Major Skeletal Muscles of Head and Neck Chapter 6 Lecture 3

The Skeletal Muscles There are about 650 muscles in the human body The Skeletal Muscles There are about 650 muscles in the human body. They enable us to move, maintain posture and generate heat. In this section we will only study a sample of the major muscles. There are about 650 muscles in the human body. They enable us to move, maintain posture and generate heat. In this unit will only study a sample of the major muscles.  

Facial muscle Closes Jaw Masseter Facial muscle Closes Jaw The masseter is one of major chewing muscles. *The origin of the masseter is on the zygomatic arch. *The insertion is on the mandible. *Contraction of the masseter will elevate the jaw.

Facial muscle Raises corner of mouth during a smile “Smiling” muscle Zygomaticus Facial muscle Raises corner of mouth during a smile “Smiling” muscle The masseter is one of major chewing muscles. *The origin of the masseter is on the zygomatic arch. *The insertion is on the mandible. *Contraction of the masseter will elevate the jaw.

Facial muscle Closes and Protrudes (puckers) Lips “kissing” muscle Orbicularis oris Facial muscle Closes and Protrudes (puckers) Lips “kissing” muscle The masseter is one of major chewing muscles. *The origin of the masseter is on the zygomatic arch. *The insertion is on the mandible. *Contraction of the masseter will elevate the jaw.

Facial and chewing muscle Buccinator Facial and chewing muscle Compresses Cheek (whistling/sucking) and holds food between teeth while chewing The masseter is one of major chewing muscles. *The origin of the masseter is on the zygomatic arch. *The insertion is on the mandible. *Contraction of the masseter will elevate the jaw.

Facial muscle Blinks and Closes Eyes Orbicularis oculi Facial muscle Blinks and Closes Eyes The masseter is one of major chewing muscles. *The origin of the masseter is on the zygomatic arch. *The insertion is on the mandible. *Contraction of the masseter will elevate the jaw.

Chewing muscle Closes jaw Temporalis Chewing muscle Closes jaw The temporalis is another chewing muscle. Note how it attaches on the side of skull. *It also elevates the mandible. Also note I did not give the origin and insertion of this muscle. You will only need to know the origin and insertion of a few of the muscles in this unit.

Facial muscle Raises Eyebrows and wrinkles forehead Frontalis Facial muscle Raises Eyebrows and wrinkles forehead The masseter is one of major chewing muscles. *The origin of the masseter is on the zygomatic arch. *The insertion is on the mandible. *Contraction of the masseter will elevate the jaw.

Sternocleidomastoideus Flexes neck and Rotates Head The first muscle we will learn is the sternocleidomastoideus. It is sometime called the sternocleitomastoid. It is the same neck muscle shown on the previous slide. * This muscle has two origins. The first origin is on the sternum manubrium. The second origin is on the clavicle. *The insertion is on the mastoid process of the skull. *Contraction of both sternocleidomastoideus muscles will flex the head. If just on of the muscles contracts, the head will rotate.

Extend Head, Adduct/Elevate Scapula Trapezius Extend Head, Adduct/Elevate Scapula The trapezius is a large muscle in the upper back. It attaches to the skull, shoulder and vertebrae of the back. *When this muscle contracts it will cause the head to extend. It will also move the scapula. The direction the scapula moves depends on which part of the trapezius contracts. The trapezius may adduct elevate or depress the scapula.

Lowers jaw (pulls corners of mouth inferiorly) Platysma Lowers jaw (pulls corners of mouth inferiorly) The trapezius is a large muscle in the upper back. It attaches to the skull, shoulder and vertebrae of the back. *When this muscle contracts it will cause the head to extend. It will also move the scapula. The direction the scapula moves depends on which part of the trapezius contracts. The trapezius may adduct elevate or depress the scapula.