MusculoSkeletal – Hips

This image illustrates the human pelvic region and lower vertebral column in an anterior view, highlighting several key anatomical structures.

At the top, we see the lumbar vertebrae, which are the five largest and heaviest vertebrae located in the lower back between the thoracic vertebrae and the sacrum. Above the lumbar vertebrae is a spinal disc, which serves as a ligament that holds the vertebrae together while also allowing for slight mobility of the spine.

Flanking the lumbar vertebrae on either side are the iliac crests, which are the top borders of the ilium—the largest bone of the pelvis. These crests form the superior border of the greater pelvis and provide attachment for the iliacus, abdominals, and other muscles.

Below the iliac crest, we find the iliac fossa, a large, smooth, concave surface on the internal side of the ilium. The ala of sacrum is the wing-like part on either side of the sacral base, connecting the sacrum to the ilia of the pelvis.

Centrally located is the sacrum, a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and its lower part with the coccyx via the sacrococcygeal symphysis.

Just below the sacrum, we see the coccyx, commonly referred to as the tailbone. It’s the final segment of the vertebral column, comprising three to five fused vertebrae.

The pelvic girdle also features the sacroiliac joints, which are the joints between the sacrum and the ilium of the pelvis, connected by strong ligaments. The sacral promontory is a prominent bulge on the front side of the sacrum, marking part of the border of the pelvic inlet.

On the lateral aspects of the pelvis, we can identify the acetabulum, a concave surface that serves as the socket for the femoral head, creating the hip joint. The femoral head is the highest part of the thigh bone (femur), fitting into the acetabulum.

Adjacent to the acetabulum, the ischium forms the lower and back part of the hip bone. The ischial spine is a pointed protrusion from the ischium, which serves as a point of attachment for ligaments and muscles.

At the junction of the ischium and pubis bones of the pelvis, we find the obturator foramen, a large opening that allows for the passage of nerves and blood vessels to the legs.

In the center, just below the acetabulum, is the pubic symphysis, a cartilaginous joint that sits between and joins the left and right superior rami of the pubic bones.

Lastly, the femur, the longest and strongest bone in the human body, is shown extending downward from the hip joint.

The image displayed shows the musculature of the human posterior pelvic and hip region with a focus on the gluteal muscles, which are key in the movement of the hip and thigh. On the left, we see the gluteus minimus, the smallest of the trio, lying directly beneath the gluteus medius. It is a fan-shaped muscle that originates on the outer surface of the ilium between the anterior and inferior gluteal lines and extends to the greater trochanter of the femur. Its primary function is to help with the rotation of the thigh outward and the abduction of the thigh, which means moving it away from the body’s central axis.

On the right, the image is layered to show both the gluteus medius and the gluteus maximus. The gluteus medius is partially covered by the gluteus maximus and is shown in a more subdued tone. It is a broad, thick, radiating muscle, situated on the outer surface of the pelvis. Its anterior fiber helps in flexing and medially rotating the thigh, while the posterior fibers extend and laterally rotate the thigh.

The gluteus maximus, shown in a darker red, is the largest and most superficial of the three gluteal muscles. It makes up a large portion of the shape and appearance of the hips. It extends from the sacrum, coccyx, and adjacent bones and fans out to attach to the femur and the iliotibial band of the fascia lata of the thigh. This powerful muscle is involved in a number of actions, including extending and laterally rotating the thigh, and it is a crucial muscle in walking, running, and climbing.

These muscles are essential not only for movement but also for the stability of the pelvis and hip joints. They are engaged in various movements of the lower body, including maintaining the trunk in the erect posture.

This illustration presents a detailed view of the hip joint with a focus on the articular capsule and the surrounding structures. The hip joint is a ball-and-socket synovial joint formed between the os coxa (hip bone) and the femur.

The central feature of this image is the articular capsule of the hip joint, which is a strong, fibrous structure that encircles the hip joint and holds it together. The capsule is composed of strong collagen fibers which appear as striations running longitudinally along the length of the capsule. This capsule provides stability to the hip joint while still allowing for a considerable range of motion.

Surrounding the capsule, we see the femoral head at the bottom right of the image, which is the ball part of the joint, fitting into the acetabulum of the hip bone. The femoral head has a smooth, rounded surface to articulate with the acetabulum, which is not visible in this view.

