Generality
The iliac bone is the hip bone and represents, together with the sacrum and the coccyx, one of the bones of the pelvis. It is an even element, which develops on the sides of the aforementioned sacrum.
From the anatomical point of view, the iliac bone can be divided into three regions: an upper region, called the ilium; a lower-posterior region, called the ischium; and finally, a lower-anterior region, identified with the term pubis.
Each iliac bone forms 3 joints: the sacro iliac joint, with the sacrum; the joint of the hip, with the femur; finally, the joint known as the pubic symphysis, with the contralateral iliac bone.
The iliac bone is the site of insertion for muscles of the abdomen, back, thigh, etc.
The pathologies that can affect the iliac bone include: bone fractures and hip pathologies.
What is the hipbone?
The iliac bone, also known as hip bone or coxal bone, is the even and symmetrical bone which, together with the sacrum and the coccyx, constitutes that anatomical structure identified with the name of pelvic girdle.
IT'S A PELVIS BONE
The hipbone, the sacrum and the coccyx represent the bones of the pelvis (or pelvic bones).
Anatomists call the pelvis, or pelvis, or pelvic region, the lower torso of the human body.
Located between the abdomen and the thighs, the pelvis comprises, in addition to the pelvic bones: the so-called pelvic cavity, the so-called pelvic floor and the so-called perineum.
Anatomy
The iliac bone forms the lateral and anterior portion of the pelvic girdle.
Each iliac bone, in fact, develops from the lateral edges of the sacrum, continues downwards and, at the same time, converges forward, joining the contralateral iliac bone and forming the so-called pubic symphysis.
From these descriptions, the reader should guess that there is a right iliac bone and a left iliac bone.
The iliac bone consists of three regions, which merge with each other at the age of 14/15. The three regions in question are the bones known as: ilium, ischium and pubis
ILIO
The ilium represents the superior portion of the ilium; of the latter, it is also the largest and largest portion.
From the anatomical point of view, it has two relevant sections, known as the ilium body and ilium wing.
Bordering the ischium and pubis and located above them, the body of the ilium forms part of the acetabulum; the acetabulum is the hollow in which the head of the femur takes place, in what is the so-called hip joint.
Moving on to the "wing of the ilium", this is the section that:
- It resides above the body;
- It connects to the sacrum, forming the so-called sacro iliac joint;
- It gives life to a bone structure, certainly known to most people, called the iliac crest.
On the wing, two surfaces are recognizable: the internal surface (or iliac fossa) and the external surface (or gluteal surface). The iliac fossa is concave and represents the point of origin of the iliac muscle; the gluteal surface, on the other hand, is convex, has semicircular lines - called gluteal lines - and represents the attachment point of the gluteal muscles.
Furthermore, on the lateral edges, with both anterior and posterior orientation, the wing has bony prominences that take the name of spines: oriented forward, the so-called anterior superior iliac spine and anterior inferior iliac spine develop; oriented backwards, instead, the so-called posterior superior iliac spine and posterior inferior iliac spine come to life.
Figure: the pelvic girdle. If the iliac bone represents the lateral portion and the anterior portion of the pelvic girdle, the sacrum and the coccyx represent the posterior portion of the latter.
ISCHIO
The ischium represents the lower and posterior part of the iliac bone. Therefore, it resides inferior to the ilium and behind the latter and the pubis. Of the three bony elements that make up the iliac bone, the ischium is the strongest and most resistant.
The ischium consists of three portions: the body, the lower branch and the upper branch.
- The body is the bony portion that is interposed between the lower and upper branches of the ischium.
- The lower branch is important because it combines with the lower branch of the pubis, giving life to the so-called ischio-pubic branch. The ischio-pubic branch forms a hole, which is called the obturator hole. The obturator nerve, the obturator artery and the obturator vein pass through the obturator foramen.
- Finally, the superior branch is relevant because it includes about one third of the acetabulum and a bony prominence called the ischial spine.
The ischium is the portion of the iliac bone, which, when sitting and projecting forward, supports the weight of the human body. To be precise, the anatomical region of the ischium on which the weight of the human body rests when is sitting position, is the so-called ischial tuberosity.
The ischium inserts two important ligaments: the sacrospinous ligament and the sacrotuberous ligament.
PUBE
The pubis represents the anterior part of the iliac bone. In fact, it resides both in front of the ilium and in front of the ischium.
It includes three relevant portions, which are: the body, the upper branch and the lower branch.
- The body localizes between the lower and upper branches and is important because, articulating with the pubis of the contralateral iliac bone, it forms the so-called pubic symphysis.
- The upper branch extends laterally to the body and is important, because it constitutes "another part of" the acetabulum (about one fifth); its medial region is flat, while its lateral region is prismoid in shape.
- Finally, the lower branch projects in the direction of the ischium and joins with the latter, forming the so-called ischio-pubic branch; it is thin and flat.
ARTICULATIONS
Each iliac bone has 3 joints apart: the sacroiliac joint, the hip joint and the pubic symphysis.
Briefly, the sacroiliac joint is the joint element that connects the lateral surface of the sacrum to the ilium of the ilium. Clearly, if there are two iliac bones, there are also two sacroiliac joints.
The hip joint, or simply hip, is the joint element that connects the acetabulum with the head of the femur. Inside the pelvic girdle, the hip is the junction point between the axial skeleton and the lower limb skeleton; it is essential for locomotion.
Finally, the pubic symphysis is the joint that connects the two iliac bones on the front.
Function
Premise: the bones of the pelvis have several tasks: first of all, to support the upper part of the body; then, to connect the skeleton of the latter to the lower limbs; finally, to insert the muscles, ligaments and tendons, which are fundamental for walking and more.
In addition to giving life to a very important joint such as the hip, the iliac bone gives rise and insertion to muscles with different locations, including: the abdomen, the back, the thigh and so on. Schematically, the muscular elements that have contact with the iliac bones are:
- The abdominal muscles known as:
- External oblique muscle
- Internal oblique muscle
- Transverse abdominal muscle
- The back muscle known as the multifidus muscle
- The gluteal muscles, therefore:
- The gluteus maximus muscle
- The gluteus medius muscle
- The gluteus minimus muscle
- The lateral rotator muscles of the hip, known as:
- Piriformis muscle
- Superior twin muscle
- Internal obturator muscle
- Lower twin muscle
- External obturator muscle
- The hamstring muscles (hamstrings, in English), that is:
- The hamstring
- The semitendinosus
- The semimembranosum
- The anterior muscles of the thigh, i.e .:
- The rectus femoris muscle
- The sartorius muscle
- The great dorsal muscle
Pathologies
Among the pathologies that can affect the iliac bone, bone fractures and hip pathologies certainly deserve a mention, with specific involvement of the acetabulum.
HIP PATHOLOGIES
The two most important pathologies of the hip, which can derive from an anomaly of the acetabulum of the iliac bone, are: coxarthrosis (or osteoarthritis of the hip) and congenital dysplasia of the hip.
BONE FRACTURES
Fractures of the iliac bone are injuries of a traumatic nature, which usually occur after accidental falls, car accidents or impacts during the practice of sports in which physical contact is required (eg rugby, American football, etc. ).
The sections of the iliac bones most subject to fracture are: the wings of the ilium and the branches (upper and lower) of the pubis.
Iliac bone fractures can be divided into two categories: stable fractures and unstable fractures. All fractures characterized by a single breaking point are stable, while all fractures characterized by two or more breaking points are unstable.
A severe hip bone fracture can result in damage to the bladder or urethra.
