LAB 4 – Muscles of the pelvis and thigh – lateral pelvis, caudal hip, and cranial thigh

Learning Objectives

  • Identify muscles of the lateral pelvis, caudal hip, and cranial thigh
  • Name the attachments of the muscles of the lateral pelvis, caudal hip, and cranial thigh
  • Name the action(s) of the muscles of the lateral pelvis, caudal hip and cranial thigh
  • Categorize muscles into “muscle action groups”
  • Connect structures to the clinically applied anatomy as emphasized.

For this lab we will dissect and learn the muscles (and other highlighted structures) of the lateral pelvis region, the caudal hip area, and the cranial hip and thigh region.  The muscles to be considered are listed below. Follow the lab guide to dissect these muscles on the carnivore specimen for your team. Then move to identifying the comparative anatomy of these muscles, and other structures highlighted, on the ungulate specimens.

Lateral pelvis (croup/rump)

  • Tensor fasciae latae m.
  • Gluteofemoralis m. (cat)
  • Superficial gluteal m.
  • Middle gluteal m.
  • Deep gluteal m.

Caudal hip

  • Internal obturator m.
  • Gemelli m.
  • Quadratus femoris m.
  • External obturator m.

Cranial thigh

  • Quadriceps femoris mm. (4 bellies)
    • Rectus femoris m.
    • Vastus medialis m.
    • Vastus lateralis m.
    • Vastus intermedius m.
  • Iliopsoas m.
  • Sartorius m. (also reviewed on medial thigh in Lab 2)

Lateral muscles of the pelvis

Tensor Fasciae Latae m.

The  tensor fasciae latae m. is a triangular muscle (looks a bit like an upside down V shape) that attaches proximally to the tuber coxae. It lies between the sartorius cranially, the middle gluteal caudodorsally, and the quadriceps distomedially. Part of its caudodorsal surface is attached to the middle gluteal near its origin. The muscle can be divided into two portions (two arms of the V). The cranial, more superficial portion is inserted on the fascia lata (lateral femoral fascia), which radiates over the quadriceps and blends with the fascial insertion of the biceps femoris. The deeper caudal portion is inserted on a layer of fascia lata that runs deep to the biceps toward the stifle on the lateral surface of the vastus lateralis m. (part of the quadriceps femoris m.)

PROXIMAL ATTACHMENT: Ilium, gluteal fascia

DISTAL ATTACHMENT: Fascia lata

ACTION: Flex the hip, extend the stifle

Observe: Identify the muscle and note its borders.  At this time, do not cut the cranially lying fascia lata, which serves as part of its insertion.  You may need to do so when isolating the quadriceps femoris m.

Gluteofemoralis m.

In the cat, the gluteofemoralis m., which is a long thin muscle caudal to the superficial gluteal m., is an additional muscle not present in the dog or ungulates.

PROXIMAL ATTACHMENT: Caudal vertebrae

DISTAL ATTACHMENT: Fascia lata

ACTION: Abduct hip or move tail laterally

Dissect: In the cat, clean and isolate the gluteofemoralis m. and transect it about a centimeter proximal to its distal attachment. Reflect the proximal portion of the muscle.

 

Superficial Gluteal m.

The superficial gluteal m. is small and lies caudal to the middle gluteal. Its fibers run distally, from the deep gluteal fascia that covers the middle gluteal and from the sacrum and the first caudal vertebra to the level of the greater trochanter of the femur, where the fibers converge before forming an aponeurosis that runs under the biceps to attach to the third trochanter.

PROXIMAL ATTACHMENT: Pelvis

DISTAL ATTACHMENT: Third trochanter

ACTION: Extend the hip and abduct the pelvic limb

Dissect: Clean and isolate the superficial gluteal m. and transect it 1 cm proximal to its aponeurosis of distal attachment to the third trochanter. In the dog, be aware of the closely related sacrotuberous ligament at the proximal attachments of the superficial gluteal and avoid transecting it.

Sacrotuberous Ligament

The sacrotuberous ligament is a fibrous band that runs from the sacrum to the lateral angle of the ischiatic tuberosity (tuber ischii) in the dog.  Recall, it is absent in the cat. It is a site of attachment for muscles.

Observe: View and palpate this ligament in the dog cadavers, and view it on prosections (wet and dry).

