Anatomy
Upper Limb
You have been asked to review a 45 year old gardener who has sustained a laceration to the dorsal surface of their wrist. You are concerned about the possibility of injury to underlying structures. The extensor retinaculum is attached to which of the following structures:
Answer:
The extensor retinaculum is attached laterally to the anterolateral radius above the styloid process and medially to the pisiform and triquetrum bones.Extensor Retinaculum
Anatomy / Upper Limb / Posterior Forearm
Last Updated: 10th April 2019
The extensor retinaculum (dorsal carpal ligament) lies obliquely across the extensor surface of the wrist joint, and holds the extensor tendons in place during movement of the wrist.
It is attached laterally to the anterolateral radius above the styloid process and medially to the pisiform and triquetrum bones. It does NOT attach to the ulna.
Contents
The extensor tendons pass through the extensor tunnel, deep to the extensor retinaculum, in six compartments lined by synovial sheaths:
- The tendons of the extensor carpi ulnaris and extensor digiti minimi have separate sheaths on the medial side of the wrist
- The tendons of the extensor digitorum and extensor indicis share a synovial sheath on the posterior surface of the wrist
- The tendons of the abductor pollicis longus and extensor pollicis brevis, the extensor carpi radialis longus and extensor carpi radialis brevis, and the extensor pollicis longus have three separate sheaths on the lateral side of the wrist
![By Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2016/12/Extensor-Retinaculum.png)
Extensor Retinaculum. (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Dorsal Compartments of Wrist: 1) Extensor pollicis brevis and abductor pollicis longus tendons 2) Extensor carpi radialis longus and brevis tendons 3) Extensor pollicis longus tendon 4) Extensor digitorum and extensor indicis tendons 5) Extensor digiti minimi tendon 6) Extensor carpi ulnaris tendon. (Image by Anatomyczar [CC BY-SA 4.0 , 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 |
