Abdominopelvic Bones: Master Anatomy with This Visual Guide

Understanding the architecture of the human body requires a solid grasp of skeletal anatomy. Specifically, the pelvic girdle serves as a crucial anchor. Medical students at institutions like the University of Michigan Medical School often utilize tools such as the Visible Body app to visualize this complex region. Indeed, precise identification of what are the bony landmarks of the abdominopelvic cavity is foundational knowledge for clinicians. The bony landmarks serve as attachment sites for muscles, ligaments, and tendons, facilitating movement and protecting vital organs. Furthermore, knowledge of these landmarks enables accurate diagnoses, guiding procedures such as abdominal palpation and informing surgical interventions.

Image taken from the YouTube channel RegisteredNurseRN , from the video titled Four Abdominal Quadrants and Nine Abdominal Regions - Anatomy and Physiology .

The human body, a marvel of biological engineering, houses a complex arrangement of organs and systems, meticulously organized within distinct cavities. Among these, the abdominopelvic cavity stands out as a critical region. It is the area where vital processes of digestion, reproduction, and waste elimination take place.

Its boundaries, though not always immediately apparent, are defined in large part by the bony structures that cradle and protect its contents.

Understanding the anatomy of this region is paramount. It is essential for healthcare professionals across numerous specialties. This understanding hinges on a firm grasp of the underlying skeletal framework.

Defining the Abdominopelvic Cavity

The abdominopelvic cavity is a continuous space that extends from the diaphragm superiorly to the pelvic diaphragm inferiorly. This expansive area is conventionally divided into two main parts: the abdominal cavity and the pelvic cavity. However, there is no physical barrier dividing them.

The abdominal cavity houses the majority of the digestive organs, including the stomach, small and large intestines, liver, gallbladder, pancreas, and spleen. It also contains the kidneys and adrenal glands.

The pelvic cavity, situated inferiorly, contains the urinary bladder, rectum, and internal reproductive organs. In females, this includes the uterus, ovaries, and fallopian tubes; in males, the prostate gland, seminal vesicles, and part of the vas deferens.

The Crucial Role of Bony Landmarks

Bony landmarks serve as essential reference points within the abdominopelvic cavity. These palpable and visually identifiable features on the skeletal framework offer invaluable guidance during physical examinations, diagnostic imaging, and surgical procedures.

Palpation, the process of examining the body by touch, relies heavily on bony landmarks to locate underlying structures and identify potential abnormalities.

For example, the location of the appendix can be approximated by identifying McBurney's point, which is defined in relation to the anterior superior iliac spine (ASIS).

In radiology, bony landmarks are used to accurately position patients for imaging studies such as X-rays, CT scans, and MRIs. This ensures that the targeted anatomical regions are properly visualized.

During surgical interventions, a precise understanding of bony landmarks is critical for guiding incisions, accessing specific organs, and avoiding damage to surrounding structures.

Thesis Statement: A Guide to Bony Anatomy

This guide aims to provide a comprehensive overview of the key bony landmarks of the abdominopelvic region. We will explain their anatomical locations, clinical significance, and practical applications.

By mastering these foundational concepts, healthcare professionals and students can enhance their understanding of regional anatomy. They can improve their diagnostic accuracy and refine their clinical skills in this vital area of the human body.

The previous discussion established the abdominopelvic cavity's significance and the utility of bony landmarks for clinical understanding. Now, we delve into the skeletal foundation upon which this cavity is built. It's imperative to first grasp the anatomy of the bones themselves. Only then can we proceed to identify the landmarks they bear, and their clinical relevance.

Foundation: The Bony Structures of the Abdominopelvic Region

The abdominopelvic cavity, as its name suggests, is not defined by a single bone, but rather by a constellation of skeletal elements working in concert. The pelvis takes center stage. But the sacrum, coccyx, and even a single lumbar vertebra (L5) play crucial supporting roles. Understanding these bones and their relationships is paramount to navigating this complex anatomical region.

The Pelvis: Definition and Overall Function

The pelvis is a basin-shaped structure located at the base of the spine. It connects the trunk to the lower limbs. Its primary functions can be broadly categorized into three key areas:

• Protection: The bony walls of the pelvis safeguard the delicate organs within the pelvic cavity, including the bladder, rectum, and reproductive organs.

