Lecture Notes: Hip & Thigh

Hip & Thigh

Assigned Reading:		Moore & Auger: pp. 217 - 247, 266 - 269, or
		Jenkins: pp. 233- 249, 254-292

I. Osteology

A. pelvic girdle - is formed anterolaterally by the left and right ossa coxae and posteromedially by the sacrum and coccyx
B. os coxa - formed by 3 bones which fused at the acetabulum during puberty
- 1. ilium - comprised of body and blade
  - a. iliac crest - superior margin; attachment of abdominal and back muscles
    - i.iliac tubercle - palpable landmark; attachment of iliotibial tract
  - b. anterior superior iliac spine - anterior end of the iliac crest; attachment of sartorius and TFL
  - c. anterior inferior iliac spine - attachment of rectus femoris
  - d. greater sciatic notch - know what passes through it; sexually dimorphic
  - e. auricular surface - iliac portion of sacro-iliac joint
  - f. iliac fossa - attachment of ilacus
- 2. ischium - comprised of body and ramus
  - a. ischial spine - attachment of sacrospinous ligament
  - b. ischial tuberosity - attachment of hip extensors and sacrotuberous ligament
  - c. lesser sciatic notch - between the ischial spine and tuberosity; know what passes through it
- 3. pubis - comprised of body and 2 rami
  - a. obturator foramen - formed by the bodies and rami of the pubis and ischium
  - b. pubic symphysis - fibrocartilaginous joint connecting the two pubes
  - c. subpubic arch - formed by the diverging inferior rami of the left and right pubes; sexually dimorphic
C. femur - sole bone of the thigh; head, neck, shaft, condyles
- 1. greater trochanter - attachment of hip abductors
- 2. lesser trochanter - attachment of hip flexors
- 3. linea aspera - on posterior aspect; attachment of hip adductors and knee extensors
- 4. medial and lateral epicondyles
- 5. adductor tubercle - superior projection of the medial epicondyle
- 6. medial and lateral condyles

II. Arthrology

A. sacro-iliac joints - bilateral synovial joints between sacrum and ilia
- 1. movement: minimal; rotation about transverse axis when standing
- 2. ligaments and osseoligamentous foramina
  - a. sacroiliac ligaments - 2 sets (anterior & posterior); limit rotation of rostral sacrum
  - b. sacrotuberous ligament- limits rotation of caudal sacrum
  - c. sacrospinous ligament - limits rotation of caudal sacrum
  - d. osseoligamentous foramina: greater and lesser sciatic
B. hip joint - synovial, ball-and-socket joint formed by the head of femur and acetabulum of the coxa
- 1. Movements of the hip
  - a. flexion/extension
  - b. abduction/adduction
  - c. medial and lateral rotation
  - d. translation is prevented by the depth and fit of the articulation between the head of femur and acetabulum; cf. glenohumeral joint
- 2. Restrainers of joint mobility
  - a. ligament of the head of femur (lig. teres) - of questionable functional significance
  - b. joint capsule and its ligaments - primary restrainers of joint mobility
    - i. iliofemoral ligament - resists extension beyond vertical (primary) and limits lateral rotation
    - ii. ischiofemoral ligament - resists extension beyond vertical (secondary) and limits medial rotation
    - iii. pubfemoral ligament - limits abduction
  - c. adduction is resisted by the opposite hindlimb

III.	Myology: Due to the extreme mobility of the hip joint, the majority of muscles which act on the hip produce several actions; hence the muscles are grouped together by muscle compartment. Each muscle's action in the three planes of motion (i.e. ext/flx; abd/add, mr/lr) and the muscles innervation are described by compartment. Your will be responsible for knowing each muscle's primary action which is given in section F below. Please note that the lesser gluteal muscles (i.e gluteus medius and minimus) serve two primary actions. The following figures may be helpful in understanding the primary action of the hip musculature:
		Hip Flexors/Extensors
		Hip Abductors/Adductors
		Hip Medial Rotators/Lateral Rotators

