Ie the region behind the pelvis, from iliac crest to gluteal fold.
- complicated by various muscles, nerves and vessels entering the lower limb through it.
Muscles: three gluteals & deeper piriformis, obturator internus, gamelli and quadratus femoris.
Bones / ligaments: back of sacrum, hip bone, upper femur, sacrotuberous and sacrospinous ligaments.
- greater sciatic foramen formed (pl 331) above / in front by greater sciatic notch of hip bone; behind by sacrotuberous ligament, below by sacrospinous ligament.
- Lesser sciatic foramen formed (Pl 331) by lesser notch & same ligaments behind and above
Well developed.
Note the fold of the buttock is not the lower glut max border, but transverse crease of hip joint.
Blood supply from superior & inferior gluteal arteries.
Lymphatics ¨ lateral group of superficial inguinal nodes.
Cutaneous nerves are both posterior and anterior rami nerves:
- Posterior rami (lateral branches) of L1-3 slope down to supply upper buttock skin.
- Posterior rami of S1-5 all cutaneous, upper 3 ¨ natal cleft; lower 2 Coc1¨ coccyx skin.
- Ant rami of upper skin from lat cut branches of subcostal and IH (T12, L1)
- Branches of lat fem cutaneous nerve supplies lower parts of buttock (L2)
- Perforating cutaneous nerve (S2-3) and Post fem cut nerve (S2-3) ¨ lower central buttock.
- \ L3-S1 not represented in skin of buttock; their dermatomes lie peripherally in limb skin; posterior axial line is between these discontinuous dermatomes.
Largest and most superficial, large powerful fibre bundles sloping 45¡ across buttock.
Arises: Wide origin from ilium, lumbar fascia & lateral mass of sacrum & sacrotuberous ligament
Inserts: deep 1/4 ¨ posterior femur (gluteal tuberosity & down); rest 3/4 ¨ iliotibial tract.
Bursae: 3 beneath it: over ischial tuberosity, greater trochanter and vastus lateralis.
Blood: inferior and superior gluteal arteries. Veins form a plexus underneath it.
Innervation: inferior gluteal nerve (L5, S1,2; anterior division sacral plexus) (see Pl 465)
Action: lateral rotation and extension at hip jt, and supports extended knee through iliotibial tract.
- if quads paralysed, can be a weak knee extensor.
- Powerful antigravity muscle with hip and knee slightly flexed, eg sitting, standing up
- Extensor of hip in extreme movement, eg running, climbing stairs, but little in quiet walking when hamstrings do most of this work.
Test: lying down, leg straight, tighten buttock, extend hip (observe and palpate).
Arises: Ilium between middle and posterior gluteal lines (see 457)
- posterior third is covered by gluteus maximus and anterior two-thirds by thick deep fascia
Inserts: lateral surface of greater trochanter (separated by a bursa)
- inserting tendon gives a strong blend with the upper iliofemoral ligament.
Arises: ilium inferior to gluteus medius (457)
Inserts: anterior surface of greater trochanter.
Innervation: medius & minimis by superior gluteal nerve (L4,5, S1 - see 465; ant division sacral plexus)
Action: abduct hip joint and anterior fibres rotate the thigh medially (cf lat rotation of glut max and other gluteal muscles).
- contract in walking to prevent pelvic tilt as foot on other side raises in walking / running.
- ¨ Trendelenburg gait, where trunk sways side-to-side if paralysed.
Test: face down, leg flexed to right angle, turn foot out against resistance.
- and do the Trendelenburg test: stand them on one leg, pelvis on opposite side should rise slightly; if it sags the test is +ve.
Important as its structures of gluteal region are described in relation to it.
Arises: front & middle 3 pieces of sacrum ¨ passes laterally behind sacral plexus ¨ exits gr sciatic foramen (filling it) ¨ upper border runs alongside gluteus medius, lower alongside superior gemellus
Inserts: rounded tendon inserting into upper greater trochanter.
Surface marking: lower border found midway between PSIS (dimple) & tips of coccyx and GT.
Innervation: n to piriformis (anterior division os sacral plexus; S1, S2.
Action: stabilise hip jt, especially in abduction (assists other short muscles in adjusting hip position).
Arises: internal surface of lateral pelvic wall (right-angle bend around lesser sciatic notch of ischium to enter the gluteal region); (bursa separates deep surface from lesser notch which is hyaline c. -coated).
- reinforced by additional fibres below from margins of the notch, ie the gamelli.
Inserts: Blended tendons insert together into medial surface of greater trochanter above the fossa.
Nerve: n to obturator internus (L5,S1,S2)
Arises: spine of ischium.