Middle Gluteal m.

The middle gluteal m. is a large, ovoid muscle that lies between the tensor fasciae latae and the superficial gluteal.  The caudodorsal border of the middle gluteal is covered by the superficial gluteal. A deep caudal portion of the middle gluteal can be isolated from the main muscle mass and this part is called the piriformis muscle (fyi). Its separate tendon inserts at the same location as the rest of the muscle mass.

PROXIMAL ATTACHMENT: Ilium

DISTAL ATTACHMENT: Greater trochanter

ACTION: Extend the hip, abduct the pelvic limb, and rotate femur medially at hip

Dissect: Clean the surface of the muscle by reflecting the deep gluteal fascia and its attached transected superficial gluteal muscle craniodorsal to the iliac crest; this reveals the fibers of the middle gluteal.  Carefully separate by blunt dissection the cranioventral border of the middle gluteal from the underlying deep gluteal. Then, starting at the middle of the cranioventral border of the middle gluteal, transect the entire muscle and reflect the distal half toward its insertion on the greater trochanter of the femur to reveal the underlying deep gluteal muscle.  Sometimes the piriformis m. is left behind during this reflection and it lies on the caudal aspect of the deep gluteal m.

Deep Gluteal m.

The deep gluteal m. is fan-shaped and completely covered by the middle gluteal. Its fibers converge to insert on the cranial face of the greater trochanter.

PROXIMAL ATTACHMENT: Ilium and ischiatic spine

DISTAL ATTACHMENT: Greater trochanter

ACTION: Extend the hip, abduct the pelvic limb, and rotate femur medially at hip

Observe: Identify the deep gluteal m.

 

Caudal muscles of the hip

The four muscles of this group are important because of their proximity to the hip. They lie caudal to the hip and extend from the ventral and dorsal surfaces of the ischium to the femur. All rotate the limb laterally. This action opposes the medial rotation by the gluteal muscles so that the thigh moves in a sagittal plane at the hip.

Internal Obturator m.

The internal obturator m. is fan-shaped on the dorsal surface of the ischium and pubis. It is so named as it lies within the confines of the pelvic cavity.  It covers the obturator foramen and its muscle fibers converge toward the lesser ischiatic notch where its tendon of attachment begins. The tendon of the internal obturator passes over the lesser ischiatic notch (and ventral to the sacrotuberous ligament in the dog).

PROXIMAL ATTACHMENT: Dorsal ischium and pubis

DISTAL ATTACHMENT: Trochanteric fossa

ACTION: Lateral rotation of femur at the hip.

Dissect: Isolate the tendon of insertion of the internal obturator m.  by removing fat and fascia covering its surface [and working caudomedial to the sacrotuberous ligament in the dog].  The tendon will be located caudal to the caudal border of the deep gluteal muscle.  Abduction of the limb releases tension on the tendon making it a little easier to elevate.  In the cat, the internal obturator m tendon is typically buried in the gemelli mm. (see next muscle) and requires more dissection to locate.

Now, with your finger, you may be able to follow the tendon to palpate the dorsal surface of the muscle belly on the dorsal surface of the ischium and pubis.  Make sure to visualize this muscle on plastinated models.

Clinical Application: Q2

Q2: One muscle that attaches to the greater trochanter of the femur is the: 

A. internal obturator m.

B. superficial gluteal m.

C. middle gluteal m.

D. biceps femoris m.

Answer 

Gemelli m.

The gemelli mm., two muscles fused together, lie under and adjacent the tendon of the internal obturator. They are interposed between the quadratus femoris (not quadriceps femoris! this is a different muscle) and external obturator distally and the deep gluteal proximally and cranially. The gemelli are deeply grooved by the tendon of the internal obturator so that their edges overlap this tendon.

PROXIMAL ATTACHMENT: Ischium

DISTAL ATTACHMENT: Trochanteric fossa

ACTION: Lateral rotation of femur at the hip.

Observe: Observe the gemelli on either side of the internal obturator’s tendon of insertion.  Note that these muscles share an attachment with the internal obturator muscle on the trochanteric fossa of the femur.

Quadratus femoris m.

Later, the quadriceps femoris m. is studied.  Note the subtle spelling difference that distinguishes very different muscles!

