From the Guidelines
Cranial nerve 7, also known as the facial nerve, controls facial muscle movement, taste sensation to the anterior two-thirds of the tongue, secretion of tears and saliva, and sensation to a small area around the ear. This control is exerted through the facial nerve's complex structure, which contains branchial motor, visceral motor, general sensory, and special sensory functions 1. The facial nerve innervates all muscles of facial expression, allowing us to smile, frown, raise our eyebrows, close our eyes, and make other facial expressions.
Key Functions of Cranial Nerve 7
- Innervation of muscles of facial expression
- Supply of parasympathetic fibers to the lacrimal gland for tear production and to the submandibular and sublingual salivary glands for saliva production
- Carriage of taste fibers from the anterior two-thirds of the tongue via the chorda tympani branch
- Sensation to a small area around the ear The facial nerve emerges from the brainstem at the cerebellopontine angle and travels through the internal auditory canal and facial canal before branching to innervate its target structures 1. Damage to the facial nerve can result in facial paralysis (Bell's palsy), decreased tear and saliva production, and altered taste sensation.
Clinical Implications
- Facial paralysis (Bell's palsy)
- Decreased tear and saliva production
- Altered taste sensation
- Hemifacial spasm
- Tinnitus, conductive and sensorineural hearing loss 1 Given the complexity and the critical functions of the facial nerve, any damage or pathology affecting this nerve can have significant implications for a patient's quality of life, emphasizing the importance of prompt and accurate diagnosis and treatment 1.
From the Research
Cranial Nerve Seven Controls
Cranial nerve seven, also known as the facial nerve, controls various functions related to facial expression, taste, and other sensory and motor activities. The key controls of cranial nerve seven include:
- Muscles of facial expression: The facial nerve innervates the muscles responsible for facial expressions, such as smiling, frowning, and eye closure 2, 3, 4, 5.
- Taste sensation: The facial nerve is responsible for conveying taste sensations from the tongue and palate 2, 3.
- Visceral sensory fibers: The nervus intermedius, a part of the facial nerve, conveys visceral sensory fibers from the tongue and palate 2.
- Preganglionic parasympathetic fibers: The facial nerve also conveys preganglionic parasympathetic fibers to the pterygopalatine and submandibular ganglia 2.
- Other functions: The facial nerve has other branches, such as the greater petrosal nerve, the chorda tympani nerve, and the posterior auricular nerve, which contribute to various sensory and motor functions 2, 4.
Muscles of Facial Expression
The muscles of facial expression, innervated by the facial nerve, include: