턱관절 근육(교근, 익돌근 등)

[문형철]

1. 인간의 턱관절 힘은 자신의 체중을 이길 수 있을만큼 어마어마함. 

2. 주동근은? masseter muscle, medial pterygoid, lateral pterygoid

3. 내외측 익돌근에 쉽게 침을 놓을 수 있구나!!

4. 교근(masseter muscle), 내외측 익돌근

-  제 5번 뇌신경인 삼차신경의 mandibular nerve의 motor fiber의 지배

- 아 .. 그래서 구안와사때 마비가 되지 않고 씹기가 가능하구나!!

5. 교근과 측두근에 근방추가 많음. 

직관적으로 알아낸 사실

- 내측익돌근과 교근은 짝힘을 이루고 있다!

panic bird.

교근(masseter muscle)

-  제 5번 뇌신경인 삼차신경의 mandibular nerve의 motor fiber의 지배

In human anatomy, the masseter is one of the muscles of mastication. In the animal kingdom, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle since it is the most superficial and one of the strongest.

The masseter is a thick, somewhat quadrilateral muscle, consisting of two heads, superficial and deep. The fibers of the two heads are continuous at their insertion.

Superficial Head[edit]

The superficial head, the larger, arises by a thick, tendinous aponeurosis from the zygomatic process of the maxilla, and from the anterior two-thirds of the inferior border of the zygomatic arch. Its fibers pass downward and backward, to be inserted into the angle of the mandible and inferior half of the lateral surface of the ramus of the mandible.

Deep Head[edit]

The deep head is much smaller, and more muscular in texture. It arises from the posterior 3rd of the lower border and from the whole of the medial surface of the zygomatic arch. Its fibers pass downward and forward, to be inserted into the upper half of the ramus and the lateral surface of the coronoid process of the mandible. The deep head of the muscle is partly concealed, anteriorly, by the superficial portion. Posteriorly, it is covered by the parotid gland.

Innervation[edit]

Along with the other three muscles of mastication (temporalis, medial pterygoid and lateral pterygoid), the masseter is innervated by the mandibular division (V3) of the trigeminal nerve. The innervation pathway is: gyrus precentralis > genu capsula interna > nucleus motorius nervi trigemini > nervus trigeminus > nervus mandibularis > musculus masseter.

The action of the muscle during bilateral contraction of the entire muscle is to elevate the mandible, raising the lower jaw. Elevation of the mandible occurs during the closing of the jaws. The masseter parallels the medial pterygoid muscle, but it is stronger.

Examination[edit]

During an extraoral examination, stand near the patient and visually inspect and bilaterally palpate the muscle. Place the fingers of each hand over the muscle and ask the patient to clench his or her teeth several times.^[1]

Pathology[edit]

The masseter muscle can become enlarged in patients who habitually clench or grind (with bruxism) their teeth and even in those who constantly chew gum. This masseteric hypertrophy is asymptomatic and soft; it is usually bilateral but can be unilateral. 

Even if the hypertrophy is bilateral, there still may be asymmetry of the face due to unequal enlargement of the muscles.This extraoral enlargement may be confused with parotid salivary gland disease, dental infections, and maxillofacial neoplasms. However, no other signs are present except those involved in changes in occlusion intraorally such as pain, and the enlargement corresponds with the outline of the muscle. Most patients seek medical attention because of comments about facial appearance and this situation may be associated with further pathology of the temporomandibular joint.^[1]

Finally, the muscle undergoes spasm with malignant hyperthermia as do other skeletal muscles but this one is easily noted since it is on the face.

교근 Trp 탐구

- 연관통은 치통, 귀의 통증!

내측 익돌근(medial pterygoid muscle)

- 연관통은 턱관절통증

The medial pterygoid (or internal pterygoid muscle), is a thick, quadrilateral muscle of mastication.

The mandibular branch of the fifth cranial nerve, the trigeminal nerve, innervates the medial pterygoid muscle.

It consists of two heads.

• The bulk of the muscle arises as a deep head from just above the medial surface of the lateral pterygoid plate.
• The smaller, superficial head originates from the maxillary tuberosity and the pyramidal process of the palatine bone.

Its fibers pass downward, lateral, and posterior, and are inserted, by a strong tendinous lamina, into the lower and back part of the medial surface of the ramus and angle of the mandible, as high as the mandibular foramen. The insertion joins the masseter muscle to form a common tendinous sling which allows the medial pterygoid and masseter to be powerful elevators of the jaw.

Given that the origin is on the medial side of the lateral pterygoid plate and the insertion is from the internal surface of the ramus of the mandible down to the angle of the mandible, its functions include:

• Elevation of the mandible (closes the jaw)
• Minor contribution to protrusion of the mandible
• Assistance in mastication
• Excursion of the mandible; contralateral excursion occurs with unilateral contraction.

내측 익돌근 Trp 탐구

외측 익돌근(lateral pterygoid muscle)

The lateral pterygoid (or external pterygoid) is a muscle of mastication with two heads. It lies superiorly to the medial pterygoid.

The upper/superior head originates on the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, and the lower/inferior head on the lateral surface of the lateral pterygoid plate.

Inferior head inserts onto the neck of condyloid process of the mandible; upper/superior head inserts onto the articular disc and fibrous capsule of thetemporomandibular joint.

The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the mandibular fossa along the articular eminence to protrude the mandible. A concerted effort of the lateral pterygoid muscles acts in helping lower the mandible and open the jaw whereas unilateral action of a lateral pterygoid produces contralateral excursion (a form of mastication), usually performed in concert with the medial pterygoids.

Unlike the other three muscles of mastication, the lateral pterygoid is the only muscle of mastication that assists in depressing the mandible (opening the jaw). At the beginning of this action it is assisted by the digastric, mylohyoid and geniohyoid muscles.

외측 익돌근 Trp 탐구

[잠보]

감사합니다~