Hip Anatomy

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Muscles of the Pelvis

	Muscle	Innervation	Origin	Insertion	Action	Nerve Root
	Flexors
1	Iliacus	femoral	iliac fossa	lesser trochanter	hip flexion	L234(P)
2	Psoas	femoral	transverse processes of L1-L5	lesser trochanter		L234(P)
3	Pectineus	femoral	pectineal line of pubis	pectineal line of femur		L234(P)
4	Rectus Femoris	femoral	AIIS, acetabular rim	Patella-tibial tubercle		L234(P)
5	Sartorius	femoral	ASIS	proximal medial tibia		L234(P)
	Adductors
1	Post adductor magnus	obturator(P) & Sciatic(tibial)	infeior pubic ramus/ischial tuberosity	lenea aspera.adductor tubercle		L234(A)
2	Adductor brevis	obturator(P)	inferior pubic ramus	linea aspera/pectineal line		L234(A)
3	Adductor longus	obturator(A)	anterior pubic ramus	linea aspera		L234(A)
4	Gracilis	obturator (A)	inf symphysis/pubic arch	proximal medial tibia		L234(A)
	External Rotators
1	Gluteus maximus	inferior gluteal	ilium post to post gluteal line	iliotibial band/gluteal sling		L5-S2(P)
2	Piriformis	piriformis	ant sacrum/sciatic notch	proximal great trochanter		S12(P)
3	Obturator externus	obturator	ischiopubic rami/obturator membrane	trochlear fossa		L234(A)
4	Obturator internus	obturator internus	ischiopubic rami/obturator membrane	medial greater trochanter(MGT)		L5-S2(A)
5	Superior gemellus	obturator internus	Outer ischial spine	MGT		L5-S2(A)
6	Inferior gemellus	quadratus femoris	ischial tuberosity	MGT		L4-S1(A)
7	Quadratus femoris	quadratus femoris	ischial tuberosity	quadrate line of femur		L4-S1(A)
	Abductors
1	Gluteus medius	superior gluteal	ilium between post and ant gluteal lines	greater trochanter		L4-S1(P)
2	Gluteus minimus	superior gluteal	ilium between ant and inf gluteal lines	ant border of greater trochanter		L4-S1(P)
3	Tensor fasciae latae(TFL)	superior gluteal	anterior iliac crest	iliotibial band		L4-S1(P)

Hip Range of Motion

Motion	Average	Functional
Flexion	115	90 (120 squat)
Extension	30
Abduction	50	20
Adduction	30
Internal Rotation	45	0
External Rotation	45	20

Sciatic Nerve

Origin: lumbosacral plexus: L4-S3
Exits pelvis via the greater sciatic notch; appears in the buttock anterior to the piriformis; passes posteriorly over the superior gemellus, obturator internus, inferior gamellus and quadratus femoris; passes deep to the biceps femoris
Travels with the PFCN and inferior gluteal artery
Branches into the Tibial Nerve and Common Peroneal Nerve.
see also Sciatic Nerve Palsy.

Hip Approaches

Anterior [Smith-Petersen]

Superficial interval: sartorius (femoral N) and tensor fasica lata (Superior gluteal N). Ascending branch of the lateral femoral circumflex artery crosses within interval and must be ligated.
Deep interval: rectus femoris (Femoral N)_ and Gluteus medius (Superior gluteal N)

Anterolateral [Watson-Jones]

Interval: tensor fascia lata (Superior gluteal N) and Gluteus medius (Superior gluteal N)

Lateral (Hardinge)

Superficial interval: splits gluteus medius (Superior gluteal N)
Deep interval: splints vastus lateralis (Femoral N)
2/3 of gluteus medius, glutues minimus and ligament of Bigelow are detached and require reattachment.
Hardinge K, JBJS 1982;64Br:17

Posterior [Moore]

Splits gluteus maximus (Inferior gluteal N)

Lateral femoral cutaneous nerve

Origin: lumbar plexus
Innervates: purely sensory, innverates the anterolateral thigh
Location: runs on the surface of the iliacus muscle and enters the thigh by passing under the inguinal ligament before piercing the fascia lata. Path can be variable.
Injury: see Meralgia Paresthetica 355.1

Superior Gluteal Nerve

Innervates: gluteus medius, gluteus minimus, tensor fascia lata.
Location: Exits the greater sicatic notch superior to the piriformis. Main branch of the superior gluteal nerve is between 4.5 and 4.9 cm above the level of the superior acetabular rim.
Generally safe to dissect up to 4 cm above the acetabulum or 5 cm above the tip of the greater trochanter.

Inferior Gluteal Nerve

Innervates: gluteus maximus.
Location: Exits through the greater sicatic notch inferior to the piriformis muscle.