Mednotes.

Hip Anatomy

The Hip Joint

  • Ball and socket
    • Deep, Stable.
    • Initially separated by hyaline cartilage
    • Join through ossification
    • Stability is assured by:
      1. Ligaments
      2. Muscles
      3. Acetabular labrum
  • Greater stability anteriorly than posteriorly
    • Least stable when flexed
    • Disarticulates posteriorly

Ligaments of the hip

There are two main types of ligaments

  • Intracapsular Ligamentum Teres femur (Ligament of head of femur)
    • This is fairly weak
    • Contains the acetabular branch of medial circumflex artery
      • Fracture of femur causes avascular necrosis as this artery is compromised

  • Extracapsular ligaments
    • These are very strong connecting to innominate bone
    • 3 ligaments:
      1. Iliofemoral ligament
      2. Pubofemoral ligament
      3. Ischiofemoral ligament

 

Muscles of the hip

There are 4 groups of muscles to consider:

  1. Gluteal muscles
  2. Flexors (Posterior compartment)
    • Psoas, pectineus, iliacus
  3. Extensors (Anterior compartment)
    • Hamstrings
  4. Adductors (Medial compartment)
Gluteal muscles
  • 3 muscles
    • All have Inferior + superior Gluteal nerve innervation (L5, S1)
  1. Gluteus maximus
    • Power extension (e.g. climbing stairs)
    • L5-S1 – Inferior gluteal nerve
  2. Gluteus medius
    • Abduction, rotation and weightbearing
    • L5, S1 – Inferior gluteal nerve

  3. Gluteus minimus 

    • Actions are the same as gluteus medius
    • L5, S1 Superior gluteal nerve
Flexor muscles
  • Four muscles:
    • These pull thigh and pelvis toward each other
    • Lumbar plexus innervation through femoral nerve (L2-L4)
  1. Psoas major

  2. Psoas minor
  3. Iliacus
    • Joins with psoas before insertion to form iliopsoas
  4. Pectineus

Hip Extensor muscles
  • AKA Hamstrings
    • Attach to both the hip and knee
      • Ischial tuberosity => tibia/fibula head
    • Therefore, they also flex the knee joint
    • Prone to damage
  • Generally sciatic innervation (L5-S2)
  1. Semitendinosus
    • Tibial branch of sciatic nerve  (L5-S2)

  2. Semimembranosus
    • Tibial branch of sciatic nerve
  3. Biceps femoris (long + short heads)
    1. Short head – Common peroneal nerve (L5-S2)

    2. Long head – Sciatic nerve (S1-S3)

Adductor muscles
  • These also cause medial and lateral rotation of femur
    • Also flex hip
  • All are supplied by the Obturator nerve (L2-L4)
  • All attach to linea aspera
  1. Adductor longus

  2. Adductor brevis

  3. Adductor magnus
    • Vertical and oblique heads
    • The adductor hiatus is formed between the heads

  4. Gracilis
    • Also flexes knee
  5. Obturator externus (relatively small)