• Weight-bearing: The pelvis transmits the weight of the upper body to the lower limbs, ensuring efficient and balanced locomotion.

• Muscle Attachment: Numerous muscles originate from or insert onto the pelvis. These muscles facilitate movement of the trunk and lower extremities.

  You also like

  Energy Graph Secrets: Spot Nonspontaneous Reactions!

The Three Main Bones of the Pelvis

The pelvis is not a single bone but is formed by the fusion of three distinct bones during development:

• Ilium: The ilium is the largest and most superior of the three bones. It forms the upper portion of the "hip bone". Its broad, wing-like structure provides extensive surface area for muscle attachment.

• Ischium: The ischium forms the posteroinferior part of the hip bone. It is characterized by the ischial tuberosity, a prominent bony landmark crucial for weight-bearing when sitting.

• Pubis: The pubis forms the anterior and inferior portion of the hip bone. It articulates with the pubis of the opposite side at the pubic symphysis.

Articulations of the Pelvis

The pelvis articulates with other skeletal structures at two key locations:

• Sacroiliac Joint (SI Joint): This joint connects the ilium of the pelvis to the sacrum, a triangular bone at the base of the spine. The sacroiliac joints are strong, weight-bearing joints that allow for limited movement. They play a crucial role in shock absorption and stability.

• Pubic Symphysis: This is a cartilaginous joint located at the midline of the pelvis. It connects the left and right pubic bones. The pubic symphysis provides stability to the anterior pelvis. It also allows for slight movement, particularly during childbirth.

Sacrum and Coccyx: Posterior Wall of the Pelvis

The sacrum and coccyx form the posterior wall of the pelvic cavity. They contribute to its structural integrity.

The sacrum is a large, triangular bone formed by the fusion of five vertebrae. It articulates with the ilium at the sacroiliac joint. This connection forms a crucial link between the spine and the pelvis.

The coccyx, or tailbone, is a small, triangular bone located at the inferior end of the sacrum. It is formed by the fusion of several rudimentary vertebrae. While small, the coccyx serves as an attachment point for various ligaments and muscles of the pelvic floor.

Bones as the Cavity's Framework

The bony framework of the pelvis, sacrum, and coccyx provides the essential architecture for the abdominopelvic cavity. This robust framework protects the internal organs, supports weight-bearing, and provides attachment points for muscles that govern movement. Without this solid foundation, the function and integrity of the abdominopelvic region would be severely compromised.

The Abdominal Contribution: L5 Vertebra

While the lumbar spine primarily resides within the abdominal region, the L5 vertebra holds a unique position. Its inferior aspect forms a functional border with the abdominopelvic cavity. Clinically, understanding the L5 vertebra's relationship to the sacrum and iliac crest is critical. It will allow the physician to perform spinal procedures, and diagnose lower back pain.

Ilium Unveiled: Key Bony Landmarks

The previous discussion established the abdominopelvic cavity's significance and the utility of bony landmarks for clinical understanding. Now, we delve into the skeletal foundation upon which this cavity is built. It's imperative to first grasp the anatomy of the bones themselves. Only then can we proceed to identify the landmarks they bear, and their clinical relevance.

The ilium, the largest and uppermost of the three bones that fuse to form the pelvis, presents a wealth of palpable and visually identifiable landmarks crucial for medical professionals. These landmarks serve as guides for various clinical procedures, diagnostic assessments, and an understanding of the underlying anatomy.

Iliac Crest: The Superior Border

The iliac crest forms the superior border of the ilium. It is a long, curved ridge that extends from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS).

This prominent ridge is easily palpable through the skin, making it a readily accessible landmark.

Clinical Significance

The iliac crest holds considerable clinical significance. It serves as a common site for bone marrow aspiration, a procedure used to collect bone marrow samples for diagnostic purposes.

The iliac crest also functions as a crucial landmark for spinal anesthesia and other regional nerve blocks.

Its height corresponds approximately to the level of the L4 vertebra, a vital reference point for lumbar punctures.

Anterior Superior Iliac Spine (ASIS): A Palpable Point

The Anterior Superior Iliac Spine, or ASIS, is a prominent projection located at the anterior end of the iliac crest.

It's easily palpable and serves as a critical reference point on the anterior aspect of the pelvis.

