6.1.3 Musculature
The muscles of the head and neck relevant to oral implantology can be categorised as muscles of mastication, which are paired muscles that aid in the process of grinding and chewing food and turning it into a bolus, and muscles of facial expression, which are generally flat paired muscles that enable movements of the face and facial expression. All muscles of mastication are innervated by branches of the mandibular division of the trigeminal nerve (CN V3), while all muscles of facial expression are innervated by branches of the facial nerve (CN VII). Tables 6.2 and 6.3 give summaries of key facts [1, 2] and Figure 6.7 shows an anatomical rendering.
Table 6.2 Muscles of mastication summary.
Sources: Al‐Faraje, L. (2013). Surgical and Radiologic Anatomy for Oral Implantology. Chicago: Quintessence Publishing Co.; Norton, N. (2007). Netter's Head and Neck Anatomy for Dentistry. Philadelphia: Saunders Elsevier.
| Muscle | Origin | Insertion | Action | Innervation |
|---|---|---|---|---|
| Masseter | Zygomatic arch and maxillary process of zygomatic bone | Lateral surface of ramus of mandible | Elevation and retraction of mandible | Masseteric nerve (CN V3) |
| Temporalis | Temporal fossa | Coronoid process and anterior margin of the ramus of the mandible | Elevation and retraction of the mandible | Deep temporal nerve (CN V3) |
| Medial pterygoid | Medial surface of lateral plate of pterygoid process, pyramidal process of palatine bone (deep head); maxillary tuberosity, pyramidal process of palatine bone (superficial head) | Medial surface of mandible | Elevation and side‐to‐side movements of mandible | Medial pterygoid nerve (CN V3) |
| Lateral pterygoid | Roof of infratemporal fossa (superior head), lateral surface of the lateral pterygoid plate (inferior head) | Pterygoid fovea of mandible and temporomandibular joint articular disc (superior head) and condylar process (inferior head) | Protrusion and side‐to‐side movements of mandible | Lateral pterygoid nerve (CN V3) |
Table 6.3 Muscles of facial expression summary.
Sources: Al‐Faraje, L. (2013). Surgical and Radiologic Anatomy for Oral Implantology. Chicago: Quintessence Publishing Co.; Norton, N. (2007). Netter's Head and Neck Anatomy for Dentistry. Philadelphia: Saunders Elsevier.
| Muscle | Origin | Insertion | Action | Innervation |
|---|---|---|---|---|
| Orbicularis oris | Deep surface of the skin of the maxilla and mandible | Mucous membranes of the lips | Closes or purses the lips | Buccal and mandibular branches of CN VII |
| Buccinator | Molar areas of the alveolar processes of maxilla and mandible | Orbicularis oris, lips, and submucosal surfaces of lips and cheeks | Keeps bolus out of vestibule, expels air from oral cavity | Buccal branch of CN VII |
| Levator labii superiorus | Frontal process of the maxilla and the infraorbital margin | Skin of the upper lip | Elevates upper lip | Buccal and zygomatic branches of CN VII |
| Depressor labii inferioris | Anterior area of oblique line of mandible | Middle of lower lip | Pulls lower lip inferiorly and laterally | Mandibular branch of CN VII |
| Levator labii superioris alaeque nasi | Frontal process of maxilla | Alar cartilage and upper lip muscles (levator labii superioris and orbicularis oris) | Elevates the upper lip and dilates nostrils | Buccal and zygomatic branches of CN VII |
| Mentalis | Frenulum of lower lip | Skin of the chin | Elevates and protrudes the lower lip | Mandibular branch of CN VII |
| Risorius | Fascia superficial to the masseter muscle | Skin of the angle of the mouth | Retracts the corners of the mouth during smiling broadly and laughing | Buccal branch of CN VII |
| Depressor anguli oris | Mandible below canines, premolars, and first molars | Skin of corner of mouth and orbicularis oris | Pulls the angle of the mouth inferiorly and laterally | Buccal and mandibular branches of CN VII |
| Levator anguili oris | Canine fossa of maxilla inferior to infraorbital foramen | Angle of the mouth | Elevates the angle of the mouth | Zygomatic and buccal branches of CN VII |
| Zygomaticus major | Zygomatic bone (lateral and posterior surfaces) | Muscles of the angle of the mouth | Pulls corner of the mouth laterally and superiorly | Zygomatic branch of CN VII |
| Zygomaticus minor | Zygomatic bone (lateral and posterior surfaces) | Corner of the upper lip | Pulls upper lip superiorly | Zygomatic branch of CN VII |
| Nasalis | Transverse part on maxilla Alar part on maxilla | Transverse on aponeurosis at bridge of nose Ala nasi | Compress nostrils Open nostrils | Buccal and zygomatic branches of CN VII |
| Procerus | Facial aponeurosis of the lower nasal bone | Skin between eyebrows |
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