Anatomy
Upper Limb
A patient sustains a fracture of the midshaft of the humerus with resultant damage to the radial nerve. He has wrist drop and is unable to extend his fingers. He is still able to supinate his forearm. Supination of the forearm is still possible through the action of which of the following muscles:
Answer:
Supination of the forearm is primarily produced by the supinator (radial nerve) and the biceps brachii (musculocutaneous nerve). Radial nerve damage will result in paralysis of the supinator muscle, but the biceps brachii muscle function is preserved.Radioulnar Joints
Anatomy / Upper Limb / Anterior Forearm
Last Updated: 10th April 2019
Radioulnar Joints. (Image by OpenStax College [CC BY 3.0 , via Wikimedia Commons)
Proximal Radioulnar Joint
Table: Anatomical Overview of the Proximal Radioulnar Joint
| Joint | Proximal Radioulnar |
|---|---|
| Type | Synovial pivot |
| Articulations | Head of radius with radial notch of ulna |
| Stabilising factors | Annular ligament |
| Movements | Pronation and supination |
The proximal radioulnar joint is a pivot type synovial joint occurring between the head of the radius and the radial notch of the ulnar. The radial head is held in position by the annular ligament of the radius.
Distal Radioulnar Joint
Table: Anatomical Overview of the Distal Radioulnar Joint
| Joint | Distal Radioulnar |
|---|---|
| Type | Synovial pivot |
| Articulations | Head of ulna with ulnar notch of radius |
| Movements | Pronation and supination |
The distal radioulnar joint is a pivot type synovial joint occurring between the head of the ulnar and the ulnar notch on the radius.
Movements
The radioulnar joints allow pronation and supination of the forearm.
Table: Movements of the Radioulnar Joints
| Movement | Main Muscles Involved | Main Nerves Involved |
|---|---|---|
| Pronation | Pronator quadratus, pronator teres | Median nerve |
| Supination | Biceps brachii, supinator | Musculocutaneous nerve, radial 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 |
