunk muscles into leS and
right halves
Intermandibularis
F: Elevates the floor of the mouth
Cucullaris
F: Elevates the scapular process
Pectoral Fin muscles:
Linea alba
Extensor or Abductor
A: Elevates pectoral fin
Horizontal septum
F: Separates epaxial and hypaxial muscles
Flexor or Adductor
A: Depresses the pectoral fin
Muscles of the gill arches and derivates.
Pelvic Fin Muscles:
Levator palatoquadrate
F: Elevates palatoquadrate
Extensor or Abductor
A: Elevates the pelvic fin
Spiracularis
Flexor or Adductor
A: Depresses the pelvic fin
Dorsal Fin Muscle:
A: Stabiliza?on of the fin
Hypobranchial Muscles:
Coracomandibularis
A: Opens mouth
• Frog
Again, you need to know the ac?on of the muscles. As in the shark, the best way is to understand
origin and inser?ons; the func?on is then usually apparent. Unless noted otherwise, you are not
responsible for muscle origins and inser?ons in frog for examina?on purposes, however.
For the external anatomy, you need to know:
Head
Tympanic membrane
Annular car?lage
Columella (Stapes)
Frontal organ
External nares
Trunk
Linea alba
Forelimb
Hindlimb
Cloacal aperture
For musculature system, you need to know:
Ventral Trunk Muscles
Pectoralis
A: Adducts, rotates, and flexes the forelimb
Rectus abdominis
A: Flexes the trunk
External oblique
A: Compresses the viscera
Dorsal Trunk Muscles
La?ssimus dorsi
A: Retracts forelimb
Rhomboideus
A: Stabiliza?on of the suprascapulae
Longissimus dorsi
A: Extends the pelvic area
Dorsal Muscles of the Head
Temporalis
A: Elevates the mandible
Masseter
A: Elevates de mandible
Ventral Muscles of the head
Intermandibularis
A: Elevates the throat
Genioglossus
A: Tongue movement
Muscles of the Shoulder and Forelimb
Deltoideus
A: Protrac?on and adduc?on of the forearm
Anconeus
A: Extends the forearm
Muscles of Pelvic Girdle and Hindlimb
Triceps femoris
A: Extends the lower limb and assists in
protrac?on of the thigh
Sartorius
A: Flexes the lower hindlimb, adducts and
protracts of the thigh
Gracilis (as a group)
A: flexes lower limb and retracts and
adducts the thigh
Plantaris longus
A: extends the foot and flexes the toes
• Cat
Note - in the cat, you are responsible for learning origin, inser?on, and ac?on of all muscles in
the to-know list.
In the head and neck, locate and know the platysma, a superficial muscle a_ached to the skin. It
moves the skin and contributes to facial expression in humans.
For the external anatomy, you need to know:
Hair
Head
Nostrils (external nares)
Eyes
Nic?ta?ng membrane
External ears (pinnae)
Whiskers (vibrissae)
Neck
Trunk
Thoracic
Abdominal
Linea alba
Pelvic
Nipples
Forelimb
Brachium
Antebrachium
Manus
Hindlimb
Femur
Pes
Tarsus
Anus
Testes (male)
Urogenital aperture (female)
Tail
For musculature system, you need to know:
Trunk muscles
Platysma
O&I: Head and neck muscles
A: Moves skin and contributes to facial
expressions
Pec?oantebrachialis
O: Manubrium of sternum
I: Antebrachium above the elbow
A: Draws forelimb toward midline
Pectoralis Major
O: Cranial half of sternum
I: Proximal 2/3 of shaS of humerus
A: Draws forelimb toward midline and turns
manus forward
Pectoralis Minor
O: Sternebrae and xiphoid process
I: Ventral border of humerus
A: Draws forelimb toward midline
Xiphihumeralis
O: Xiphoid process of the sternum
I: Ventral border of humerus
A: Draws forelimb toward midline
Abdominal Muscles
External Oblique
O: Lumbodorsal fascia of ribs
I: Distal por?on of sternum and linea alba
A: Compresses the abdominal region
Internal Oblique
O: Lumbodorsal fascia of ribs
I: Linea alba
A: Compresses the abdominal region
Transversus abdominis
O: Costal car?lage of pos. ribs, transverse
process of L. vertebrae, ventral border of
ilium
I: Linea alba from sternum to pubis
A: Compresses abdomen.
