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?
Upper part: lumbar arteries
Lower part: femoral artery
What action does psoas major have at the lumbar spine?
Exerts large compressive forces
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?
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, 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?
Between anterior and posterior gluteal lines from the gluteal aponeurosis to the greater trochanter
What are the attachment sites of the gluteus minimus?
Between anterior and inferior gluteal lines to the greater trochanter and the hip joint capsule
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
