The muscles of the head include the tongue, muscles of facial expression, extra-ocular muscles and muscles of mastication.
The tongue comprises of intrinsic and extrinsic muscles. It receives motor innervation from the hypoglossal nerve. Sensation of the tongue can be divided into taste, and general sensation.
The muscles of facial expression are located in the subcutaneous tissue. The attach into the skin, and contract to exert their effects. The muscles of facial expression can be divided in to three groups: orbital, nasal and oral.
The orbital muscles of facial expression exert control over movement of the eyelids. They are Orbicularis oculus and corrugator supercilia. Innervated by the facial nerve, these muscles protect the cornea from damage.
The nasal muscles of facial expression exert control over movements of the nose, and the skin around it. Innervated by the facial nerve, the three muscles in this group are: nasalis, procerus, and depressor septi nasi.
The oral muscles of facial expression are responsible for movements of the mouth and lips. The two key muscles in this group are Orbicularis oris and buccinator, both receiving motor innervation by the facial nerve.
Located within the orbit, the extra-ocular muscles control the movements of the eyeball and superior eyelid. The levator palpebrae superioris functions to elevate the upper eyelid, receiving motor innervation from the oculomotor nerve (CN3). There are six muscles involved in control of eyeball movements: superior, inferior, medial and lateral recti muscles, as well as the superior and inferior oblique muscles. The extra-ocular muscles receive motor innervation from the oculomotor nerve. The exceptions to this rule are the superior oblique, which is innervated by the trochlear nerve, and the lateral rectus muscle, which is innervated by the abducens nerve.
The muscles of mastication develop from the first pharyngeal arch. The four muscles: masseters, temporalis, medial pterygoid and lateral pterygoid are associated with jaw movements receiving motor innervation from the mandibular nerve (CNV3).
In this section, learn more about the muscles of the head: the tongue, muscles of facial expression, extra-ocular muscles and muscles of mastication
