MSK ANATOMY PART 2

PART 2

1. What are the boundaries of the axilla?(BRACHILLE LECTURE)

• Apex/inlet:

• Floor:

• Anterior wall:

• Posterior wall:

• Medial wall:

• Lateral wall:

2. The anterior axillary fold =.
   The posterior axillary fold =

3. what surrounds the axillary artery, vein, and brachial plexus

4. How is the brachial plexus formed, and what are its 5 organizational levels?

5. What are prefixed and postfixed brachial plexuses?

6. Clinical relevance of postfixed plexus:

7. How are the brachial plexus cords related to the axillary artery?

8. The names lateral, medial, posterior cords are based on their relationship to the…..part of the axillary artery.

9. What are the branches of the roots of the brachial plexus?

10. C5 also contributes to the phrenic nerve BUT WHATS THE MAIN POINT

11. What branches arise from the upper trunk and lateral cord?

12. C5–C7 + anterior arm muscles,WHICH NERVE?

13. What are the branches of the medial cord?

14. The median nerve is formed by:

15. What are the branches of the posterior cord?

16. What are the origin, termination, parts, and branches of the axillary artery?

• Apex/inlet: 1st rib, clavicle, superior border of scapula

• Floor: skin + fascia stretched between anterior and posterior walls

• Anterior wall: pectoralis major, pectoralis minor, clavipectoral fascia

• Posterior wall: subscapularis, teres major, latissimus dorsi

• Medial wall: serratus anterior + upper 4–5 ribs + intercostal muscles

• Lateral wall: intertubercular groove of humerus

2. The anterior axillary fold = pectoralis major.
   The posterior axillary fold = latissimus dorsi + teres major.

3. AXILLARY SHEATH

4. Formation: ventral rami of C5–T1 Roots + trunks → posterior triangle of neck -Divisions → behind clavicle -Cords + branches → axilla

5. Prefixed:

   • Superior root = C4

   • Inferior root = C8

   Postfixed:

   • Superior root = C6

   • Inferior root = T2

6. The inferior trunk may be compressed by the 1st rib, producing neurovascular symptoms in the upper limb.

7.  In the 1st part, the Medial Cord is behind the artery, and Lateral/Posterior cords are lateral to it BUT IN THE SECOND PART ITS Lateral Cord: Lateral to artery Medial Cord: Medial to artery Posterior Cord: Posterior to artery

8. 2ND PART

9. C5 → dorsal scapular nerve

   • Levator scapulae

   • Rhomboid major

   • Rhomboid minor

   C5–C7 → long thoracic nerve

   • Serratus anterior

   Clinical: injury to the long thoracic nerve → winged scapula.

10. C5 also contributes to the phrenic nerve, but the phrenic nerve is considered a branch of the cervical plexus, not the brachial plexus.

11. Upper trunk:

    • Nerve to subclavius → C5–C6

    • Suprascapular nerve → C5–C6

    Lateral cord:

    • Lateral pectoral nerve → C5–C7

    • Musculocutaneous nerve → C5–C7

    • Lateral root of median nerve → C5–C7

12. think muesculocutaneous nerv.

13. Medial pectoral nerve → C8–T1 Medial cutaneous nerve of arm → C8–T1 Medial cutaneous nerve of forearm → C8–T1 Medial root of median nerve → C8–T1 Ulnar nerve → C7–T1

14. LATERAL ROOT+ MEDIAL ROOT

15. Upper subscapular nerve → C5–C6 Lower subscapular nerve → C5–C6 Thoracodorsal nerve → C6–C8 Axillary nerve → C5–C6 Radial nerve → C5–T1

16. Origin: continuation of subclavian artery at lateral border of rib 1

    Termination: becomes brachial artery at inferior border of teres major

    Divided by: pectoralis minor

1. What is Erb-Duchenne palsy, and what deformity does it produce?

2. A newborn has an arm hanging by the side, medially rotated, with a pronated forearm

3. What is Klumpke palsy, and what deformity does it produce?

4. What happens to the axillary vein at the 1st rib, and what is clinically important about its relationship to the axillary artery and brachial plexus?

5. Which two nerves are particularly at risk during axillary lymph node dissection, and what happens if each is injured?

6. these vessels form collateral circulation around the scapula/shoulder.

1. traction injury to C5–C6, particularly the upper trunk.

