Gluteal region
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Topographic Anatomy of the Gluteal Region


The *gluteal region* is located posteriorly, between the iliac crests superiorly and the gluteal fold inferiorly. It forms the bulk of the buttocks and plays a key role in locomotion and posture, involving powerful muscles, neurovascular structures, and bony landmarks.


*1. Skeletal Framework*


The skeletal foundation of the gluteal region includes parts of the pelvis, sacrum, and femur:

1. *Ilium*:

  - *Iliac crest*: Forms the upper boundary of the gluteal region.

  - *Anterior superior iliac spine (ASIS)*: Found anteriorly, an important landmark for muscle attachment.

  - *Posterior superior iliac spine (PSIS)*: Found posteriorly and marked by skin dimples in the lower back.

 

2. *Ischium*:

  - *Ischial tuberosity*: The bony prominence that serves as a weight-bearing structure when sitting and an attachment site for muscles.

 

3. *Sacrum*:

  - *Sacral hiatus*: An important landmark for the sacroiliac joint and attachment of ligaments.


4. *Femur*:

  - *Greater trochanter*: Located laterally, an important bony landmark for muscle attachments in the hip joint.


2. Muscles of the Gluteal Region*

The gluteal region contains several powerful muscles, divided into *superficial* and *deep* layers, responsible for the movement of the hip joint, including extension, abduction, and external rotation.


Superficial Muscles*:

1. *Gluteus Maximus*:

  - *Origin*: Ilium, sacrum, coccyx, and sacrotuberous ligament.

  - *Insertion*: Iliotibial tract and gluteal tuberosity of the femur.

  - *Function*: Extends and externally rotates the thigh, assists in rising from a seated position and climbing stairs.

  - *Innervation*: Inferior gluteal nerve.


2. *Gluteus Medius*:

  - *Origin*: Outer surface of the ilium.

  - *Insertion*: Greater trochanter of the femur.

  - *Function*: Abducts and medially rotates the thigh, stabilizes the pelvis during walking.

  - *Innervation*: Superior gluteal nerve.


3. *Gluteus Minimus*:

  - *Origin*: Outer surface of the ilium, below the origin of the gluteus medius.

  - *Insertion*: Greater trochanter of the femur.

  - *Function*: Abducts and medially rotates the thigh, stabilizes the pelvis during walking.

  - *Innervation*: Superior gluteal nerve.


4. *Tensor Fasciae Latae*:

  - *Origin*: ASIS and anterior part of the iliac crest.

  - *Insertion*: Iliotibial tract.

  - *Function*: Stabilizes the pelvis, assists in flexion, abduction, and medial rotation of the thigh.

  - *Innervation*: Superior gluteal nerve.


#### *Deep Muscles*:


1. *Piriformis*:

  - *Origin*: Anterior surface of the sacrum.

  - *Insertion*: Greater trochanter of the femur.

  - *Function*: Externally rotates and abducts the thigh.

  - *Innervation*: Nerve to piriformis (S1-S2).


2. *Obturator Internus*:

  - *Origin*: Obturator membrane and surrounding bone.

  - *Insertion*: Greater trochanter of the femur.

  - *Function*: Externally rotates the thigh.

  - *Innervation*: Nerve to obturator internus.


3. *Superior and Inferior Gemelli*:

  - *Origin*: Superior (ischial spine), Inferior (ischial tuberosity).

  - *Insertion*: Greater trochanter of the femur.

  - *Function*: Externally rotate the thigh.

  - *Innervation*: Nerve to obturator internus (superior) and nerve to quadratus femoris (inferior).


4. *Quadratus Femoris*:

  - *Origin*: Lateral aspect of the ischial tuberosity.

  - *Insertion*: Intertrochanteric crest of the femur.

  - *Function*: Externally rotates the thigh.

  - *Innervation*: Nerve to quadratus femoris.


3. Neurovascular Structures of the Gluteal Region*


The *gluteal region* is richly supplied by nerves and vessels that pass through the greater sciatic foramen.


Nerves*:

1. *Sciatic Nerve*:

  - Largest nerve in the body, exiting the pelvis through the greater sciatic foramen, passing beneath the piriformis, and continuing down the posterior thigh.

  - *Function*: Supplies sensation and motor function to the lower extremity.


2. *Superior Gluteal Nerve*:

  - Exits through the greater sciatic foramen above the piriformis.

  - *Innervation*: Gluteus medius, gluteus minimus, and tensor fasciae latae muscles.


3. *Inferior Gluteal Nerve*:

  - Exits through the greater sciatic foramen below the piriformis.

  - *Innervation*: Gluteus maximus.


4. *Pudendal Nerve*:

  - Passes through the greater sciatic foramen, then re-enters the pelvis through the lesser sciatic foramen.

  - *Function*: Innervates structures in the perineum.


Vascular Supply*:

1. *Superior Gluteal Artery*:

  - Exits the pelvis through the greater sciatic foramen above the piriformis and supplies the gluteus medius, minimus, and tensor fasciae latae.


2. *Inferior Gluteal Artery*:

  - Exits the greater sciatic foramen below the piriformis, supplying the gluteus maximus and some of the deep gluteal muscles.


3. *Venous Drainage*:

  - Parallels the arterial supply, with veins draining into the superior and inferior gluteal veins.


4. Borders of the Gluteal Region*

- *Superior*: Iliac crest.

- *Inferior*: Gluteal fold.

- *Medial*: Sacrum and coccyx.

- *Lateral*: Greater trochanter of the femur.


*5. Important Structures and Pathways*


*Greater Sciatic Foramen*:

This foramen allows for the passage of key neurovascular structures from the pelvis to the gluteal region, including the *sciatic nerve, **superior and inferior gluteal arteries*, and associated veins and nerves.


*Lesser Sciatic Foramen*:

The pudendal nerve and internal pudendal artery re-enter the pelvis through this foramen to supply the perineum.


*Piriformis Syndrome*:

Compression or irritation of the sciatic nerve as it passes beneath the piriformis muscle can cause pain radiating down the leg, often mimicking symptoms of sciatica.


*6. Clinical Considerations*

1. *Intramuscular Injections*:

  - The *gluteus medius* is a common site for intramuscular injections, as it avoids major nerves and vessels.

2. *Sciatica*:

  - Compression of the sciatic nerve, leading to radiating pain along the course of the nerve.

3. *Piriformis Syndrome*:

  - Pain and discomfort caused by the compression of the sciatic nerve by the piriformis muscle.


Clinical correlation[edit | edit source]

Intramuscular injections are applied to the upper, outer quadrant of the gluteal landscape.