Hip

Source: Wikipedia, the free encyclopedia.
For the cultural description of hip, see Buttocks.
For other uses, see Hip (disambiguation).
Hip
Bones of the hip region
Right hip of a female human
Details
Identifiers
Latincoxa
Greekισχίο
MeSHD006615
TA98A01.2.08.005
A01.1.00.034
TA2316, 158
FMA24964
Anatomical terminology

In vertebrate anatomy, the hip, or coxa[1](pl.: coxae) in medical terminology, refers to either an anatomical region or a joint on the outer (lateral) side of the pelvis.

The hip region is located

muscle tendons and soft tissues overlying the greater trochanter of the femur.[2] In adults, the three pelvic bones (ilium, ischium and pubis) have fused into one hip bone
, which forms the superomedial/deep wall of the hip region.

The hip joint, scientifically referred to as the acetabulofemoral joint (art. coxae), is the ball-and-socket joint between the pelvic acetabulum and the femoral head. Its primary function is to support the weight of the torso in both static (e.g. standing) and dynamic (e.g. walking or running) postures. The hip joints have very important roles in retaining balance, and for maintaining the pelvic inclination angle.

Pain of the hip may be the result of numerous causes, including nervous, osteoarthritic, infectious, traumatic, and genetic.

Structure

Region

The hip joint, also known as a ball and socket joint, is formed by the acetabulum of the pelvis and the femoral head, which is the top portion of the thigh bone (femur). It allows for a wide range of movement and stability in the lower body.[3]

The proximal femur is largely covered by muscles and, as a consequence, the greater trochanter is often the only palpable bony structure in the hip region.[4]

Articulation

Radiograph of a healthy human hip joint

The hip joint is a ball and socket

head of the femur and the cup-like acetabulum of the pelvis.[5] The socket of the acetabulum is pointing downwards and anterolaterally. The socket is also turned such that the outer edge of its roof is more lateral than outer edge of the floor.[5] It forms the primary connection between the bones of the lower limb and the axial skeleton of the trunk and pelvis. Both joint surfaces are covered with a strong but lubricated layer called articular hyaline cartilage
.

The cuplike acetabulum forms at the union of three pelvic bones — the

ball and socket joint where the roughly spherical femoral head is largely contained within the acetabulum and has an average radius of curvature of 2.5 cm.[8] The acetabulum grasps almost half the femoral ball, a grip deepened by a ring-shaped fibrocartilaginous lip, the acetabular labrum, which extends the joint beyond the equator.[6] The centre of the acetabulum (fovea) does not articulate to anything. Instead, it is lined with fat pad and attached to ligamentum teres. The acetabular labrum is horse-shoe shaped. Its inferior notch is bridged by transverse acetabular ligament.[5] The joint space between the femoral head and the superior acetabulum is normally between 2 and 7 mm.[9]

The head of the femur is attached to the shaft by a thin neck region that is often prone to fracture in the elderly, which is mainly due to the degenerative effects of osteoporosis.

Transverse and sagittal angles of acetabular inlet plane.

The acetabulum is oriented inferiorly, laterally and anteriorly, while the femoral neck is directed superiorly, medially, and slightly anteriorly.

Articular angles

Acetabular angle (or Sharp's angle)

triradiate cartilages (Hilgenreiner's line) and another line passing through the inferior angle of triradiate cartilage to superior acetabular rim. The angle measures 35 degrees at birth, 25 degrees at one year of age, and less than 10 degrees by 15 years of age.[11] In adults the angle can vary from 33 to 38 degrees.[12]

The sagittal angle of the acetabular inlet is an angle between a line passing from the anterior to the posterior acetabular rim and the sagittal plane. It measures 7° at birth and increases to 17° in adults.[11]

Wiberg's centre-edge angle (CE angle) is an angle between a vertical line and a line from the centre of the femoral head to the most lateral part of the acetabulum,

radiograph.[14]

The vertical-centre-anterior margin angle (VCA) is an angle formed from a vertical line (V) and a line from the centre of the femoral head (C) and the anterior (A) edge of the dense shadow of the subchondral bone slightly posterior to the anterior edge of the acetabulum, with the radiograph being taken from the false angle, that is, a lateral view rotated 25 degrees towards becoming frontal.[14]

The articular cartilage angle (AC angle, also called acetabular index

cutoff values
to classify the angle as abnormally increased include:

  • 30° up to 4 months of age.[20]
  • 25° up to 2 years of age.[20]

Femoral neck angle

The angle between the longitudinal axes of the femoral neck and shaft, called the caput-collum-diaphyseal angle or CCD angle, normally measures approximately 150° in newborn and 126° in adults (coxa norma).[21][dubious – discuss]

An abnormally small angle is known as coxa vara and an abnormally large angle as coxa valga. Because changes in shape of the femur naturally affects the knee, coxa valga is often combined with genu varum (bow-leggedness), while coxa vara leads to genu valgum (knock-knees).[22]

Changes in trabecular patterns due to altered CCD angle. Coxa valga leads to more compression trabeculae, coxa vara to more tension trabeculae.[21]

Changes in the CCD angle is the result of changes in the stress patterns applied to the hip joint. Such changes, caused for example by a dislocation, change the trabecular patterns inside the bones. Two continuous trabecular systems emerging on the auricular surface of the sacroiliac joint meander and criss-cross each other down through the hip bone, the femoral head, neck, and shaft.