Nerve: n to obturator internus
Arises: ischial tuberosity.
Nerve: n to quadratus femoris
(8) Quadratus Femoris (469)
Arises: ischial tuberosity, forms a rectangular muscle. (456-7)
Inserts: quadrate tubercle of femur. Separated from back of femoral neck by obturator externus.
- lies edge to edge with inferior gemellus above and adductor magnus below.
Nerve: n to quadratus femoris (L4,5,S1)
Action: together with above 3 muscles stabilises hip joint. Together laterally rotate the extended thigh.
- also abduct the extended thigh
i) Superior gluteal nerve: (L4,L5,S1) emerges from greater notch above piriformis, then disappears beneath glut medius to run b/n it and minimus (supplies both and ends in TFL).
- no cutaneous supply
ii)
Superior gluteal artery: once above piriformis divides into superficial and deep branches
-
superficial: enters
deep glut max to supply it and overlying skin
-
deep: passes
lateral b/n glut med and minimus ¨ upper and lower
branches to ASIS anastomosis and two glutei
& trochanteric anastomoses respectively.
i) Inferior gluteal nerve ¨ (L5,S1,S2) deep surface of glut max, no cutaneous supply.
ii) Inferior gluteal artery ¨ b/n piriformis and superior gemellus, muscular branches supply piriformis, obturator internus, and glut max
- anastomoses with trochanteric and cruciate anastomoses
- artery to sciatic nerve given off
- cutaneous branches ¨ buttock and back of thigh.
iii) Pudendal nerve ¨ (S2,3,4) short course in buttock, turns forward around the sacrospinous ligament (lying just medial to spine of ischium) ¨ passes back through lesser sciatic foramen to enter the pudendal canal.
iv) Internal pudendal artery ¨ similar course to nerve, lying on its lateral side.
Ð crosses tip of ischial spine; compress it to control perineal haemorrhage
Ð companion veins run on each side of the artery
v) Nerve to obturator internus ¨ (L5,S1) lies lateral to pudendal (see 469), loops around ischial spine ¨ muscle, deep fascia in side wall of ischioanal fossa. (& S gemellus).
vi) Sciatic nerve (L4,5 S1,2,3) ¨ (see 468) emerges below piriformis lateral to inferior gluteal and pudendal.
- point 1/3 way from ischial tuberosity to PSIS marks entry point of nerve into gluteal region.
- passes down over obturator internus & quadratus femoris ¨ hamstring compartment, disappearing beneath biceps femoris. Lies under glut max in buttock.
- Surface marking at top of thigh is midway b/n gr trochanter and ischial tuberosity
- Tibial (L4-S3) and common peroneal (L4-S2) components separate in upper popliteal fossa (can be higher; if very high then common peroneal may pierce piriformis)
vii) Posterior femoral cutaneous nerve (S1,2,3) ¨ (405,469) lies on sciatic, under g max.
- below buttock passes vertically down midline to back of thigh & leg as low as mid-calf. Beneath FL on hamstrings (hence separated from sciatic here)
- gluteal branches curl around lower border of glut max to skin over buttock convexity
- perineal branch winds medially forward b/n gracilis and FL to posterior part of scrotum (labia)
- shares S2,3 with parasympathetic nerves carrying pain from pelvic viscera, hence referred pain is felt at back of thigh and calf: distinguish this from sciatica.
viii) Nerve to quadratus femoris (L4,5,S1) ¨ lies deep to sciatic; over back of hip joint (gives it an articular branch), runs deep to obturator internus & gamelli ¨ quadratus
- also supplies inferior gemellus.
Supplies head of femur (along with a trickle from obturator artery through ligament of the head.
Lies near the trochanteric fossa posterosuperiorly.
Suppliers: descending branch of superior gluteal artery, ascending branches of lateral and medial circumflex femoral arteries, and usually the interior gluteal artery.
- branches pass along the neck of the femur with retinacular fibres of capsule.
At level of middle of lesser trochanter.
Suppliers: where lateral and medial circumflex femoral arteries meet
- joined by ascending branch of first perforating artery
- cross completed by descending branch of inferior gluteal artery.
Upper outer quadrant: avoids damage to sciatic nerve. Borders are iliac crest and gluteal fold.
A ball & socket (multiaxial) synovial jt.
- though stability and ROM generally are inversely proportional, hip as much of both.
- stability largely afforded by tight fit of head; mobility by long femoral neck.
Cup shaped, formed by fusion of three hip bones; covered with hyaline cartilage in a C-shape
- this is broadest above, where weight transferred while erect.
Labrum deepens the acetabulum (rim of fibrocartilage) enclosing the femoral head for stability
- is triangular in section, base attached to acetabular rim.
