Dominic Stone
The facial nerve, also known as the seventh cranial nerve, is a nerve in the head that sends signals from the brain to the face and vice versa. It is responsible for providing motor innervation to the facial muscles, enabling expressions such as smiling, frowning, and wrinkling the nose. The nerve also has sensory and parasympathetic functions, including taste sensation and tear production. The facial nerve has five branches with distinct motor functions, controlling various muscles in the face and neck, such as the forehead muscles, orbicularis oculi, and platysma muscle.
| Characteristics | Values |
|---|---|
| Cranial nerve | 7th |
| Carries nerve fibres that control | Facial movement and expression |
| Carries nerves involved in | Taste to the anterior 2/3 of the tongue |
| Tear production | |
| Moderating sensitivity to noise volume | |
| Several other muscles not involved in routine facial expression | |
| Number of branches | 5 |
| Branches | Frontal (or temporal), zygomatic, buccal, marginal mandibular, and cervical |
| Functions of branches | Controls forehead muscles, helps close eyes, moves nose and enables blinking, raises upper lip and corners of mouth, draws lower lip down, allows movement in chin and lower corners of mouth |
| Condition caused by malfunctioning | Facial nerve palsy or Bell's palsy |
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What You'll Learn
The facial nerve controls muscles of facial expression
The facial nerve, or cranial nerve 7 (CN VII), controls several muscles in the face, including those that help us smile, frown, wrinkle our nose, and raise our eyebrows. Facial nerves are responsible for forming facial expressions, communicating orally, tasting, and tear production. Facial nerves carry nerve fibres that control facial movement and expression.
The facial nerve has five branches with distinct motor functions: the frontal (or temporal) branch, the zygomatic branch, the buccal branch, the marginal mandibular branch, and the cervical branch. Each of these branches provides input to a group of muscles of facial expression. The frontal branch controls the forehead muscles. The zygomatic branch helps close the eyes. The buccal branch allows movement of the nose and enables blinking, raising the upper lip, and smiling. The marginal mandibular branch draws the lower lip down and travels through the middle ear to the stapedius muscle, which helps the inner ear respond to loud noises. The cervical branch allows movement in the chin and the lower corners of the mouth by controlling the platysma muscle in the neck.
Facial nerve palsy, or paralysis, can occur when the facial nerve malfunctions, particularly in its motor functions. Bell's palsy causes temporary facial paralysis, usually only affecting the muscles on one side of the face. Ramsay Hunt syndrome is a complication of varicella-zoster virus infections, causing facial nerve paralysis, intense ear pain, and a painful rash on the ear, face, or mouth. Hemifacial spasm is another condition caused by overactivity in the motor branches of the facial nerve, resulting in frequent facial muscle twitches.
The facial nerve also carries nerves involved in taste, transmitting signals to the anterior two-thirds of the tongue, and tear production in the lacrimal gland. It has small branches that moderate our sensitivity to noise volume (stapedius muscle) and several other muscles not involved in routine facial expression. The facial nerve is comprised of three nuclei: general visceral efferent, special visceral afferent, and general somatic afferent.
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It provides motor innervation to muscles around the ear
The facial nerve, or cranial nerve 7 (CN VII), is responsible for providing motor innervation to several muscles in the face, including those around the ear. These muscles enable essential functions such as smiling, frowning, wrinkling the nose, raising eyebrows, and forming facial expressions.
The nerve to the stylohyoid muscle, a branch of the facial nerve, innervates the stylohyoid muscle, which is responsible for raising the hyoid bone. This muscle is crucial for maintaining the stability of the tongue and larynx during swallowing and speech.
The facial nerve also plays a role in innervating the stapedius muscle, which is involved in moderating our sensitivity to sound volume. This muscle is supplied by the nerve to stapedius, another branch of the facial nerve. The stapedius muscle helps protect the inner ear from loud noises and is essential for maintaining hearing health.
Additionally, the facial nerve contributes to the innervation of the posterior belly of the digastric muscle. This muscle is involved in various functions, including mastication and swallowing. The digastric muscle works in conjunction with other muscles to produce smooth and coordinated movements during these processes.
The facial nerve has five main branches: frontal (or temporal), zygomatic, buccal, marginal mandibular, and cervical. Each of these branches has distinct motor functions and innervates specific muscles around the face and ear, enabling a wide range of facial expressions and movements.
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The nerve has sensory and parasympathetic functions
The facial nerve is the seventh cranial nerve and it provides motor innervation to the facial muscles, enabling facial expressions. The nerve is comprised of three nuclei: general visceral efferent, special visceral afferent, and general somatic afferent. The general visceral efferent (parasympathetic secretomotor) supplies the submandibular and sublingual salivary glands, as well as the lacrimal gland. The special visceral afferent provides taste sensation from the anterior two-thirds of the tongue. The general somatic afferent provides cutaneous sensations from the pinna and the external auditory meatus.
