Anatomy
Lower Limb
The muscles of the posterior leg are all innervated by which of the following nerves:
Answer:
The muscles of the posterior leg are divided into the superficial group (the gastrocnemius, the plantaris and the soleus) and the deep group (the popliteus, the flexor hallucis longus, the flexor digitorum longus and the tibialis posterior). They are all innervated by the tibial nerve.Posterior Leg Muscles
Anatomy / Lower Limb / Posterior Leg
Last Updated: 11th April 2019
The muscles of the posterior leg are divided into the superficial group (the gastrocnemius, the plantaris and the soleus) and the deep group (the popliteus, the flexor hallucis longus, the flexor digitorum longus and the tibialis posterior).
Table: Function and Innervation of the Posterior Leg Muscles
| Muscle | Function | Innervation |
|---|---|---|
| Gastrocnemius | Plantarflexion of foot and flexion of leg | Tibial nerve |
| Plantaris | Plantarflexion of foot and flexion of leg | Tibial nerve |
| Soleus | Plantarflexion of foot | Tibial nerve |
| Flexor digitorum longus | Flexion of lateral four toes | Tibial nerve |
| Flexor hallucis longus | Flexion of great toe and plantarflexion of foot | Tibial nerve |
| Tibialis posterior | Plantarflexion and inversion of foot, support of medial arch | Tibial nerve |
Innervation
They are all innervated by the tibial nerve.
Function
The gastrocnemius plantarflexes the foot at the ankle and also flexes the leg at the knee.
The plantaris plantarflexes the foot at the ankle and flexes the leg at the knee.
The soleus plantarflexes the foot at the ankle.
The flexor digitorum longus flexes the lateral four toes. It is involved with gripping the ground during walking and propelling the body forward off the toes at the end of the stance phase of gait.
The flexor hallucis longus flexes the great toe and contributes to plantarflexion of the foot at the ankle joint.
The tibialis posterior inverts and plantarflexes the foot and provides dynamic support to the medial arch of the foot during walking. The tibialis posterior distally curves forward under the medial malleolus and enters the medial side of the foot to attach to the medial tarsal bones, mainly to the tuberosity of the navicular and adjacent region of the medial cuneiform.
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2017/01/Posterior-Leg-Superficial.jpg)
Posterior Leg Muscles (Superficial): Gastrocnemius (green), Soleus (red), Plantaris. (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2017/01/Posterior-Leg-Deep.jpg)
Posterior Leg Muscles (Deep): Flexor Digitorum Longus (green), Tibialis Posterior (red), Flexor Hallucis Longus (blue). (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], 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 |
