Nerve supply of the nasal cavity: olfactory nerve, V1 and V2
Smell travels in the olfactory nerve, while touch and pain in the nose travel in the trigeminal nerve (cranial nerve V), through its first two branches (divisions), V1 and V2.
Remember
Smell is carried by the olfactory nerve, and touch and pain by the trigeminal nerve: V1 takes the upper front of the nose and V2 takes the lower back.
The nose has two quite separate sensory nerve supplies, one for smell and one for ordinary sensation.
Smell is carried by the olfactory nerve (cranial nerve I). The olfactory mucosa lines the roof of the nasal cavity and houses neurones that respond to aromas, and their fibres pass up through the cribriform plate, the perforated bone in the roof of the nasal cavity, into the skull. A fracture across the skull base can shear these fibres where they cross the plate, so the sense of smell is lost (anosmia) while trigeminal sensation is preserved.
General sensation, meaning touch, pain and temperature, travels instead in the trigeminal nerve (cranial nerve V). Two of the three branches of the nerve, called divisions, share the cavity. The ophthalmic division (V1, the division at the eye) supplies the anterosuperior (front and upper) part, and the maxillary division (V2, the division at the upper jaw) supplies the posteroinferior (back and lower) part.
Branches of V2 such as the nasopalatine and greater palatine nerves leave the pterygopalatine fossa (a small space behind the maxilla where the maxillary nerve branches). The nasopalatine nerve runs along the nasal septum (the partition between the two nasal passages) to supply the lining of the posterior septum.
So match both the region and the type of sensation: V1 for the front and top of the nose, V2 for the back and bottom, and the olfactory nerve for smell.
Key facts
- Smell
- is carried by the olfactory nerve (cranial nerve I) through the cribriform plate, not by the trigeminal nerve.
- Anterosuperior cavity
- general sensation comes from the ophthalmic division (V1) of the trigeminal nerve.
- Posteroinferior cavity
- general sensation comes from the maxillary division (V2) of the trigeminal nerve.
- Posterior nasal septum
- the nasopalatine nerve, a branch of V2, supplies it.
- Skull base fracture
- olfactory fibres can be sheared where they cross the cribriform plate, so loss of smell with normal nasal sensation places the injury in the olfactory nerve.
- Pterygopalatine fossa
- contains branches of the maxillary nerve and the pterygopalatine ganglion, so surgery there can injure V2 nasal branches.
Exam traps
- The olfactory nerve does not carry touch or pain from the nose, because its fibres carry smell, so damage to them changes smell rather than causing reduced sensation.
- The ophthalmic division (V1) does supply the inside of the nose, but only the anterosuperior part, so it is not the nerve for general sensation in the back and lower cavity.
- Facial nerve fibres in the greater petrosal nerve stimulate secretion from the nasal glands, so they do not carry general sensation from the nose.
Read the full notes
Tested in 6 SimpleMed+ questions
Practice it in Head and Neck, with the answer and a full explanation after every question.
Practice these questions