The quadratus femoris m. is short and thick. It lies deep to the biceps femoris, where it is interposed between the adductor medially, the biceps femoris laterally, and the external obturator and gemelli dorsally. Its fibers are at right angles to the long axis of the thigh. The dorsal border of the quadratus femoris lies closely applied to the ventral border of the gemelli.

PROXIMAL ATTACHMENT: Ischium

DISTAL ATTACHMENT: Intertrochanteric crest

ACTION: Lateral rotation of femur at the hip. (Secondary: extend the hip)

Dissect: Reflect the proximal part of the transected biceps femoris m. in order to dissect and isolate the margins of the exposed portion the quadratus femoris from the lateral side.  Dissect it directly ventral to the caudal border of the gemelli mm.  What is viewed is only a small section of this relatively elongated rectangular muscle.  View this muscle on platinated models, to appreciate its full extent and attachments. It should be examined from both the medial and lateral sides.

External obturator m.

The external obturator m. is fan-shaped (like its internal partner) and arises on the ventral surface of the pubis and ischium. It is so names because it lies on the outside of the pelvic cavity.  It also covers the obturator foramen. Its caudal border is covered by the quadratus femoris, whereas its cranial border is hidden by the adductor.

PROXIMAL ATTACHMENT: Ventral ischium and pubis

DISTAL ATTACHMENT: Trochanteric fossa

ACTION: Lateral rotation of femur at the hip.

Observe: Observe the external obturator muscle on plastinated models.  It is not dissected on the cadaver, however, its caudal lateral margin may be noted between the quadratus femoris and gemelli mm.

Cranial muscles of the thigh

Quadriceps femoris mm.

The quadriceps femoris m. has four heads of origin (hence its name), which are fused distally. They are a) the rectus femoris m., b) the vastus lateralis m., c), the vastus intermedius m., and d) the vastus medialis m., all of which will be dissected independently. The vastus muscles attach proximally to the femur and the rectus femoris muscle attaches to the ilium. All heads functionally attach distally to the tibial tuberosity. The patella lies within the tendon of insertion. The quadriceps femoris m. is the most powerful extensor of the stifle joint and its action is necessary for the animal to support its weight normally.

The patella, a large sesamoid bone (the human ‘kneecap’), is intercalated in the insertion of the quadriceps. The muscle heads attach to the patella.  The patella articulates with the trochlea of the femur (forming the femoropatella joint). From the patella, the patellar ligament extends distally to attach to the tibial tuberosity. It represents the functional tendon of insertion of the quadriceps femoris.

Dissect: At this time, the fascia lata will likely need to be transected and reflected to expose the quadriceps femoris heads laterally.  Keep the fascia lata attached to the tensor fasciae latae muscle proximally. The sartorius muscle may need to be transected to access the rectus femoris and medial head of the quadriceps. If it is transected, cut both parts midway between the proximal and distal attachments and reflect the distal parts to their insertions on the patella and cranial border of the tibia.

Read the muscle descriptions below and dissect the margins of the quadriceps femoris m. sharply and bluntly until the four heads are identified.

The rectus femoris is the most cranial component of the quadriceps femoris.  Proximally, it is circular in transverse section and it is sandwiched between the vastus muscles.  Because the rectus femoris arises from the ilium it also functions as a flexor of the hip, along with its stifle extension action shared with the other 3 heads.

The vastus lateralis lies lateral and caudal to the rectus femoris, to which it is fused distally. The vastus lateralis is partly separated from the vastus intermedius by an intermuscular septum. Notice that the vastus lateralis arises from the proximal part of the lateral lip of the caudal rough surface of the femur.

The vastus intermedius lies directly on the cranial surface of the femur and is quite intimately fused with the other two vasti.  It arises with the vastus lateralis, from the lateral side of the proximal end of the femur.

Dissect: Push the rectus femoris m. laterally or medially so that the deeper lying vastus intermedius m. can be visualized, and palpated.  If it cannot be seen, the rectus femoris muscle may be transected. Due to the fusion of the 3 vasti muscles at their deep margins, a clear distinction may not be apparent from lateral to intermediate to medial. When directly palpating the muscle covering the cranial surface of the shaft of the femur, the vastus intermedius m. is being palpated.