A. post-axial compartment (innervated by the gluteal nerves (dorsal division of sacral plexus) or sacral VR)
- 1. gluteus maximus - (inf. gluteal n.) ext, abd, lr
- 2. tensor fascia lata - (sup gluteal n) flx, abd, mr,
- 3. gluteus medius - (sup. gluteal n.) abd, mr, ext
- 4. gluteus minimus - (sup. gluteal n.) abd, mr, flx
- 5. piriformis - (VR of S2,3) lr, abd, ext
B. anterior compartment (innervated by femoral nerve (dorsal division of lumbar plexus) and lumbar VR)
- 1. iliopsoas - formed by common tendon of psoas major (L2,3) and iliacus (femoral n); flx
- 2 sartorius - (femoral n) flx, lr, abd
- 3. quadriceps femoris - (femoral n.) - note only rectus femoris acts about hip joint
  - a. rectus femoris - flx
  - b. vastus medialis
  - c. vastus intermedius
  - d. vastus lateralis
C. medial compartment (typically innervated by the obturator nerve (ventral division of lumbar plexus))
- 1. pectineus - (femur or obturator n.) add, mr, flx
- 2. adductor longus - (obturator n.) add, mr, flx
- 3. gracilis - (obturator n.) add, flx, mr
- 4. obturator externus - (obturator n.) add, lr
- 5. adductor brevis - (obturator n.) add, mr, flx
- 6. pubofemoral portion of adductor magnus - (obturator n.) add, mr, flx
D. posterior compartment (innervated by the ventral division nerves of the sacral plexus)
- 1. 4 small lateral rotators
  - a. obturator internus - (obturator internus n.) lr
  - b. superior gemellus - (obturator internus n.) lr
  - c. inferior gemellus - (quadratus femoris n.) lr
  - d. quadratus femoris - (quadratus femoris n) lr
- 2. 4 large extensors - share common origin, innervation and action
  - a. long head of biceps femoris - (tibial n.) ext, add, lr
  - b. semitendinosis - (tibial n) ext, add, mr
  - c. semimembranosus - (tibial n) ext, add, mr
  - d. ischiocondylar portion of adductor magnus - (tibial n) ext, add, mr
E. lateral compartment - composed of single muscle which does not act about the hip joint; innervated by common peroneal n (dorsal division of sacral plexus)
- 1. short head of biceps femoris - (common peroneal n) - flexor of the knee joint]
F. Primary muscle action
- 1. Flexors - muscles whose line of action passes anterior to the axis rotation; innervated chiefly by the dorsal division of the lumbar plexus
  - a. psoas major (VR L2,3)
  - b. iliacus (femoral n.)
  - c. sartorius (femoral n.)
  - d. rectus femoris (femoral n)
  - e. tensor fascia lata (superior gluteal n)
- 2. Extensors - muscles whose line of action passes posterior to the axis of rotation; innervated chiefly by the ventral divisions of the sacral plexus (except gluteus maximus)
  - a. gluteus maximus (inf. gluteal n.)
  - b. long head of biceps femoris (tibial n.)
  - d. semitendinosis (tibial n.)
  - d. semimembranosis (tibial n.)
  - e. ischiocondylar portion of adductor magnus (tibial n.)
- 3. Adductors - muscles whose line of action passes inferior to the axis of rotation; innervated by the ventral division of the femoral nerve
  - a. pectineus (obturator n. (occasionally femoral innervation)
  - b. adductor longus (obturator n.)
  - c. gracilis (obturator n.)
  - d. adductor brevis (obturator n.)
  - e. pubofemoral portion of adductor magnus (obturator n.)
- 4. Abductors - muscles whose line of action passes superior to the axis of rotation; innervated by a dorsal division nerve of the sacral plexus.
  - a. gluteus medius (sup gluteal n.)
  - b. gluteus minimus (sup. gluteal n.)
- 5. Lateral rotators - muscles whose line of action passes posterior to the axis of rotation; listed from superior to inferior; diverse innervation
  - a. piriformis (VR of S2,3)
  - b. superior gemellus (n. to obturator internus)
  - d. obturator internus (n. to obturator internus)
  - d. inferior gemellus (n. to quadratus femoris)
  - e. obturator externus (obturator n.)
  - f. quadratus femoris (n. to quadratus femoris)
- 6. medial rotators - muscles whose line of action passes anterior to the axis of rotation; innervated by a dorsal division nerve of the sacral plexus.
  - a. gluteus medius (sup gluteal n.)
  - b. gluteus minimus (sup. gluteal n.)
G. "Hamstrings"
- Some texts mistakenly refer to the biceps femoris, semimembranosis and semitendinosus as the "hamstring" muscles or simply "hamstrings". In fact, the hamstring ( or tendo calcaneus communis) refers to the combined tendons of the superficial digital flexors, triceps surae, biceps femoris and semitendinosus which collectively attach to the tuber calcis (calcaneus) of the hock (tarsus) in domestic animals. This stout tendon is used to hang or string-up the hindquarters or "ham" cut of meat-producing animals, hence the term. Since humans are rarely used for such purpose and since the homology is clearly inaccurate, "hamstrings" must be considered an abattoirical rather than anatomical term.