Affected functions:

• Shoulder abduction

• Shoulder lateral rotation

• Forearm supination

Resulting position — "policeman's tip":

• Arm adducted

• Arm medially rotated

• Forearm extended

• Forearm pronated

2. Erb palsy (C5–C6).

3. Cause: injury to the lower roots C8–T1.

   Possible causes:

   • Cervical rib

   • Birth injury

   • Excessive abduction of arm

   Mainly affected: intrinsic/small muscles of the hand.

   Deformity: claw hand

   • Hyperextension of MCP joints

   • Flexion of IP joints

4. During "subclavian" vein puncture, the actual point of entry may be into the terminal axillary vein, with the needle tip quickly entering the subclavian vein.Axillary vein lies superficial to the axillary artery and brachial plexus.This makes the vein relatively accessible for venous procedure

5. Long thoracic injury = winged scapula
   Thoracodorsal injury = weakened latissimus function without characteristic deformity

6. Important contributors include:

   • Suprascapular artery

   • Transverse cervical artery

   • Subscapular artery

   • Circumflex scapular artery

   • Branches of subclavian/axillary systems

7. Axillary artery VEINS branches

8. Internal thoracic artery AND VEINS

9. Intercostal arteries AND VEINS

(MUSCLES OF BACK LECTURE)

1. How are the back muscles divided, and how do the groups differ in nerve supply, function, and examples?

2. Give the insertion, actions, and nerve supply of trapezius. What happens if its nerve is injured?

3. Patient cannot shrug shoulder against resistance →NERVE

4. Give the attachments, actions, and nerve supply of latissimus dorsi. What is the clinical consequence of injury to its nerve?

5. What are the attachments, actions, and innervation of levator scapulae and the rhomboids?

6. Which group is supplied by posterior rami

7. Compare the actions of erector spinae and transversospinales.

8. What are the attachments, nerve supply, and actions of serratus anterior? What happens when its nerve is injured?

9. Give the origin, insertion, nerve supply, and actions of pectoralis major.

10. Compare pectoralis minor, subclavius,

1. Extrinsic = movement of upper limb/rib
   Intrinsic = vertebral column/posture
   Intrinsic muscles = posterior rami

nsertion:

• Lateral 1/3 of clavicle

• Acromion

• Spine of scapula

Actions:

• Upper fibers → elevate scapula

• Middle fibers → retract scapula

• Lower fibers → depress scapula

• Upper + lower fibers → rotate scapula to help raise arm above head

Nerve: Spinal accessory nerve (CN XI)

Lesion →

• Drooping shoulder

• Weak shoulder shrug

• Difficulty raising arm above head

2. think CN XI → trapezius.Clavicle - lateral 1/3- Scapula - acromion and spinous proces

3. Insertion:

   • Bicipital groove of humerus

   Actions:

   • Extension

   • Adduction

   • Medial rotation of arm

   Nerve: Thoracodorsal nerve (C6–C8)

   Injury → weakness pulling body upward, e.g.:

   • Climbing

   • Pull-ups

4. RHOMBOIS MAJOR+ MINOR ——-.>Insertion → medial border of scapula Action → retraction Nerve → dorsal scapular nerve Levator scapulae

   • Insertion → medial border of scapula

   • Action → elevates + medially rotates scapula

   • Nerve → dorsal scapular nerve (C5)

5. Intrinsic/deep back muscles.

6. Erector spinae

   Bilaterally:

   • Extend vertebral column

   • Pull head posteriorly

   Unilaterally:

   • Laterally flex vertebral column

   • Bend head toward contracting side

   Transversospinales

   Bilaterally:

   • Extend the back

   Unilaterally:

   • Rotate trunk/head toward the opposite side

7. Insertion: ventral surface of medial border + inferior angle of scapula

   Nerve: long thoracic nerve

   Actions:

   • Protracts scapula

   • Holds medial border/inferior angle against thoracic wall

   • Important for movements such as punching/boxing

   Long thoracic nerve injury → serratus anterior paralysis → winged scapula.

