Anatomy
Upper Limb
You are examining the arm of a 23 year old electrician who has sustained a fracture of the humerus following a fall. On examination he finds flexion of the wrist painful. The flexor muscles of the anterior forearm all originate from which of the following structures:
Answer:
The flexor muscles of the anterior forearm all originate from the medial humeral epicondyle.Anterior Forearm Muscles
Anatomy / Upper Limb / Anterior Forearm
Last Updated: 10th April 2019
The flexor muscles of the anterior forearm all originate from the medial humeral epicondyle.
Compartments
The anterior forearm is divided into:
- The superficial compartment consisting of the:
- flexor carpi ulnaris
- flexor carpi radialis
- palmaris longus
- pronator teres
- The intermediate compartment consisting of the:
- flexor digitorum superficialis
- The deep compartment consisting of the:
- flexor digitorum profundus
- flexor pollicis longus
- pronator quadratus
![By Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2016/12/Anterior-Compartment-Forearm.png)
Anterior Forearm Muscles (Superficial). (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
![By Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2016/12/Anterior-Compartment-Forearm-2.gif)
Anterior Forearm Muscles (Deep). (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Innervation
All of the muscles in the anterior forearm are innervated by the median nerve, except for the flexor carpi ulnaris and the medial half of the flexor digitorum profundus which are innervated by the ulnar nerve.
Function
Table: Function and Innervation of the Anterior Forearm Muscles
| Muscle | Function | Innervation |
|---|---|---|
| Flexor carpi ulnaris | Flexion and adduction of wrist | Ulnar nerve |
| Flexor carpi radialis | Flexion and abduction of wrist | Median nerve |
| Palmaris longus | Flexion of wrist | Median nerve |
| Pronator teres | Pronation of forearm | Median nerve |
| Flexor digitorum superficialis | Flexion of MCPJ and PIPJ of all four digits, flexion of wrist | Median nerve |
| Flexor pollicis longus | Flexion of MCPJ and IPJ of thumb | Median nerve |
| Flexor digitorum profundus | Flexion of MCPJ and DIPJ of all four digits, flexion of wrist | Lateral half by median nerve, medial half by ulnar nerve |
| Pronator quadratus | Pronation of forearm | Median nerve |
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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 |
