Anatomy
Upper Limb
Question 24 of 24
A 21 year old mechanic presents to ED after sustaining a crush injury to his middle finger whilst at work. Which of the following muscles is least likely to be affected:
Answer:
The palmar interossei insert into the extensor hoods of the index, ring and little finger; there is no palmar interosseous muscle attaching to the middle finger and hence it is least likely to be affected in this injury.Interosseus Muscles
Anatomy / Upper Limb / Wrist and Hand
Last Updated: 10th April 2019
Attachments
- The interossei muscles originate from and lie between the metacarpal bones.
- The dorsal interossei insert into the extensor hoods and proximal phalanges of the index, middle and ring finger.
- The palmar interossei insert into the extensor hoods of the index, ring and little finger.
Function
- The four dorsal interossei act to abduct the index, middle and ring fingers at the MCPJs (DAB).
- The three palmar interossei act to adduct the index, ring and little fingers at the MCPJs (PAD).
- Because the interossei muscles insert into the extensor hoods, they also contribute to the complex flexion and extension movements of the interphalangeal joints of the digits.
Innervation
- The interossei muscles are all innervated by the ulnar nerve.
Interossei Muscles. (Image modified by FRCEM Success. Original by OpenStax [CC BY 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 |