8. Insertion:

   • Lateral lip of bicipital groove

   Nerve supply:

   • Medial pectoral nerve

   • Lateral pectoral nerve

   Actions:

   • Adduction

   • Medial rotation

   • Flexion of arm

9. Pectoralis minor

   • Origin → ribs 3–5

   • Insertion → coracoid process

   • Nerve → medial pectoral nerve

   • Action → depresses shoulder

   Subclavius

   • Origin → 1st rib/costochondral junction

   • Insertion → subclavian groove on inferior clavicle

   • Nerve → nerve to subclavius

   • Action → steadies clavicle

1. What are the boundaries and clinical significance of the auscultatory triangle and lumbar triangle?

2. What are the boundaries and contents of the quadrangular space?

3. Compare the triangular space and triangular interval: boundaries and structures passing through each.

4. What are the four rotator cuff muscles, their nerves, actions, and insertions?

5. Stabilize the humeral head within the glenoid cavity while preserving movement.AND Abducts 0–15°

6. what are the actions and innervation of deltoid?

7. WHAT IS Important sequence for abduction:

8. WHAT IS Clavipectoral fascia AND WHERE IS IT PIERCED BY?

Also remember that initial shoulder abduction (0–15°) is driven by supraspinatus (suprascapular nerve), whereas the deltoid takes over from 15–90°.

1. Auscultatory triangle

   Boundaries:

   • Medial border of scapula

   • Trapezius

   • Latissimus dorsi

   Clinical significance:

   • Area where breath sounds are most easily heard with a stethoscopE

Lumbar triangle / Triangle of Petit

Boundaries:

• Latissimus dorsi

• Posterior border of external oblique

• Iliac crest

Clinical significance:

• Potential site of abdominal hernia

• Pus may emerge through the abdominal wall.

2. oundaries:

   • Superior → teres minor

   • Inferior → teres major

   • Medial → long head of triceps

   • Lateral → surgical neck of humerus

   Contents:

   • Axillary nerve

   • Posterior circumflex humeral artery + vein Clinical relevance: injury around the surgical neck of humerus can endanger the axillary nerve.

3. Triangular space

   Boundaries:

   • Superior → teres minor

   • Inferior → teres major

   • Lateral → long head of triceps

   Contains:

   • Circumflex scapular artery + vein

   Triangular interval

   Boundaries:

   • Superior → teres major

   • Medial → long head of triceps

   • Lateral → shaft of humerus

   Contains:

   • Radial nerve

   • Profunda brachii artery

4. ROTATOR CUFF MUSCLES

5. Insertion:

   • Deltoid tuberosity of humerus

   Nerve:

   • Axillary nerve

   Actions by fibers:

   • Anterior → flexion + medial rotation

   • Middle → abduction 15°–90°

   • Posterior → extension + lateral rotation

6. Supraspinatus: 0–15°
   Deltoid: 15–90°

7. Clavipectoral fascia

   Located between:

   Subclavius + pectoralis minor

   Pierced by:

   • Lateral pectoral nerve

   • Thoracoacromial artery

   • Cephalic vein

   • Lymphatic vessels

LEG AND FOOT

1. What are the muscles of the posterior compartment of the leg, and how are they divided?

2. Which superficial posterior-compartment muscles plantar-flex the ankle, and which also flex the knee?

3. What structures pass deep to the flexor retinaculum from posterior → anterior?

4. If asked which nerve passes under the flexor retinaculUM?

5. A muscle initiates flexion of an extended knee by laterally rotating the femur on a fixed tibia. Which muscle?

6. What is its nerve supply?

7. Which muscle flexes the MTP and IP joints of the lateral four toes?

8. Does it assist ankle plantar flexion?

9. Which muscle flexes the MTP and IP joints of the great toe?

10. What other action does it have?

11. Which deep posterior muscle plantar-flexes AND inverts the foot?

12. Where does it insert mainly?

13. What muscles are found in each layer of the sole?

14. Which muscles of the sole are supplied by the medial plantar nerve?

15. What about the lateral plantar nerve?

16. What are the muscles of the anterior compartment?

17. What are the actions of tibialis anterior?

18. Dorsiflexion + inversion →

19. Which anterior-compartment muscle extends the lateral four toes?

20. Which extends the great toe?

21. Which dorsiflexes + everts the foot?

22. All are supplied by the??

23. What are the muscles of the lateral compartment, their nerve supply, and their main actions?

24. Eversion =??

25. A patient has numbness specifically in the skin between the great toe and second toe. Which nerve is involved?

26. A patient develops foot drop after an injury near the neck of the fibula. Which nerve is most likely injured?

27. Why does this cause foot drop?

28. What sensory deficit may occur?

29. tibial nerve 2 branches?

