Mastication Flashcards
Glossus
Of or pertaining to the tongue.
Glottis (or glottidis)
Relative to the larynx
Brachio
Relative to the upper arm
Brachy
Short
Cephal
Head
Lingual
Relative to tonge
Oral (oris)
Relative to the mouth
Mental (mentis)
– Relative to the chin
Mylo
– molar tooth or tail tooth in Greek
The muscles of mastication are innervated by
Trigeminal nerve
Oral cavity
Starting point of GIT Lips, tongue, gum, dentition, palate & salivary glands
Neck muscles
- Sternohyoideus (and the rest of hyoideus muscles: thyroi, crycoth, myohyoid)
- Sternocephalicus
- Brachiocephalicus
Muscles of mastication
- Temporalis
- Masseter
- Pterygoideus medialis
- Digastricus
- Mylohyoid
Sternohyoideus
The sternohyoid is a strap like infrahyoid muscle that connects the hyoid bone with the clavicle and sternum.
Along with the omohyoid muscle, it comprises the superficial plane of infrahyoid muscles, while the sternothyroid and thyrohyoid belong to the deep layer. The function of this muscle is to reestablish the breathing process by pulling the hyoid bone and larynx inferiorly after deglutition.
Origin: Manubrium of sternum, medial end of clavicle
Insertion: Inferior border of body of hyoid bone
Action: Depresses hyoid bone (from elevated position)
Innervation: Anterior rami of spinal nerves C1-C3 (via ansa cervicalis)
Blood supply: Superior thyroid artery
Sternocephalicus
Origin: It arises as a unit on the manubrium sterni.
Insertion: Mastoid part of the temporal bone and to the dorsal nuchal line of the occipital bone.
Action: To draw the head and neck to one side.
Nerve: Ventral branches of the cervical nerves and branches of the accessory nerve.
Brachiocephalicus
The brachiocephalicus lies on the neck deep to the sphincter colli superficialis and platysma. It is a long, flat muscle that extends from intersection clavicularis between brachium and the head and neck. It contents on its deep part a claviuclar remnant.
Origin: Clavicular tendon and the distal end of the cranial surface of the humerus.
Insertion: Dorsal surface of the neck.
Action: Bilateral fixation of the neck.
Nerve: Brachiocephalic.
Temporalis
The temporalis muscle is a thin, fan-shaped muscle situated within the temporal fossa of the skull. Along with the medial pterygoid, lateral pterygoid and masseter muscles, it belongs to the group masticatory muscles. The temporalis muscle runs superficially, from the temporal bone to the coronoid process of mandible.
Origin: Temporal fossa (up to inferior temporal line), Temporal fascia
Insertion: Apex and medial surface of coronoid process of mandible
Action: Anterior fibres: Elevates mandible
Posterior part: Retracts mandible
Innervation: Deep temporal branches (of mandibular nerve (CN V3))
Blood supply: Deep temporal branches of maxillary artery, middle temporal branches from superficial temporal artery
Masseter
Masseter muscle is a paired, strong, thick and rectangular muscle that is originating from the zygomatic arch and extends down to the mandibular angle. It consists of a superficial and a deep part.
Origin: Superficial part: maxillary process of zygomatic bone, Inferior border of zygomatic arch (anterior 2/3)
Deep part: deep/inferior surface of zygomatic arch (posterior 1/3)
Insertion: Lateral surface of ramus and angle of mandible
Innervation: Masseteric nerve of mandibular nerve (CN V3)
Blood supply: Masseteric artery
Function: Elevates and protrudes mandible
Pterygoideus medialis
The primary function of the pterygoid muscles is to produce movements of the mandible at the temporomandibular joint. Both muscles are innervated by branches of the mandibular division of the trigeminal nerve (CN V3), and receive their blood supply from branches of the maxillary artery.
Protrusion, elevation, medial movement of mandible
Digastricus
Digastric is a small paired muscle located in the anterior compartment of the neck. It belongs to a group of muscles called the suprahyoid muscles
Origin: Anterior belly: digastric fossa of mandible
Posterior belly: mastoid notch of temporal bone
Insertion: Body of hyoid bone (via intermediate tendon and its fibrous sling)
Action: Depresses mandible
Elevates hyoid bone during chewing, swallowing
Innervation: Anterior belly: mylohyoid nerve (of inferior alveolar nerve) (CN V3)
Posterior belly: digastric branch of facial nerve (CN VII)
Blood supply: Anterior belly: facial artery
Posterior belly: occipital artery
Mylohyoid
Mylohyoid muscle is one of the suprahyoid muscles that, together with geniohyoid muscle forms the floor of the oral cavity.
Along with the other suprahyoid muscles (digastric, geniohyoid and stylohyoid), it connects the hyoid bone to the skull. The functions of this muscle are to facilitate speech and deglutition by elevating the floor of the mouth and hyoid bone and depressing the mandible.
Origin: Mylohyoid line of mandible
Insertion: Mylohyoid raphe, body of hyoid bone
Action: Forms floor of oral cavity, elevates hyoid bone and floor of mouth, depresses mandible
Innervation: Nerve to mylohyoid (of inferior alveolar nerve (CN V3))
Blood supply: Sublingual, inferior alveolar and submental arteries
Orbicularis oris
around the lips – important in herbivores
Origin: Medial aspects of maxilla and mandible, perioral skin and muscles, modiolus
Insertion: Skin and mucous membrane of lips
Action: Closes mouth, compresses and protrudes lips
Innervation: Buccal branch of facial nerve (CN VII)
Blood supply: : Facial artery - Superior and inferior labial arteries
Maxillary artery - Mental and infraorbital arteries
Superficial temporal artery - Transverse facial artery
Incisive
raise upper lip and pull lower lip downwards
elevates, everts and protrudes the lower lip, and wrinkles the skin of the chin.
Origin: Incisive fossa of mandible
Insertion: Skin of chin (Mentolabial sulcus)
Action: Elevates, everts and protrudes lower lip, wrinkles skin of chin
Innervation: Mandibular branch of facial nerve (CN VII)
Blood supply: Inferior labial branch of facial artery, mental branch of the maxillary artery
Nasolabial elevator
– opens nostrils and elevates upper lip
Levator of the upper lip
The levator labii superioris muscle is a three-part muscle useful for facial expression and dilation of the mouth. It runs down alongside the lateral aspect of the nose. Its primary function is in raising the upper lip.
Caninus muscle
The levator anguli oris (caninus) is a facial muscle of the mouth arising from the canine fossa, immediately below the infraorbital foramen. It elevates angle of mouth medially. Its fibers are inserted into the angle of the mouth, intermingling with those of the zygomaticus, triangularis, and orbicularis oris.