THE SKELETAL SYSTEM Focus on the Pelvic Girdle and lower limb

General anatomical terms to know  Process  Ramus  Trochanter  Tuberosity  Tubercle  Crest  Line  Spine  Head  Neck  Condyle  Trochlea  Facet  Fossa  Sulcus  Foramen  Canal of meatus  Fissure  Sinus

Appendicular Skeleton  126 bones  Includes  bones of the limbs (appendages)  Supporting bones of the pectoral and pelvic girdles (connect limbs to axial skeleton)

 Includes sacrum, coccyx and coxal (hip) bones  Function: transfers weight of the upper body to the legs; designed for stability and locomotion more massive than the pectoral girdle more firmly attached to the axial skeleton  Sacroiliac joint = articulation of hip bone with sacrum  Hip joint = articulation of hip bone with femur (acetabulum) Pelvic Girdle

The Coxal Bones (2; hip bones)  TWO coxal bones  Each hip bone results from the fusion of three separate components which fuse together: 1. The ilium 2. The ischium 3. Pubis symphisis  The ilium, ischium and pubis together form a deep socket called the acetabulum which articulates with the head of the femur

The Ilium  Largest, most superior component of the coxal bone  Broad curved surface provides large surface area for attachment of muscles, tendons and ligaments  Iliac crest = “the hip”  Iliac spine can be seen is especially thin people

The ilium – superior portion of the hip  Iliac crest (superior)  ASIS = anterior superior iliac spine  PSIS = posterior superior iliac spine  Iliac fossa = wide depression  Ala = the other side of the iliac fossa  Arcuate line (medial)  Sacral articulation  Anterior, posterior and superior gluteal lines (attachments for gulteal muscles)  Greater sciatic notch

The Ischium  Most Inferior and strongest part of the coxal bone  Ischial tuberosity (inferior surface) supports the body’s weight when sitting; attachment site for hamstrings  Ischial Spine: separates the greater and lesser sciatic notch.  Obturator foramen – passageway for nerves and blood vessels from abdominal cavity to lower limbs  Lesser Sciatic Notch- smooth notch covered with cartilage- attachment for tendons

Pubis  Most anterior part of the coxal bone  Also called pubic bone

Acetabulum:  Latin for little cup of vinegar  Deep socket formed were the ilium, ischium and pubis bones articulate  Accepts the head of the femur to form the hip joint  Ball and socket joint

Male vs Female  Differences in shape and size result from variations in body size and muscle mass  Female pelvis: Smoother, lighter in mass and less prominent markings  Some differences are adaptations for child-bearing (to support the weight of the fetus and to ease passage of baby during birth)  Female pelvis: broad, low pelvis, larger pelvic outlet, broader pubic angle

Male vs Female

Male vs Female Pelvis  Female pelvis:  Pelvic weight- bones of the pelvis are lighter and thinner  Pelvic inlet(brim)- rounded and oval shaped  Pelvic outlet- rounded and larger  Subpubic angle- female greater than 80 degrees  Ischial spines- greater distance between the ischial spines  Lesser pelvic cavity- shorter and wider in females- this is why females tend to have broader hips.

Male vs Female

Bones of the Lower Limbs  Thigh = femur  Leg = tibia and fibula  Foot = tarsals, metatarsals and phalanges

The Femur  Heaviest strongest bone in the body  Structures to know: greater and lesser trochanters, intertrochanteric crest, gluteal tuberosity, lateral and medial condyles, intercondylar fossa (notch), patellar surface  Head of femur articulates with acetabulum of pelvis girdle  Neck of femur = common fracture site  Slants medially to join with the leg bones which brings the knees in line with the center of gravity

 Head- articulates with the acetabulum  Neck- weakest part of the femur-common area for fractures  Greater trochanter- insertion of gluteus muscles  Lesser trochanter- insertion of the psoas muscle

 Epicondyles- attachment of ligaments and muscles  Trochlear groove(patellar groove)- articulates with the patella  Condyles- articulate with the condyles of the tibia- distribute weight to the knee  Intercondylar fossa: separates the condyles of the femur- attaches the cruciate ligaments

The Femur head neck Greater trochanter Lesser trochanter Gluteal tuberosity Lateral condyle Medial condyle Patellar surface Intercondylar Fossa (notch) Intertrochanteric crest

Guess Who??

The Leg  Two bones connected by interosseous membrane  Tibia (shin) = larger, medial bone Forms knee joint with femur Medial malleolus forms the ankle  Fibula = thin and stick-like No part in forming knee joint lateral malleolus forms the ankle  Structures to know: medial and lateral condyles, intercondylar eminence, tibial tuberosity, medial and lateral malleolus, tibiofibular joints, anterior crest,

The Leg

The Foot  Two important functions:  Support of body weight  Serves as a lever to propel our body forward  Tarsals (7 bones)  Calcaneous = heel bone  Talus = “ankle” lies between the tibia and the calcaneous  Metatarsals (5 bones) = sole of foot  Phalanges (14 bones) = toes  Each toe has 3 phalanges except the big toe which has 2

The Foot

Arches of the Foot  3 arches  Two longitudinal (medial and lateral)  One transverse  Ligaments bind the foot bones together  Tendons help hold the bones firmly in the arched position  Weak arches = “flat feet” or “fallen arches”

Can you identify the following: