Anatomy
Upper Limb
A 54 year old woman presents to ED having sustained a laceration to the palm of her hand while gardening. She is unable to oppose her thumb, but sensation is intact. Which of the following nerves has most likely been injured:
Answer:
The recurrent branch of the median nerve innervates the thenar muscles (flexor pollicis brevis, abductor pollicis brevis, opponens pollicis) and has no sensory function. Damage to this nerve results in weakness of abduction, opposition and flexion of the thumb. The anterior interosseous nerve is a branch of the median nerve and innervates the deep muscles of the anterior forearm - damage to this nerve would result in weakness of thumb flexion but not opposition as described in this patient.Median Nerve
Anatomy / Upper Limb / Anterior Arm / Anterior Forearm / Innervation of Upper Limb
Last Updated: 8th April 2019
The median nerve is formed from the medial and lateral brachial plexus cords and contains fibres from all five roots (C5 - T1).
Table: Anatomical Overview of the Median Nerve
| Nerve | Median |
| Nerve roots | C5 – T1 |
| Plexus cords | Medial and lateral cords |
| Motor Supply | All the anterior forearm muscles (except for the flexor carpi ulnaris and the medial half of the flexor digitorum profundus), the thenar muscles (flexor pollicis brevis, abductor pollicis brevis, opponens pollicis) and the lateral two lumbricals |
| Sensory supply | Lateral aspect of palm and palmar surface and fingertips of lateral three and a half digits |
Anatomical course
The median nerve originates in the axilla before passing down the medial side of the arm (initially lateral to the brachial artery before crossing over to the medial side of the brachial artery). It enters the anterior compartment of the forearm via the antecubital fossa, travelling between the flexor digitorum profundus and flexor digitorum superficialis muscles, before entering the hand via the carpal tunnel and bifurcating into its terminal branches.
![By Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2016/12/Median-Nerve-1.gif)
Median Nerve. (Image by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Branches
Table: Branches of the Median Nerve
| Branches of Median Nerve | Origin | Supply |
| Median nerve | Axilla | Superficial and intermediate compartment of anterior forearm (pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, NOT flexor carpi ulnaris) |
| Anterior interosseous nerve | Forearm | Deep compartment of anterior forearm (flexor pollicis longus, pronator quadratus, lateral half of flexor digitorum profundus) |
| Palmar cutaneous branch | Forearm | Skin over the lateral aspect of the palm |
| Recurrent branch of median nerve | Hand | Thenar muscles (flexor pollicis brevis, abductor pollicis brevis, opponens pollicis) |
| Palmar digital branch | Hand | Lateral two lumbricals and skin over the palmar surface and fingertips of the lateral three and a half digits |
The median nerve directly innervates the pronator teres, the flexor carpi radialis, the palmaris longus and the flexor digitorum superficialis. It gives off no major branches in the arm, but gives rise to the anterior interosseous nerve (innervating the flexor pollicis longus, the pronator quadratus, and the lateral half of the flexor digitorum profundus) and the palmar cutaneous nerve (innervating the lateral aspect of the palm) in the forearm.
In the hand the median nerve bifurcates into the recurrent branch of the median nerve (innervating the thenar muscles) and the palmar digital branch (innervating the lateral two lumbricals and the skin over the palmar surface and fingertips of the lateral three and a half digits).
Report A Problem
Is there something wrong with this question? Let us know and we’ll fix it as soon as possible.
Loading Form...
- 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 |