Importance

The ASIS is not only a readily identifiable bony landmark, but also a vital attachment site for several muscles and ligaments.

The inguinal ligament, a crucial structure in the groin region, attaches to the ASIS.

Certain abdominal muscles, such as the sartorius, also originate from this bony prominence.

Anterior Inferior Iliac Spine (AIIS): Muscle Attachment Site

Located just inferior to the ASIS, the Anterior Inferior Iliac Spine (AIIS) is another important landmark on the ilium.

While not as easily palpable as the ASIS, the AIIS plays a significant role as a muscle attachment site.

Role as an Attachment Site

The AIIS serves as the origin point for the rectus femoris, one of the primary quadriceps muscles responsible for knee extension and hip flexion.

Its location and function highlight the ilium's crucial role in lower limb movement.

Posterior Superior Iliac Spine (PSIS): Superficial Landmark

The Posterior Superior Iliac Spine (PSIS) is located at the posterior end of the iliac crest. It is often visible as a dimple in the skin, particularly in leaner individuals.

Clinical Relevance

The PSIS, while seemingly subtle, has clinical relevance. It serves as a superficial landmark for identifying the sacroiliac joint.

Pain referred from the sacroiliac joint may be localized near the PSIS, making its palpation important in clinical assessment.

Posterior Inferior Iliac Spine (PIIS): The Inferior Partner

Inferior to the PSIS lies the Posterior Inferior Iliac Spine (PIIS). This landmark marks the inferior aspect of the ilium posteriorly.

Relationship to Sacroiliac Joint

The PIIS is situated close to the sacroiliac joint. Its location is critical for understanding the anatomy of this articulation.

The PIIS, in conjunction with the PSIS, provides valuable information about the orientation and potential dysfunction of the sacroiliac joint.

Ilium: Bone Features

The ilium is characterized by a large, wing-like structure called the ala or wing of the ilium.

This broad surface provides extensive areas for muscle attachment. It is also the location of the iliac fossa, a shallow depression on the medial surface.

Understanding the ilium's features, including its crest, spines, and fossa, is essential for comprehending its biomechanical role in weight-bearing, locomotion, and overall structural support.

Iliac landmarks provide crucial reference points, but the pelvic story doesn’t end there. Moving inferiorly and posteriorly, we encounter the ischium, another vital component of the pelvic bone. Its distinct bony features play a pivotal role in supporting our weight and facilitating muscle attachments, particularly in the lower limbs. The ischium also features a significant obstetrical landmark.

Ischium's Identity: Landmarks of Support and Attachment

The ischium, one of the three bones that fuse to form the os coxae (hip bone), is characterized by two prominent landmarks: the ischial tuberosity and the ischial spine. These features are indispensable for understanding weight distribution, muscle function, and certain aspects of childbirth.

Ischial Tuberosity: The "Sitting Bone"

The ischial tuberosity is a large, rounded eminence that forms the most inferior part of the ischium.

It is located at the posterolateral aspect of the pelvic outlet.

Weight-Bearing Significance

Perhaps the most well-known function of the ischial tuberosity is its role in weight-bearing.

When seated, the majority of our body weight is concentrated on these two bony prominences, earning it the moniker "sitting bone."

This weight-bearing function is facilitated by the bursa (fluid-filled sac) located between the tuberosity and the overlying gluteus maximus muscle, which reduces friction during movement and prolonged sitting.

Muscle Attachment Site

In addition to its weight-bearing role, the ischial tuberosity serves as a major attachment site for several important muscles, including:

• Hamstring muscles (biceps femoris, semitendinosus, and semimembranosus): These muscles are responsible for knee flexion and hip extension.

• Adductor magnus: This powerful muscle adducts and extends the hip.

• Sacrotuberous ligament: This strong ligament connects the sacrum to the ischial tuberosity, contributing to pelvic stability.

The convergence of these muscular and ligamentous attachments highlights the ischial tuberosity's crucial role in lower limb movement and pelvic stability.

Ischial Spine: Obstetrical Landmark

The ischial spine is a sharp, triangular projection that arises from the posterior border of the ischium, near the junction of the ilium and ischium.

It projects medially into the pelvic cavity.

Role in Obstetrics and Gynecology

The ischial spine is a critical landmark in obstetrics and gynecology.

During labor, the station of the fetal head is assessed relative to the ischial spines.

