Anatomy
Lower Limb
A 76 year old woman presents with left flank pain and fever. A CT scan has shown a psoas abscess. The psoas major muscle acts primarily to produce which of the following movements:
Answer:
The iliacus and psoas major muscles originate as separate muscles but insert by a common tendon onto the femur and together are referred to as the iliopsoas muscle, which is a powerful flexor of the thigh at the hip joint and also contributes to lateral rotation of the thigh at the hip joint.Anterior Thigh Muscles
Anatomy / Lower Limb / Anterior Thigh
Last Updated: 10th April 2019
The sartorius, iliacus, psoas major and pectineus (in addition to the rectus femoris of the quadriceps femoris muscle) are all flexors of the thigh at the hip joint.
Table: Function and Innervation of the Anterior Thigh Muscles
| Muscle | Function | Innervation |
|---|---|---|
| Sartorius | Flexion, abduction and lateral rotation at hip and flexion at knee | Femoral nerve |
| Iliacus | Flexion and lateral rotation at hip | Femoral nerve |
| Psoas major | Flexion and lateral rotation at hip | Anterior rami L1 – L3 |
| Pectineus | Adduction and flexion at hip | Femoral nerve |
Sartorius
The sartorius is innervated by the femoral nerve. It acts to flex the thigh at the hip joint and flex the leg at the knee joint. It also abducts the thigh and rotates it laterally, as when resting the foot on the opposite knee when sitting.
Iliopsoas
The iliacus and psoas major muscles originate as separate muscles but insert by a common tendon onto the femur and together are referred to as the iliopsoas muscle, which is a powerful flexor of the thigh at the hip joint and also contributes to lateral rotation of the thigh at the hip joint. The iliacus is innervated by the femoral nerve. The psoas major is innervated by the anterior rami of spinal nerves L1 - L3.
Pectineus
The pectineus is innervated by the femoral nerve. It acts to adduct and flex the thigh at the hip joint.
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2017/01/Hip-Flexors-295x1024.jpg)
Anterior Thigh Muscles: Pectineus (green), Sartorius (blue), Iliacus (red), Psoas major (yellow). (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 |
