Derivatives of branchial arcs: 1st arc -m. mylohyoideus, venter anterior m. digastrici; 2nd arc-m. stylohoideus, venter posterior m. digastrici, platysma; other - m. sternocleidomastoideus
Autohtone muscles: anterior – m. sternohyoideus, m. sternothyroideus, m. thyrohyoideus, m. omohyoideus, m. geniohyoideus; lateral – mm. scalene anterior, mediuset posterior; forevertebral – m. longuscolli, m. longuscapitis, m. rectus capitis anterior, m. rectiscapitislateralis
Superficial:
m. platysma – draw back skin of the neck, prevent under skin veins from compression, draw back angles of mouth
m. sternocleidomastoides–makes inclination of neck department of vertebral column with raising of head
Middle:
m. mylohyoideus, m. digastricus m. styloideus, m. geniohyoideus – lift up hypoglossalis bone
Muscles located below from hypoglossalis bone:
m. sternohyoideus – draw bachhypoglossalis bone
m. sternothyroideus – let down the larynx
m. thyrothyroideus – when it faxaed with hypoglossalis bone, it draw up the larynx
m. omohyoideus – stretch the fascia of the neck, widen large venous trunk, draw back hypoglossalis bone
Deep:
m. scalenus (anterior, medius, posterior) – lift up upper ribs, act as respiratory muscles
Forevertebral muscles:
m. longuscolli – bend neck part of vertebral column
m. longuscapitis, mm. recti capitis (anterior and lateralis) – bend head forward
44 Muscles of the head. Mimic and chewing muscles: properties of their structure, functions, blood & nerve supply, lymphatic drainage.
THE MUSCELS OF THE HEAD
With the exception of the striated muscles of the sight and hearing organs and the upper part of the digestive system (described in respective sections of this volume), all the muscles of the head can be divided into the following two groups:
1. Muscles of mastication: derivatives of the first visceral (mandibular) arch. Innervation: nervus trigeminus.
2. Muscles of facial expression: derivatives of the second visceral (hyoid) arch. Innervation: nervus facialis.
1. The auricular muscle (the lateral belly of the epicranial mascle) are very poorly developed in most humans and have no function. The remnants of the human auricular musculature are a classical example of rudimentary organs. Persons who can literally move their ears,
MUSCLES SURROUNDING THB EYES
2. The procerus muscle (m. procseus) arises from the bones of the ridge of the nose and the aponeurosis of the nasal muscle and is inserted into the skin of the glabella where it interlaces with the frontal belly of the epicra- nius. By drawing down the skin of this region, it causes transverse wrinkling of the skin above the bridge of the nose.
3. The orbicular oculi muscle (st. orbicularis oculi) surrounds the eyelids; its wide peripheral orbital part (pars orbitalis) is on the bony margin of the orbit, while the central palpebral part (part palpebratE) is on the eyelids Isolated contraction of the upper fibres of this part draws the skin of the forehead and the eyebrow downward; as a result the eyebrow is straightened out, and the transverse wriakles on the forehead are smoothed out. In this respect it is an antagonist of the venter frontalis.
They draws the eyebrows toward each other and causes the formation of vertical wrinkles ia the space between the eyebrows above the bridge of the nom. In addition to the vertical wrinkles, short transverse wrinkles often form above the bridge of the nom in the middle one third of the forehead as the result of simultaneous action by the venter frontalis. This position of the eyebrows indicates suffering, pain, or other strong emotions.
MUSCLES AROUND THB MOUTH
4. The levator labii superforfs muscle fold. When contracted, the muscle raises the upper lip and thus makes the nasolabial sulcus deeper; it pulls the ala of the nose upward and dilates the nares.
5. The zygomatic minor muscle (m. zygomaticus minar) arises from the zygomatic bone and is inserted into the nasolabial fold which it deepens dur- ing contraction.
6. The zygomaticus major muscle (m. sygmnaticuss majar) The action of the zygomaticus major muscie is perhaps the most important in the expres- sion of laughter on the face.
7. The risorius muscle another muscle important in the expression of laughter. This small transverse slip arises from the parotid and masseteric fasciae and passes to the angle of the mouth. It is often absent. It stretches the mouth in laughing; in some persons it is attached to the skin of the cheeks and when it contracts, a small depression (dimple) forms laterally to the angle of the mouth.
8. The depressor anguli oris muscle is a trian- gular muscular plate. Its base arises from the inferior border of the mandible laterally of the mental tubercle. Its pulls is inserted into the skin of the angle of the mouth and the upper lip. It pulls down the angle of the mouth and straightens out the nasolabial fold. Depression of the angles of the mouth produces the expression of grief.
9. The levator anguli oris musde It arises from the canine fossa (and was formerly called m. caninus) below the infra- orbitalforamen and is inserted into the angle of the mouth. It raises the angle of the mouth.
10. The depressor labii inferioris muscle (m. depressor labii inferiorly) lies directly on the bone. It arises on the border of the mandible where it is a continuation of the platysma muscle, passes obliquely, and is invited into the skin of the whole lower lip including its border. It pulls the lip down and a little laterally, as occurs, for ezample, in expressions of disgust.
1l. The mentalis muscle (m. vitalis) is one of the strongest in the group of muscles of facial expression. It ariser from the juga alveolaria of the lower incisors and the canine tooth and is inserted into the skin of the chin. It raises the skin of the chin (with the formation of small dimples in it) and pushes the lower lip upward, pressing it to the upper lip.
12. The buccinator muscle (m. buccusator) ia a wide quadrangular muscle forming the lateral wall of the oral cavity and directly adjoining the mucous membrane.