At the top left, we can observe part of the os coxa, specifically the area around the acetabulum, though the socket itself is covered by the articular capsule in this depiction. The acetabulum is a deep cup-like structure that accommodates the femoral head.

The hip joint is one of the most important joints in the body for weight-bearing activities such as standing, walking, and running. The articular capsule contributes significantly to the joint’s stability by resisting dislocation and providing a sealed environment for the joint fluid that lubricates the joint surfaces.

This image presents a posterior view of the human pelvis and lower spine, highlighting the musculoskeletal structure. At the top of the image, we can see the lumbar spine, consisting of five vertebrae. These are the largest segments of the vertebral column and are responsible for supporting much of the body’s weight and enabling flexible movement.

The pelvic girdle is prominently displayed, comprising the hip bones on either side, the sacrum, and the coccyx. The hip bones are large, irregular bones that form a solid ring called the bony pelvis. Each hip bone is made up of three parts: the ilium, ischium, and pubis, which are fused in adults but separate in children.

The sacrum is a triangular bone situated at the lower part of the spine and wedged between the two hip bones. Below the sacrum, the coccyx, or tailbone, is visible as a small, triangular bone that represents the vestigial remnants of a tail.

On either side of the sacrum, we see the iliac wings of the pelvis, which spread out like fans and serve as attachment points for muscles and ligaments. The ilium is the broad, flaring portion of the hip bone.

The image also highlights two key muscle groups in red. These are the gluteus maximus muscles, the largest and most superficial of the gluteal muscles, which shape the contour of the buttocks. The gluteus maximus muscles are responsible for the movement of the hip and thigh, including extension, abduction, and lateral and medial rotation of the thigh. They play a critical role in maintaining the body upright and are engaged during activities such as climbing stairs and rising from a seated position.

Notably, the white structures spreading across and around the hip bones are the iliacus muscles. These muscles fill the iliac fossa, the concave surface on the inner side of the ilium. They work in concert with the psoas major muscles (not visible in this image) to form the iliopsoas, which is the strongest flexor of the thigh at the hip joint.

The anatomy displayed is essential for the support and movement of the human body, especially in terms of the stability and mobility of the lower back and hips.

This image illustrates a lateral view of the human pelvis and proximal femur, focusing specifically on the bursae associated with the hip joint.

A bursa is a small fluid-filled sac that acts as a cushion to reduce friction between bones and the tendons or muscles around a joint. In this depiction, four bursae are indicated:

  1. The ischial tuberosity bursa is located over the ischial tuberosity—the part of the pelvis that bears the weight when sitting. Bursae in this area minimize the friction for the gluteus maximus muscle as it moves over the ischial tuberosity.

  2. The iliopsoas bursa is the largest bursa in the body. It lies between the iliopsoas muscle and the pelvic bone or the femoral head. It facilitates the smooth movement of the iliopsoas muscle during flexion and extension movements of the thigh.

  3. The trochanteric bursa is found near the greater trochanter of the femur, which is the prominent bony point where the thigh bone turns inwards. The bursa serves to ease the movement of the tendons of the gluteus medius and minimus over the greater trochanter when the hip is in motion.

  4. Lastly, the gluteus medius bursa is situated between the gluteus medius muscle and the greater trochanter. Similar to the trochanteric bursa, it helps in reducing the friction during the movement of the gluteus medius muscle over the femur.

The lumbar spine is seen at the top of the image, and the hip bone, including the ilium and the acetabulum, are shown. The femur is represented by the head, neck, and a portion of the shaft. The gluteus maximus muscle is visible in the background, covering the posterior aspect of the hip joint. The bursae play a crucial role in ensuring the smooth motion of these muscles and tendons over bony prominences.

This image presents an anterior view of the pelvis with a focus on the piriformis muscle and its relationship with the sciatic nerve. The piriformis is a small muscle located deep in the buttock, behind the gluteus maximus. It runs from the lower spine to the top of the femur and functions to rotate the hip and turn the leg and foot outward.

The sciatic nerve is shown in yellow, highlighting its path as it runs beneath the piriformis muscle. This nerve is the longest and widest single nerve in the human body, extending from the lower end of the spinal cord, down the buttock and the back of the thigh, all the way to the foot.