The facial nerve has a wide range of functions, and its branches transmit a combination of sensory, motor, and parasympathetic fibres. The nerve arises in the pons, an area of the brainstem, and exits the skull via the stylomastoid foramen. The first extracranial branch is the posterior auricular nerve, which provides motor innervation to the occipital belly of the occipitofrontalis muscle and the intrinsic auricular muscles. The nerve also innervates the skin around the external acoustic meatus and the retroauricular region.
The digastric and stylohyoid branches of the facial nerve carry motor fibres to the respective muscles. The stylohyoid muscle is a suprahyoid muscle of the neck that is responsible for raising the hyoid bone. The facial nerve then pierces the parotid gland and bifurcates into five motor branches. These branches are known as superior (temporofacial) and inferior (cervicofacial) trunks, which give rise to its five terminal branches: temporal, zygomatic, buccal, marginal mandibular, and cervical.
The cervical branch supplies the platysma muscle in the neck. The temporal branches supply the frontalis, orbicularis oculi, and corrugator supercilii muscles. The zygomatic branch supplies the orbicularis oculi. The buccal branch supplies the orbicularis oris, buccinator, and zygomaticus. The marginal mandibular branch supplies the depressor labii inferioris, depressor anguli oris, and mentalis.
The parasympathetic fibres of the facial nerve are carried by the greater petrosal and chorda tympani branches. The greater petrosal nerve provides preganglionic parasympathetic innervation to the lacrimal gland, as well as the mucous glands of the nasal cavity, maxillary sinus, and palate. The chorda tympani carries special sensory fibres to the anterior two-thirds of the tongue and parasympathetic fibres to the submandibular and sublingual glands.
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It controls muscles that allow smiling, frowning, wrinkling the nose, etc
The facial nerve, or cranial nerve VII, controls the muscles of facial expression, enabling movements such as smiling, frowning, and wrinkling the nose. It provides motor and sensory innervation to the muscles formed by the second pharyngeal arch, including the posterior belly of the digastric, stylohyoid, and stapedius muscles.
The facial nerve is comprised of three nuclei: general visceral efferent, special visceral afferent, and general somatic afferent. The general visceral efferent nucleus supplies preganglionic parasympathetic fibres to the submandibular and sublingual salivary glands, as well as the lacrimal gland. The special visceral afferent nucleus provides taste sensation from the anterior two-thirds of the tongue. The general somatic afferent nucleus provides cutaneous sensations from the pinna and the external auditory meatus.
The facial nerve exits the skull through the stylomastoid foramen and gives off several branches, including the posterior auricular nerve, which controls movements of the scalp muscles around the ear. The nerve then enters the parotid gland and divides into five branches: temporal, zygomatic, buccal, marginal mandibular, and cervical. Each of these branches supplies a group of muscles involved in facial expression.
The temporal branch supplies the frontalis, orbicularis oculi, and corrugator supercilii muscles, which are involved in raising the eyebrows and closing the eyes. The zygomatic branch supplies the orbicularis oculi muscle, which is involved in blinking and squinting. The buccal branch supplies the orbicularis oris, buccinator, and zygomaticus muscles, which are involved in smiling, pursing the lips, and puffing out the cheeks. The marginal mandibular branch supplies the depressor labii inferioris, depressor anguli oris, and mentalis muscles, which are involved in lowering the corner of the mouth and depressing the lower lip. The cervical branch supplies the platysma muscle in the neck, which is often tensed during shaving.
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The nerve has five branches with distinct motor functions
The facial nerve is the seventh cranial nerve, and it has five branches with distinct motor functions. These branches are responsible for innervating the muscles of facial expression, enabling us to smile, frown, wrinkle our noses, and raise our eyebrows. The nerve provides motor control to the facial muscles, allowing for various facial expressions.
The first motor branch is the nerve to the stapedius muscle, which arises within the facial canal and passes through the pyramidal eminence. This branch supplies motor fibres to the stapedius muscle of the middle ear, which is responsible for dampening vibrations and protecting the hearing apparatus during loud sounds.
The second branch is the posterior auricular nerve, which ascends in front of the mastoid process and innervates the muscles of the outer ear. It also supplies the occipital part of the occipitofrontalis muscle. This nerve is responsible for controlling the movements of some of the scalp muscles around the ear.
The third branch is the nerve to the posterior belly of the digastric muscle, which innervates this muscle in the neck. The fourth branch is the nerve to the stylohyoid muscle, a suprahyoid muscle of the neck that raises the hyoid bone.
Finally, the fifth branch is the cervical branch, which supplies the platysma muscle in the neck, allowing movement in the chin and the lower corners of the mouth.
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Frequently asked questions
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a nerve in your head that sends signals from your brain to parts of your face and vice versa.
The facial nerve controls the muscles of facial expression, allowing you to smile, frown, wrinkle your nose, raise your eyebrows, puff out your cheeks, and more.
The facial nerve also has sensory and parasympathetic functions. It plays a key role in hearing and taste sensation from the front two-thirds of the tongue.
