These videos have been excerpted from Netter’s Video Dissection Modules on Student Consult.
[ Ссылка ]
Step 2
Once the skin of the face and the anterior half of the scalp have been removed, concentrate first on the fairly superficial muscles that act on the mouth, eyes and forehead. These are: the mentalis, the orbicularis oris, the depressor labii inferioris, the depressor anguli oris, the levator labii superioris alaeque nasi, and the orbicularis oculi - both its orbital and palpebral parts - and the frontal belly of the occipito-frontalis or epicranius muscle. Peel one of the scalp flaps toward the orbit and note that the scalping plane beneath the frontalis extends into the eyelid.
If possible, identify some of the deeper muscles, which will require removal of the buccal fat pad, while being careful to damage the facial artery. These muscles include the risorius, the nasalis, and the zygomaticus major and minor muscles. The zygomaticus muscles are seen here as fibers extending toward the zygomatic bone. On the forehead, look for the vertical fibers of the procerus muscle and the laterally oriented fibers of the corrugator supercilii.
Key Terms
• Muscles of facial expression: the superficial muscles of the face, scalp and neck that permit these areas to show expressions and control the size and shape of the entryway to the nose, mouth and eyes N25. There are 20 muscles on each side and all are innervated by the facial nerve N24. The most important muscles to know are those that surround the eye (orbicularis oculi) and the mouth (orbicularis oris), and form the cheek (buccinator). Knowledge of these muscles is essential to understanding the major signs and symptoms of Bell’s palsy.
• Mentalis muscle: the muscle of the chin N25. It arises on each side from the mandible, just inferior to the incisor teeth and projects downward to insert into the skin of the chin. It is the muscle that protrudes the lower lip, and when it meets the upper lip, there is protrusion of that lip too. Note that when the lower lip is protruded, the skin over the chin becomes tight and immobile. The mentalis is the muscle used to express doubt.
• Orbicularis oris muscle: the muscle that surrounds the mouth N25 N35. The fiber arrangement is complex because many adjacent muscles with different orientations merge with, and contribute to, the orbicularis oris. This greatly strengthens and stabilizes this muscle, and permits the lips and mouth to have many different movements and to assume a variety of shapes. The orbicularis oris is the muscle that allows the mouth to be tightly closed so that food, especially liquids, doesn’t escape.
• Depressor labii inferioris muscle: arises from the oblique line of the mandible and inserts on the skin of the lower lip, blending with the orbicularis oris muscle. Inferiorly, this muscle is continuous with the fibers of the platysma muscle. It is innervated by the mandibular branch of the facial nerve.
• Depressor anguli oris muscle: arises from the oblique line of the mandible. Its fibers converge to insert into the angle of the mouth. It is continuous with inferiorly with the platysma muscle and with the orbicularis oris and risorius at its insertion. It depresses and draws the angle of the mouth laterally, and it is innervated by the mandibular branch of the facial nerve. N25
ABOUT:
The project was made possible by several very dedicated faculty and staff at University of North Carolina, Chapel Hill--especially O.W. Henson and Noelle A. Granger--and partner schools, and by a grant from the Fund for the Improvement of Post-Secondary Education of the US Department of Education. This channel includes over 400 short videos highlighting the steps in a full-body human dissection in the gross anatomy lab. Each step is narrated and key structures labeled.