The inset circle provides a magnified view, showing the close proximity of the sciatic nerve to the piriformis muscle. It is this relationship that can sometimes lead to piriformis syndrome, where the muscle irritates or compresses the sciatic nerve, causing pain, tingling, or numbness in the buttock and along the path of the nerve.

The pelvic bones, including the ilium and sacrum, provide the structure to which the piriformis muscle attaches. The anatomical illustration emphasizes the potential for neurological impingement where the sciatic nerve passes in close association with the piriformis muscle.

This illustration provides an anterior view of the pelvis, highlighting the piriformis muscles in relation to the pelvic bones and the proximal femur.

The piriformis muscles are shown in a deep red color, originating from the anterior surface of the sacrum—the triangular bone at the base of the spine—and inserting at the greater trochanter of the femur, which is the bony prominence on the upper thigh bone.

The ilium, part of the hip bones, is displayed on either side of the pelvis, forming the broad, wing-like structures on the upper part of the pelvis. The sacrum is the central part of the pelvic girdle and articulates with the ilium at the sacroiliac joints, which are not distinctly labeled here but are located where the ilium meets the sacrum.

The femur is the long bone of the thigh, and only the upper part is shown here. The greater trochanter is a significant landmark on the femur, serving as the point of attachment for the piriformis and several other muscles that are not depicted in this image.

The piriformis is an important muscle for several reasons: it helps to stabilize the hip joint, rotates the femur outward when the hip is extended, and abducts the femur (moves it away from the body) when the hip is flexed. Understanding the anatomy of the piriformis and its relationship with surrounding structures is important for diagnosing and treating conditions related to hip pain and sciatic nerve compression.

The image depicts an anterior view of the human pelvis and femur, focusing on the condition known as “Coxa Saltans,” or more commonly referred to as “Snapping Hip Syndrome.” This condition is characterized by a snapping sensation felt in the hip, which is often audible, during certain movements such as walking, getting up from a chair, or swinging the leg around.

At the top of the image, the tensor fasciae latae muscles are shown in red. These muscles are found on the outer side of the thigh and function to help flex and abduct the thigh at the hip joint. They are enclosed within the fasciae latae, which is a layer of fibrous tissue that covers the thigh muscles.

Extending from the tensor fasciae latae muscles down the side of the thigh is the iliotibial band (IT band), labeled in the image. This is a thick band of connective tissue that runs along the outside of the thigh, from the pelvis to the shinbone, and is critical for stabilizing the knee during activities like running.

The two inset circles highlight the regions where the snapping typically occurs in the syndrome. The upper circle shows the tensor fasciae latae and the iliotibial band as they pass over the greater trochanter of the femur. The lower circle shows the iliotibial band as it passes over the lateral epicondyle of the knee.

Snapping hip syndrome can be caused by several factors, including tightness in the iliotibial band, movements that cause the band to repeatedly rub over the greater trochanter, or the movement of the tendon of the muscle over bony structures.

In this condition, the snapping or popping sound is usually painless and harmless, though it can be accompanied by discomfort or pain in some cases, potentially leading to inflammation of the bursa (trochanteric bursitis) if the friction becomes excessive. Treatment often includes stretching, strengthening exercises, and sometimes modifications in activity or physical therapy to address the symptoms.

This illustration shows an anterior view of the human pelvis, highlighting the sacroiliac joint and its condition known as sacroiliitis, which is the inflammation of one or both of the sacroiliac joints. These joints are found where the lower spine and pelvis connect.

The sacroiliac joints are depicted in blue, indicating the area where the sacrum meets the ilium of the pelvis. The sacrum is the triangular-shaped bone at the base of the spine, and the ilium is the large, wing-like part of the pelvis. These joints help support the weight of the upper body when standing and act as shock absorbers.

The inset circle provides a closer look at the sacroiliac joint, showing redness around the joint area to represent inflammation. Sacroiliitis can cause pain in the buttocks or lower back, and may extend down one or both legs. The degree of pain can vary from mild discomfort to severe pain that can be disabling.

Sacroiliitis is a common feature of inflammatory conditions of the spinal column, such as ankylosing spondylitis, and can also result from trauma, pregnancy, infection, or arthritis. Treatment for sacroiliitis typically involves a combination of rest, physical therapy, and medication to reduce pain and inflammation. In more severe cases, joint injections or surgery may be considered.

