Lower Limb Anatomy

• This lecture introduces the skeleton of the lower limb
• Consists of 30 bones, adapted for weight bearing

Lower Limb Components

• Pelvic girdle
• Thigh
• Leg
• Foot

Appendicular Skeleton

• The lower limb is part of the appendicular skeleton

Bones of the Lower Limb

• Pelvic girdle has 2 hip bones
• The Sacrum is part of the axial skeleton
• There are 2 Femurs (thigh bones)
• There is 1 Patella (knee cap)
• There are 2 Tibias (shin bone of leg)
• There are 2 Fibulas (calf bone of leg)
• There are 7 x 2 Tarsals (ankle)
• There are 5 x 2 Metatarsals (foot)
• There are 14 x 2 Phalanges (digits/toes)

Function

• Adapted for weight-bearing functions
• Responsible for locomotion
• Allows for bipedal posture

Pelvic Girdle details

• Consists of 2 hip bones (coxae), the sacrum, and the coccyx
• These bones together form the pelvis

Hip Bone Components

• Each hip bone is formed by 3 fused bones
• Ilium
• Pubis
• Ischium

Ilium Anatomy

• Superior, fan-shaped part
• Margins include:
  • 4 spines: ASIS, AIIS, PSIS, PIIS
  • 3 lines: anterior, posterior, and inferior gluteal lines
  • 1 crest: iliac crest
  • 1 notch: greater sciatic notch
• Broadest part extends between the arcuate line and iliac crest

Pelvic Girdle Function

• Supports and protects abdominal, pelvic organs and developing foetus
• Attaches lower limbs to the trunk
• Transmits weight of upper body from vertebral column to lower limbs

Acetabulum

• The ilium, ischium, and pubis meet inside the "vinegar cup" acetabulum
• Acetabulum sits on the lateral surface of the hip bone
• The Acetabulum is a shallow, concave (cup-shaped) socket
• It articulates with the head of the femur to form the hip joint

Ilium Features:

• Iliac fossa is a broad, concave area
• Iliac tuberosity is a rough, elevated area
• Auricular surface articulates with the sacrum
• Arcuate line is a curved ridge

Ischium:

• Broad based and bears the weight of the body when sitting
• Consists of:
  • Ischial ramus
  • Ischial spine
  • Ischial tuberosity
  • Lesser sciatic notch

Pubis features:

• Consists of:
  • Superior pubic ramus
  • Inferior pubic ramus
• Pubic tubercle is a prominent projection
• Obturator foramen is a large opening
• Pubic symphysis is the joint cartilage between left and right pubic bones

Obturator Foramen:

• Is a large oval opening in the hip bone
• Bounded by the pubis and ischium rami.
• Closed by the obturator membrane
• The obturator canal allows the obturator nerve and vessels to pass

Determining Anatomical Position of the hip bone:

• ASIS and the anterosuperior aspect of the pubis (pubic tubercle) lie in the same coronal plane
• Symphysial surface of the pubis is vertical, parallel to the median plane
• Ischial spine and upper part of pubic symphysis lie on the same horizontal plane
• Acetabulum faces inferolaterally, with the acetabular notch directed inferiorly
• Obturator foramen lies inferomedial

More Pelvis Facts

• Resembles a basin shape
• It is a bony ring interposed between the movable vertebral column
• Supports vertebral column, and the lower limbs rest on it
• A true and false pelvis divides it by the pelvic brim

Pelvis Types

• False (greater) pelvis sits above the pelvic brim and supports the abdominal organs
• The true (lesser) pelvis sits inferior to the pelvic brim and contains the pelvic organs
• Space below the pelvic outlet is the perineum

Differences in Male and Female Pelvis

• The male and female pelvis differ in many aspects
• The female pelvis is:
  • Smoother and lighter
  • Less prominent for muscle and ligament attachments
  • Modified for childbearing

Female Pelvis Modification for Child Birth

• Enlarged pelvic outlet
• Broad pubic angle (greater than 100 degrees)
• Less curvature of the sacrum and coccyx
• Wide, circular pelvic inlet
• Broad, low pelvis
• Ilia project laterally, not upwards

Femur

• Extends from the hip to the knee

• Proximal end includes the femoral head, neck and trochanter

• Distal end inlcudes the femoral condyles

• The bone of the thigh

• It is the longest and heaviest bone in the body

• Articulates with the hip bone at the hip joint

• Articulates with the tibia at the knee joint

• In the erect posture, it is slightly inclined medially

Femur regions:

• Proximal end: head, neck, greater and lesser trochanters, intertrochanteric line and crest
• Shaft: linea aspera, gluteal tuberosity, popliteal surface
• Distal end: lateral and medial epicondyles, lateral and medial condyles and patella surface

Additional Proximal end Notes

• The Articular capsule attaches to this area
• the intertrochanteric line forms the intertrochanteric crest posteriorly

Femoral Head Information

• The femoral head articulates with the pelvis at the acetabulum
• It connects with the ligament at the fovea capitis
• Fovea capitis is the small pit in the head's center
• Femoral neck joins femur head and shaft

Trochanters

• Greater and lesser trochanters; large, rough projections at junction of neck and shaft
• Site for tendon attachments
• Trochanter is a very large lump, larger than a tuberosity and tubercle

Linea Aspera of the Femur

• Ridge along center of posterior thigh that provides attachment for hip muscles

Shaft Specifics

• The middle third of the shaft is triangular in shape.
• The posterior margin is broad and forms the linea aspera
• The medial & lateral margins continue superiorly as the pectineal line and gluteal tuberosity
• The medial & lateral margins runs inferiorly as the medial & lateral supracondular ridges
• The popliteal surface is most distally located between the ridges

Distal end:

• Lateral and medial epicondyles - Projections above the knee joint
• Medial and lateral condyles: Rounded surfaces & form part of knee joint
  • Separated by the intercondylar fossa posteriorly
  • Separated by patellar surface anteriorly and inferiorly
• Adductor tubercle: small prominence above medial epicondyle for muscle attachment

Femoral Fractures:

• Fracture of the neck of the femur is most frequently
• The neck of the femur is the narrowest and weakest part of the bone
• The neck lies at a marked angle to the line of weight-bearing (pull of gravity)

Distinguishing Femur Anterior vs. Posterior

• Locate the femoral head which articulates medially with the acetabulum of the hip bone
• Determine which side is anterior or posterior
• Patellar surface (anterior)
• Intercondylar fossa (posterior)

Patella Information

• A flat triangular, sesamoid bone
• Located anterior to the distal end of femur

Patella features:

• Anterior surface: roughened
• Borders include base (superior border), medial and lateral borders
• Apex is pointed inferiorly
• Posterior surface: smooth and oval, with medial and lateral facets articulating with the condyles of the femur

Patella function:

• Protects tendon against friction
• Changes the direction of the pull
• Increases mechanical advantage

Introduction to the skeletal structure of the lower limb. The lecture outlines the components of the pelvic girdle, thigh, leg, and foot. It also covers the bones in the lower limb including the hip bone, femur, patella, tibia, and fibula.