Lecture 23: Gluteal Region and Posterior Thigh Flashcards
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
what is the orientation of the pelvis?
tilted anteriorly so that ASIS is in the same plane as the symphysis pubis!
what does pelvis comprise?
- Pelvis comprises of 2 hip
bones ( ischium, ilium,
pubis) + the sacrum +
coccyx
need to know these
what ligaments hold the pelvis together?
-sacrospinous
-sacrotuberous(continuous with the posterior
sacroiliac ligament )
what does the crossing over of the sacrospinous and sacrotuberous ligaments form?
greater and lesser sciatic foramina
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)
the lesser sciatic foramen function
Is the passageway for structures
entering or leaving the perineum.
e.g. Pudendal Nerve (supplies groin
region)
Gluteal muscles
Glut max
Med
Min
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
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
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
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)
obturator internus: O, I, Nerve, Action
O: obturator foramen and membrane
I: greater trochanter
Action: externally rotates thigh
Nerve: nerve to OI (sacral plexus)
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)
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