Rectus abdominis
O: Pubis
I: Costal car?lage and proximal sternum
A: Compresses abdomen, pulls sternum and
ribs caudally
Lower Back- Lumbar & Thoracic
Longissimus dorsi (as a group)
O: Ilium and neural spines of vertebrae
I: Processes of anterior vertebrae
A: Extends vertebral column
La?ssimus dorsi
O: Spinous process thoracic to lumbar
vertebrae
I: Medial surface of humerus
A: Pulls forelimb dorsocaudally
Clavotrapezius
O: Lambdoidal ridge, spine of axis
I: Clavicle
A: Protracts humerus
Clavobrachialis
Clavicle
Medial surface of ulna distal
Flexes the forearm
Muscles of the Neck
Sternomastoid
O: Cranial end of manubrium
I: Lambdoidal ridge and mastoid por?on of
temporal bone
A: As a pair, flexion of the head; individually,
turns the head
Muscles of the Head
Masseter
O: Zygoma?c arch
I: Masseteric fossa of mandible
A: Elevates mandible
Temporalis
O: Temporal bone and zygoma?c arch
I: Coronoid process of mandible
A: Elevates mandible
Digastric
O: Mastoid and jugular processes
I: Mandible
A: Depresses mandible
A: Acts synergis?cally with the triceps
brachii in extending the forearm
Muscles of the Shoulder:
Brachioradialis
O: Humerus
I: Styloid process of the radius
A: Supinates manus
Supraspinatus
O: Supraspinous fossa
I: Grater tuberosity of the humerus
A: Protracts the humerus
Infraspinatus
O: Infraspinous fossa
I: Lateral surface of the greater tuberosity of
the humerus
A: Rotates the humerus laterally
Teres Major
O: Cranial border of the scapula
I: Proximal end of the humerus
A: Flexes and rotates the humerus medially
Muscles of the Brachium:
Biceps Brachii (as a group)
O: Glenoid fossa of the scapula
I: Radial tuberosity
A: Flexes the forearm synergis?cally with
the brachialis; tends to supinate the manus;
and stabilizes the shoulder joint.
Triceps Brachii (as a group)
O: (1) Lateral head—deltoid ridge of
proximal end of the humerus; (2) Long
head—near glenoid fossa of axillary border
scapula; (3) medial head—consists of three
parts, all of which originate from humerus
I: Surface of the olecranon of the ulna
A: Extends the forearm
Anconeous
O: Lateral epicondyle
I: Ulna
Muscles of the Antebrachium:
Muscles of the Thigh:
Sartorius
O: Crest and ventral border of the ilium
I: Patella, ?bia and fascia of the knee
A: Adducts and rotates the femur, extends
the shank
Gracilis
O: Symphysis of the ischium and the pubis
I: ?bia and fascia of the shank
A: Adducts and retracts the leg
Biceps Femoris
O: Ischial tuberosity
I: Tibia and patella
A: Abducts thigh and flexes the shank
Quadriceps Complex (as a group):
• Vastus Medialis
O: Femur
I: Tibial tuberosity
A: Extends the shank
• Rectus Femoris
O: Illium near the acetabulum
I: In common with the vastus medialis
and lateralis
A: Extends the shank
• Vastus Lateralis
O: Greater trochanter and adjacent area
of the femur
I: In common with the vastus medialis
and rectus femoris
A: Extends shank
• Vastus Intermedius
O: Femur
I: In common with the other three
members of this complex
A: Extends shank
Muscles of the Shank:
Tibialis Cranialis
O: Proximal end of the ?bia and the fibula
I: Medial surface of the first metatarsal
aSer passing beneath the extensor
re?culum
A: Flexes the pes
Gastrocnemius
O: Patella, superficial fascia of the shank,
sesamoid bone, aponeurosis from the
plantaris and adjacent ?bia,
I: Proximal end of the calcaneus
A: Extends the pes
Plantaris
O: Sesamoid bone
I: In common with gastrocnemius
A: Acts synergically with the gastrocnemius
and the soleus to extend the pes
Soleus
O: Fibula
I: In common with gastrocnemius and
contributes to the forma?on of the Achilles
tendon
A: Synergis?c extension of the pes with the
gastrocnemius and plantaris
Muscles of the hip:
Gluteus Maximus
O: Last sacral and first caudal vertebrae, as
well as adjacent fascia
I: Greater trochanter of the femur
A: Abducts the thigh
Gluteus Medius
O: Crest and lateral surface of the illium, last
sacral and first caudal vertebrae and
adjacent fascia
I: Greater trochanter of the femur
A: Abducts the thigh
For your por(olio:
From now and on, your porsolio is a group contribu?on:
• Document how you are performing each procedure, any sugges?ons to find muscles or
make some dissec?ons be_er. I may use some of your text on the Lab Dissec?on Guide
we are crea?ng, and you can be one of the contributors.
• I am also interested in high quality pictures, diagrams or drawings with clear views of
structures.