30. gastrocenamous important point

31. soleus important feature

32. The tendon penetrates the fibrous membrane of the joint capsule of the knee. • The tendon passes between the lateral meniscus and the fibrous membrane • The it attaches to and originates from a depression at the anterior end of the groove on the lateral femoral condyle???

33. In the sole, it crosses inferior to the tendon of the flexor hallucis longus muscle

34. Flexor digitorum brevis and abductor hallucis supplied by?

35. The Abductor digiti minimi supplied by the

36. Adductor hallucis and flexor digiti minimi brevis are supplied by

37. Flexor hallucis brevis is supplied by

38. interossi intervatd by

39. tibialis anterior insertionn is?

40. Insertion: Base of 5th, metatarsal bone?

41. extensor hoods?

42. dorsalis pedis artery?

A vascular surgeon evaluates a patient with suspected peripheral artery disease by palpating the dorsalis pedis pulse. To locate this pulse accurately, where should the physician place their fingers on the dorsum of the foot?

• A.

  Lateral to the tendon of extensor hallucis longus

  Correct answer

  The dorsalis pedis artery (continuation of the anterior tibial artery) is best palpated on the dorsum of the foot just lateral to the prominent tendon of the extensor hallucis longus.

• dorsal interossi abducts toes (dab)

• pad

1. Superficial: Gastrocnemius, Soleus, Plantaris
   Deep: Popliteus, Flexor digitorum longus, Flexor hallucis longus, Tibialis posterior.
   Nerve: Tibial nerve.
   Artery: Posterior tibial artery.

2. Gastrocnemius, Soleus and Plantaris → plantar-flex ankle.
   Gastrocnemius + Plantaris → also flex knee.
   All are supplied by the tibial nerve. G ANATOMY LEG AND FOOT

3. Tibialis posterior → FDL → posterior tibial vessels → tibial nerve → FHL

Mnemonic: Tom Does Very Nice Hats. G ANATOMY LEG AND FOOT

4. → tibial nerve.

5. : Popliteus.

6. Tibial nerve.

7. Flexor digitorum longus (FDL).

8. YES

9. Flexor hallucis longus (FHL).

10. Assists plantar flexion of the ankle.

11. Tibialis posterior.

12. Tuberosity of navicular + adjacent medial cuneiform.

13. 1st layer:

    • Abductor hallucis

    • Flexor digitorum brevis

    • Abductor digiti minimi

    2nd layer:

    • Quadratus plantae

    • Lumbricals

    3rd layer:

    • Flexor hallucis brevis

    • Adductor hallucis

    • Flexor digiti minimi brevis

    4th layer:

    • 3 plantar interossei

    • 4 dorsal interosse

14. A:

    • Abductor hallucis

    • Flexor digitorum brevis

    • Flexor hallucis brevis

    • 1st lumbrical. G ANATOMY LEG AND FOOT

15. Supplies most of the remaining intrinsic muscles, including the interossei, adductor hallucis, flexor digiti minimi brevis, quadratus plantae and lumbricals except the 1st.

16. A:

    • Tibialis anterior

    • Extensor digitorum longus

    • Extensor hallucis longus

    • Fibularis tertius

    Nerve: Deep fibular nerve
    Artery: Anterior tibial artery

17. Dorsiflexion + inversion of the foot.
    Also helps maintain the medial longitudinal arch.

    Nerve: Deep fibular nerve

18. Tibialis anterior.

19. Extensor digitorum longus.

20. Extensor hallucis longus.

21. Fibularis tertius.

22. Deep fibular nerve.

23. A:
    Muscles: Fibularis longus + Fibularis brevis
    Nerve: Superficial fibular nerve
    Actions: Plantar flexion + eversion

24. think fibularis muscles.

25. Deep fibular nerve.

    It supplies the 1st interdigital web space, the only cutaneous area supplied by this nerve. G ANATOMY LEG AND FOOT

    Clinical variation: Deep fibular nerve entrapment can cause pain radiating to this same web space (“ski boot syndrome”).

