Lower limb anatomy (pelvis) + intro to spine Flashcards
The pelvis
The pelvic girdle is made up of two hip/innominate bones / hemipelvis
Separated posteriorly by sacrum and anteriorly at symphysis pubis
Bony ring, strongly held by extensive ligamentous complex
Each comprised of three parts:
Ilium (iliac bone)
Ischium
Pubis
In regional / soft tissue anatomy is split into two parts:
False/greater pelvis; superior and part of abdomen
True/lesser pelvis; inferior and has an inlet and outlet
Oblique line from symphysis pubis to sacral promontory (l5s1)
For msk purposes this is less significant
Pelvic inlet/outlet
Ring-shaped structures within true pelvis
Inlet:
superior
Circular/heart-shaped bony ring
Junction between abdomen/pelvis
Angled 50-60 degrees to coronal plane
Outlet:
Inferior
Diamond-shaped bony/ligamentous
Junction between pelvis and perineum (pelvic floor)
Anterior formed by inferior pubic rami, posterior by ligaments
Horizontal plane
What are the functions of the pelvis?
bearing the weight of individuals superior to the pelvis, stabilizing them, and allowing them to sit and stand as the legs located inferiorly move.
The hip bones / hemipelvis
Also called innominate bones
Paired bones (useful in image interpretation)
Comprised of 3 primary ossification centres (parts):
Ilium (not ileum)
Ischium
Pubis
Formed separately but fuse in adolescence (15-25)
Ossification centres
Primary:
Ilium (8th week in utero)
Ischium (4 months)
Pubic (4-5months)
Secondary (common sites for avulsion) fracture):
Ilium: iliac crests and aiis (puberty)
Ischial tuberosity (PubERTY)
Symphysis pubis (puberty)
Fusion between ~15-25 years
Iliac bone / ilium
Medial aspect adjoins abdomen, lateral is lower limb (relates to origin of structures)
Fan-shaped
Key features/soft tissue attachments:
Iliac crest/tubercle
Iliac fossa (internal)
Gluteal surface (external)
Anterior superior iliac spine (ASIS)
Posterior Superior ILIAC spine (PSIS)
Anterior inferiors iliac spine (AIIS)
Superior rim of acetabulum
Ilium attachments
Iliac crest – quadratus lumborum/transversus abdominus
Iliac fossa – iliacus
Gluteal surface – gluteus medius/minimus
ASIS – Sartorius
AIIS – rectus femoris
ischium
Postero-inferior part of the pelvic bone
Forms large part of obturator foramen and acetabulum
Ischial tuberosity origin for hamstring muscles
Ischial spine – attachment site
Pubic bone
infero-anterior part of the pelvic bone
C-shaped, body and superior and inferior pubic rami
body flattened medially to form symphysis pubis
Pubic tubercle insertion for inguinal ligament
Forms obturator foramen with inferior ischium
Primary attachment for adductor muscle group
SYMPHYSIS PUBIS
Cartilaginous joint between left and right pubic bones – function??
Articular surfaces covered by hyaline (articular) cartilage
Joined by fibrocartilage
More movement in women than men, changes related to pregnancy/post-partum
The hip joint
Synovial joint
Ball-and-socket between femoral head and acetabulum
Designed to be strong and stable (in comparison to other joints)
Relatively limited movement (when compared to shoulder)
Movements:
Flexion/extension
Abduction/adduction
Internal-external rotation
circumduction
acetabulum
Formed by combination of ilium, ischium, and pubic bones
Large-deep cup surrounds femoral head
Deepened by rim of fibrocartilage called labrum
Peripheral articular surface covered by hyaline cartilage; thickest superiorly – why?
Central acetabular fossa is roughened attachment point
Inferior notch allows passage of neurovascular structures
Proximal femur
Characterised by four structures (OSSIFICATION CENTRES):
Femoral head (articular surface)
FEMoRAL NECK (metaphysis)
Greater and lesser trochanters
Prone to clinically significant fractures with high levels of morbidity/mortality
OSSIFICATION CENTRES
Primary:
Diaphysis/shaft (8th week in utero)
Secondary:
Epiphysis /femoral head (6 months)
Greater trochanter (4 years)
Lesser trochanter (13 yearS)
Fusion between ~16-18 years
Femoral head
Femoral head round and smooth, covered with articular cartilage
Central depression called fovea capitis; attachment for ligamentum teres
variable minimal blood supply to femoral head through this fovea; important in fractures
Femoral neck
Approximately 125 degree angle with diaphysis
Slight anterior angulation
Intra-capsular
Tensile/compressive trabecular pattern
Important to diagnose fractures here
Trochanteric region
Great trochanter laterally:
extends anteriorly and posteriorly
Several ridges and depressions for attachments
Gluteus medius/minimus, obturator and gemelli muscles
Lesser trochanter postero-medially:
Tendon of psoas and iliacus muscles
Inter-trochanteric line (anteriorly) and crest (posteriorly)
The hip joint
Surrounded by synovial membrane
Capsule Extends distally to base of neck of femur (intra-capsular)
Covered by strong fibrous joint capsule
Reinforced by 3 sets of ligaments from 3 parts of pelvic bone
Blood supply
complex blood supply
Majority comes from branches from the femoral artery
Inserts at base of neck and extends proximally into head
Key principle behind hip fracture management; risk of avascular necrosis
the femur
Long bone:
Epiphysis (x2)
Metaphysis (x2)
Diaphysis
Other Bony features proximally (hip) and distally (knee)
Strongest/longest in the skeleton
Diaphysis very strong; relatively rarely fractured without significant trauma/pathology
FEMORAL DIAPHYSIS
Main feature is the linea aspera (rough line) posteriorly
Ridge along posterior diaphysis
Major site of muscle attachment; adductors
musculatur
compartments plus accessory muscles
Anterior (quadriceps femoris):
Vastus medialis, intermedius, lateralis
Rectus femoris
Medial (adductors):
Adductor magnus, longus,brevis
pectineus
Gracilis
Posterior (hamstrings):
Biceps femoris (Long/short head)
Semimembranosus
semitendinosus
Neurovascular structures
Large vascular and nervous structures
Femoral artery, vein, and nerve
Sciatic nerve runs between hamstrings
Significant role in high velocity injuries