The spines represent zero station, indicating that the fetal head has reached the mid-pelvis.

A negative station indicates that the fetal head is above the ischial spines, while a positive station indicates that it is below.

This assessment is essential for monitoring the progress of labor and determining the need for intervention.

Landmark for Nerve Blocks

The ischial spine is also used as a landmark for pudendal nerve blocks, a common technique for providing pain relief during childbirth or for treating chronic pelvic pain.

The pudendal nerve, which provides sensation to the perineum, can be anesthetized near the ischial spine, effectively blocking pain signals in the region.

Ischium Overview: Understanding Position

In summary, the ischium is a foundational bone in the pelvis, critically positioned to support weight and facilitate lower limb movement.

Its landmarks—the ischial tuberosity and ischial spine—serve as key reference points for understanding anatomy, diagnosing conditions, and guiding clinical procedures.

The ischial tuberosity's robust structure makes it ideal for weight-bearing and muscle attachment, while the ischial spine is invaluable in obstetrical assessments and pain management.

Together, these landmarks highlight the ischium's integral role in the structure and function of the abdominopelvic region.

Moving anteriorly, the focus shifts to the pubis, a bone that meets its counterpart at the midline to form the anterior aspect of the pelvic ring. This region, though smaller than the ilium or ischium, plays a critical role in pelvic stability and provides essential attachment points for muscles crucial to both movement and core stability. The pubis presents its own set of distinct landmarks that are vital for understanding pelvic function and diagnosing certain clinical conditions.

Pubis Points: Stability and Attachment

The pubis, also known as the pubic bone, is one of the three bony components that fuse to form the acetabulum and the os coxae (hip bone). Situated anteriorly and medially, it contributes significantly to the integrity of the pelvic girdle. Key landmarks on the pubis, including the pubic symphysis, pubic crest, and pubic tubercle, are not only palpable but also serve as crucial sites for muscle and ligament attachments, impacting pelvic stability and influencing movement patterns of the lower limbs and trunk.

Pubic Symphysis: The Midline Joint

The pubic symphysis is a cartilaginous joint that sits at the midline of the body, where the left and right pubic bones meet. This amphiarthrodial joint, characterized by a fibrocartilaginous interpubic disc, allows for limited movement, primarily acting as a shock absorber and providing flexibility during activities like walking and running.

During pregnancy, the hormone relaxin causes increased laxity of the ligaments surrounding the pubic symphysis, increasing its mobility to facilitate childbirth. This increased mobility, however, can sometimes lead to pain and instability, a condition known as symphysis pubis dysfunction (SPD).

The pubic symphysis is vital for pelvic stability, resisting forces that would otherwise cause separation of the anterior pelvis. It plays a crucial role in distributing weight and forces between the lower limbs and the trunk.

Pubic Crest: Muscle Attachments

Extending laterally from the pubic symphysis on each pubic bone is the pubic crest, a raised bony ridge that serves as a significant attachment site for several abdominal muscles.

These muscles include the rectus abdominis, obliquus externus abdominis, and transversus abdominis.

The pubic crest provides a firm anchor point that allows these muscles to effectively contribute to trunk flexion, rotation, and stabilization of the abdominal wall.

The integrity and strength of these muscle attachments are essential for core stability and proper posture. Any injury or weakness in these muscles can lead to lower back pain, pelvic instability, and impaired movement patterns.

Pubic Tubercle: Inguinal Landmark

Located laterally and inferiorly to the pubic crest, the pubic tubercle is a small, prominent bony projection on the anterior surface of the pubic bone.

Its significance lies in its role as the primary attachment point for the inguinal ligament, a crucial structure that spans from the anterior superior iliac spine (ASIS) to the pubic tubercle.

The inguinal ligament forms the base of the inguinal canal, a passageway through which structures such as the spermatic cord (in males) or the round ligament of the uterus (in females) and blood vessels pass.

The pubic tubercle is a key landmark for identifying the location of the inguinal canal.

Palpation of the pubic tubercle is a common clinical technique used to assess for inguinal hernias, where abdominal contents protrude through a weakened area in the abdominal wall near the inguinal canal.