26. Common fibular nerve.

27. Injury causes loss of dorsiflexion, producing foot drop.

28. Variable sensory loss over the anterolateral leg and dorsum of the foot.

29. Tibial nerve (branch of sciatic nerve). • It has two cutaneous branches, the sural nerve and the medial calcaneal nerve. • The sural nerve supplies skin on the lower posterolateral surface of the leg and the lateral side of the foot and little toe

30. Insertion : tendon). > the calcaneal tendon (Achilles Special Features : The lateral head may contain a sesamoid bone called fabella

31. The muscle contains a rich plexus of veins, which is connected to the great saphenous vein by a series of perforating veins

32. poplitius

33. flexor digitorum longus

34. medial planter N.

35. lateral planatar nerve

36. lateral planatar

37. medial planatar

38. lateral planter N

39. Insertion: Medial cuneiform and base of 1st, metatarsal bone

40. fibularis tertius

41. The tendons of the extensor digitorum longus, extensor digitorum brevis, and extensor hallucis longus pass into the dorsal aspect of the digits and expand over the proximal phalanges to form dorsal digital expansions, forming extensor hoods

42. he dorsalis pedis artery (continuation of the anterior tibial artery) begins as the anterior tibial artery crosses the ankle joint. It passes inferiorly, as the deep plantar artery, between the two heads of the first dorsal interosseous muscle to join the deep plantar arch in the sole (Its pulse of the dorsalis pedis artery on the dorsal surface of the foot can be fel

BACK OF THIGH

1. Which muscles make up the hamstrings, and where are they positioned?

2. What are the origins of the 3 hamstrings?

3. Give the origin, insertion, nerve supply, and actions of biceps femoris

4. A lesion affects the common fibular division of the sciatic nerve. Which hamstring component is denervated?

5. Give the origin, insertion, nerve supply, and actions of semitendinosus.

6. Give the origin, insertion, nerve supply, and actions of semimembranosus.

7. Which hamstrings flex the knee, extend the hip, and medially rotate?

8. Which hamstring contributes to pes anserinus, and where does it insert?

9. What forms the four muscular boundaries of the popliteal fossa?

10. What form the floor and roof of the popliteal fossa?

11. What are the major contents of the popliteal fossa?

12. Describe the course and termination of the popliteal artery.

13. How do the tibial and common fibular nerves course through the popliteal fossa?

14. Where is the popliteal vein relative to the artery, and what does it become?

15. A patient has a lesion involving the medial hamstrings. Which actions are weakened, and which nerve division is affected?

1. A:

   • Biceps femoris → lateral

   • Semitendinosus → medial

   • Semimembranosus → medial

   Exam trap: Biceps femoris is the lateral hamstring; the other two are medial.

2. A:

   • Biceps femoris long head → inferomedial upper ½ ischial tuberosity

   • Semitendinosus → same area

   • Semimembranosus → superolateral upper ½ ischial tuberosity

   High-yield: Long head BF + semitendinosus share the origin.

3. A:

   • Long head: ischial tuberosity → tibial division

   • Short head: linea aspera → common fibular division

   • Both insert → head of fibula

   • Hip: extends + laterally rotates

   • Knee: flexes + laterally rotates

4. A: Short head of biceps femoris.

   Why:
   Long head → tibial division
   Short head → common fibular division.

   This is a classic distinction.

5. A:

   • Origin → ischial tuberosity

   • Insertion → medial proximal tibia via pes anserinus

   • Nerve → tibial division of sciatic

   • Hip → extension + medial rotation

   • Knee → flexion + medial rotation

6. A:

   • Origin → superolateral upper ½ ischial tuberosity

   • Insertion → medial/posterior medial tibial condyle

   • Nerve → tibial division of sciatic

   • Hip → extension + medial rotation

   • Knee → flexion + medial rotation

7. A: Semitendinosus + semimembranosus.

   Contrast:
   Biceps femoris → lateral rotation.

8. A: Semitendinosus contributes to pes anserinus.

   It inserts on the upper medial surface of the tibia, behind sartorius and gracilis.

   S.G.S. = sartorius, gracilis, semitendinosus

9. A:
   Superolateral: biceps femoris
   Superomedial: semitendinosus + semimembranosus
   Inferolateral: lateral head gastrocnemius + plantaris
   Inferomedial: medial head gastrocnemius

   Shape: diamond-shaped.

10. A:
    Floor: knee joint capsule, adjacent femur/tibia, popliteus.
    Roof: skin + superficial fascia + deep fascia.