IV. Fascia of the thigh

A. fascia lata - deep fascia of the thigh
B. iliotibial tract - lateral thickening of the fascia lata to which gluteus maximus and tensor fascia lata insert
C. saphenous opening (fossa ovalis) - thin, elliptical region of the fascia lata through which the great saphenous vein passes

V. Femoral triangle - intermuscular space inferior to the inguinal ligament

A. boundaries:
- 1. base (upper boundary): inguinal ligament
- 2. lateral: sartorius
- 3. medial: adductor longus
- 4. roof: fascia lata
- 5. floor: iliopsoas and pectineus
B. contents (from lateral to medial)
- 1. femoral nerve
- 2. femoral artery
- 3. femoral vein
- 4. inguinal lymphatics (deep)
C. femoral sheath - inferior extension of transversalis fascia which encloses proximal 3-4 cm of femoral artery and vein; "traditionally " divided into three compartments: lateral (femoral artery), middle (femoral vein), medial (lymphatics)
- 1. femoral canal - medial compartments of femoral sheath; contains lymphatics and fat; upper opening is femoral ring which is the site of femoral hernias

VI. Arteries

A. femoral - direct continuation of external iliac; changes name after entering femoral triangle
- 1. profunda femoris - arises from posterior aspect of femora a. within triangle
  - a. lateral femoral circumflex - arises just after origin of profunda; can arise directly from femoral a.; participates in anastomoses about the hip through its numerous branches
    - i. descending branch - descends to participate in arterial anastomosis of knee joint
  - b. medial femoral circumflex - arises opposite lateral femoral circumflex or alternatively from femoral a.; passes between iliopsoas and pectineus; major blood supply to head and neck of femur; participates in anastomoses about the hip through its numerous branches
  - c. perforating arteries - typically 3+ which supply the muscles of the medial and posterior compartments
- 2. descending genicular a - arises distally just above adductor hiatus; particpates in arterial anstomosis of knee joint
B. Arterial anastomoses of the hip joint - provided primarily by branches of the internal iliac and femoral aa; majority unnamed
- 1. important internal iliac branches: obturator, superior gluteal, inferior gluteal
- 2. important femoral / profunda femoris branches: lateral femoral circumflex, medial femoral circumflex, perforating aa
- 3. cruciate anastomosis - located on posterior of thigh at lower border of quadratus femoris; fomed by medial and lateral femoral circumflex aa, first perforating a and inferior gluteal a

VII. Superficial veins

A. great saphenous - starts anterior to medial malleolus and drains to femoral vein via saphenous opening
B. small saphenous - starts posterior to lateral malleolus and ends in popliteal vein within popliteal fossa