Pubis: A Keystone of the Pelvic Ring

In summary, the pubis bone, although relatively small, is an integral component of the pelvic girdle. It provides critical anterior stability, contributes to the formation of the acetabulum, and serves as a vital anchor point for muscles essential to abdominal and lower limb function. Understanding the anatomy and clinical significance of the pubic symphysis, pubic crest, and pubic tubercle is essential for healthcare professionals in diagnosing and managing a wide range of musculoskeletal and pelvic conditions. The pubis plays a crucial role in distributing forces, supporting movement, and protecting vital structures within the abdominopelvic cavity.

The Acetabulum: Where Bones Connect

Having journeyed through the individual landmarks of the ilium, ischium, and pubis, it’s time to appreciate how these distinct structures converge to create a pivotal element of the abdominopelvic region: the acetabulum. This deep, hemispherical socket represents the functional heart of the hip joint, dictating the range and stability of the lower limb.

Acetabulum: The Hip Socket Defined

The acetabulum, quite literally translating to "vinegar cup" in Latin (a testament to its cup-like shape), is the deep, hemispherical socket located on the lateral aspect of the pelvis. It serves as the articulation point for the head of the femur, thereby forming the hip joint. Its primary function is to provide a stable and congruent articulation surface, allowing for a wide range of motion while maintaining joint integrity.

A Tripartite Structure: Ilium, Ischium, and Pubis

What makes the acetabulum particularly interesting is its formation. It's not a feature of a single bone, but rather a fusion of all three pelvic bones: the ilium, ischium, and pubis.

• Approximately two-fifths of the acetabulum is formed by the ilium, contributing to its superior and posterior aspects.
• The ischium contributes to another two-fifths, forming the posterior and inferior portions of the socket.
• Finally, the pubis forms the remaining one-fifth, contributing to the anterior aspect.

This collaborative construction underscores the interdependence of these bones in ensuring the structural integrity and biomechanical efficiency of the hip joint. The point where these three bones fuse within the acetabulum is marked by the triradiate cartilage which fuses during adolescence.

Functionality: Stability and Mobility

The acetabulum's depth is crucial for hip joint stability. A deep socket provides greater bony coverage of the femoral head, reducing the risk of dislocation. However, this depth must be balanced with the need for mobility.

The acetabular labrum, a fibrocartilaginous rim attached to the acetabular rim, further deepens the socket and provides a seal, enhancing joint stability and contributing to the negative intra-articular pressure that helps hold the femoral head in place.

Having examined the individual bones that constitute the abdominopelvic region, from the expansive ilium to the weight-bearing ischium and the connecting pubis, we now turn our attention to the clinical significance of these bony landmarks. Their importance extends far beyond anatomical study; they serve as vital guides in medical examinations, procedures, diagnosis, and treatment.

Clinical Compass: Clinical Significance of Bony Landmarks

The bony landmarks of the abdominopelvic region are not mere surface features. They are fundamental reference points for navigating the complexities of the human body. Their precise knowledge allows healthcare professionals to accurately locate internal structures, perform targeted interventions, and diagnose a wide range of conditions.

Bony Landmarks in Medical Examinations and Procedures

Palpation, the art of examining the body by touch, relies heavily on the identification of bony landmarks. The iliac crest, for instance, is routinely palpated to estimate the level of the L4 vertebra during spinal anesthesia or lumbar puncture.

Similarly, the anterior superior iliac spine (ASIS) serves as a key reference point for measuring leg length discrepancy and assessing pelvic alignment.

The ischial tuberosities are essential landmarks for determining proper seating posture and preventing pressure sores in individuals with limited mobility.

In surgical procedures, bony landmarks provide crucial guidance for incisions, minimizing the risk of damaging underlying structures. The pubic tubercle, for example, helps surgeons locate the inguinal canal during hernia repairs.

Clinical Conditions Associated with Bony Landmarks

Many clinical conditions manifest with pain, tenderness, or deformities related to specific bony landmarks. Iliac crest pain syndrome, for example, involves pain and inflammation at the iliac crest, often due to overuse or direct trauma.

Ischial bursitis, also known as "weaver's bottom," causes pain and tenderness around the ischial tuberosity, commonly seen in individuals who sit for prolonged periods.

Osteitis pubis, an inflammation of the pubic symphysis, can cause groin pain and tenderness at the pubic crest, frequently observed in athletes.