This image provides a view of the anterior lower torso with an emphasis on the iliopsoas muscle group, consisting of the psoas major, psoas minor, and iliacus muscles.

The psoas major muscles are large, thick, and triangular muscles that originate from the sides of the lumbar vertebrae and extend through the pelvis to attach to the lesser trochanter of the femur. The psoas major is the stronger and larger of the two psoas muscles, and it plays a key role in flexing the hip joint and lifting the upper leg towards the body.

Above the psoas major, the psoas minor muscles are depicted. They are much smaller and not as common, present in only about 50% of the population. When present, they run parallel to the psoas major muscles, originating from the lumbar vertebrae and inserting into the pelvis. The psoas minor assists in flexing the lower spine.

The iliacus muscles are broad, flat muscles that fill the iliac fossa on the inner surface of the ilium, part of the hip bones. They join the psoas major muscles to form the iliopsoas, which is the primary flexor of the thigh. This combined muscle group inserts into the lesser trochanter of the femur.

Together, the iliopsoas is crucial for walking, running, and standing upright, as it stabilizes the lower back and allows the hip to flex. When the body is in motion, these muscles work in coordination to control the movement of the hip and lower spine. The health and function of the iliopsoas muscle group are important for posture and locomotion.

This image compares the structural differences between a male and a female pelvis. The male pelvis, on the left, is characterized by a narrower pubic arch – the angle formed below the pubic symphysis. This narrower arch is typically less than 90 degrees. The pelvic cavity itself appears more heart-shaped and the bone structures are more robust. These features are adapted for supporting a male’s generally heavier build and stronger musculature.

On the right, the female pelvis is depicted with a wider pubic arch, often greater than 90 degrees, which is one of the adaptations for childbirth. The pelvic inlet, the upper opening of the pelvis, is broader and more circular, providing more space in the pelvic cavity. This difference accommodates the needs of pregnancy and childbirth, allowing more room for the passage of a baby.

Additionally, the female pelvis shows more flared iliac wings and a shorter sacrum, further distinguishing it from the male pelvis. Overall, the female pelvis is wider and shallower, while the male pelvis is taller and more narrow.

These anatomical differences are a classic example of sexual dimorphism in human skeletal structure, where the physical differences between the sexes are related to biological and functional adaptations.

This image provides a posterior view of the human skeletal system, emphasizing the ligaments. Ligaments are fibrous connective tissues that connect bones to other bones, providing stability and support to the joints.

The major ligaments visible here are the ones at the shoulders, elbows, hips, knees, and in the spinal column. The shoulder and hip joints, both ball-and-socket joints, have ligaments that form capsular structures to secure the bones in the joint. At the shoulder, these ligaments help to stabilize the relatively mobile and flexible joint. At the hip, they are thicker and stronger, providing stability to a weight-bearing joint.

In the elbow and knee regions, the ligaments are crucial for hinge-like movements. At the elbow, they connect the humerus to the ulna and radius, while at the knee, the prominent ligaments include the cruciate ligaments inside the joint capsule that cross over each other to stabilize the front-to-back motion and the collateral ligaments along the sides of the knee to control sideways motion.

In the spinal column, ligaments run along the vertebrae to provide support and limit the movement, ensuring the spine’s structural integrity. These include the longitudinal ligaments that run the length of the spine along the front and back of the vertebral bodies.

The ligaments are represented in this image with a different color to differentiate them from the bones, and their role is crucial in the musculoskeletal system, providing joint stability and helping to prevent excessive movements that could lead to injuries.

The image shows a posterior view of the human skeletal structure focusing on the ligaments of the pelvic girdle and lower spine in purple. The ligaments are the fibrous connective tissues that connect bones to other bones, providing stability and flexibility to the joints and skeletal structure.

Here, the purple structures illustrate the complex network of ligaments that support the sacroiliac joints, where the spine meets the pelvis, and the ligaments along the spine itself. These ligaments help stabilize the sacrum -- the shield-shaped bony structure at the base of the lumbar vertebrae and at the upper and back part of the pelvic cavity. They also support the connection between the sacrum and the ilium of the hip bones.

Additionally, the ligaments extend along the length of the spine, connecting the vertebrae to each other. They play a crucial role in maintaining the integrity of the spinal column, allowing for controlled movements and flexibility, and preventing dislocation and injury by limiting excessive movement.

