Appendicular Skeleton- Lower Extremities Flashcards
What is the pelvis?
- Composed of 4 bones: sacrum, coccyx and right/left ossa coxae (hip bones)
- Portracts and supports the viscera in the inferior part of the ventral body cavity
- Pelvic girdle refers to the ossa coxae only
What are the ossa coxae? (pelvis)
- Hip bones that are each formed by 3 separate bones: ilium, ischium and pubis (fuse between 13 and 15 years of age)
- Each ossa coxae articulates posteriorly with an auricular surface of the sacrum at the sacroiliac joint
- Has a large, curved depression called the acetabulum which articulates with the femur (c- shaped lunate surface in particular)
What is the ilium? (ossa coxae)
- Largest of the 3 coxal bones
- Forms the superior region and the largest portion of the acetabular surface
What is the ala? (ilium)
- Wide, fan-shaped portion of the ilium
- Terminates inferiorly at a ridge called the arcuate line on the medial surface
- On the medial side is a depression called the iliac fossa
What are gluteal lines? (ilium)
- On the lateral surface of the ilium
- Anterior, posterior and inferior lines
- Attachment sites for the gluteal muscles of the buttock
WHat is the auricular surface? (ilium)
- On the posteromedial side of the ilium
- Large and roughened area where the ilium articulates with the sacrum and sacroiliac joint
What is the iliac crest? (ilium)
- The superior most ridge of the ilium
- The ridge of bone you can palpate on your lateral sides at the hips is the iliac crest
- Arises anteriorly from a projection called the anterior superior iliac spine
- Extends posteriorly from the posterior superior iliac spine
- Located inferiorly to the ala of the ilium are the anterior inferior iliac spine and posterior inferior iliac spine
What is the greater sciatic notch? (ilium)
- Adjacent to the posterior inferior iliac spine
- Through which the sciatic nerve travels to the lower limb
What is the ischium? (pelvis)
- Fuses with the ilim near the superior and posterior margins of the acetabulum
- Accounts for the posterior 2 fifths of the acetabular surface
- The ischial spine is posterior to the acetabulum and is triangular and projects medially
- Bulky bone superior to the ischial spine is the ischial body
What is the lesser sciatic notch? (ischium)
- A semicircular depression inferior to the ischial spine
What is the ischial tuberosity? (ischium)
- Roughened projection on the posterolateral border the ischium
- Also called sitz bones because they support the weight of the body when seated
- An elongated ramus extends from the tuberosity toward its anterior fusion with the pubis
What is the pubis? (pelvis)
- Fuses with the ilium and ischium at the acetabulum
- Ischial ramus fuses anteriorly with the inferior pubic ramus to form the ischiopubic ramus
- Superior pubic ramus originates at the anterior margin of the acetabulum
What is the obturator foramen? (pubis)
- A space in the os coxae that is encircled by both pubic and ischial rami
What is the pubic crest? (pubis)
- Roughened ridge that is located on the anterosuperior surface of the superior ramus
- Ends at the pubic tubercle
What is the pubic tubercle? (pubis)
- An attachment site for the inguinal ligament and terminates the pubic crest
What is the symphyseal surface? (pubis)
- Denotes the site of articulation between pubic bones
- A roughened area on the body of the pubis
What is the pectineal line? (pubis)
- On the medial surface of the pubis
- Originates and extends diagonally across the pubis to merge with the arcuate line
What is the pelvic brim?
- A continuous oval ridge that extends from the pubic crest, pectineal line and arcuate line to the rounded inferior edges of the sacral ala and promontory
- Helps subdivide the entire pelvis into a true pelvis and a false pelvis
What is the true pelvis?
- Also known as the lesser pelvis
- Lies inferior to the pelvic brim
- Encloses the pelvic cavity and forms a deep bowl that contains pelvic organs
What is the false pelvis?
- Also known as the greater pelvis
- Lies superior to the pelvic brim
- Enclosed by the ala of the iliac bones
- It forms the inferior region of the abdominal cavity and houses the inferior abdominal organs
What is the pelvic inlet?
- Also known as the superior pelvic aperture
- Is superiorly positioned space enclosed by the pelvic brim (space on the inside- hole)
- Opening at the boundary between the true pelvis and the false pelvis
What is the pelvic outlet?
- Also known as the inferior pelvic aperture
- Is the inferiorly placed opening bounded by the coccyx, the ischial tuberosities and the inferior border of the pubic symphysis
- Covered by muscles and skin and forms the body region called the perineum
What is the preauricular sulcus?
- Which is a depression/groove between the greater sciatic notch and the sacroiliac articulation
- Males tend to not have this sulcus
What is the subpubic angle?
- Is the angle formed when the left and right pubic bones are aligned at their pubic symphysis
- In females this is much wider and convex
What are the lower limbs?
- Arrangement and number of bones is similar to those of the upper limb
- Adapted for weight bearing and locomotion
- Shaped differently then the upper extremities and articulate differently with comparable bones of the upper limb
Each lower limb contains 30 bones: 1 femur, 1 patella, 1 tibia, 1 fibula, 7 tarsal bones, 5 metatarsal bones, 14 phalanges