Furthermore, fractures of the pelvis, especially those involving the acetabulum, can significantly disrupt the biomechanics of the hip joint, leading to chronic pain and disability. Understanding the anatomy of these bony structures is crucial for accurate diagnosis and effective management of these conditions.

Bony Landmarks in Diagnosis and Treatment Planning

The precise location and orientation of bony landmarks are invaluable for interpreting imaging studies such as X-rays, CT scans, and MRIs. These landmarks help radiologists and clinicians accurately assess the alignment of the pelvis, identify fractures or dislocations, and evaluate the extent of soft tissue injuries.

In treatment planning, bony landmarks guide the placement of injections, nerve blocks, and other interventions. For instance, the ischial spine serves as a critical landmark for pudendal nerve blocks, which are used to manage chronic pelvic pain and perineal pain.

Moreover, understanding the relationships between bony landmarks and surrounding structures is essential for rehabilitation programs. Therapists use these landmarks to assess muscle imbalances, improve joint mobility, and restore optimal function after injury or surgery.

In essence, mastery of abdominopelvic bony landmarks transforms from theoretical knowledge into a practical toolkit. This toolkit is vital for healthcare practitioners committed to precision, safety, and effective patient care.

Having examined the individual bones that constitute the abdominopelvic region, from the expansive ilium to the weight-bearing ischium and the connecting pubis, we now turn our attention to the clinical significance of these bony landmarks. Their importance extends far beyond anatomical study; they serve as vital guides in medical examinations, procedures, diagnosis, and treatment.

Seeing is Believing: Visual Guide and Palpation Techniques

The study of anatomy, particularly when it involves intricate bony structures, is greatly enhanced by visual learning. Combining visual resources with hands-on palpation solidifies understanding and builds confidence in clinical settings.

A thorough grasp of the skeletal framework, particularly the abdominopelvic region, hinges on the ability to both visualize and physically locate key landmarks.

The Power of Visual Learning in Anatomy

Visual aids are indispensable tools in anatomical education. Detailed anatomical charts, 3D models (both physical and digital), and medical imaging (radiographs, CT scans, MRIs) provide invaluable spatial context.

These resources allow learners to build a mental map of the abdominopelvic region, layering the bony framework with its associated musculature, vasculature, and nervous structures.

Visual learning bridges the gap between theoretical knowledge and practical application, facilitating a deeper and more lasting comprehension of anatomical relationships.

Palpation: The Art of Anatomical Touch

While visual learning provides a crucial foundation, palpation brings anatomy to life. Palpation is the skill of using touch to identify and assess anatomical structures through the skin.

It allows healthcare professionals to directly interact with the body, confirming their visual understanding and developing a keen sense of anatomical variation.

Palpating the Anterior Superior Iliac Spine (ASIS)

The ASIS is a readily palpable landmark, making it an ideal starting point for learning palpation techniques in the abdominopelvic region.

Technique:

1. Position the patient supine (lying on their back).

2. Locate the iliac crest, the superior border of the ilium.

3. Slide your fingers anteriorly along the iliac crest until you feel a distinct bony prominence – this is the ASIS.

4. Confirm your location by asking the patient to flex their hip against resistance; you should feel the sartorius muscle contract, originating near the ASIS.

Palpating the Iliac Crest

The iliac crest, the superior border of the ilium, is another prominent and easily accessible bony landmark.

Technique:

1. Position the patient either supine or standing.

2. Place your hands on the patient's lateral abdomen.

3. Palpate along the curved, upper edge of the pelvis. The entire length of the iliac crest is usually palpable, though the amount of subcutaneous tissue will change how it feels on examination.

4. The iliac crest is often used as a landmark for injecting medications or drawing bone marrow, so becoming familiar with palpating it is important.

Palpating the Ischial Tuberosity

The ischial tuberosity, often referred to as the "sitting bone," can be palpated in the gluteal region.

Technique:

1. Position the patient prone (lying on their stomach) or in a seated position with their knees flexed.

2. Locate the inferior border of the gluteus maximus muscle.

3. Palpate deeply in the gluteal region, just inferior to the gluteus maximus, until you feel a firm, bony prominence – this is the ischial tuberosity.

4. It may be more difficult to palpate when the patient is standing or sitting with extended knees due to the gluteus maximus covering the ischial tuberosity more completely.

Video: Abdominopelvic Bones: Master Anatomy with This Visual Guide

Play Video