The strength and elasticity of these ligaments provide a delicate balance that allows for movement while maintaining structure, making them vital components of the musculoskeletal system.

The image provides a detailed posterior view of the human pelvic and spinal regions, focusing on the ligaments, which are represented in a purple color.

In this illustration, the ligaments of the spine are particularly prominent. These include the supraspinous ligament, which extends from the seventh cervical vertebra down to the sacrum, running along the tips of the spinous processes. There’s also the interspinous ligament, located between the spinous processes of the vertebrae.

The ligaments around the pelvis are critical for joint stability. We can observe the sacroiliac ligaments, which are strong bands connecting the sacrum to the ilium at the sacroiliac joints. These ligaments are some of the strongest in the body and are crucial for transferring weight between the upper body and the legs.

The sacrotuberous and sacrospinous ligaments are also visible. These ligaments extend from the sacrum to the ischial tuberosity and ischial spine, respectively, and serve to prevent rotation of the iliac bones on the sacrum.

These ligaments play essential roles in providing stability to the pelvis and the lower back, supporting the body’s weight, and allowing for various movements while limiting excessive motion that could lead to injury.

In the image, we see a posterior view of the human pelvis and lower spine with emphasis on certain ligaments, represented in red.

These red structures are the iliolumbar ligaments, which extend from the transverse processes of the lumbar vertebrae to the iliac crest of the pelvis. These ligaments are crucial for stabilizing the lumbar spine where it joins the pelvis, preventing excessive movement that could lead to injury.

Above the iliolumbar ligaments, the white structures protruding laterally from the spine are the ribs, which attach to the thoracic vertebrae. The series of bones running down the middle is the vertebral column, which supports the body’s structure and houses the spinal cord.

The broader white structures forming the base of the pelvis are the ilium bones, and below them, the rounded heads of the femurs (thigh bones) can be seen. The femurs articulate with the pelvis at the hip joints, which are not directly visible in this view but are located where the femur heads are closest to the pelvis.

The ligaments depicted in red provide a visual representation of the connective tissue that plays a vital role in maintaining the structural integrity of the lower back and pelvis, aiding in both stability and flexibility.

The image illustrates a posterior view of the human pelvis and lower spine, highlighting the sacroiliac ligaments in red. These ligaments are critical structures that connect the sacrum to the ilium bones of the pelvis, providing stability to the sacroiliac joint.

The sacroiliac ligaments are divided into the anterior and posterior sacroiliac ligaments. In this view, we can see the posterior sacroiliac ligaments, which are thicker and stronger than the anterior ones. They cover the back of the joint and serve to resist the natural tendency of the lower part of the sacrum to be pushed forward by the spine’s weight.

Above the sacroiliac ligaments, the spinal column is visible, with the lumbar spine at the lower end. The ilium bones form the broad, wing-like portions of the pelvis on each side. Below, we can see the heads of the femurs, which articulate with the pelvis at the hip joints to form the ball-and-socket joint.

The sacroiliac ligaments, depicted in red, are crucial for transferring weight and movement from the upper body to the lower limbs, and for absorbing impact when walking or running. Their strength and elasticity are key to preventing over-movement at the joint, which could lead to instability or pain.

The image presents a posterior view of the human pelvis and lower spine, specifically highlighting the hip joint capsules in red. The hip joint capsule is a strong, fibrous structure that encircles the hip joint and encompasses the head of the femur and the acetabulum of the pelvis. This capsule is crucial in maintaining the stability of the hip joint, limiting excessive motion, and providing the necessary lubrication for joint movement through the synovial fluid contained within.

Above the hip joints, the spinal column is seen extending upwards, with the lumbar spine transitioning into the thoracic spine where it is connected to the ribs. The broad, wing-like structures on each side of the pelvis are the ilium bones, which form the uppermost part of the hip bone.

The femur, or thigh bone, is visible below the hip joints. The rounded portion at the top of each femur is the femoral head, which fits into the acetabulum of the pelvis to form the ball-and-socket hip joint. This joint structure allows for a wide range of motion, including flexion, extension, abduction, adduction, and rotational movements.

The ligaments shown in white are likely the sacrotuberous and sacrospinous ligaments, which stabilize the sacrum to the bones of the pelvis, and the various ligaments associated with the spine that help in maintaining its alignment and structural integrity. These ligaments work together with the muscles and bones to support body weight, enable movement, and protect the internal organs.