The vastus medialis arises from the medial side of the proximal end of the cranial surface of the femur and the proximal end of the medial lip of the caudal rough surface. It is inserted with the other heads of the quadriceps on the tibial tuberosity.

PROXIMAL ATTACHMENTS: Rectus femoris = ilium; Vastus mm. = proximal femur

DISTAL ATTACHMENT: Tibial tuberosity

ACTION: Extend the stifle (Secondary: rectus femoris m. also flexes the hip)

 

Iliopsoas m.

The iliopsoas m., pronounced with a silent “p”, is a sublumbar muscle now visible at its insertion on the lesser trochanter of the femur. This end of the muscle lies between the pectineus medially and the rectus femoris laterally. The iliopsoas represents a fusion of the psoas major and iliacus muscles. The psoas major is long and arises from the ventral aspect of the transverse processes and bodies of lumbar vertebrae. It passes caudally and ventrally under the cranioventral aspect of the ilium, where it joins the iliacus. The iliacus is short and arises from the smooth ventral surface of the ilium between the arcuate line and the lateral border of the ilium. The two muscle masses continue caudoventrally as the iliopsoas to their conjoined insertion on the lesser trochanter. The action of the iliopsoas is to flex the hip joint and the lumbar vertebral column. It is the major flexor of the hip joint. The femoral nerve emerges from the muscle as it passes through the fibers of the iliopsoas m.  This is one of the few places to readily observe the femoral nerve on the lab cadavers (revisited in the nervous system).

PROXIMAL ATTACHMENT: Ilium and lumbar vertebrae

DISTAL ATTACHMENT: Lesser trochanter

ACTION: Flex the hip

Dissect: Dissect as needed to observe the iliopsoas m. between the pectineus and rectus femoris mm. Observe the femoral nerve as it passes through the fibers of this muscle.

Sartorius m.

The sartorius m. gets a brief mention here again because its cranial belly in the dog passes along the cranial margin of the thigh region.  It has been considered in detail in Lab 2, the medial thigh section.

Ungulate comparative anatomy

Observe: Refer to the prosected ungulate cadavers and additional specimens and models to identify and study the following content.  Certain muscles have been transected midbody or at their attachments to facilitate viewing deeper structures.

Lateral muscles of the pelvis

The middle gluteal m. is a substantial bulk of muscle.  It is a powerful extensor of the hip joint, attaching to the greater trochanter (and specifically, the caudal part of the greater trochanter in the horse).

Observe: Identify the middle gluteal m. and the previously noted superficial gluteal (horse) or gluteobiceps (artiodactyls). The sacral attachments of the superficial gluteal (or gluteobiceps) are cut so the muscle can be reflected ventrally to expose the termination of the middle gluteal m. on the greater trochanter of the femur.

The tensor fasciae latae m. and fascia lata lie craniolaterally on the thigh with the muscle partially covering the middle gluteal.

Observe: Identify the tensor fasciae latae and fascia lata. It has been transected to allow the deeper dissection.

Deep to the middle gluteal m. is an extra gluteal muscle in ungulates called the accessory gluteal m..  The accessory gluteal m. has a distinct tendon of attachment to the greater trochanter (and specifically, the cranial part of the greater trochanter in the horse).  Deep to the tendon of attachment of the accessory gluteal m. to the greater trochanter is the trochanteric bursa.  A deep gluteal m. is also present, to finish out the gluteal muscle story in ungulates.

Observe: Identify the gluteal muscles in the ungulate prosections, and the trochanteric bursa in the horse  The middle gluteal m. has been transected and elevated to provide a view of the accessory and deep gluteal mm.  As a point of reference, the sciatic nerve crosses over the superficial surface of the deep gluteal.  The accessory gluteal m. has been transected – elevate its distal tendonous attachment to view the trochanteric bursa. Appendix on synovial structures.

Clinical relevance:

Trochanteric bursitis (‘whorlbone’ lameness): inflammation of the bursa is a cause of lameness in performance horses. There is a whorl in the hair coat in the region of the bursa, hence the name ‘whorlbone lameness’ may be used in racehorse parlance.

Lateral view of the horse pelvis depicting the superficial muscles, ligaments, and nerves. 9

 

Cranial muscles of the thigh

Observe: Once again, refer to the prosected ungulate cadavers and additional specimens and models to identify and study the following content.  Detached prosected limbs are useful to review. Certain muscles have been transected midbody or at their attachments to facilitate viewing deeper structures.

