The hip joint is the articulation between the acetabulum of the pelvis and the head of the femur. The acetabulum has contributions from the ilium, ischium and pubis. The hip joint is structurally a synovial spheroid joint and functionally a diarthrosis type of joint. The hip joint has motion in all three body planes, a triplanar joint. The movements available are flexion, extension, abduction, adduction, circumduction, internal rotation and external rotation.
pelvic region, hip joint, con’t I. LIGAMENTS
A. Extracapsular Ligaments / Extrinsic Ligaments - ligaments outside of the joint cavity
- in general, spiral around the hip joint from posterior to anterior; therefore, are taut (tight) when the hip is extended, and limit extension of the hip joint anterior view
1. Iliofemoral Ligament / Ligament of Bigelow
- attaches proximally to the inferior part of the anterior inferior iliac spine and the iliac part of the acetabular rim (lip)
- passes distally as 2 bands
- one of the strongest ligaments in the body
a. upper band
- attaches to the superior part of the intertrochanteric line
b. lower band
- attaches to the inferior part of the intertrochanteric line
2. Pubofemoral Ligament
- attaches proximally to the pubic part of the acetabular rim and the lateral part of the superior pubic ramus
- passes distally and blends with the capsule of the hip joint (medially) posterior view
1. Iliofemoral Ligament (upper band)
- the posterosuperior fibers of this ligament can be seen from this view
- these fibers pass anteriorly around the hip joint to insert on the superior part of the intertrochanteric line
2. Ischiofemoral Ligament
- attaches proximally to the ischial part of the acetabular rim
- passes superolaterally over the posterior surface of the hip joint to blend with the capsule of the hip joint at the femoral neck
B. Intracapsular Ligaments / Intrinsic Ligaments
- thickenings of the joint capsule or located within the joint cavity posterior view and frontal plane cross section view
1. Zona Orbicularis
- the thickened constricted area of the capsule around the neck of the femur (the fibers are circularly oriented)
- visible on the posteroinferior surface where extracapsular ligaments are less prominent
- a ligament with no bony attachments
- initially believed to hold the femoral head into the acetabulum, but it is not strong enough by itself
gluteal region, hip joint, intracapsular ligaments, con’t
2. Transverse Acetabular Ligament
- attaches to the edges of the acetabular notch, at the margins of the lunate surface, converting it into the acetabular foramen for the passage of articular vessels 3. Ligamentum Capitis Femoris / Ligamentum Teres Femoris /
Ligament of the Head of the Femur
- attaches proximally to the margins of the acetabular notch and the transverse acetabular ligament within the acetabulum
- passes along the acetabular fossa, which is covered with adipose tissue and attaches distally to the margins of the fovea capitis femoris
- this is a weak ligament which transmits the artery to the head of the femur - important in infants (under age 3 years) as the artery is the primary supply to the femoral head until this age
C. Other Structures
1. Capsule
- the fibrous joint capsule attaches proximally to the exterior rim of the acetabulum
- distally the capsule attaches to the neck of the femur; anteriorly to the inferior margin of the femoral neck at the intertrochanteric line and posteriorly to the mid-region of the neck (only the proximal one-half of the femoral neck is within the capsule posteriorly)
- the extrinsic ligaments are in the same location so the femoral neck on the posterior side is covered only about ½ of the distance
a. Zona Orbicularis – described above
b. Retinacula
- bundles of longitudinal capsular fibers that reflect superiorly along the femoral neck after having reached the inferior margin of the capsular limits - provide for passage of blood vessels from the capsule and synovial lining to the head of the femur; main area for passage of vessels to nourish the head and neck of the femur after 3 years of age
2. Acetabular Labrum / Glenoid Labrum
- a pad of fibrocartilage that lies along and attaches to the acetabular rim
- function: to deepen the joint which provides a better fit between the bone ends
3. Synovium (dashed lines)
- lines all of the structures contained within the joint capsule except the articular surfaces of the bones, so all intrinsic ligaments are extrasynovial - the synovium that lines the retinacula of the capsule are raised into folds through which the blood vessels pass
gluteal region, hip joint, con’t
4. Arterial Supply to the Hip Joint
a. Artery to the Ligamentum Capitis Femoris
- a branch of the acetabular artery, after it passes into the acetabulum via the acetabular foramen, which then passes along the acetabular fossa
- supplies the head of the femur, but is not the primary supply after age 3 years - the acetabular artery arises from the posterior division of the obturator artery
b. Medial Femoral Circumflex Artery (not pictured)
- the ascending branch passes along the femoral intertrochanteric crest and gives rise to branches which pass through the retinacula to supply the femoral head and neck
- anastomose with branches in the femoral head
c. Lateral Femoral Circumflex Artery (not pictured)
- the ascending branch passes along the femoral intertrochanteric line and gives rise to branches which pass through the retinacula to supply the head and neck of the femur
- anastomose with branches in the femoral head
d. Superior Gluteal Artery (not pictured)
- branches that arise from the deep branch and continue laterally and inferiorly to supply the hip joint
e. Inferior Gluteal Artery (not pictured)
- branch(es) which pass laterally and inferiorly to supply the piriformis and superior gemellus muscles then continue to the hip joint