In this posterior view of the human pelvis and lower spine, the focus is on the large muscles attached to the femur, depicted in red. These are the gluteus maximus muscles, the largest and most superficial muscles of the buttocks. They originate from the ilium, sacrum, and coccyx and insert into the iliotibial tract and the gluteal tuberosity of the femur. These muscles are responsible for the extension, outward rotation, and abduction of the hip joint, as well as maintaining the body in an erect posture.

The lumbar spine is shown with its vertebrae stacked above the sacrum, which is wedged between the iliac bones of the pelvis. The iliac bones have a large, fan-like shape and, together with the sacrum and coccyx, form the bony structure of the pelvis.

The white fibrous structures extending across the pelvis and spine are various ligaments that provide support and stability to the joints. In particular, the sacroiliac ligaments can be seen spanning between the sacrum and ilium, reinforcing the sacroiliac joint.

Below the gluteus maximus muscles, the femurs, or thigh bones, are visible with their proximal ends featuring the greater trochanters, which are the points of attachment for these muscles as well as several other muscles and ligaments. These structures work in concert to facilitate movement and provide support for the upper body.

The image illustrates a posterior view of the human pelvis and lower spine, highlighting the sacroiliac ligaments in red. These ligaments are a critical component of the pelvic girdle, providing stability to the sacroiliac joints where the sacrum meets the ilium bones of the pelvis.

The sacroiliac ligaments are comprised of both the anterior and posterior sacroiliac ligaments. Here, the illustration likely shows the posterior sacroiliac ligaments which are situated on the back of the pelvis. They are some of the strongest ligaments in the body and are essential for transmitting the weight of the upper body to the lower limbs and for providing stability to the pelvis during movement.

Above the sacroiliac ligaments, we see the lumbar spine with its vertebrae extending upwards, transitioning into the thoracic spine where ribs are connected. The ilium bones are shown flanking the sacrum, forming the uppermost and largest part of the pelvis.

Below, the proximal ends of the femurs (thigh bones) are visible, articulating with the pelvis at the hip joints to form the ball-and-socket joint. This arrangement allows for a wide range of motion in the lower limbs.

The sacroiliac ligaments’ role is vital as they help to absorb shock and reduce stress on the pelvis and the spine during activities such as walking, running, and lifting.

The image shows a posterior view of the human pelvis and lower spine, with the sacrum situated between the two ilium bones of the pelvis. Highlighted in red are the sacrotuberous ligaments, which are strong triangular-shaped structures that connect the lower part of the sacrum and the coccyx to the ischial tuberosity of the pelvis. These ligaments play a crucial role in stabilizing the sacrum and preventing its rotation. They also help bear the weight of the body when in a sitting position.

Above the sacrotuberous ligaments, the spinal column is depicted, with the lumbar vertebrae transitioning into the thoracic region, where the ribs are attached. The ilium bones flank the sacrum, which together with the coccyx, form the pelvis.

The femurs, or thigh bones, are visible below, articulating with the pelvis at the hip joints. These joints are not directly visible in this view, but they allow for the wide range of motion necessary for leg movement.

The integrity of the sacrotuberous ligaments is essential for maintaining proper biomechanics of the pelvis and the lower back, especially during the movement of the lower limbs and while carrying the weight of the upper body.

In the given image, we are looking at a posterior view of the human pelvis and lower spine, where the sacrum is centrally located between the two ilium bones. Highlighted in red, we see the sacrum itself, which is a triangular bone that forms the base of the spinal column and the upper back part of the pelvic cavity.

The sacrum is composed of fused vertebrae. It joins with the ilium bones on either side at the sacroiliac joints, which are not distinctly colored in this illustration. These joints are supported by a network of strong ligaments that provide stability and distribute the weight of the upper body to the pelvis and lower limbs.

Above the sacrum, the image shows the continuation of the vertebral column, transitioning from the lumbar spine to the thoracic spine where ribs are attached. The thoracic spine continues upwards, leading towards the cervical spine and the skull, which are not in view.

Below the sacrum, the two femurs, or thigh bones, are presented. The femurs have a ball-like head that fits into the hip sockets (acetabulum of the ilium bones), forming the hip joints which are critical for lower limb mobility and support during activities such as walking, running, and sitting. The red coloration of the sacrum in this image serves to emphasize its anatomical position and importance within the pelvic structure.

