Human Anatomy - Kotsan I. Ya. 2009

Muscles and Fasciae of the Head
Muscles of the Cranial Vault

The Muscles of the cranial vault include a single epicranial Muscle (m. epicranius), which comprises two parts: the occipitofrontalis and the temporoparietalis muscles.

The occipitofrontalis muscle (m. occipitofrontalis) is formed by the occipital and frontal bellies, between which lies a broad, thin aponeurosis known as the epicranial aponeurosis (galea aponeurotica). The occipital belly (venter occipitalis) originates from the highest nuchal line and the Base of the mastoid process of the Temporal bone, ascending to blend into the fibers of the posterior part of the epicranial aponeurosis. Divided by a median fibrous plate, the occipital belly consists of two symmetrical parts. The frontal belly (venter frontalis) is more strongly developed. It arises from the anterior fascicles of the epicranial aponeurosis and inserts into the Skin of the eyebrows. A median fibrous plate running along the midline of the forehead similarly divides the frontal belly into two quadrilateral segments. The epicranial aponeurosis (galea aponeurotica) forms a thin yet remarkably strong fibrous sheet covering the greater part of the cranial vault. Vertically oriented Connective Tissue bundles firmly anchor this sheet to the scalp. A layer of loose connective tissue lies between the epicranial aponeurosis and the BONES OF THE cranial vault, allowing the Hair-bearing skin of the scalp, together with the epicranial aponeurosis, to move freely over the vault when the occipitofrontalis muscle contracts.

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Fig. 107. The Skull and facial muscles.

(after M. M. Kurepina)

1 — corrugator supercilii muscle, 2 — frontal belly of the epicranial muscle, 3 — temporalis muscle, 4 — procerus muscle, 5 — orbicularis oculi muscle, 6 — zygomaticus major muscle, 7 — nasalis muscle, 8 — masseter muscle, 9 — levator anguli oris muscle, 10 — buccinator muscle, 11 — orbicularis oris muscle, 12 — depressor anguli oris muscle, 13 — depressor labii inferioris muscle, 14 — mentalis muscle, 15 — cartilages of the nasal septum/alar cartilages, 16 — piriform aperture, 17 — angle of the Mandible, 18 — canine fossa, 19 — Zygomatic bone, 20 — frontal process of the Maxilla, 21 — nasal part of the Frontal bone, 22 — supraorbital arch, 23 — frontal tuber, 24 — squamous part of the frontal bone

Fig. 108. Facial muscles and integument of the face. (after M. M. Kurepina)

1 — frontal tuber, 2 — supraorbital arch, 3 — glabella, 4 — lower eyelid, 5 — dorsum of the Nose, 6 — ala of the nose, 7 — nostril, 8 — nasolabial fold, 9 — angle of the Mouth, 10 — lower lip, 11 — levator labii superioris alaeque nasi muscle, 12 — levator labii superioris muscle, 13 — risorius muscle, 14 — platysma, 15 — zygomaticus major muscle, 16 — masseteric fascia, 17 — zygomaticus minor muscle, 18 — anterior auricular muscle, 19 — superior auricular muscle, 20 — temporal fascia, 21 — aponeurosis of the epicranial muscle

The temporoparietalis muscle (m. temporoparietalis) is located on the lateral surface of the cranium. Its muscle fibers originate from the medial side of the auricular Cartilage and, diverging in a fan-like manner, insert into the lateral margin of the epicranial aponeurosis.

Function of the epicranial muscle: contraction of the occipital belly of the occipitofrontalis pulls the epicranial aponeurosis and consequently the scalp posteriorly; contraction of the frontal belly pulls the aponeurosis and the attached scalp anteriorly; when the aponeurosis is fixed, the muscle forms transverse wrinkles on the forehead, elevates the eyebrows, and widens the palpebral fissure, imparting an expression of surprise to the face. The temporoparietalis muscle is vestigial, with weak action, and is capable of slightly moving the auricle upward and forward.

Innervation: Facial Nerve.