Pelvic Organs and Structures

Kidneys and Urinary System

The kidneys and urinary system are essential for filtering blood, producing urine, and maintaining homeostasis.

• Kidneys: Composed of cortex, pyramids (medulla), papillae, major and minor calyces, renal pelvis, and ureters.

• Bladder: Features the urethral opening, trigone, and internal urethral sphincter.

• Urethra: Includes prostatic, membranous, and penile (bulbous & spongy) parts, with external urethral sphincter.

Example: The trigone is a triangular area in the bladder important for clinical identification of infections.

Adrenal Glands and Major Vessels

The adrenal glands sit atop the kidneys and are supplied by major vessels that also serve the pelvic organs.

• Adrenal glands: Located above the kidneys, involved in hormone production.

• Major vessels: Abdominal aorta, inferior vena cava, renal and gonadal arteries and veins.

• Common, external, and internal iliac arteries and veins supply the pelvis and lower limbs.

Example: The internal iliac artery branches supply pelvic organs, gluteal region, and medial thigh.

Pelvic Muscles and Ligaments

Muscles of the Pelvis

Pelvic muscles support pelvic organs, facilitate movement, and maintain continence.

• Psoas major and iliacus: Hip flexors, form the iliopsoas muscle.

• Quadratus lumborum: Stabilizes the lumbar spine.

• Pelvic diaphragm: Includes piriformis, obturator internus, coccygeus, levator ani (puborectalis, pubococcygeus, iliococcygeus).

• Urogenital diaphragm: Supports pelvic organs.

• Perineal muscles: Bulbospongiosus, ischiocavernosus, superficial and deep transverse perineal muscles.

Example: The levator ani is crucial for pelvic floor support and continence.

Pelvic Ligaments

Ligaments stabilize the pelvis and support organs.

• Inguinal ligament: Runs from the anterior superior iliac spine to the pubic tubercle.

• Sacrospinous and sacrotuberous ligaments: Connect sacrum to ischium, form boundaries of the greater and lesser sciatic foramina.

• Iliolumbar ligament: Connects the ilium to the lumbar vertebrae.

Example: The sacrotuberous ligament helps prevent excessive rotation of the pelvis.

Thigh and Leg: Muscles, Vessels, and Bones

Anterior and Medial Thigh

The anterior and medial thigh muscles are responsible for hip flexion, knee extension, and thigh adduction.

• Great saphenous vein: Major superficial vein of the leg.

• Femoral triangle: Contains femoral nerve, artery, and vein.

• Quadriceps femoris: Includes rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis; extends the knee.

• Adductors: Longus, brevis, magnus; pectineus, gracilis, obturator externus.

Example: The femoral triangle is a key site for vascular access in medical procedures.

Gluteal Region

The gluteal muscles are important for hip extension, abduction, and stabilization.

• Gluteus maximus, medius, and minimus: Major hip extensors and abductors.

• Piriformis, superior and inferior gemellus, obturator internus, quadratus femoris: Lateral rotators of the thigh.

Example: The gluteus maximus is the largest muscle in the body and is essential for climbing stairs.

Posterior Thigh and Knee

Posterior thigh muscles flex the knee and extend the hip.

• Hamstrings: Semitendinosus, semimembranosus, biceps femoris.

• Quadriceps tendon and patellar ligament: Connect quadriceps to tibia via patella.

• Menisci: Medial and lateral fibrocartilaginous pads in the knee.

• Cruciate ligaments: ACL and PCL stabilize the knee.

• Collateral ligaments: Medial and lateral, provide side-to-side stability.

Example: The ACL prevents anterior displacement of the tibia relative to the femur.

Anterior and Lateral Leg

Muscles in the anterior and lateral leg dorsiflex and evert the foot.

• Tibialis anterior: Dorsiflexes and inverts the foot.

• Extensor hallucis longus: Extends the big toe.

• Extensor digitorum longus: Extends the toes.

Example: The tibialis anterior is active during walking to clear the foot from the ground.

Posterior Leg

Posterior leg muscles plantarflex the foot and flex the toes.

• Gastrocnemius: Has medial and lateral heads; plantarflexes the foot.

• Soleus: Deep to gastrocnemius; also plantarflexes the foot.

• Flexor digitorum longus, flexor hallucis longus: Flex the toes.

• Calcaneal (Achilles) tendon: Common tendon for gastrocnemius and soleus.

Example: The Achilles tendon is the strongest tendon in the body.

Foot: Muscles, Bones, and Ligaments

Foot Muscles

Muscles of the foot control toe movement and maintain the arches.

• Dorsalis pedis: Artery supplying the dorsal foot.

• Extensor digitorum brevis, extensor hallucis brevis: Extend toes and big toe.

• Plantar aponeurosis: Thick connective tissue supporting the arch.

• Flexor digitorum brevis, abductor hallucis, abductor digiti minimi: Flex and abduct toes.

Example: The plantar aponeurosis is involved in plantar fasciitis.

Bones of the Lower Limb

The bones of the lower limb provide structure, support, and facilitate movement.

• Femur: Head, neck, fovea capitis, greater and lesser trochanter, intertrochanteric crest, linea aspera, gluteal tuberosity, medial and lateral condyles, epicondyles, adductor tubercle, patellar surface.

• Patella: Apex, base, facets (medial and lateral).

• Tibia: Lateral and medial condyles, intercondylar eminence, medial malleolus, tibial tuberosity, soleal line.

• Fibula: Head, lateral malleolus.

• Foot: Seven tarsals (talus, calcaneus, cuboid, navicular, 3 cuneiforms), metatarsals, proximal, middle, and distal phalanges.

Example: The medial malleolus is a common site for ankle fractures.

Ankle Ligaments

Ankle ligaments stabilize the joint and prevent excessive movement.

Additional info: These ligaments are commonly injured in ankle sprains.

Bony Landmarks and Joints

Bony Landmarks

Bony landmarks serve as attachment sites for muscles and ligaments.

• Anterior superior iliac spine (ASIS), pubic tubercle, ischial tuberosity, iliac crest, acetabulum, obturator foramen, greater and lesser sciatic notches.

Example: The ASIS is used to measure limb length and locate the inguinal ligament.

Joints

Major joints of the pelvis and lower limb allow for movement and stability.

• Sacroiliac joint: Connects sacrum and ilium.

• Pubic symphysis: Cartilaginous joint between pubic bones.

Example: The sacroiliac joint transmits weight from the upper body to the lower limbs.

Summary Table: Major Muscles of the Lower Limb

Additional info:

• Some structures may not be visible on cadavers and may only be seen on anatomical models.

• Clinical relevance: Knowledge of these structures is essential for understanding injuries, surgical approaches, and physical examination techniques.