  • In the hip bone, one system arises on the upper part of the auricular surface to converge onto the posterior surface of the
    superior gluteal line
    , and is reflected laterally onto the upper part of the acetabulum.
  • In the femur, the first system lines up with a system arising from the lateral part of the femoral shaft to stretch to the inferior portion of the femoral neck and head. The other system lines up with a system in the femur stretching from the medial part of the femoral shaft to the superior part of the femoral head.[23]

On the lateral side of the hip joint the fascia lata is strengthened to form the iliotibial tract which functions as a tension band and reduces the bending loads on the proximal part of the femur.[21]

Capsule

Main article: Capsule of hip joint

Proximally, capsule of the hip joint is attached to the edge of the acetabulum, acetabular labrum, and transverse acetabular ligament. Distally, it is attached to the trochanters of the femur and intertrochanteric line anteriorly. Posteriorly, it is attached to a junction between medial two-thirds and lateral one-third of the femoral neck,[5] one finger breadth away from the intertrochanteric crest.[22] From its attachment at the femoral neck, the fibres of the capsule reflected backwards towards the acetabulum, carrying retinacula vessels supplying the femoral head.[5] The part of femoral neck outside the capsule is shorter in front than posteriorly.[22]

The strong but loose fibrous capsule of the hip joint permits the hip joint to have the second largest range of movement (second only to the shoulder) and yet support the weight of the body, arms and head.

The capsule has two sets of fibers: longitudinal and circular.

  • The circular fibers form a collar around the femoral neck called the zona orbicularis.
  • The longitudinal retinacular fibers travel along the neck and carry blood vessels.

Ligaments

Extracapsular ligaments. Anterior (left) and posterior (right) aspects of right hip.
Intracapsular ligament. Left hip joint from within pelvis with the acetabular floor removed (left); right hip joint with capsule removed, anterior aspect (right).

The hip joint is reinforced by four ligaments, of which three are extracapsular and one intracapsular.

The extracapsular ligaments are the iliofemoral, ischiofemoral, and pubofemoral ligaments attached to the bones of the pelvis (the ilium, ischium, and pubis respectively). All three strengthen the capsule and prevent an excessive range of movement in the joint. Of these, the Y-shaped and twisted iliofemoral ligament is the strongest ligament in the human body. It has a tensile strength of 350 kg.[22] Iliofemoral ligament is a thickening of the anterior capsule extending from anterior inferior iliac spine to intertrochanteric line.[5] Ischiofemoral ligament is the thickening of posterior capsule of the hip and pubofemoral ligament is the thickening of the inferior capsule.[5] In the upright position, iliofemoral ligament prevents the trunk from falling backward without the need for muscular activity, thus preventing excessive hyperextension. In the sitting position, it becomes relaxed, thus permitting the pelvis to tilt backward into its sitting position. Ischiofemoral prevents excessive extension and the pubofemoral ligament prevents excess abduction and extension.[24]

The

femoral neck, is covered by the other ligaments which partly radiate into it. The zona orbicularis acts like a buttonhole on the femoral head and assists in maintaining the contact in the joint.[22]
All three ligaments become taut when the joint is extended - this stabilises the joint, and reduces the energy demand of muscles when standing.[25]

The intracapsular ligament, the ligamentum teres, is attached to a depression in the acetabulum (the acetabular notch) and a depression on the femoral head (the fovea of the head). It is only stretched when the hip is dislocated, and may then prevent further displacement.[22] It is not that important as a ligament but can often be vitally important as a conduit of a small artery to the head of the femur, that is, the foveal artery.[26] This artery is not present in everyone but can become the only blood supply to the bone in the head of the femur when the neck of the femur is fractured or disrupted by injury in childhood.[27]

Blood supply

The hip joint is supplied with blood from the

head of the femur when the blood supply from the medial and lateral circumflex arteries are disrupted (e.g. through fracture of the neck of the femur along their course).[27]

The hip has two anatomically important anastomoses, the cruciate and the trochanteric anastomoses, the latter of which provides most of the blood to the head of the femur. These anastomoses exist between the femoral artery or profunda femoris and the gluteal vessels.[28]

Muscles and movements

Main article: Muscles of the hip

The hip muscles act on three mutually perpendicular main axes, all of which pass through the center of the

adduction around a sagittal axis (forward-backward);[29] and a combination of these movements (i.e. circumduction, a compound movement in which the leg describes the surface of an irregular cone).[22]
Some of the hip muscles also act on either the vertebral joints or the knee joint, that with their extensive areas of origin and/or insertion, different part of individual muscles participate in very different movements, and that the range of movement varies with the position of the hip joint.[22] Additionally, the
triceps coxae.[30][22]

The movements of the hip joint is thus performed by a series of muscles which are here presented in order of importance[22] with the range of motion from the neutral zero-degree position[29] indicated:

Clinical significance

A

lower back pain
.

