Lesson 14, Muscles of the Body.pptx

Human Anatomy Muscles of the Body (Head and Neck) Course: BL3420 Date: 2/14/24 Instructor: Benjamin T. Enslow, M.D. Email: [email protected] Phone: (830) 391-4298 Office: Moody 214 Text: Chapter 11; Select Muscle Tables Slides Adapted From: PowerPoint® Lecture Presentations prepared by Leslie Hen...

Human Anatomy Muscles of the Body (Head and Neck) Course: BL3420 Date: 2/14/24 Instructor: Benjamin T. Enslow, M.D. Email: [email protected] Phone: (830) 391-4298 Office: Moody 214 Text: Chapter 11; Select Muscle Tables Slides Adapted From: PowerPoint® Lecture Presentations prepared by Leslie Hendon University of Alabama, Birmingham Molly Selba University of Florida Copyright © 2020 Pearson Education, Inc. All Rights Reserved Brachiocephalic trunk Left Common Carotid Left Subclavian Superior Aortic arch Vena Cava AscendingDescending Aorta Aorta ior V e Cava na Left anterior descending arte ry Right M ar ar gi te n a ry l Infer HAPPY VALENTINE’S DAY! Left Pulmonary Pulmonary Left Artery Trunk Auricle Pulmonary Veins coron a artery ry Right Auricle You make my heart have premature ventricular contractions. Cardiac Apex To: Anatomy BL3420 From: Dr. Enslow (Now go study the muscles…) Learning Objectives: Identify the major muscles of facial expression. Explain how these muscles give rise to various facial expressions. Identify the major muscles of mastication. Explain how these muscles give rise to the motion of the jaw while chewing. Identify the major muscles of the anterior neck and throat. Explain how these muscles assist in moving the tongue and swallowing food. Explain how the the muscles of the anterior neck give rise to head movement. Muscles of Facial Expression The muscles of facial expression lie in the face and the scalp, just deep to the skin. All are thin muscles that vary in shape; tend to be fused to adjacent muscles. Unlike other skeletal muscles, facial muscles insert on the skin, not on the bones. Muscles of Facial Expression- The Scalp Epicranius (aka “Occipitofrontalis”) Bipartite muscle- consists of two muscle bellies connected by the epicranial aponeurosis Frontal belly Description: Covers forehead and dome of skull; no bony attachments Action: Elevates eyebrows (as in surprise); wrinkles forehead skin horizontally Occipital belly Description: overlies posterior occiput Action: Pulls scalp posteriorly Muscles of Facial Expression- The Scalp Muscles of Facial Expression- The Scalp Corrugator supercilii Small muscle to eyebrow Draws eyebrows medially and inferiorly (angry eyebrows) Orbicularis oculi Sphincter muscle of eyelid; surrounds orbit Closes eye (blinking, squinting) Zygomaticus Muscle pair extending diagonally from cheekbone to corner of mouth Raises lateral corner of mouth (smiling) Orbicularis oris Multilayered muscle of lips; fascicles run mostly circular Closes lips; (puckering) Mentalis Muscle pair that forms Vshaped muscle mass on chin Wrinkles chin and protrudes lower lip (pout) Platysma Unpaired, thin, sheetlike superficial neck muscle Tenses skin of neck (like during shaving) Risorius Slender muscle inferior and lateral to zygomaticus Draws corner of lip laterally; tenses lips; synergist of zygomaticus Levator labii superioris Then muscle between orbicularis oris and inferior eye margin Opens lips; elevates and furrows the upper lip Depressor labii inferioris Small muscle running from mandible to lower lip Depresses lower lip Depressor anguli oris Small muscle lateral to depressor labii inferioris Depresses corners of mouth inferiorly and laterally Buccinator Thin, horizonal cheek muscle Principle muscle of the cheek Deep to masseter muscle Compresses cheek (as in whistling and sucking); holds food between teeth during chewing; well- Muscles of Facial Expression Muscles of Facial Expression Muscles of Mastication- Superficial The prime movers of jaw closure are the powerful masseter and temporalis muscles, which can be felt bulging through the skin when the teeth are clenched. Masseter Temporalis