Anatomy
Cranial Nerve Lesions
A 54 year old man presents to ED with severe headaches and vomiting. Imaging shows a tumour causing compression at the jugular foramen. Which of the following clinical features would you most expect to see in this patient:
Answer:
Both the glossopharyngeal nerve (afferent pathway of gag reflex) and the vagus nerve (efferent pathway of gag reflex), together with the spinal accessory nerve exit the skull through the jugular foramen. Hearing is primarily a function of the vestibulocochlear nerve. Sensation of the face is supplied by the trigeminal nerve. Muscles of facial expression (including those responsible for closing the eye) are innervated by the facial nerve. Tongue movements are primarily a function of the hypoglossal nerve.Cranial Nerve Overview
Anatomy / Central Nervous System / Cranial Nerve Lesions
Last Updated: 24th February 2019
There are 12 pairs of cranial nerves arising from the brain.
| Cranial Nerve | Origin | Exit from Skull | Function |
|---|---|---|---|
| Olfactory Nerve (I) | Cerebrum | Cribriform Plate | SA: smell |
| Optic Nerve (II) | Cerebrum | Optic Canal | SA: vision |
| Oculomotor Nerve (III) | Midbrain | Superior Orbital Fissure | GSE: levator palpebrae superioris, superior rectus, inferior rectus, medial rectus, inferior oblique
GVE: sphincter pupillae, ciliary muscles |
| Trochlear Nerve (IV) | Midbrain | Superior Orbital Fissure | GSE: superior oblique |
| Trigeminal Nerve (V): | Pons | Superior Orbital Fissure (V1); Foramen Rotundum (V2); Foramen Ovale (V3) | GSA: sensory from most of head
BE: temporalis, masseter, medial and lateral pterygoids, tensor tympani, tensor veli palatini, anterior belly of digastric, mylohyoid |
| Abducens Nerve (VI) | Pons | Superior Orbital Fissure | GSE: lateral rectus |
| Facial Nerve (VII) | Pons | Internal Acoustic Meatus; Stylomastoid Foramen | GSA: sensory from external acoustic meatus and skin posterior to ear
SA: taste from anterior two-thirds of tongue GVE: lacrimal gland, submandibular and sublingual salivary glands, mucous membranes of nasal cavity and palate BE: muscles of face and scalp, stapedius, posterior belly of digastric, stylohyoid |
| Vestibulocochlear Nerve (VIII) | Pons | Internal Acoustic Meatus | SA: balance and hearing |
| Glossopharyngeal Nerve (IX) | Medulla | Jugular Foramen | GVA: sensory from carotid body and sinus, posterior one-third of tongue, palatine tonsils, upper pharynx, and mucosa of middle ear and pharyngotympanic tube
SA: taste from posterior one-third of tongue GVE: parotid salivary gland BE: stylopharyngeus |
| Vagus Nerve (X) | Medulla | Jugular Foramen | GSA: sensory from skin posterior to ear and external acoustic meatus, and dura in posterior cranial fossa
GVA: sensory from aortic body chemoreceptors and aortic arch baroreceptors, mucous membranes of pharynx, larynx, oesophagus, bronchi, lungs, heart, and abdominal viscera of foregut and midgut SA: taste from epiglottis GVE: smooth muscle and glands in pharynx, larynx, thoracic viscera and abdominal viscera in foregut and midgut BE: palatoglossus, muscles of soft palate (except tensor veli palatini), muscles of pharynx (except stylopharyngeus), muscles of larynx |
| Spinal Accessory Nerve (XI) | Medulla | Jugular Foramen | BE: sternocleidomastoid and trapezius |
| Hypoglossal Nerve (XII) | Medulla | Hypoglossal Canal | GSE: hyoglossus, genioglossus, styloglossus and intrinsic muscles of tongue |
(GSA = General Somatic Afferent; GVA = General Visceral Afferent; SA = Special Afferent; GSE = General Somatic Efferent; GVE: General Visceral Efferent; BE = Branchial Efferent)
Cranial Nerve Origins (Left) and Cranial Nerve Exits (Right). (Image modified by FRCEM Success. Original by Patrick J. Lynch, medical illustrator (Patrick J. Lynch, medical illustrator) [CC BY 2.5 , 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 |