This image provides a posterior view of the human pelvis and lower spine, highlighting in red the paths of the sacrotuberous and sacrospinous ligaments. These ligaments are essential for stabilizing the pelvis and contributing to the integrity of the sacroiliac joints.

The sacrotuberous ligaments are the longer, more visible ligaments running diagonally from the sacrum to the ischial tuberosity of the pelvis. They help to resist forward tilting of the sacrum and bear the weight of the body when sitting.

The sacrospinous ligaments, while not as clearly depicted, are typically located more medially and run from the sacrum to the ischial spine. These ligaments work with the sacrotuberous ligaments to prevent posterior rotation of the ilium on the sacrum.

Above these ligaments, the lumbar vertebrae extend upwards, leading to the thoracic spine where ribs are connected. The ilium bones form the broad “wings” of the pelvis on each side. The femur bones, or thigh bones, are seen at the bottom of the image with their proximal ends articulating with the pelvis at the hip joints.

Together, these ligaments, bones, and joints form a complex structure that supports the weight of the upper body, allows for a range of lower body movements, and protects vital organs within the pelvic cavity.

In this image, we see the posterior aspect of the human pelvis and lumbar spine, highlighting the iliac crest and the sacroiliac joints in red.

The iliac crests are the superior borders of the ilium bones, which are part of the pelvis. These crests are significant for muscle attachment and are easily palpable in most individuals; they are commonly known as the “hip bones” when felt at the sides of the body.

The sacroiliac joints, also colored in red, are located where the ilium bones meet the sacrum centrally. These joints are supported by strong ligaments and provide stability to the pelvis, acting as a buffer in transmitting the upper body’s weight to the lower limbs.

The lumbar spine is visible above, with the vertebrae aligned in a column leading to the thoracic spine, where the ribs attach. Below the sacroiliac joints, the femurs, or thigh bones, articulate with the pelvis at the hip joints, which are not explicitly highlighted in this view.

The red coloring here emphasizes the bony landmarks and joints crucial for structural support and movement. The iliac crests serve as attachment sites for several muscles and ligaments, while the sacroiliac joints play a key role in the body’s load-bearing and movement mechanics.

TermDefinition
AcetabulumA concave surface on the pelvic bone that serves as the socket for the femoral head, forming the hip joint.
Ala of SacrumThe wing-like part on either side of the sacral base, connecting the sacrum to the ilia of the pelvis.
CoccyxThe final segment of the vertebral column, commonly referred to as the tailbone, comprising three to five fused vertebrae.
Femoral HeadThe highest part of the thigh bone (femur), fitting into the acetabulum to form the hip joint.
Gluteus MaximusThe largest and most superficial of the gluteal muscles, involved in extending and laterally rotating the thigh, as well as in maintaining the trunk in an erect posture.
Gluteus MediusA muscle partially covered by the gluteus maximus, involved in flexing, medially rotating, and abducting the thigh.
Gluteus MinimusThe smallest of the gluteal muscles, located beneath the gluteus medius, helping with thigh rotation and abduction.
Iliac CrestThe top border of the ilium, forming the superior border of the greater pelvis and providing attachment for muscles.
Iliac FossaA large, smooth, concave surface on the internal side of the ilium.
Ischial SpineA pointed protrusion from the ischium, serving as a point of attachment for ligaments and muscles.
IliopsoasA combination of the iliacus and psoas major muscles, the strongest flexor of the thigh at the hip joint.
Lumbar VertebraeThe five largest and heaviest vertebrae located in the lower back, between the thoracic vertebrae and the sacrum.
Obturator ForamenA large opening created by the ischium and pubis bones of the pelvis, allowing for the passage of nerves and blood vessels to the legs.
Pelvic GirdleThe structure formed by the sacrum and the two hip bones (ilium, ischium, and pubis) on either side.
Pubic SymphysisA cartilaginous joint that sits between and joins the left and right superior rami of the pubic bones.
Sacral PromontoryA prominent bulge on the front side of the sacrum, marking part of the border of the pelvic inlet.
Sacroiliac JointsThe joints between the sacrum and the ilium of the pelvis, connected by strong ligaments.
SacrumA large, triangular bone at the base of the spine and at the upper, back part of the pelvic cavity, inserted like a wedge between the two hip bones.