    Superficial fascia contains small saphenous vein + posterior cutaneous nerve of thigh.

11. A:

    • Tibial nerve

    • Common fibular nerve

    • Popliteal vein

    • Popliteal artery

    Superficial → deep:
    Nerves → vein → artery

12. Continuation of femoral artery.
    It is the deepest major structure in the fossa.
    Passes obliquely downward.
    Ends by dividing into anterior + posterior tibial arteries.

13. Both are branches of sciatic and enter beneath biceps femoris.

    Tibial: descends vertically.
    Common fibular: follows medial border of biceps femoris.

    Both are more superficial than the popliteal vessels.

14. A:
    It lies superficial to the popliteal artery and travels with it.

    Superiorly, it continues as the femoral vein.

15. A:
    Weak knee flexion, hip extension, and medial rotation.

    Affected muscles: semitendinosus + semimembranosus.

    Nerve: tibial division of sciatic nerve.

    Contrast: biceps femoris → lateral rotation.

GLUTEAL

1. What defines the gluteal region, and what are the functions of its 2 major ligaments?

2. What structures pass through the greater sciatic foramen superior to piriformis?

3. What structures pass through the greater sciatic foramen inferior to piriformis?

4. What enters and exits the lesser sciatic foramen?

5. Give the origin, insertion, nerve supply and actions of gluteus maximus.

6. Why is gluteus maximus the chief antigravity muscle of the hip?

7. What are the actions and nerve supply of gluteus medius and minimus?

8. A patient has superior gluteal nerve injury. What happens and why?

9. Give the origin, insertion, nerve supply, action and key importance of piriformis.

10. Give the origin, insertion, nerve supply and action of obturator internus.

1. Gluteal region: behind pelvis, iliac crest → gluteal fold.
   Ligaments: sacrospinous + sacrotuberous.
   They convert sciatic notches → greater/lesser sciatic foramina and stabilize sacrum/prevent posterior rotation.

2. Superior gluteal nerve + superior gluteal vessels.

   TRAP: Piriformis divides the greater sciatic foramen into above vs below.

3. A:

   • Inferior gluteal nerve/vessels

   • Sciatic nerve

   • Posterior cutaneous nerve of thigh

   • Pudendal nerve + internal pudendal vessels

   • Nerve to obturator internus

   • Nerve to quadratus femoris

   High-yield: Most structures pass below piriformis.

4. Enters: pudendal nerve + internal pudendal vessels.
   Exits: tendon of obturator internus.

   Think: Pudendal nerve leaves pelvis → loops around → re-enters through lesser sciatic foramen.

5. Origin: ilium, sacrum/coccyx, sacrotuberous ligament.
   Insertion: ¾ IT tract; deep fibers → gluteal tuberosity.
   Nerve: inferior gluteal (L5–S2).
   Action: hip extension + lateral rotation.

6. Powerful hip extension raises the trunk against gravity.

   Important activities:

   • Standing from sitting

   • Running

   • Climbing stairs

   Also stabilizes hip/knee through the iliotibial tract.

7. Both:

   • Abduct thigh

   • Medially rotate thigh

   • Stabilize pelvis during walking

   Nerve: superior gluteal nerve (L4–S1).

8. Paralysis/weakness of gluteus medius + minimus → inability to stabilize pelvis during single-leg stance.

   The pelvis drops on the unsupported/swing side → Trendelenburg sign and waddling gait.

9. Origin: anterior sacrum.
   Insertion: upper greater trochanter.
   Nerve: nerve to piriformis (S1–S2).
   Action: lateral rotation + abduction of femur.
   Importance: landmark dividing greater sciatic foramen into superior/inferior parts.

10. Origin: medial obturator membrane + adjacent bone.
    Insertion: greater trochanter.
    Nerve: nerve to obturator internus (S1–S2).
    Action: lateral rotation + abduction of femur.

    Key anatomical fact: Its tendon bends ~90° through the lesser sciatic foramen

1. What are the attachments, actions and nerve supplies of the superior and inferior gemelli?

2. : Give the origin, insertion, nerve supply and action of quadratus femoris.

