Biology 241 – Lab
LAB #15
(15th/21 Lab Sessions for Fall Quarter, 2008)
TOPICS TO BE COVERED:
»Demonstration/Dissection/Identification of the Muscles of the Hip
»Demonstration/Dissection/Identification of the Muscles of the Upper Hindlimb (“Thigh”)
»Demonstration/Dissection/Identification of the Muscles of the Lower Hindlimb (“Leg”)
DESIRED OUTCOMES:
After completing the activities described for this lab session, students should:
»Be able to identify the five hip muscles:
Fascia latae Tensor fascia latae Gluteus medius
Gluteus maximus
Caudofemoralis
»Be able to identify the thirteen upper hindlimb (thigh) muscles:
Sartorius Gracilis
Adductor femoris
Adductor longus
Pectineus
Iliopsoas
Vastus lateralis
Vastus medialis
Vastus intermedius
Rectus femoris
Biceps femoris
Semimembranosus
Semitendinosis
»Be able to identify the four lower hindlimb (leg) muscles:
Biceps gastrocnemius
Soleus
Peroneus (longus and brevis)
Tibialis anterior
MATERIALS NEEDED:
»Gloves
»Safety Glasses (or your own glasses)
»Dissection Trays (large, flat pans)
»Preserved cats
»Dissection Tools (large forceps, scissors, blunt probes, dissection needles, scalpels)
»Photographic Atlas, Ch. 1, Ch. 8, Ch. 19
»Cat Atlas
Activity #1: Demonstration/Dissection/Identification of the Muscles of the Hip
Clear the superficial fat and fascia away from the hip and thigh, being careful not to damage the spermatic cord if your specimen is a male. Upon examination of the lateral aspect of the thigh, you should be able to
identify a thick, yellowish-white, glistening structure: the fascia latae, which is a tough, aponeurosis on the
anterior and lateral aspect of the thigh into which several of the hip muscles and superficial thigh muscles insert.
Great care should be taken NOT to cut this structure away; however, it will need to be reflected eventually to
view the deeper muscles of the thigh.
FASCIA LATAE: The fascia latae is a connective tissue structure (an aponeurosis) continuous proximally with the fascia of the gluteal muscles; distally it is attached to the ligaments of the patella and is continuous with the fascia of the lower limb.
TENSOR FASCIA LATAE: The tensor fascia latae is a thick, “upside down heart” shaped muscle
which is continuous with the proximal portion of the fascia latae. It originates from the crest of the ilium and
neighboring fascia and inserts on the fascia latae. As its name describes, when this muscle contracts, it acts to
tighten the fascia latae (which helps stabilize the knee joint) and to draw the thigh anteriorly.
Biology 241 – LAB #15 – continued
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GLUTEUS MEDIUS: Posterior to the tensor fascia latae lies the gluteus medius. This is the largest of
the gluteal muscles in the cat. This muscle originates from the ilium and the transverse processes of the last sacral and first caudal vertebrae. It inserts on the greater trochanter of the femur and acts as an abductor of the thigh.
GLUTEUS MAXIMUS: Just posterior to the gluteus medius lies the gluteus maximus, a small, triangular hip muscle. This muscle lies between the gluteus medius and the caudofemoralis. It originates from the transverse processes of the last sacral and first caudal vertebrae and inserts on the greater trochanter. It abducts the
thigh.
CAUDOFEMORALIS: Just posterior to the gluteus maximus, lies the caudofemoralis. It originates
from the transverse processes of the second and third caudal vertebrae and inserts on the patella and idnto the
surrounding fascia by a thin tendinous band. . The caudofemoralis abducts the thigh and extends the knee. It
has no homolog in humans.
Activity #2: Demonstration/Dissection/Identification of the Muscles of the Upper Hindlimb (“Thigh”)
Examine the medial aspect of the thigh and the following muscles will be identifiable:
SARTORIUS: The sartorius is a wide, superficial muscle covering the anterior half of the medial
aspect of the thigh. It originates from the crest and ventral border of the ilium and inserts on the tibia, patella,
and fascia of the knee. Because it crosses both the hip and knee joints, it has dual action: to adduct and rotate
the femur at the hip and to extend the knee. (Note: The motion(s) brought about by this muscles are the ones involved in “crossing one leg” over the other. Since tailors do this when they are sewing, this muscle was so named. Sartus is
the past participle of the Latin verb “to mend” and sartorius is Latin for “like a tailor”!) In the human, the sartorius is
the longest muscle in the body.
GRACILIS: The gracilis is a very broad muscles that covers the posterior portion of the medial aspect
of the thigh. It originates from the ischium and the pubic symphysis and inserts by a broad aponeurosis on the
medial surface of the tibia. It adducts the thigh at the hip and draws it posteriorly.
ADDUCTOR FEMORIS and ADDUCTOR LONGUS (aka: ADDUCTOR GROUP): Deep to the gracilis is the adductor femoris. It is a large muscle with an origin from the ischium and the pubis. It inserts on the
femur and acts to adduct the thigh. Anterior to the adductor femoris is the adductor longus muscle. It is a narrow muscle that originates from the ischium and pubis and inserts on the proximal surface of the femur. It, too,
adducts the thigh.