At the 2022 Consumer Electronics Show, a company named Safeware announced an airbag belt that is designed to prevent hip fractures among such uses as the elderly and hospital patients.[32]

Abnormal orientation of the acetabular socket as seen in hip dysplasia can lead to hip subluxation (partial dislocation), degeneration of the acetabular labrum. Excessive coverage of femoral head by the acetabulum can lead to pincer-type femoro-acetabular impingement (FAI).[5]

Sexual dimorphism and cultural significance

Dancers often stand with hands on hips.

In humans, unlike other animals, the hip bones are substantially different in the two sexes. The hips of human females widen during puberty.[33] The femora are also more widely spaced in females, so as to widen the opening in the hip bone and thus facilitate childbirth. Finally, the ilium and its muscle attachment are shaped so as to situate the buttocks away from the birth canal, where contraction of the buttocks could otherwise damage the baby.

The female hips have long been associated with both fertility and general expression of sexuality. Since broad hips facilitate childbirth and also serve as an anatomical cue of sexual maturity, they have been seen as an attractive trait for women for thousands of years. Many of the classical poses women take when sculpted, painted or photographed, such as the Grande Odalisque, serve to emphasize the prominence of their hips. Similarly, women's fashion through the ages has often drawn attention to the girth of the wearer's hips.

Additional images

  • Hip joint. Lateral view.
    Hip joint. Lateral view.
  • Hip joint. Lateral view.
    Hip joint. Lateral view.
  • Muscles of Thigh. Anterior views.
    Muscles of Thigh. Anterior views.
  • Illustration of Hip (Frontal view).
    Illustration of Hip (Frontal view).
  • X-ray of the hip, with measurements used in X-ray of hip dysplasia in adults.[34]
    X-ray of the hip, with measurements used in X-ray of hip dysplasia in adults.[34]

See also

Notes

  1. ^ Latin coxa was used by Celsus in the sense "hip", but by Pliny the Elder in the sense "hip bone" (Diab, p 77)
  2. ^ "hip region". MediLexicon. Retrieved 2018-08-02.
  3. ^ Green, Shelby (15 December 2022). "Everything You Need to Know About Hip Anatomy". Feel Good Life. Retrieved 17 December 2022.
  4. ^ Thieme Atlas of Anatomy (2006), p 381
  5. ^
    ISBN 978-0-7020-2971-4
    .
  6. ^ a b Faller (2004), pp 174-175
  7. ^ Thieme Atlas of Anatomy (2006), p 365
  8. ^ Thieme Atlas of Anatomy (2006), p 378
  9. PMID 15308525
    .
  10. PMID 19753150
    .
  11. ^
    ISBN 978-1-60406-923-5
    .
  12. PMID 29399468
    .
  13. ^
    ISBN 978-3-540-20640-8
    .
  14. ^
    PMID 12931799
    .
  15. ISBN 978-0-323-28683-1
    .
  16. ^ Setia, Rahul; Gaillard, Frank. "Developmental dysplasia of the hip". Radiopaedia. Retrieved 2018-03-01.
  17. PMID 15958160
    .
  18. ISBN 978-0-08-053856-3
    .
  19. ^ Frank Gaillard. "Acetabular angle". Radiopaedia. Retrieved 2018-03-01.
  20. ^
    ISBN 978-1-4557-5360-4
    .
  21. ^ a b c Thieme Atlas of Anatomy (2006), p 367
  22. ^
    ISBN 3-13-533305-1
    .
  23. ^ Palastanga (2006), p 353
  24. PMID 29262200
    .
  25. ^ teachmeanatomy.net Archived 2013-01-03 at the Wayback Machine. teachmeanatomy.net. Retrieved on 2013-07-12.
  26. ^ Hip Fracture in Emergency Medicine at Medscape. Author: Moira Davenport. Updated: Apr 2, 2012
  27. ^ a b Thieme Atlas of Anatomy (2006), pp 383, 440
  28. ^ Clemente (2006), p 227
  29. ^ a b Thieme Atlas of Anatomy (2006), p 386
  30. ISBN 978-1-4963-4721-3.{{cite book}}: CS1 maint: location missing publisher (link
    )
  31. ^ a b "Hip Fractures". OrthoInfo - AAOS. April 2009. Archived from the original on 29 June 2017. Retrieved 27 September 2017.
  32. ^ Patterson, Dan (2022-01-06). "Smart beds, disease detectors and other cool tech at CES". CBS News. Retrieved 2022-01-06.
  33. ^ "Reproductive Anatomy and Physiology". The Harriet and Robert Heilbrunn Department of Population and Family Health. Retrieved June 5, 2009.
  34. PMID 26885391. (Attribution 4.0 International (CC BY 4.0)

References

External links

Look up hip in Wiktionary, the free dictionary.
Wikimedia Commons has media related to Hip.


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