The Pelvic Girdle & Lower Limb

PELVIC GIRDLE Pelvic Girdle – consists of two hip bones that articulate with each other anteriorly at the symphysis pubis and posteriorly with the sacrum. The pelvic girdle, sacrum and coccyx form the bowl-shaped pelvis. Functions of pelvis: a) Supports the trunk of the body b) Provides attachments for the lower limbs c) Protects the organs in the pelvic portion of the abdominopelvic cavity (bladder, internal reproductive organs, distal end of the large intestine)

1. Hip bones (os coxae; coxal bones; pelvic bones; innominate bones) - Each hip bone is made up of three bones: ilium, ischium, and pubis. These 3 bones are fused in the region of the acetabulum, (the cuplike depression that articulates with the head of the femur), and form the hip bone. a. Ilium: 1. The largest and most superior portion of the hip bone 2. joins the sacrum at the sacroiliac joint 3. Anterior superior iliac spine – can be felt lateral to the inguinal area; important surgical landmark CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

b. Ischium : 1. Lowest part of the hip bone 2. Ischial tuberosity – bears weight when sitting 3. Ischial spine –Distance between the ischial spines is the shortest diameter of the pelvic outlet. c. Pubis : 1. Anterior portion of hip bone 2.The large opening, the obturator foramen, lies within each pubis. (The largest foramen in the body.) 3.Pubic bones are fused anteriorly at the symphysis pubis CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Differences between male and female pelves: a 2. Differences between male and female pelves: a. Female: 1) iliac bones more flared 2) pubic arch is broader 3)distance between ischial spines and between ischial tuberosities is greater 4) sacral curvature is shorter and flatter All of these result in a wider pelvic cavity (pelvic canal) in the female. Why are there these differences?

b. Differences reflect the function of the female pelvis as a birth canal. Also, the bones are lighter in the female.

Male & Female Pelvis A) Female pelvis – B) Male pelvis Usually wider in all diameters and roomier than that of the male B) Male pelvis

Greater & Lesser Pelves Pelvic brim – line drawn from the sacral promontory downward to the superior margin of the symphysis; margin that separates the upper, greater pelvis from the lower, lesser pelvis: a) Greater pelvis – helps support the abdominal organs b) Lesser pelvis - surrounds a short, canal-like cavity that has an upper inlet (pelvic inlet) and lower outlet, (pelvic outlet). An infant passes through this cavity, (birth canal), during childbirth.

Articulations of the hip bones: Auricular surface – sacrum Acetabulum – head of the femur. (Ligament of the head of the femur inserts in the acetabulum) Pubic bones fused at the symphysis pubis

Features of the Hip Bone Acetabulum Ischium Ischial tuberosity Ilium Ischial spine Iliac crest Iliac fossa Sacroiliac joint Pubis Anterior superior iliac spine Symphysis pubis Posterior superior iliac spine Pubic arch Greater sciatic notch Obturator foramen Lesser sciatic notch

Lower Limb - Leg The bones of the leg provide the framework for the thigh, lower leg, and foot. Bones are a femur, tibia, fibula, tarsals, metatarsals and phalanges. 1. Femur (thigh bone) a. Extends from the hip to the knee b. Longest bone in the body. c. Fovea capitis – pit on the head of the femur where a ligament attaches and inserts in the acetabulum, helping anchor the head of the femur Articulations: Head - acetabulum of the hip bone Medial & lateral condyles –condyles of the tibia Patellar surface – patella CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Femur Proximal features Distal features Head - Lateral epicondyle Fovea capitis - Medial epicondyle Neck - Lateral condyle Greater trochanter - Medial condyle Lesser trochanter - Patellar surface - Intercondylar fossa Diaphysis Gluteal tuberosity Linea aspera

2. Patella (knee cap): a. Sesamoid bone in patellar tendon, (from the quadriceps femoris group of muscles) that passes anteriorly over the knee. b. Functions in lever actions associated with lower limb movements.

3. Tibia (shin bone) a. Larger, medial bone of lower leg. b. Tibial tuberosity - point of attachment for the patellar ligament (continuation of the patellar tendon) Articulations: Medial & lateral condyles – condyles of the femur Distal end – Talus of the ankle; protrudes medially Features: - Medial condyle -Anterior crest - Lateral condyle - Medial malleolus - Tibial tuberosity - Intercondylar eminence CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

4. Fibula a. Slender bone lying lateral to the tibia b. Does not bear body weight; stabilizes the ankle joint; site for many muscle attachments Articulations: Head – Tibia, just below lateral condyle *does not enter knee joint Lateral malleolus – ankle; protrudes laterally Features: - Head -Lateral malleolus .

Foot 1. Ankle = Tarsus. Composed of 7 tarsal bones. 2. Instep = Metatarsus. 5 metatarsal bones 3. Toes = phalanges. 14 phalangeal bones

Called the tarsus – made of 7 tarsal bones Talus Calcaneus Navicular 1. ANKLE “Tarsus” Called the tarsus – made of 7 tarsal bones Talus Calcaneus Navicular Medial cuneiform Intermediate cuneiform Lateral cuneiform Cuboid Mnemonic for remembering the tarsal bones: The Circus Needs More Interesting Little Clowns CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Talus articulates with tibia & fibula, forming the ankle joint. Calcaneus (heel bone) –Largest tarsal bone. Helps support body weight. Calcaneal tuberosity – attachment site for the Calcaneal tendon = Achille’s tendon (tendon of gastrocnemius, or calf muscle) and other muscles that move the foot.

2. INSTEP Composed of 5 metatarsal bones, numbered 1-5 (beginning medially) 1. articulate with the tarsus 2. Heads on distal end form the ball of the foot 3. Tarsals & metatarsals bound by ligaments, forming the arches of the foot, which provide a stable, springy base for the body 3. TOES Composed of 14 phalanges Proximal phalanx, middle phalanx, distal phalanx Big toe = Hallux; lacks middle phalanx