MSK 6 - Anatomy of the Hip Joint

Question 1

What 2 major features does the hip joint consist of?

What is its ROM + stability like?

Answer 1

1) Ball (femoral head) + 2) Socket (acetabulum of hip bone)

- Large ROM and a very strong joint.

Question 2

On a blank picture of the hip joint - be able to identify the acetabulum, head of the femur, neck of the femur, greater + lesser trochanter’s, and the inter trochanteric line

Answer 2

kk.

Question 3

Where is the intertrochanteric crest?

Answer 3

Seen on posterior view, raised portion of bone in between the greater and lesser trochanter’s.

Question 4

What 3 bones are fused to form the hip bone?
What are these bones separated by?
Where is the acetabulum + what is its role?

Answer 4

• 1) Ilium (top), ischium (bottom, lateral), pubis (bottom, medial).
• Separated by tri-radiate cartilage (fusion begins at 15-17 Y/O, finished by 20-25)
• The acetabulum is on the superior aspect of the ischium and pubis, where the hip bone converges. This is the socket of the joint where the femoral head attaches.

Question 5

What 2 features strengthen the hip joint?

Answer 5

1) Acetabular Labrum - fibrocartilaginous rim around the acetabulum. Transverse acetabular ligament strengthens inferior portion of acetabulum as labrum doesn’t run around the entire edge.
2) Joint capsule - Capsular fibres in a spiral course - in extension the capsule helps pull the femoral head into the acetabulum to increase stability.

Question 6

What 3 joint ligaments that extend from the hip bone to femur, strengthen the joint capsule?
What movements do they prevent + which are the strongest/weakest?

Answer 6

1) Iliofemoral (strongest) - inverted Y-shape, protects hip joint superiorly + anteriorly, prevents hyperextension
2) Pubofemoral - protects anteriorly + inferiorly. Prevents over-abduction and hyperextension
3) Ischiofemoral (weakest) - attaches posteriorly to greater trochanter. Prevents excessive internal rotation

Question 7

What is the main flexor and 3 assisting muscles that allow for hip flexion?
What nerve supplies these muscles?

Answer 7

Main flexor = Iliopsaos (iliacus + psoas major merging) to insert into the lesser trochanter.

Nerve supply = Lumbar plexus (L1-L3)

1) Rectus femoris - quadriceps muscle, crossing the hip and knee joint.
3) Sartorius - crossing hip and knee joint (synergist)
3) Pectinous - hip flexor

Nerve supply = femoral nerve

Question 8

What 3 muscles allow for hip adduction?
What 3 muscles assist hip adduction?
What nerve supplies these muscles?

Answer 8

1) Adductor magnus, 2) adductor brevis 3) adductor longis
1) Gracilis 2) obturator externus 3) pectineus
- The obturator nerve

Question 9

What 4 muscles allow for hip extension?

What are all of these muscles innervated by?

Answer 9

1) Gluteus maximus
2) Biceps femoris - both long and short heads
3) Semitendinosus - on top of tendon
4) Semimembranosus - most medial

• All innervated by the tibial part of the sciatic nerve - except the short head of biceps femoris (innervated by common fibular division of sciatic nerve).

Question 10

What are the 2 hip abductor muscles?

What 2 muscles assist hip abduction?

Answer 10

• 1) Gluteus medias 2) Gluteus minimus

- Tensor fascia lata + sartorius

Question 11

What 2 regions are the gluteal region muscles divided into?

Answer 11

• The superficial and deep muscles

Question 12

What are the 3 main superficial gluteal region muscle and their roles?
What is their innervation and blood supply?

Answer 12

1) Gluteus maximus - main extensor of the thigh, used when force is requires, e..g.: running (inferior gluteal nerve + artery)

2 + 3) Gluteus medius and minimus - abducts and medially rotates thigh. Stabilises pelvis during walking and prevents pelvis drop on opposite limb (superior gluteal nerve + artery).

Question 13

What are the 5 deep muscles of the gluteal region?

What is their main actions?

Answer 13

1) Piriformis 2) Gemellus superior 3) Obturator internus 4) Gemellus inferior 5) Quadratus femoris
- External rotation of the thigh + abduction of the thigh

Question 14

Why is the piriformis muscle an important anatomical landmark?

Answer 14

It divides the gluteal region into the superior and inferior regions. The sciatic nerve enters the gluteal region inferior to the piriformis - visible as a flat band w/a 2cm width.

Question 15

Which sites in the gluteal region are safe for IM injections?

Answer 15

1) Dorsogluteal site safe for use from 3 Y.O

2) Ventrogluteal site preferred in children over 7 and adults but requires compliance.

Question 16

What are the 5 nerves that supply the hip joint and the anatomical regions they supply?

Answer 16

1) Sciatic nerve (posteriorly)
2) Femoral nerve (anteriorly)
3) Obturator nerve (inferiorly)
4) Superior gluteal nerve (superiorly)
5) Nerve to quadratus femoris (posteriorly)

Question 17

What are the major + minor sources of blood supply to the hip joint?
What is the consequence of an intracapsular femoral neck fracture?

Answer 17

Major = Deep femoral artery –> splits into the medial and lateral circumflex femoral artery

Minor = Artery of the ligamentum teres (a branch of the obturator artery) which supplies the femoral head in a child but inadequately perfuses femoral head in adult (adult reliant on retinacular arteries).

NB: Intracapsular femoral neck fracture can tear the retinacular arteries, and result in avascular necrosis (AVN) of the femoral head.

Question 18

What are the causes + consequences of superior gluteal nerve damage?

Answer 18

Causes = complication of hip surgery, infection to buttock, fracture of greater trochanter, hip join dislocation.

Consequences = weakened abduction of lower limb + trendelenburg sign (pelvic droop on unsupported/unaffected side)