lower limb Flashcards
(49 cards)
lower limb division
divided into 2 functional parts:
1. pelvic girdle (bony pelvis)
- connects lower limb to axial skeleton
- bones of free lower limbs
- femur
- patella
- tibia
- fibula
- tarsals
- metatarsals
- phalanges
pelvic girdle
pelvic girdle = hip bones + sacrum
anteriorly:
connected by pubic symphysis (cartilaginous joint, not synovial)
posteriorly:
connected to axial skeleton at sacroiliac joints (fibrous joints)
includes:
- 2 hip bones (each formed by fusion of 3 bones)
- sacrum
hip bone
= fusion of 3 bones
- ilium
- ischium
- pubis
ilium
body (thick): weight-bearing
ala (wing): muscle attachment
iliac crest: important site for bone marrow biopsy
iliac fossa: site of iliacus muscle attachment (hip flexor)
landmark for sciatic nerve
ischium
forms: posteroinferior hip & part of acetabulum
ramus of ischium + inferior pubic ramus = ischiopubic ramus –> inferomedial boundary of obturator foramen
key landmarks:
- ischial spine: below greater sciatic notch
- ischial tuberosity: rough projection; origin for hamstrings; weight-bearing when sitting
hip joint
type: synodal ball-and-socket
formed by:
- acetabulum (hip bone)
- head of femur
function:
- transfers body weight
- allows mobility with stability
pubis
anteromedial part of hip bone
superiorly connected to ilium
inferiorly connected through ischiopubic ramus to ischium
provides external attachment for muscles of medial thigh
acetabulum
large cup shaped cavity on lateral side of hip bone
articulate with proximal epiphysis of femur = hip joint
incomplete inferiorly at acetabular notch BUT protected by transverse acetabular ligament
proximal femur
longest, heaviest bone in body
main role: transfers weight from hip to tibia
proximal structures:
1. head: spherical, with articular cartilage
2. fovea capitis: site of ligamentum teres attachment
blood supply:
- obturator artery
- medial/lateral circumflex femoral arteries (main in adults)
hip joint capsule
- proximally (to the pelvis):
- attaches to the rim of the acetabulum and the transverse acetabular ligament - distally (to the femur):
- attaches anteriorly to the intertrochanteric line,
posteriorly to the neck of the femur, above the intertrochanteric crest.
structure:
- fibrous outer layer: strong collagen fibers oriented in a spiral fashion, giving strength and stability
- synovial membrane (inner layer): secretes synovial fluid for joint lubrication and nourishment of articular cartilage
function:
- stabilizes the femoral head within the acetabulum
- allows mobility for flexion, extension, abduction, adduction, rotation
- prevents dislocation, especially in standing and weight-bearing
reinforcing ligaments in the hip joint capsule
- iliofemoral ligament
- pubofemoral ligament
- ischiofemoral ligament
- zona orbicularis
iliofemoral ligament
strongest
anterior ligament
origin: anterior inferior iliac spine (AIIS)
insertion: intertrochanteric line of femur
function:
- prevents hyperextension of the hip
- supports upright posture
pubofemoral ligament
anterior ligament
origin: superior pubic ramus
insertion: merges with iliofemoral ligament and joint capsule
function:
- limits abduction and extension of the hip
ischiofemoral ligament
posterior ligament
origin: ischial part of acetabular rim (posterior)
insertion: base of greater trochanter
function:
- limits internal rotation and extension of the hip
zona orbicularis
circular fibers around femoral neck
function:
- acts like a collar holding the femoral head in the acetabulum
- reinforces the capsule circumferentially
hip movements and ligament behavior
EXTENSION
main ligaments limiting it
- iliofemoral
- pubofemoral
- ischiofemoral
= all 3 ligaments are taut in extension, stabilizing the hip in upright stance
FLEXION
- slackening of iliofemoral & others
= most ligaments are relaxed, flexion is least restricted
ABDUCTION
- pubofemoral
= taut during abduction to limit lateral movement
ADDUCTION
- superior fibers of ischiofemoral
- iliofemoral
= prevents excessive medial movement
INTERNAL ROTATION
- ischiofemoral
= taut during medial rotation
EXTERNAL ROTATION
- iliofemoral
= taut during lateral rotation
Flexion | 🔸 Slackening of iliofemoral & others | Most ligaments are relaxed, flexion is least restricted. |
anterior thigh muscles
- iliopsoas
- sartorius
- rectus femoris
- pectineus
iliopsoas
main and strongest hip flexor
- psoas major
- psoas minor (often absent)
- iliacus
sartorius
type: large, superficial muscle crossing hip and knee joints
origin: anterior superior iliac spine (ASIS)
insertion: proximal medial tibia
actions:
AT HIP JOINT
- flexion
- abduction
- lateral (external) rotation of the thigh
AT KNEE JOINT
- flexion of the leg
- internal rotation of the leg (but only when the knee is flexed)
quadriceps femoris
largest muscle group on the anterior thigh
- rectus femoris
- vastus lateralis
- vastus medialis
- vastus intermedius
insertion: all four converge into the quadriceps tendon which passes over the patella (knee cap)
- inserts at the tibial tuberosity via the patellar ligament
main action:
- extension of the leg at the knee joint
- rectus femoris also flexes the thigh at the hip, working with the iliopsoas muscle
- rectus femoris stabilizes the hip joint during movement
pectineus
origin: superior ramus of pubis
insertion: pectineal line of femur
actions:
- adduction of thigh
- flexion of thigh
- assists in lateral (external) rotation
medial thigh muscles
- adductor brevis
- adductor longus
- adductor magnus
- gracilis
- obturator externus
adductor brevis
origin: body and inferior ramus of pubis
insertion: proximal medial femur
main actions:
- adducts thigh
- assists in flexion of the thigh
- assists in lateral (external) rotation of the thigh
adductor longus
origin: body of pubis, inferior to pubic crest
insertion: middle third of linea aspera of femur
main actions:
- adducts thigh
- assists in thigh flexion
