In this article, we shall look at the anatomical course of the nerve, and the motor, sensory and parasympathetic functions of its terminal branches. The course of the facial nerve is very complex. There are many branches, which transmit a combination of sensory, motor and parasympathetic fibres. The nerve arises in the pons , an area of the brainstem. It begins as two roots; a large motor root , and a small sensory root the part of the facial nerve that arises from the sensory root is sometimes known as the intermediate nerve. Here, they are in very close proximity to the inner ear.
The Facial Nerve (CN VII)
Facial nerve - Wikipedia
The temporal bone contributes to the lower lateral walls of the skull. It contains the middle and inner portions of the ear, and is crossed by the majority of the cranial nerves. In this article, we shall look at the different parts of the temporal bone, their articulations, and any clinical correlations. Fig 1 — Lateral view of the skull. The temporal bone has been highlighted. The temporal bone itself is comprised of five constituent parts. The squamous, tympanic and petromastoid parts make up the majority of the bone, with the zygomatic and styloid processes projecting outwards.
Temporal bone:Facial nerve
The middle ear consists of the tympanic cavity and the antrum. The antrum is a large aircell superior and posterior to the tympanic cavity and connected to the tympanic cavity via the aditus ad antrum. The epitympanum or attic is the upper portion of the tympanic cavity above the tympanic membrane, and contains the head of the malleus and the body of the incus. The tympanic membrane, the malleus, incus and stapes transfer soundwaves to the stapes footplate, which is attached to the base of the cochlea in the oval window. At the most inferior level we see the facial nerve passing inferiorly to finally reach the stylomastoid foramen not shown in this image.
It emerges from the pons of the brainstem , controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue. It arises from the brainstem from an area posterior to the cranial nerve VI abducens nerve and anterior to cranial nerve VIII vestibulocochlear nerve. The facial nerve also supplies preganglionic parasympathetic fibers to several head and neck ganglia. The facial and intermediate nerves can be collectively referred to as the nervus intermediofacialis.