The bulk of the cranial thigh muscles is represented by the four(4)-bellied quadriceps femoris m. muscle unit.  This muscle is critical for normal weight bearing in the pelvic limb, with its primary action being stifle extension.

Observe: Identify the dissected quadriceps femoris m. by proximally separating the rectus femoris m. from the vastus lateralis m. and vastus medialis m.  Reflect the tensor fasciae latae m. out of the way to view the quadriceps femoris bellies.  Elevate and retract the rectus femoris head laterally or medially to expose, or at least to palpate, the vastus intermedius m. lying on the cranial surface of the femur.

 

Clinical relevance:

Quadriceps femoris m. is the major extensor of the stifle, innervated by the femoral n.

Q3: What does femoral n. paralysis look like?

Answer

Muscle Chart and Additional Structures

Muscle Action Groups
Flexors of the hip
  • Tensor fasciae latae m.
  • Iliopsoas m.
  • Sartorius m.
Extensors of the hip
  • Gluteofemoralis m.
  • Superficial Gluteal m.
  • Middle Gluteal m.
  • Deep Gluteal m.
Lateral rotators of the femur
  • Internal Obturator m.
  • Gemelli m.
  • Quadratus femoris m.
  • External obturator m.
Extensors of the stifle
  • Quadriceps femoris mm.
Muscle/structure Attachments/comments Action/comments
Tensor fascia latae m.
  1. Ilium, gluteal fascia
  2. Fascia lata
 Flex the hip, extend the stifle
Gluteofemoralis m.
(cat only)
  1. Caudal vertebrae
  2. Fascia lata
 Abduct hip or move tail laterally
Superficial gluteal m.
  1. Pelvis
  2. Third trochanter (horse and carnivore); fuses with biceps femoris in artiodactyls to form gluteobiceps m.
 Extend the hip and abduct the pelvic limb
Sacrotuberous ligament
(canine feature)		 Fibrous band connecting sacrum to ischiatic tuberosity Attachment site for muscles in canine.
Middle gluteal m.
(and piriformis, FYI)
  1. Ilium
  2. Greater trochanter (caudal part of greater trochanter in horse)
 Extend the hip, abduct the pelvic limb, and rotate femur medially at hip
Accessory gluteal m.
(ungulates only)
  1. Pelvis
  2. Greater trochanter of femur, (cranial part in horse)
 Extend the hip, abduct the pelvic limb – ungulate only.
Trochanteric bursa
(horse feature)		 lies deep to tendon of accessory gluteal as it inserts on greater trochanter. Identify in horse specifically.
Deep gluteal m.
  1. Ilium and ischiatic spine
  2. Greater trochanter (caudal part in horse)
 Extend the hip, abduct the pelvic limb, and rotate femur medially at hip
Internal obturator m.
(carnivore only)
  1. Dorsal ischium and pubis
  2. Trochanteric fossa
 Lateral rotation of femur at the hip.
Gemelli mm.
(carnivore only)
  1. Ischium
  2. Trochanteric fossa
 Lateral rotation of femur at the hip.
Quadratus femoris m.
(carnivore only)
  1. Ischium
  2. Intertrochanteric crest
 Lateral rotation of femur at the hip. (Secondary: extend the hip)
External obturator m.
(carnivore only)
  1. Ventral ischium and pubis
  2. Trochanteric fossa
 Lateral rotation of femur at the hip.
Quadriceps femoris m.
  • Vastus lateralis
  • Vastus intermedius
  • Vastus medialis
  • Rectus femoris
  1. Rectus femoris=ilium; Vastus mm.=proximal femur
  2. Tibial tuberosity
 Extend the stifle. (Secondary: rectus femoris also flexes hip)
Iliopsoas m.
(carnivore only)
  1. Ilium and lumbar vertebrae
  2. Lesser trochanter
 Flex the hip
Sartorius m.
  1. Ilium
  2. Cranial part=patella; Caudal part=tibia
 Flex the hip

(Secondary: cranial part extends the stifle; caudal part flexes the stifle)

 

License

Unit 2: Musculoskeletal System Copyright © by Mathew Gerard and Lindsey Cobb. All Rights Reserved.

Share This Book