Anatomy
Lower Limb
You are examining a 65 year old man who presents with left leg weakness. You note a loss of power to the left quadriceps femoris muscles. The quadriceps femoris muscles are innervated by which of the following nerves:
Answer:
The quadriceps femoris muscles are innervated by the femoral nerve.Quadriceps Femoris Muscle
Anatomy / Lower Limb / Anterior Thigh
Last Updated: 10th April 2019
The quadriceps femoris is made up of four individual muscles; the rectus femoris, the vastus medialis, the vastus intermedius (deep to the rectus femoris) and the vastus lateralis which all insert onto the patella by the common quadriceps femoris tendon. Because the vastus muscles insert into the margins of the patella as well as into the quadriceps femoris tendon, they stabilise the position of the patella during knee joint movement.
Table: Function and Innervation of the Quadriceps Femoris Muscles
| Muscle | Function | Innervation |
|---|---|---|
| Rectus femoris | Flexion at hip and extension at knee | Femoral nerve |
| Vastus lateralis | Extension at knee | Femoral nerve |
| Vastus medialis | Extension at knee | Femoral nerve |
| Vastus intermedius | Extension at knee | Femoral nerve |
Function
The quadriceps femoris muscles are the main extensors of the leg at the knee joint. The rectus femoris crosses both the knee and the hip joint (in contrast to the vastus muscles which only cross the knee joint), and therefore also assists in flexion of the thigh at the hip joint.
Innervation
The quadriceps femoris muscles are innervated by the femoral nerve.
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2017/01/Knee-Extensors-295x1024.jpg)
Quadriceps Femoris Muscles: Rectus Femoris (red), Vastus Medialis (blue), Vastus Lateralis (green). (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
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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 |
