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LS Plexus
Study Q's for Lumbosacral Plexus 2a
Question | Answer |
---|---|
The majority of the lumbar plexus (L1-L4) is formed within the belly of what muscle? | psoas major |
Where is the majority of the sacral plexus (L4-S4) located? | superficial to piriformis muscle |
All seven nerves in the lumbar plexus are formed in the posterior division except for the __________________ nerve. | Obturator Nerve L2-L4 (anterior division) |
What is the most proximal portion of the sacral plexus? | Lumbosacral Trunk. Fused L4-L5 |
Where does the sciatic nerve (L4-S3 mixed) split to become the Common Peroneal (L4-S2 PD) and Tibial (L4-S3 AD) portions? | Distal 1/3 in posterior aspect of the thigh. Splits as it enters popliteal fossa. |
What structures pass through popliteal fossa? Describe Superficial to Deep | Tibal Nerve, Common Peroneal Nerve, Popliteal Vein, Popliteal Artery. Bonus: Which ones are vulnerable to injury and how? |
How many nerves make up the sacral plexus? | Eight. (nine if you count the sciatic portions as two) |
Describe the positioning of the subcostal nerve? | (T12 PD) Most superior nerve in the lumbar plexus. Inferior to 12th rib, deep to peritoneum, superficial to QL |
Spinal nerves ____________________ and _______________can be joined together and split at the lateral border of the QL | Iliohypogastric (T12-L1 PD) and Ilioinguinal (L1 PD) |
The subcostal, ilihypogastric, and ilioinguinal nerves have primarily ¬¬¬¬¬_________________ innervation and supply the _______________________________ | Cutaneous, Lower aspect of anterolateral abdominal wall. Small portion in anterior aspect of thigh in region of inguinal ligament (Ilioinguinal) |
Describe the course of the IH and II nerves in the anterolateral abdominal wall | IH:emerges lat. aspect of upper psoas m. and runs across QL. Dives into trans. abdominus muscle II: emerges lat. psoas major, across QL and upper iliacus, along iliac crest in oblique coruse, then dives into transverse abdominus Courses in inguinal canal* |
Which cutaneous nerve supplies the anterior lateral aspect of the thigh? | Lateral Femoral Cutaneous Nerve (L2,L3 PD) |
Which lumbar plexus nerve supplies the cremaster muscle and a small patch of skin on the proximal region of the thigh? | Genitofemoral Nerve (L1, L2 PD) |
What are the cutaneous innervations of the medial aspect of the thigh? | Femoral Nerve: anterior and medial femoral cutaneous branches and Obturator Nerve: distal aspect medial thigh |
What are the three junctional regions of the lower limb? | Gluteal Region, Inguinal Region, and Femoral Triangle. Bonus question: what are the boundaries of the femoral triangle? |
Where is a potential entrapment point for the Lateral Femoral Cutaneous Nerve (L3,L3 PD)? | Where nerve pierces investing fascia (or IT band) of thigh to enter subcutaneous tissue |
What structure does the femoral nerve pass in order to enter the thigh? | The femoral nerve is located just lateral to the psoas major and passes DEEP to the inguinal ligament to enter the thigh |
How does the posterior femoral cutaneous nerve enter the gluteal region? What does it innervate? | Passes through Greater Sciatic foramen and inferior to piriformis muscle. Innervates skin of posterior thigh and popliteal region |
The greater saphenous vein is _____________positioned and joins the _____________vein while the small saphenous vein is______________positioned and joins the____________ vein | Medial and anteriorly:Femoral vein Lateral and Posteriorly: Popliteal Vein |
What three positional changes do our hip undergo in development? | Medial Rotation, Adduction, and Extension |
Which two structures reflect the rotation that occurs at our hips during development? | Sartorius Muscle and Ischiofemoral Ligament |
Discuss the location of the Superior Gluteal Artery and Inferior Gluteal Artery relative to nerves of Sacral Plexus | SG=runs between Lumbosacral Trunk and S1. IG=runs between S2 and S3 |