3. Match the major gluteal nerves to the muscles they supply.

4. Compare the superior and inferior gluteal arteries.

5. Where is the safe site for gluteal IM injection, and what structure is being protected?

1. Both attach to the obturator internus tendon and assist its action.

   Superior: ischial spine → nerve to obturator internus.
   Inferior: ischial tuberosity → nerve to quadratus femoris.

   Action: lateral rotation + abduction.

2. Origin: anterior to ischial tuberosity.
   Insertion: quadrate tubercle/intertrochanteric crest.
   Nerve: nerve to quadratus femoris.
   Action: lateral rotation of femur.

3. Superior gluteal → gluteus medius + minimus.
   Inferior gluteal → gluteus maximus.
   Nerve to piriformis → piriformis.
   Nerve to obturator internus → obturator internus + superior gemellus.
   Nerve to quadratus femoris → quadratus femoris + inferior gemellus.

4. Both arise from internal iliac artery.

   Superior gluteal: exits greater sciatic foramen above piriformis → accompanies superior gluteal nerve.

   Inferior gluteal: exits below piriformis → accompanies inferior gluteal nerve; mainly supplies gluteus maximus.

5. Upper outer quadrant of buttock.

   It minimizes risk of injuring the sciatic nerve, which passes through the gluteal region.

The things I REALLY want you to know

If you can retrieve these without looking, you're in a much stronger position:

Piriformis = landmark

Above piriformis:
→ superior gluteal nerve + vessels

Below piriformis:
→ sciatic nerve
→ inferior gluteal nerve + vessels
→ posterior cutaneous nerve of thigh
→ pudendal nerve + internal pudendal vessels
→ nerves to obturator internus + quadratus femoris

Superior gluteal nerve
→ gluteus medius + minimus
→ Trendelenburg

Inferior gluteal nerve
→ gluteus maximus

Gluteus maximus
→ extension + lateral rotation

Gluteus medius/minimus
→ abduction + medial rotation

Deep lateral rotators
→ piriformis, obturator internus, gemelli, quadratus femoris

Safe IM injection
→ upper outer quadrant → avoid sciatic nerve

SUMMARY

Rapid-Fire Self-Test

1. What nerve innervates Gluteus Maximus?

   • .

2. If the left superior gluteal nerve is cut, which side of the pelvis drops during walking?

   • 
     

3. What is the safe quadrant for gluteal injections?

4. Which muscle exits the pelvis through the greater sciatic foramen?

5. Which muscle tendon exits through the lesser sciatic foramen?

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1. Answer: Inferior Gluteal Nerve

2. Answer: The Right side (the unsupported swing limb).

3. Answer: Outer upper (superolateral) quadrant.

4. Answer: Piriformis.

5. Answer: Obturator Internus.

1. : What is fascia lata, what does its lateral thickening form, and what opening does it contain?

2. What are the key features of fascia lata?

3. Give the origin, insertion, nerve supply and actions of sartorius.

4. Name the 4 quadriceps heads, their common insertion/nerve, and main action.

5. What distinguishes rectus femoris from the three vasti?

6. Compare iliacus and psoas major by origin, innervation and action.

7. What are the boundaries, floor and roof of the femoral triangle?

8. What structures lie in the femoral triangle from lateral → medial?

9. Describe the origin, course, termination and major branch of the femoral artery.

   
   
   

1. A:

   • Anterior: iliopsoas, sartorius, quadriceps → femoral N

   • Medial: adductors, gracilis, pectineus, obturator externus → mainly obturator N

   • Posterior: hamstrings → sciatic N

   Trap: Pectineus can receive femoral innervation.

2. Thick deep fascia surrounding thigh.
   Laterally thickens → iliotibial tract.
   Contains saphenous opening, through which great saphenous vein enters femoral vein.

3. A:
   O: ASIS
   I: upper medial tibia
   N: femoral N
   Actions: hip flexion + abduction + lateral rotation; knee flexion.

   Memory: “tailor's muscle.”

4. Rectus femoris, vastus lateralis, medialis, intermedius.

   All → quadriceps tendon → patella → ligamentum patellae → tibial tuberosity.

   Nerve → femoral N.

   Action → knee extension.

   RF is the only head crossing the hip → also flexes hip.

5. Rectus femoris: crosses hip + knee → hip flexion + knee extension.

   Vasti: cross only knee → knee extension.

   RF originates from AIIS + ilium above acetabulum.

