Muscles

Diaphragm (C3-C5) Distends abdomen, enlarges vertical dimension of thorax, depresses central tendon of diaphragm

Serratus posterior superior (C7, T1-T4) Elevates rib cage

Levator constarum brevis (T2-T12) Elevates rib cage

Levator constarum logis (T2-T12) Elevates rib cage

External intercostal (T2-T12) Elevates rib cage

Diaphragm – primary muscle of inspiration.

External Intercostals – elevates rib cage and assists in respiration.

Internal Intercostals – elevate rib cage and assists in respiration.

Sternocleidomastoid – elevates the sternum, rib cage, clavicle to assist in inhalation.

Scalenes (anterior, middle, and posterior) – elevate ribs 1 and 2 to assist in inhalation.

Pectoralis Major – elevate the sternum which increases the transverse dimension of the rib cage.

Pectoralis Minor – increase transverse dimension of the rib cage. This muscle is a shoulder extensor.

T.I.E.R.

Transverse abdominus – compress the abdomen.

Internal oblique – rotates the trunk, flexes the trunk, and compresses the abdomen.

External oblique – bilateral contraction flexes the vertebral column unilateral contraction rotates the trunk.

Rectus abdominus – flexes the vertebral column (sit-ups)

Extrinsic muscles of the larynx divided into suprahyoids and infrahyoids.

Suprahyoids (above the hyoid) - elevate the larynx

1. Digastric (anterior and posterior bellies) – anterior draws the hyoid up and forward and posterior draws hyoid up and back.

2. Stylohyoid – pulls the hyoid bone posteriorly and upward.

3. Mylohyoid - elevates the hyoid or depresses the mandible.

4. Geniohyoid - elevates the hyoid bone and depresses the mandible.

Infrahyoids (below the hyoid) – depress the larynx. Use T.O.S.S. to remember. 

1. Thyrohyoid - decreases the distance between the thyroid and hyoid, especially anteriorly.

2. Omohyoid (2 bellies because of shoulders) - pull down the hyoid bone.

• 3. Sternohyoid - pulls down the hyoid bone.
• 4. Sternothyroid - pulls the thyroid cartilage downward.

Function: Extrinsic muscles support the larynx and fix it in position. Primary function is to influence laryngeal height or tension as a gross unit. (Example: the larynx moves vertically as a whole in the neck for lifting, swallowing, phonating, and many vegetative tasks). Also it alters the shape & filtering characteristic of the supraglottic vocal tract, modifying vocal pitch, loudness, and quality.

Intrinsic muscles of the larynx (C.L.I.P.T.)

1. Cricothyroid - elongates and tenses the vocal folds. It decreases the space between the thyroid and cricoid. This increases the distance between the thyroid and arytenoids (PARS RECTA and PARS OBLIQUE).

2. Lateral Cricoarytenoid - adducts the vocal folds.

3. Interarytenoids - adduct the vocal folds (Transverse bundle - adducts the vocal folds and Oblique bundle - regulators of medial compression)

4. Posterior Cricoarytenoid - abduct the vocal folds.

5. Thyroarytenoid - adducts, tenses, relaxes the vocal folds (Vocalis muscle -tenses the vocal folds and Thyromuscularis - relaxes the vocal folds).  

Function: Intrinsic muscles control sound and production. Primary function is to alter the shape and configuration of the glottis, by modifying the position and tension, and edge of the vocal folds.

12 to 6 o’ clock

Levator Labii Alaeque Nasi Superioris-elevates the upper lip.

Levator Labii Superioris-elevates the upper lip.

Zygomatic Minor-elevates the upper lip.

Levator Anguli Oris-elevates corner of the mouth and medially.

Zygomatic Major-elevates and retracts the angle of the mouth.

Buccinator-retracts the corners of the lips and it moves food onto the grinding surfaces of the molars.

Risorious-retracts the corners of the lips which facilitate for smiling and grinning.

Orbicularis Oris-pulls the lips closer together. A labial seal.

Platysma-depresses the mandible.

Depressor Anguli Oris-depresses the corners of the mouth and helps compress the upper lip against the lower lip.

Depressor Labii Inferioris-pulls the lips down and out.

Mentalis-elevates and wrinkles the chin and pulls the lip out.

Intrinsic muscles (for precise articulatory performance)

Superior longitudinal-elevates and deviates tip; assists in the retraction if inferior longitudinal contracts too.

Inferior longitudinal-pulls the tip downward and deviates tip, assists in retraction if co-contracted with the superior longitudinal muscle.

Transverse muscles-narrows the tongue.

Vertical muscles-pulls the tongue down to flatten.

Extrinsic muscles (move the tongue as a unit)

Genioglossus-the prime mover of the tongue; anterior fibers retract the tongue; posterior fibers protrude the tongue; the combination anterior and posterior fibers depress the tongue in the middle.

Hyoglossus-pulls the sides of the tongue down.

Styloglossus-draws the tongue back and up.

Palatoglossus-depresses the soft palate or elevates back of the tongue.

Mandibular elevators

• Masseter-elevates the mandible which places maximum force on the molars-process of chewing food.
• Temporalis
• Medial Pterygoid (internal)

• Muscles of protrusion
• Lateral Pterygoid (external)

Mandibular Depressors

• Digastric (anterior and posterior bellies)
• Mylohyoid
• Geniohyoid
• Platysma

• Elevators:
• -Levator veli palatine-elevates and retracts the posterior velum.
• -Musculus uvalae-elevates and shortens the soft palate.

• A dilator of the Eustachian tube
• -Tensor veli palatine

• Depressors:
• -Palatoglossus-elevates the tongue or depresses the velum. It forms the anterior faucial pillars
• -Palatopharyngeus-depresses the velum and narrows the pharynx. It forms the posterior faucial pillars.

Superior Pharyngeal Constrictor muscle-pulls the pharyngeal wall forward; narrows the pharyngeal diameter which is important during swallowing; helps form the velopharyngeal seal and prevents bolus from entering the nasopharynx.

Middle Pharyngeal Constrictor muscle-narrows the diameter of the pharynx.

Inferior Pharyngeal Constrictor muscle-narrows the superior orifice of esophagus.

Cricopharyngeus muscle-remains contracted during rest and relaxes during swallowing in order to allow food to pass into the esophagus.

Salpingopharyngeus-elevates the lateral pharyngeal wall

Stylopharyngeus-elevates and opens the pharynx.