Week 4: Hip & Thigh Muscles 1 Flashcards
Describe the muscles, action, and innervation of the anterior compartment of the hip and gluteal region:
Muscles:
1. Psoas major
2. Iliacus
Action: Hip flexion
Innervation:
1. Ventral rami L1-L3
2. Femoral nerve L2-4
Describe the muscles, action, and innervation of the posterior compartment of the hip and gluteal region:
Muscles: Gluteus maximus
Action: Hip extension
Innervation: Inferior gluteal
Describe the muscles, action, and innervation of the lateral compartment of the hip and gluteal region:
- Muscles: Gluteus medius, gluteus minimus, tensor fascia lata
Action: Pelvic stability during single leg stand, hip abduction and internal rotation (anterior fibres) or external rotation (posterior fibres)
Innervation: Superior gluteal - Muscle: Piriformis
Action: External rotation
Innervation: S1-2 - Muscle: Obturator internus, gemellus superior and inferior
Action: External rotation
Innervation: Nerve to obturator internus - Muscle: Quadratus femoris
Action: External rotation
Innervation: Nerve to quaratus femoris - Muscle: Obturator externus
Action: External rotation
Innervation: Obturator nerve
What is the general function of those muscles located anterior to the hip joint?
Hip flexion
Describe the attachment sites of the psoas major:
- Sides of bodies and transverse processes of T12 and L1-5
- Via the iliopsoas tendon into the lesser trochanter of femur
What is the main vascular supply of the psoas major?
Rich network of vessels, mainly derived from lumbar arteries (upper part) and femoral artery (lower part)
What action does psoas major have at the lumbar spine?
Exerts large compressive forces (does not produce specific movements such as flexion/extension due to its location close to the axis of rotation of the spine
Where is the psoas minor located?
It is absent in about 40% of individuals but when present lies anterior to psoas major
What is the iliacus?
- A fan shaped muscle, which occupies the iliac fossa and is a powerful hip flexor
- Its fibres converge into the lateral side of the tendon of psoas major to form the iliopsoas tendon distally
What are the proximal and distal attachment sites of the iliacus?
- Proximal: Iliac crest and most of the iliac fossa & ala of sacrum
- Distal: Lesser trochanter of femur
What is the vascular supply of the iliacus muscle?
Similiar arterial network as psoas major – mostly femoral and obturator artery and vein
How would you test the function of iliopsoas?
Resisted hip flexion, with knee flexed
What are the attachment sites of gluteus maximus?
- Posterior gluteal line and area of bone above and behind it, posterior surface of sacrum and coccyx, sacrotuberous ligament
- Iliotibial band, gluteal tuberosity and lateral intermuscular septum
Describe the architecture of the gluteus maximus:
- Cross-sectional area: Large
- Fascicle direction: Parallel, directed inferiorly and laterally
What are the functions of the gluteus maximus?
- Extension at hip joint, upper fibres contribute to hip abduction
- Lateral rotation of the hip
- Extension of pelvis on femur (i.e. standing upright from a bent over position)
- Stabilises femur on tibia by tensing the fascia lata (via iliotibial band) when the knee extensors are relaxed
Based on its location explain why gluteus maximus may act as a lateral rotator of
the femur at the hip joint:
Runs medial to lateral therefore when the muscle shortens the femur will laterally rotate
What is the vascular supply of the gluteus maximus?
Inferior gluteal artery and vein (alongside the inferior gluteal nerve)
What are the attachment sites of the gluteus medius?
External aspect of ilium between the anterior and posterior gluteal lines from the gluteal aponeurosis to the greater trochanter (posterosuperior and lateral aspects)
What are the attachment sites of the gluteus minimus?
Outer surface of ilium between anterior and inferior gluteal lines to the greater trochanter (anterior aspect) and the hip joint capsule (a few deeper fibres)
Describe the architecture of the gluteus medius:
- Large
- Fan-shaped converging to a strong, flattened tendon
- 3 neuromuscular compartments - anterior, middle, posterior
- Anterior fibres contribute to hip internal rotation, posterior fibres aid external rotation
Describe the architecture of the gluteus minimus:
- Smaller, deep to gluteus medius
- Fan-shaped converging to its
distal attachment - 2 neuromuscular compartments - anterior and
posterior - Anterior fibres contribute to hip internal rotation, posterior fibres aid external rotation
What is the vascular supply of the gluteus medius and minimus muscles?
Superior gluteal artery and veins (alongside superior gluteal nerve)
Describe the function of the deep gluteal muscles during single leg support either in standing or walking:
- Gluteus medius and minimus muscles on the stance side contract concentrically to hold the pelvis level and slightly elevate the swinging limb side in the coronal plane
- They effectively approximate the ilium to the greater trochanter
- This prevents the downward sag of the pelvis on the non-stance (unsupported) side.
Describe the function of the deep gluteal muscles when moving the lower limb on a stable pelvis:
- Abduction of the hip - both muscles and all compartments to varying degrees
- Anterior fibres of both muscles contribute to hip internal rotation and the posterior fibres to hip external rotation
What is the result of dysfunction of gluteus medius and minimus during stance:
Trendelenburg’s sign: downward sag of the non-stance side of pelvis, in single leg stance e.g. weakness on the right would result in downward sag on the left
What is the result of dysfunction of gluteus medius and minimus during gait:
Trendelenburg’s gait: same as ‘sign’ when walking - can result from muscle weakness secondary to pain (e.g. with osteoarthritis of the hip joint) or nerve damage to the superior gluteal nerve e.g. due to posterior dislocation of the hip
What are the attachment sites of the tensor fascia lata?
- Anterior part of the external lip of the iliac crest, outer surface ASIS and notch below the spine
- Inserts distally into the iliotibial tract
Along with the tensor fascia lata, what muscle shares a common insertion onto the ASIS?
Sartorius
Describe the architecture of the tensor fascia lata:
Fusiform
What is the function of the tensor fascia lata?
- Flexion and abduction of hip
- Also a weak internal rotator
What is the vascular supply of the tensor fascia lata?
Superior gluteal artery and veins
Describe the attachments, passage of tendon and architecture of the piriformis:
Attachments: Pelvic surface of sacrum between and lateral to the sacral foramina 1- 4
Passage of tendon:
- Passes through the greater sciatic foramen
- Attaches via a round tendon into upper border, medial side of greater trochanter
Architecture: Flat and triangular
Describe the attachments, passage of tendon and architecture of the gemellus superior:
Attachments:
- Ischial spine
- Joins the tendon of obturator internus to attach with it (attaches to medial surface of greater trochanter above trochanteric fossa)
Passage of tendon: Passes lateral ward above the tendon of the obturator internus
Architecture: Small tapered muscle
Describe the attachments, passage of tendon and architecture of the obturator internus:
Attachments:
- Obturator foramen (bony margin) and obturator membrane
- Greater trochanter, above trochanteric fossa
Passage of tendon: Tendon passes through the lesser sciatic foramen, turns 90° angle
Architecture: Fan shaped muscle
Describe the attachments, passage of tendon and architecture of the gemellus inferior:
Attachments:
- Ischial tuberosity
- Tendon lies along the underside of the obturator internus tendon and unites with it ( attaches to medial surface of greater trochanter above trochanteric fossa)
Passage of tendon: Passes lateralward below the tendon of the obturator internus
Architecture: - Small tapered muscle
Describe the attachments and architecture of the quadratus femoris:
Attachments:
- Upper part of the lateral border of ischial tuberosity
- Quadrate line which extends vertically downward from the intertrochanteric crest of the femur
Architecture: Thick quadrilateral muscle
What is the blood supply of the pirifomis?
Superior gluteal vessels
What is the blood supply of the obturator internus and gemelli?
Internal pudendal vessels
What is the blood supply of the quadratus femoris?
Inferior gluteal vessels
What is the blood supply of the obturator externus?
Obturator vessels
What nerve innervates the piriformis?
Branches of first and second sacral nerves
What is the relationship of the sciatic nerve to the piriformis muscle?
- The sciatic nerve usually passes out of the greater sciatic foramen inferior to the piriformis
muscle - Variation can occur, and the nerve may split into its 2
divisions (common fibular and tibial) superior to piriformis – some nerves pass above the
muscle, through it etc.
What is piriformis syndrome?
Trigger points or tightness in piriformis, as well as muscle hypertrophy and sciatic nerve compression is implicated in the development of the piriformis
Can the piriformis be palpated?
Not directly - skin, superficial fascia, deep fascia, gluteus maximus, piriformis
