Intrinsic Musculature of the Pelvic Limb Anatomy PDF

# Intrinsic Musculature of the Pelvic Limb ## The Intrinsic Muscles of the Hindlimb - The power developed by these muscles is transferred to the trunk through the **coxofemoral** or hip joint and **sacroiliac** joints, which are supported by the muscles of the hindlimb. ## The Intrinsic Musculat...

# Intrinsic Musculature of the Pelvic Limb ## The Intrinsic Muscles of the Hindlimb - The power developed by these muscles is transferred to the trunk through the **coxofemoral** or hip joint and **sacroiliac** joints, which are supported by the muscles of the hindlimb. ## The Intrinsic Musculature: ### Muscles of the Hip ### Muscles of the Stifle ### Muscles of the Tarsus ### Muscles of the Digits ## Muscles of the Hip: - **Rump Muscles:** The Lateral Muscle of the Pelvis: - They extend between the **ilium** and the thigh and are arranged in several layers. - **Caudal Muscles of the Thigh:** - **Hamstring** group of muscles - they extend from the **ischium** to the **tibia**, and their tendinous components continue as part of the common **calcanean** tendon to the **calcaneus**. - **Medial Muscles of the Thigh:** - They extend between the pelvic floor and the **femur** on the medial side of the thigh. - **Inner Pelvic Muscles:** - They extend between the pelvis and the **trochanteric fossa** of the **femur**. ## Rump Muscles: The Lateral Muscle of the Pelvis: - **Tensor Fascia Latae Muscle:** - **Origin:** The **tuber coxae** and adjacent part of the **ilium**, the aponeurosis of the **middle gluteal** muscle. - **Insertion:** The **fascia lata**. - **Action:** Draws limb forwards, tensor of the fascia. - **Superficial Gluteal Muscle:** - **Origin:** The lateral border of the **sacrum**, first caudal vertebra, partly by means of the **sacrotuberous** ligament, the cranial dorsal iliac spine by means of the deep gluteal fascia. - **Insertion:** The third **trochanter**. - **Action:** **Extensor** and **flexor** of the hip joint. - **Middle Gluteal Muscle:** - **Origin:** The crest and gluteal surface of the **ilium**. - **Insertion:** The greater **trochanter.** - **Action:** **Extensor** of the hip joint, draws limb outwards and backwards. - **Deep Gluteal Muscle:** - **Origin:** From the lateral surface of the **ilial** shaft, near the **iliac** spine. - **Insertion:** The cranial aspect of the greater **trochanter**. - **Action:** Draws limb outwards and backwards. - **Piriform Muscle:** - It is the deep caudal portion of the **middle gluteal** and it is covered by the **superficial gluteal** muscle. - **Origin:** last sacral vertebra and the **sacrotuberous** ligament. - **Insertion:** distally to the greater **trochanter** on the lateral surface of the **femur**. - **Action:** Draws limb outwards and backwards. ## Inner Pelvic Muscles: - **External Obturator Muscle:** - **Origin:** Outer surface of the **obturator foramen**. - **Insertion:** The **trochanteric fossa**. - **Action:** Draws hindlimb outwards. - **Quadratus Femoris:** - **Origin:** The ventral surface of the caudal part of the **ischium**. - **Insertion:** **Intertrochanteric crest**. - **Action:** Draws hindlimb outwards. - **Internal Obturator Muscle:** - **Origin:** Inner surface of the **obturator foramen**. - **Insertion:** The **trochanteric fossa** of the **femur**. - **Action:** Draws hindlimb outwards. - **Gemellus Muscles:** - **Origin:** The lateral surface of the **ischium,** caudal to the **acetabulum** and ventral to the lesser ischiatic notch. - **Insertion:** The **trochanteric fossa**. - **Action:** Draws hindlimb outwards. ## Cranial Muscles of the Thigh - **Quadriceps Femoris:** Is divided into four heads of origin which are fused distally. - **Origin:** From the **femur** and the **ilium**. - **Insertion:** The **tibial tuberosity**. - **Action:** Most powerful **extensor** of the stifle joint and is necessary for the animal to support its weight. - **Patella:** - **Origin:** A sesamoid bone, is intercalated in the large tendon of insertion of the quadriceps. It articulates with the trochlea of the ** femur.** - **Patellar Ligament:** - It extends from the patella to the **tibial tuberosity**. It is the tendon of insertion of the **quadriceps femoris**. - **Rectus Femoris:** - The straight muscle of the thigh. - **Origin:** **Ilium**, cranial to the **acetabulum**. - **Insertion:** **Patella,** tibial tuberosity. - **Action:** **Extensor** of the stifle joint; **flexor** of the hip joint. - **Vastus Lateralis:** - Lies lateral and caudal to the rectus femoris, to which it is fused distally. - **Origin:** Lateral surface of **femur**. - **Insertion:** **Patella,** tibial tuberosity. - **Action:** **Extensor** of the stifle joint. - **Vastus Intermedius:** - Lies directly on the smooth cranial surface of the **femur** and is quite intimately fused with the other two **vasti**. - **Origin:** Medial surface of **femur**. - **Insertion:** **Patella,** tibial tuberosity. - **Action:** **Extensor** of the stifle joint. - **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. - **Origin:** Medial surface of **femur**. - **Insertion:** **Patella,** tibial tuberosity. - **Action:** **Extensor** of the stifle joint. ## Caudal Muscles of The Thigh - This group consists of three primary muscles: - **Biceps femoris:** laterally - **Semitendinosus:** caudally - **Semimembranosus:** medially - **Biceps Femoris:** - **Origin:** The **sacrotuberous** ligament and the ischiatic tuberosity. - **Insertion:** By means of **fascia lata** and crural fascia to: - The **patella,** patellar ligament, cranial border of the **tibia**. - By means of the **crural fascia** to: The subcutaneous part if the **tibial** body; the **tuber calcanei**. - **Action:** Extends **hip** and **hock**. Its cranial part extends, caudal part **flexes stifle**. - **Semitendinosus:** - **Origin:** The **ischiatic tuberosity**. - **Insertion:** The **distocranial** border of the **tibia**. - **Action:** **Flexor** of the **stifle** joint; **extensor** of the **hip** joint. - **Semimembranosus:** - **Origin:** The **ischiatic tuberosity**. - **Insertion:** The distal medial lip of the caudal rough surface of the **femur**. - **Action:** **Extensor** of the **stifle** joint; draws limb inwards. ## Medial Muscles of the Thigh - This group consists of four primary muscles: - **Sartorius Muscle** - **Gracilis Muscle** - **Pectineal Muscle** - **Adductor Muscles** - **Sartorius Muscle:** - **Origin:** - **Cranial part:** The crest of the **ilium** and the thoracolumbar fascia. - **Caudal Part:** The cranial ventral iliac spine and the adjacent ventral border of the **ilium.** - **Insertion:** - **Cranial Part:** The **patella,** in common w/ the rectus femoris of the quadriceps. - **Caudal Part:** The cranial border of the **tibia,** in common w/ the gracilis. - **Action:** Adducts and draws hindlimb forwards. - **Gracilis Muscle:** - **Origin:** Aponeurosis on the **symphysis**. - **Insertion:** The cranial border of the **tibia** and, w/ the **biceps femoris** and **semitendinosus,** the **tuber calcanei**. - **Action:** Adducts hindlimb. - **Pectineus Muscle:** - **Origin:** From the **iliopubic eminence** and the pubic tubercle via the prebubic tendon. - **Insertion:** The distal end of the medial lip of the caudal rough face of the **femur.** - **Action:** Adduction of thigh. - **Adductor Muscles:** - **Origin:** The entire pelvic **symphysis** by means of the **symphysial** tendon, the adjacent part of the **ischiatic** arch, and the ventral surface of the **pubis** and **ischium**. - **Insertion:** Medial border of the **femur**. - **Action:** Adducts hindlimb. ## Muscles of The Crus: - The muscles of the crus comprise **extensors** and **flexors** of the **tarsus** and **extensors** and **flexors** of the digit. - They are grouped in two masses according to the location of their bellies: - One on the craniolateral aspect of the **tibia** (Craniolateral group). - The other one on the caudal aspect of the **tibia** (Caudal groups). ## Craniolateral Muscles of the Crus: - This group can be divided into: - **Flexors of the tarsus:** - **Cranial Tibial Muscle:** - **Origin:** The **extensor groove** and the adjacent articular margin of the **tibia,** the lateral edge of the cranial **tibial** border. - **Insertion:** The plantar surface of the base of **metatarsals** I and II. - **Action:** **Flexor** of tarsus. - **Long Fibular Muscle:** - **Origin:** The lateral condyle of the **tibia,** the proximal end of the **fibula,** and the lateral epicondyle of the **femur** by means of the lateral collateral ligament of the **stifle**. - **Insertion:** The fourth **tarsal** boney, the plantar aspect of the base of the **metatarsals**. - **Action:** **Flexor** of tarsus, draws limb inwards. - **Short Fibular Muscle:** - **Origin:** Only present in dogs. - **Third Fibular Muscle:** - **Origin:** Not present in dogs. - **Extensors of the Digits:** - **Long Digital Extensor Muscle:** - **Origin:** The **extensor fossa** of the **femur**. - **Insertion:** The **extensor** processes of the distal phalanges of digits II, III, IV, and V. - **Action:** **Extensor** of the digits, **extensor** of stifle joint. - **Lateral Digital Extensor Muscle:** - **Origin:** **Fibula** and lateral condyle of **tibia**. - **Insertion:** **Middle phalanx** of 5th or 4th digit. - **Action:** **Extensor** of the digits. - **Long Extensor Muscle of First Digit:** - **Origin:** **Fibula.** - **Insertion:** 2nd digit. - **Action:** **Extensor** of the 2nd digit. ## Caudal Muscles of the Crus: - **Gastrocnemius Muscle:** - **Origin:** The medial and lateral supracondylar tuberosities of the **femur**. - **Insertion:** The proximal surface of the **tuber calcanei**. - Contributes the major component of the common **calcanean tendon.** - **Action:** **Extensor** of the **tarsus**, **flexor** of the stile joint. - **Superficial Digital Flexor Muscle:** - **Origin:** The lateral supracondylar tuberosity of the **femur.**' - **Insertion:** The **tuber calcanei** and the bases of the middle phalanges of digits II, III, IV, and V. - **Action:** **Flexor** of the **stifle** joint; flexor of the digits; **extensor** of the tarsus. - **Deep Digital Flexor Muscle:** - Consists of three separate heads: - **Caudal Tibial Muscle** - **Lateral Digital Flexor Muscle** - **Medial Digital Flexor Muscle** - **Origin:** The caudal aspect of the proximal two thirds of the **tibia,** the proximal half of the **fibula,** and the adjacent interosseous membrane. - **Insertion:** The **flexor tubercle** on the plantar surface of the base of each of the distal phalanges. - **Action:** **Flexor** of the digits. - **Popliteus Muscle:** - **Origin:** The lateral epicondyle of the **femur**. - **Insertion:** The proximal third of the caudal surface of the **tibia**. - **Action:** **Flexor** of the **stifle** joint; draws limb inwards. - It courses caudally, medial to the lateral collateral ligament. - At the junction of the tendon with the muscle, there is a sesamoid that articulates with the caudal aspect of the lateral condyle of the **tibia**.