PECTINEUS: The pectineus is anterior to adductor longus. It is a deep, small muscle posterior to both
the femoral artery and the deep femoral vein. It originates from the anterior border of the pubis and inserts on
the proximal end of the femur. It functions to adduct the thigh.
ILIOPSOAS: Deep to the femoral artery, vein, and nerve, and lateral to the pectineus muscle, is the
iliopsoas. In humans it is composed of two muscles: the iliacus and the psoas major. It originates from lumbar
vertebrae and inserts on the medial aspect of the proximal femur. It flexes and laterally rotates the thigh.
Biology 241 – LAB #15 – continued
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Collectively, the next four muscles comprise the quadricieps femoris, or “quads”. The quadriceps femoris
covers the entire anterior surface of the thigh which is also about one-half the area of it. Collectively, all four
separate heads of this quadriceps muscle are united distally via a common insertion: the patellar ligament
This ligament contains the patella and inserts on the proximal end of the tibia, at the anterior tibial tuberosity.
The action of all four muscles is to act together as a powerful extender of the leg at the knee. In order to properly expose these muscles, one must reflect the sartorius and must also free both borders of the tensor fascia latae.
Once reflected, it can be observed that the muscles of the quadriceps femoris converge and all insert onto the
patella through the patellar ligament. The four heads of the quadriceps femoris are the:
VASTUS LATERALIS: The large muscle on the anterolateral surface of the thigh is the vastus lateralis. It originates along the entire length of the lateral surface of the femur.
VASTUS MEDIALIS: The large muscle on the medial surface of the femur is the vastus medialis which
originates on the shaft of the femur.
RECTUS FEMORIS: The large, cylindrical rectus femoris lies between the vastus medialis and vastus
lateralis muscles and originates on the acetabulum.
VASTUS INTERMEDIUS: This muscle lies deep to the rectus femoris. Instead of reflecting the rectus femoris to expose the vastus intermedius, we will leave the rectus femoris muscle in place. It originates on
the shaft of the femur.
Lastly, for superficial muscles of the upper hindlimb, we discuss those along the lateral and posterior
aspect of the thigh. There are three of these; and collectively they are referred to as the “hamstrings”.
BICEPS FEMORIS: The large, broad muscle covering the lateral region of the thigh is the biceps femoris. It originates from the ischial tuberosity and inserts on the tibia. The biceps femoris enables two actions:
abduction of the thigh at the hip and flexion of the leg at the knee.
SEMIMEMBRANOSUS: A large, posterior muscle lying deep to the gracilis and medial to the semitendinosus is the semimembranosus. It originates from the ischium and inserts on the medial epicondyle of the
femur and medial surface of the proximal tibia. It enables extension of the thigh at the hip (drawing of the thigh
posteriorly).
SEMITENDINOSUS: On the posterior aspect of the thigh, a straplike muscle, the semitendinosus,
originates from the ischial tuberosity and inserts via a thin tendon on the medial side of the tibia. It enables
flexion of the leg at the knee.
Activity #3: Demonstration/Dissection/Identification of the Muscles of the Lower Hindlimb (“Leg”)
As we proceed into the lower hindlimb region (what is referred to as the “leg” in humans: that area of the
body from the knee to the ankle) it is well to insure that you have made your ankle “cuff cuts” at the level (or distal
to) the calcaneus. Only by doing so will you be able to see the tendinous insertions of the next several muscles.
Some of these muscles are most easily identified by following their tendons to the point of attachment to the
periosteum of bone.
(BICEPS) GASTROCNEMIUS: The “gastroc” or calf muscle, is the very large muscle on the posterior aspect of the lower hindlimb. It has two heads of origin, medial and lateral (origins: from the distal end of the
femur and from the fascia of the knee) whose insertions are united in the calcaneal tendon to insert on the calcaneus. The action of this muscle is to extend the foot at the ankle.
Biology 241 – LAB #15 – continued
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SOLEUS: Deep to the gastrocnemius, but visible on the lateral surface of the calf, is the soleus. The
soleus originates on the fibula and inserts on the calcaneus. Its action is to extend the foot at the ankle.
PERONEUS (LONGUS, BREVIS and TERTIUS): Deep to the soleus on the posterior and lateral surfaces, you will be able to view the peroneus muscles. The peroneus brevis lies deep to the tendon of the soleus,
originating from the distal portion of fibula and inserting on the base of the fifth metatarsal. The peroneus longus is a long, thin muscle that lies on the lateral surface, originating from the proximal portion of the fibula and
inserting by a tendon which passes through a groove on the lateral malleolus and turns medially to attach to the
bases of the metatarsals. (There is also a peroneus tertius, which lies along the tendon of the peroneus longus,
originating on the fibula and inserting on the base of the fifth metatarsal. The peroneus longus and tertius are
both flexors of the foot at the ankle, while the peroneus brevis is an extensor of the foot.
TIBIALIS ANTERIOR: On the anterior surface of the tibial bone, the anterior tibialis originates from
the proximal ends of the tibia and fibula and inserts on the first metatarsal. It is a flexor of the foot at the ankle.