- Continues across acetabular notch inferiorly as the transverse ligament.
Haversian pad occupies the central non-articular part of the acetabulum.
- fovea centrally attaches ligamentum teres (l. of head) from transverse ligament and notch.
Capsule (454)
Circumferentially around labrum, and transverse ligament. Loose but very strong.
¨ Inserts into neck of femur: anteriorly to intertrochanteric line; posteriorly for half this distance.
- neck fibres are reflected back from attachments to the articular margin of the head as the retinacular fibres, these bind down nutrient arteries (mostly from trochanteric anastomosis)
- ¨ basis of avascular necrosis in subcapital NOF.
1) Iliofemoral: Anterior. Strongest. Triangular, from lower ASIS to intertrochanteric line.
- margins are thick, appears as an inverted V. Limits extension.
2) Pubofemoral: Anteroinferior. Deep to above. From superior ramus and pubic bone ¨ capsule.
3) Ischiofemoral: Posterior. Weakest. From posterior acetabulum ¨ pass laterally along capsule ¨ spiral up to blend with capsule (Òzona orbicularisÓ) \ hourglass appearance on arthrogram.
Attaches to articular margins. Lines capsule, reflects back along neck to line retinacular fibres.
- also invests the Haversian fat pad and ligament of the head in a sleeve.
- 10% communicated with the iliac bursa between a perforation b/n 2 anterior ligaments.
Iliac bursa, one under glut med & glut min, 3 under glut max (over ischial tuberosity, greater trochanter and upper vastus lateralis.
Anteriorly: Psoas major separates capsule from femoral artery; more medially pectineus lies between capsule & FV. Nerve is in a groove b/n iliacus & psoas tendons, Iliacus has a bursa under it.
Superiorly: reflected head of rectus and glut min (laterally) are in contact with capsule.
Inferiorly: obturator externus spirals below to reach femoral neck.
Posteriorly: piriformis with ob externus below it; gamelli separate sciatic nerve from capsule.
Laterally: capsule blends with iliotibial tract.
Medially: acetabular fossa (ovary adjacent internally in females), separated by obturator internus, obturator nerve and vessels, and peritoneum.
Capsule and synovium = nearby vessels
Head, intracapsular neck = trochanteric anastomosis (mostly via medial circumflex a.)
- art of lig of head of femur important in young children only; atrophies usually by age 7).
Femoral nerve via n. to rectus femoris.
Obturator nerveÕs anterior division.
Articular twigs from sciatic.
- these 3 also supply the knee, hence pain may be referred down there.
Circumduction & internal / external rotation.
Flexion: psoas, iliacus, assisted by rectus, sartorius and pectineus.
- 120o, ltd by presence of abdomen / hamstring tension. Is rotation in transverse axis.
Extension: Glut max at extremes, otherwise hamstrings.
- 20o, ltd by iliofemoral ligament.
Adduction: Rotation in AP axis, pectineus, adductors longus, brevis, magnus & the gracilis.
- ltd by other leg, or if not then by tension of glut med/min. 30o.
Abduction: Gluts med & min. Assisted by TFL and sartorius.
- limited by tension in adductors and in pubofemoral ligament to 60o.
- abductors essential in standing on one leg and walking / running
- sitting, gamelli and obturator act as abductors, eg getting out of a car.
Rotation: vertical axis through femoral head; this is not the same as the shaft axis hence trochanter moves forward in medial rotation and backwards in lateral.
- medial: ant glut med & min + TFL; restricted by lateral rotators and ischiofemoral lig. 40o.
- Lateral: piriformis, obturator internus, gamelli, quadratus femoris and obturator externus assisted by glut max & sartorius. Restricted by medial rotators and iliofemoral lig. 40o.
i) snug fit of head in labrum
ii) reinforcing ligaments, especially iliofemoral
iii) short gluteal muscles
Least stable when flexed and adducted; dislocation needs force eg MVA ¨ posterior dislocation.
Anterior: b/n sartorius and TFL, detaching TFL, rectus and ant glut med to get into upper anterior part.
Anterolateral: b/n TFL and glut med, retracting or detaching glut med / min.
- note the ascending lateral circumflex femoral vessels and sup glut nerve in upper end.
Posterior: split mid glut max, piriformis, obturator internus and gamelli near femoral attachments.
- turn cut ends of obturator internus and gamelli back, rolling them over sciatic n. to protect it.
Injection / Aspiration: 5cm below ASIS anteriorly, pointing up, back, medially.
- or laterally passing in front of FT, parallel with femoral neck, entering through lower glut med/min.