DIMS Lectures Pelvic Anatomy PDF

Here is the complete pdf lecture of pelvic anatomy by Dr. Tahir Malik

Introduction to Pelvic Anatomy

The pelvis is a vital anatomical region that plays a crucial role in support, movement, reproduction, and internal organ protection. Understanding its structure is essential for medical students, especially those interested in orthopedics, gynecology, urology, and surgery.

The pelvis serves as the junction between the trunk and lower limbs, supporting the weight of the upper body while enabling movement and providing protection to vital internal organs, including the reproductive and urinary systems.

Bones of the Pelvis

The pelvic girdle consists of four bones:

Ilium – The largest and uppermost portion of the pelvis.
Ischium – The lower and posterior part of the pelvis, forming the sitting bones.
Pubis – The anterior part of the pelvis, forming the pubic symphysis.
Sacrum and Coccyx – Part of the axial skeleton, forming the posterior wall of the pelvis.

Features of the Pelvic Bones

Acetabulum – The socket for the femoral head, forming the hip joint.
Obturator Foramen – A large opening that allows the passage of nerves and blood vessels.
Pelvic Inlet and Outlet – Define the birth canal in females.
Greater and Lesser Sciatic Notches – Passage for important neurovascular structures.

Joints of the Pelvis

Sacroiliac Joint – Connects the sacrum to the ilium, transferring weight from the spine to the lower limbs.
Pubic Symphysis – A cartilaginous joint that provides slight movement for flexibility and shock absorption.
Hip Joint (Acetabulofemoral Joint) – A ball-and-socket joint that allows mobility of the lower limb.

Muscles of the Pelvic Region

The pelvic muscles are divided into two groups:

1. Pelvic Floor Muscles (Supportive Muscles)

These muscles form the pelvic diaphragm, supporting the pelvic organs:

Levator Ani Group: Includes puborectalis, pubococcygeus, and iliococcygeus, responsible for bowel and urinary continence.
Coccygeus Muscle: Assists in supporting the pelvic organs.

2. Pelvic Wall Muscles (Locomotor Muscles)

Obturator Internus – Lateral rotation of the thigh.
Piriformis – Lateral rotation and stabilization of the hip joint.
Iliopsoas – Composed of psoas major and iliacus, responsible for hip flexion.

Nerve Supply of the Pelvis

Pelvic structures receive innervation from two major plexuses:

Lumbar Plexus (L1-L4): Provides motor and sensory innervation to the lower limb.
Sacral Plexus (L4-S4): Gives rise to important nerves:
- Sciatic Nerve – Largest nerve, supplying the lower limb.
- Pudendal Nerve – Responsible for sensory and motor control of perineal structures.
- Inferior Gluteal Nerve – Innervates gluteus maximus for hip extension.

Blood Supply of the Pelvis

The pelvis receives blood supply primarily from the internal iliac artery, which gives rise to:

Superior and Inferior Gluteal Arteries – Supply the gluteal muscles.
Obturator Artery – Supplies the medial thigh and pelvic wall.
Uterine Artery (in females) – Supplies the uterus.
Prostatic Branches (in males) – Supply the prostate gland.

Clinical Relevance

Common Pelvic Disorders and Conditions

Pelvic Fractures – High-energy trauma, common in motor vehicle accidents.
Pelvic Organ Prolapse – Weakening of pelvic floor muscles leading to organ descent (common in multiparous women).
Hip Dislocation – Usually posterior, often due to trauma.
Piriformis Syndrome – Compression of the sciatic nerve by the piriformis muscle, leading to buttock and leg pain.
Pudendal Neuralgia – Chronic pelvic pain due to pudendal nerve entrapment.
Obstetric-Related Conditions:
- Cephalopelvic Disproportion (CPD): When the fetal head is too large for the birth canal.
- Pelvic Floor Dysfunction: Includes stress urinary incontinence and fecal incontinence.

Case Example:

A 40-year-old male is brought to the emergency department after a high-impact road traffic accident (RTA). He complains of severe lower abdominal and pelvic pain, along with inability to move his legs properly. His vitals show BP: 90/60 mmHg, HR: 130 bpm, and he appears pale. On examination, there is tenderness and bruising over the pelvis, with an unstable pelvic girdle upon gentle palpation. Blood is noted at the urethral meatus, and a high-riding prostate is detected on digital rectal examination.