6. Iliacus: iliac fossa → femoral N → hip flexion.

   Psoas major: T12–L5 vertebral bodies/discs + transverse processes → anterior rami L1–L3 → hip flexion.

   Both insert at lesser trochanter and act as hip flexors.

7. Base: inguinal ligament
   Lateral: sartorius
   Medial: adductor longus
   Apex: continues into adductor canal

   Floor medial → lateral: adductor longus → pectineus → iliopsoas.

   Roof: fascia lata + saphenous opening.

8. Nerve → artery → vein → lymphatics

   = NAVEL

   Femoral nerve lies outside the femoral sheath.

   Femoral artery, vein and lymphatics are enclosed by the femoral sheath.

9. Continuation of external iliac artery after passing beneath inguinal ligament.

   → femoral triangle → adductor canal → adductor hiatus.

   After hiatus → popliteal artery.

   Major branch: profunda femoris, the major blood supply of thigh.

1. Describe the femoral vein and distinguish the great vs small saphenous veins.

2. What are the course, major motor branches and cutaneous territories of the femoral nerve?

3. What are the major medial thigh muscles and their principal actions?

4. : Why is adductor magnus unusual? Give its 2 parts, innervation and key anatomical feature.

5. Which medial thigh muscles have notable nerve-supply exceptions?

6. What is a femoral hernia, where does it occur, and why can it strangulate?

1. Femoral vein = continuation of popliteal vein → becomes external iliac vein above inguinal ligament.

   Tributaries include great saphenous + profunda femoris veins.

   Great saphenous: medial dorsal venous arch → femoral vein.

   Small saphenous: lateral dorsal venous arch → popliteal vein.

2. From lumbar plexus → emerges lateral to psoas → passes posterior to inguinal ligament → enters femoral triangle outside femoral sheath.

   Motor: iliacus, pectineus, sartorius, quadriceps.

   Cutaneous:

   • medial/intermediate cutaneous nerves → anterior thigh

   • saphenous nerve → medial leg

3. Pectineus: flexes + adducts thigh
   Gracilis: adducts thigh + flexes knee
   Adductor longus: adduction + medial rotation
   Adductor brevis: adduction + medial rotation
   Adductor magnus: powerful adduction + medial rotation
   Obturator externus: lateral rotation

   Most are supplied by obturator N.

4. A:
   Pubic part: obturator N → adduction + medial rotation.

   Ischial part: sciatic N → adduction.

   Ischial part inserts on adductor tubercle.

   A gap between its parts = adductor hiatus, transmitting femoral vessels → popliteal vessels.

   Major trap: Adductor magnus has dual innervation.

5. A:

   • Pectineus → femoral N (classically; may receive obturator/accessory obturator)

   • Adductor magnus → obturator + sciatic

   • Obturator externus → obturator N

   • Gracilis → obturator N

   Exam focus: Don't assume every medial muscle is simply obturator nerve.

6. Abdominal viscera protrude through the femoral ring → femoral canal.

   Presents as a mass inferolateral to pubic tubercle.

   May enlarge toward the saphenous opening.

   Strangulation risk: rigid/sharp lacunar ligament can constrict the hernia.

HE EXAM TRAPS I WANT YOU TO KNOW COLD

These are the ones I'd actively test yourself on:

NAVEL

Femoral Nerve → Artery → Vein → Empty space/Lymphatics

Femoral nerve = OUTSIDE femoral sheath.

Femoral artery

External iliac → femoral → adductor hiatus → popliteal

Femoral vein

Popliteal → femoral → external iliac

Great saphenous

medial dorsal venous arch → femoral vein

Small saphenous

lateral dorsal venous arch → popliteal vein

Quadriceps

4 heads → knee extension
Rectus femoris alone crosses hip

Iliopsoas

major hip flexor

Adductor magnus

obturator + sciatic
adductor hiatus → femoral vessels

Femoral hernia

femoral ring/canal → inferolateral to pubic tubercle

SUMMARY

Your lecture says the adductor hiatus gives passage for “femoral vessels.” More precisely, the femoral artery and vein pass through the hiatus and become the popliteal artery and vein posterior to the knee.

And one other important nuance: the lecture's “femoral nerve supplies pectineus” is a useful exam answer, but pectineus can have variable/accessory innervation, so don't let that confuse you if you encounter it in a more detailed source