Anatomy
Lower Limb
Question 48 of 180
A 54 year old man presents to the ED complaining of a numbness over the posterior thigh. The skin in this area is primarily supplied by which of the following nerves:
Answer:
The posterior cutaneous nerve of the thigh, nerve from the sacral plexus, supplies skin over the posterior thigh and upper leg.Cutaneous Innervation of Lower Limb
Anatomy / Lower Limb / Innervation of Lower Limb
Last Updated: 10th April 2019
Table: Cutaneous Innervation of the Lower Limb
| Nerve | Origin | Skin Supplied |
|---|---|---|
| Lateral cutaneous nerve of thigh | Lumbar plexus (L2, L3) | Lateral thigh |
| Anterior cutaneous nerve | Femoral nerve | Anterior thigh and anteromedial knee |
| Cutaneous branch | Obturator nerve | Medial thigh |
| Posterior cutaneous nerve of thigh | Sacral plexus (S1 – S3) | Posterior thigh and upper leg |
| Saphenous nerve | Femoral nerve | Anteromedial knee, medial leg and foot |
| Lateral sural cutaneous nerve | Common fibular nerve | Upper lateral leg |
| Superficial fibular nerve | Common fibular nerve | Lower anterolateral leg and dorsum of foot |
| Deep fibular nerve | Common fibular nerve | Webspace between 1st and 2nd toe |
| Sural nerve | Tibial nerve | Lower posterolateral leg, heel and foot |
| Medial calcaneal nerve | Tibial nerve | Medial side and sole of heel |
| Medial and lateral plantar nerves | Tibial nerve | Sole of foot anterior to heel |
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/01/Cutaneous-Innervation-Leg.png)
Cutaneous Innervation of Lower Limb. (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/01/Cutaneous-Innervation-Foot.png)
Cutaneous Innervation of Foot. (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Cutaneous Innervation of Thigh
- The skin over the hip and gluteal region is supplied by the posterior and anterior rami of lumbosacral nerves (L1 – S3).
- The lateral cutaneous nerve of the thigh, nerve from the lumbar plexus, supplies skin over the lateral thigh.
- The anterior cutaneous nerve, branch of the femoral nerve, supplies skin over the anterior thigh and anteromedial knee.
- The obturator nerve supplies skin over the upper medial thigh.
- The posterior cutaneous nerve of the thigh, nerve from the sacral plexus, supplies skin over the posterior thigh and upper leg.
Cutaneous Innervation of Leg
- The saphenous nerve, branch of the femoral nerve, supplies the skin over the anteromedial knee, medial leg and the medial side of the foot as far anteriorly as the head of the 1st metatarsal.
- The lateral sural nerve, branch of the common fibular nerve, supplies the skin over the upper lateral leg.
- The superficial fibular nerve supplies the area of skin over the lower anterolateral leg and the dorsum of the foot (except for the webspace between the 1st and 2nd toe and the lateral side of the little toe).
- The deep fibular nerve supplies the skin over the webspace between the 1st and 2nd toe.
- The sural nerve, branch of the tibial nerve, supplies the skin over the lower posterolateral leg, heel and foot.
- The medial calcaneal nerve, branch of the tibial nerve, supplies the skin over the medial side and sole of the heel.
- The medial and lateral plantar nerves, branches of the tibial nerve, supply the skin over the sole of the foot anterior of the heel.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
