Lecture 23: Gluteal Region and Posterior Thigh Flashcards by Sofya Silina

gluteal region boundaries

The gluteal region lies:
* Posterior to the pelvis
* Bounded superiorly by the iliac crests
* Inferiorly by the gluteal sulcus created by the Gluteus Maximus muscles

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what is the orientation of the pelvis?

tilted anteriorly so that ASIS is in the same plane as the symphysis pubis!

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what does pelvis comprise?

Pelvis comprises of 2 hip
bones ( ischium, ilium,
pubis) + the sacrum +
coccyx

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need to know these

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what ligaments hold the pelvis together?

-sacrospinous
-sacrotuberous(continuous with the posterior
sacroiliac ligament )

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what does the crossing over of the sacrospinous and sacrotuberous ligaments form?

greater and lesser sciatic foramina

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the greater sciatic foramen function

Allows passage to all the lower limb
arteries and nerves OUT from the
pelvis and into the gluteal region e.g.Sciatic Nerve
(7 nerves, 3 arteries, 1
muscle)

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the lesser sciatic foramen function

Is the passageway for structures
entering or leaving the perineum.
e.g. Pudendal Nerve (supplies groin
region)

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Gluteal muscles

Glut max
Med
Min

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Gluteus maximus: O, I, Nerve, Action

O: superior portion of illium & sacrotuberous lig( + posterior sacrum, coccyx)

I: ITB, gluteal tuberosity of femur

Action: extends and laterally rotates thigh
Extends hip - Critical for going from sitting
to standing up

Nerve: inferior gluteal n ( L5, S1, S2 from sacral plexus)
Artery: inferior gluteal a

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gluteus medius : O, I, Nerve, Action

O: posterior surface of illium
I: greater trochanter of femur
Action: abducts and internally rotates thigh + steadies pelvis when walking
Nerve: superior gluteal nerve( L4, L5, S1)
Artery: superior gluteal a

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gluteus minimus: O, I, Nerve, Action

O: posterior surface of illium
I: greater trochanter of femur
Action: abducts and internally rotates thigh
Nerve: superior gluteal nerve( L4, L5, S1)
Artery: superior gluteal a

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piriformis: O, I, Nerve, Action

VERY IMPORTANT IN HAL(PST)

O: anterior surface of sacrum, sacrotuberous lig
I: greater trochanter
Action: externally rotates thigh
Nerve: sacral plexus

(exits pelvis via greater sciatic foramen)

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obturator internus: O, I, Nerve, Action

O: obturator foramen and membrane
I: greater trochanter
Action: externally rotates thigh
Nerve: nerve to OI (sacral plexus)

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superior and inferior gemelli: O, I, Nerve, Action

O: ischial spine( s) and ischial tuberosity(i)
I: greater trochanter
Action: externally rotate thigh
Nerve: nerve to OI (s), nerve to QF(i)

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quadratus femoris: O, I, Nerve, Action

O: ischial tuberosity
I: quadrate tubercle( intertrochanteric creast of femur)
Action: externally rotates thigh
Nerve: nerve to QF( sacral plexus)

tensor fascia lata: O, I, Nerve, Action

O: ASIS, iliac creast
I: ITB
Action: abducts thight, dynamis stabilizer
Nerve: superior gluteal

gluteus medius, minimus, TFL function

Function - Abductors of thigh - that function
to stabilize pelvis when walking
When raising leg to take a step, weight of
body shifts to standing leg. To prevent pelvis
tilting to side of raised leg the opposite side
abductors need to be very powerful

posterior thigh muscles

-biceps femoris
-semitendinosus
-semimebranosus
-adductor magnus

biceps femoris: O, I, Nerve, Action

O: Long head: ischial tuberosity. Short head: posterior femur( linea aspera)
I: head of fibula
Action: Dynamic support for lateral side of knee = important for knee stability. Flexes and externally rotates the leg at knee, extends thigh at hip.
Nerve: Sciatic:
long head: tibial.
Short: peroneal( L4-S2)

semitendinosus : O, I, Nerve, Action

O: ischial tuberosity
I: superior part of medial tibia( pens anserinus)
Nerve: sciatic( tibial n) L5, S1, S2
Action: flexes and internally rotates leg, extends thigh

semimebranosus: O, I, Nerve, Action

O: ischial tuberosity
I: medial condyle of tibia
Nerve: sciatic nerve( tibial n) L5, S1, S2
Action: flexes and internally rotates leg, extends thigh

adductor magnus-hamstring part:
O, I, Nerve, Action

O:
hamstring part: ischial tuberosity
adductor part: inferior pubic ramus
I: adductor tubercle on femur.
Nerve: sciatic( tibial n)
Action: extends thigh

what is the importance of periformis as a landmark

Arteries and nerves arising above piriformis
= superior gluteal A+N
Arteries and nerves arising below piriformis
= inferior gluteal A+N+ Sciatic

nerves of the gluteal region

* Nerves to gluteal region are from sacral plexus (L4-S4) * Superior gluteal nerve(L4, L5, S1) supplies gluteus medius and minimus * Inferior gluteal nerve(L5, S1, S2) supplies gluteus maximus * Other muscles have own nerves (quad femoris, obturator internus, piriformis) * Post femoral cutaneous n S1-3. supplies skin of lower buttock and post compartment of thigh * Sciatic N (L4,5,S1,2,3) has no branches in gluteal region * Pudendal nerve supplies perineal structures

vessels of the gluteal region. Where do they arise from?

* The gluteal arteries arise from the Internal Iliac Arteries * The Superior and Inferior Gluteal arteries leave the pelvis through the Greater Sciatic Foramen and, along with their corresponding nerves, pass superior and inferior to Piriformis * The Internal Pudendal Artery also leaves the pelvis via the Greater Sciatic Foramen, but then hooks around the Ischial spine to enter the pelvis via the Lesser Sciatic Foramen * The Superior and Inferior Gluteal Arteries anastomose then further anastomose with the circumflex arteries (branches of the Profunda Femoris that supply femoral head)

where is it safe to give intra-gluteal injections?

* The gluteal region is a common site for intra-muscular injections as it provides a large muscular area for venous absorption. * With respect to the Sciatic nerve, the buttock has a ‘safe’ side; the lateral side. * The safe area to give these injections is therefore the superolateral part of the buttock.( upper lateral quadrant) *cannot inject into the upper medial quadrant because sometimes the sciatic nerve can emerge superior to periformis( or tibial and peroneal part can be split up)

Clinical Applications -Trendelenburg Gait

* Gluteus Medius has an important role in pelvic stabilization, particularly when walking. * Injury to this muscle (or the the Superior Gluteal Nerve) results in a characteristic stance and gait pattern. Thigh abduction on the affected side is weakened and the resulting gait is referred to as a Gluteal or Trendenlenburg gait * When asked to stand on one leg, Gluteus Medius usually contracts to support the pelvis and stop it from tilting to the lifted side. * When a person with a non-functioning Gluteus Medius stands on the affected leg, the pelvis will tilt down on the unaffected side (the ‘sound side sags’). * As this person walks, to clear the leg on the unaffected side they must lean over to the side with the Glut Med insufficiency- giving the characteristic Trendelenburg gait.

Clinical Applications: Avulsion of insertion of gluteus medius

-snapped tendon -muscle not used= becomes fatty degenerated ->abnormal gate

Clinical Applications- Hamstring Injuries( causes, what happens)

* Usually due to kicking or running sports. * Hamstring injuries can be muscle strains or tears or can avulse the ischial tuberosity completely. * Rx conservative or surgery