Muscles of Mastication

(ORIGIN, INSERTION AND ENNERVATION)

2010-2011

IntroductionThe muscles of mastication originate on the

skull and insert into the mandible. They are innervated by the mandibular branch , or V3.

The main muscles of mastication are four pairs of muscles (Masseter, Temporal, Medial and Lateral Pterygoid) attached to the mandible and they are innervated by the mandibular branch , or V3.

Masseter muscle

Origin: zygomatic arch and zygomatic bone

Insertion: lateral surface of ramus and the angle of the mandible

Innervation: nerve to masseter, from mandibular division of trigeminal nerve (V)

Temporalis Muscle

Origin: temporal fossa and temporal fascia

Insertion: coronoid process and anterior surface of the ramus of the mandible

Innervation: anterior and posterior deep temporal nerves from mandibular division of trigeminal nerve (V)

Lateral and Medial Pterygoid Muscles,

Lateral Pterygoid Muscle: Origin: superior head: greater wing

of sphenoid; inferior head: lateral surface of lateral pterygoid plate

Insertion: superior head: capsule & articular disk of tempormandibular joint; inferior head: neck of mandible

Innervation: lateral pterygoid branch of mandibular division of trigeminal nerve (V)

Medial Pterygoid Muscle: Origin: medial surface of the lateral

pterygoid plate, pyramidal process of palatine bone, tuberosity of maxilla

Insertion: medial surface of ramus and angle of mandible

Innervation: medial pterygoid branch of mandibular division of trigeminal nerve (V)

Accessory MusclesThe accessory muscles of mastication are: Digastric, Mylohyoid, Stylohyoid, Geniohyoid, Stylohyoid, Thyrohoid, Sternothyroid and Sternohyoid muscles)

Origin: anterior belly: digastric fossa of the mandible; posterior belly: mastoid notch of the temporal bone

Insertion: body of the hyoid via a fibrous loop over an intermediate tendon

Innervation: anterior belly: mylohyoid nerve, from the mandibular division of the trigeminal nerve (V); posterior belly: facial nerve (VII)

Digastric Muscle

Origin: mylohyoid line of mandible

Insertion: midline raphe and body of the hyoid bone

Innervation: mylohyoid nerve from the inferior alveolar nerve, a branch of the mandibular division of the trigeminal nerve (V)

Mylohyoid Muscle Geniohyoid Muscle• Origin: mental spine on the

lingual surface of the mandible• Insertion: body of hyoid bone

• Innervation: the first cervical nerve in the neck

Stylohyoid Muscle Hyoglossus Muscle

Origin: from the styloid process of the base of the skull

Insertion: the posterior part of the hyoid bone.

Innervation: a branch of the facial nerve (VII).

Origin: upper border of greater horn of the hyoid and body of the hyoid bone

Insertion: mingles with intrinsic muscles of the tongue

Innervation: hypoglossal nerve (XII)

Origin: mental spine on inner aspect of mental symphysis

Insertion: fans out to insert into the tongue from tip to base

Innervation: hypoglossal nerve (XII)

Origin: styloid process Insertion: side of the tongue Innervation: hypoglossal nerve

(XII)

Genioglossus Muscle Styloglossus Muscle

Sternothyroid muscle: Origin: the upper of the sternum. Insertion: an oblique line on the side of the thyroid cartilage of the larynx. Innervation: the second and third cervical nerves.

Thyrohoid muscle: Origin: the oblique line on the lateral side of the thyroid cartilage Insertion: the hyoid bone. Innervation: the first cervical nerve.

Sternohyoid Muscle Origin: the upper border of the manubrium of the sternum. Insertion: the front part of the body of the hyoid bone. Innervation: the second and third cervical nerves.

Omohyoid Muscle Origin: belly arises from the upper border of the scapula (shoulder blade); belly

arises from the hyoid bone. Insertion: the sternomastoid (sternocleidomastoid) muscle in the side of the neck Innervation: the second and third cervical thyroid arteries

ReferenceRichard W. Brand & Donald E. Isselhard,

Anatomy of Orofacial Structures, ed 7, US, 2003, Mosby.