Orbicularis oris Buccinator Masseter Powerful muscle that covers lateral aspect of ramus of mandible Closes jaw Temporalis Recall that the buccinator muscles also play role in mastication by holding food between teeth during Fan-shaped muscle that covers parts of the temporal, frontal, and parietal bones Closes jaw; elevates and retracts mandible; maintains position of the mandible at rest Muscles of Mastication- Deep Side-to-side (grinding) movements of mastication are brought about by the pterygoid muscles. Lateral pterygoid Lateral pterygoid Medial pterygoid Muscles of mastication, deep Masseter pulled away Deep two-headed muscle; lies superior to medial pterygoid Protracts mandible and produces side-to-side (grinding) movements Medial pterygoid Deep two-headed muscle that runs along internal surface of mandible and is largely concealed by that bone. Acts with lateral pterygoid to protract mandible and to produce side-to-side (grinding) movements. Muscles of the Anterior Neck and Throat Aid in closing the air passageway of the larynx during swallowing-so that food is not inhaled into the lungs- by lifting the larynx superiorly and anteriorly, under the cover of a protective flap (the epiglottis). Suprahyoid muscles- anterior neck muscles that lie superior to the hyoid bone Digastric Mylohyoid Anterior belly Digastric Stylohyoid Hyoid bone Omohyoid (superior belly) Sternohyoid Posterior belly Stylohyoid Stylohyoid (cut) Thyrohyoid Sternocleidomastoid Slender muscle below angle of jaw; parallels posterior belly of digastric Elevates and retracts the hyoid, thereby elongating the floor of the mouth during swallowing. Mylohyoid Omohyoid (inferior belly) Two bellies united by an intermediate tendon, forming a V-shape under the chin Opens mouth and depresses mandible. Elevates hyoid. Sternothyroid Flat, triangular muscle just deep to digastric muscle; forms a sling that makes the floor of the anterior mouth. Elevates and protracts the hyoid; widens the pharynx for receiving food during swallowing. Muscles of the Anterior Neck and Throat Suprahyoid muscles- anterior neck muscles that lie superior to the hyoid bone Aid in closing the air passageway of the larynx during swallowing-so that food is not inhaled into the lungs- by lifting the larynx superiorly and anteriorly, under the cover of a protective flap (the epiglottis). Stylohyoid Geniohyoid Styloid process Tongue Genioglossus Styloglossus Hyoglossus Stylohyoid Geniohyoid Hyoid bone Runs from chin to hyoid bone, deep to mylohyoid Elevates and protracts the hyoid Muscles of the Anterior Neck and Throat As swallowing ends, the infrahyoid muscles pull the hyoid bone and larynx inferiorly to their original position. Infrahyoid muscles- anterior neck muscles that lie inferior to the hyoid bone Sternohyoid Mylohyoid Anterior belly Digastric Stylohyoid Hyoid bone Omohyoid (superior belly) Sternohyoid Posterior belly Stylohyoid (cut) Thyrohyoid Sternothyroid Lateral and deep to sternohyoid Thyrohyoid Appears as a superior continuation of sternothyroid muscle Omohyoid Sternocleidomastoid Omohyoid (inferior belly) Most medial muscle of the neck Sternothyroid Straplike muscle with two bellies united by an intermediate tendon; lateral to sternohyoid All depress the hyoid bone. Muscles of the Anterior Neck and Throat d is moved by muscles that originate on the axial skeleton inferiorly. Sternocleidomastoid (SCM) 1st cervical vertebra Mastoid process Two-headed muscle, deep to the platysma on anterolateral surface of neck. Flexes and laterally rotates the head. Middle scalene Sternocleidomastoid Scalenes Anterior scalene Posterior scalene Anterior Anterior, middle, and posterior Located more laterally than anteriorly on neck; deep to platysma and sternocleidomastiod Elevates first two ribs (aid in inspiration); flex and rotate neck. The sternocleidomastoid muscles (SCM) divide each side of the neck into a posterior and an anterior triangle. Sternocleidomastoid Anterior triangle Posterior triangle Trapezius Clavicle Triangles of the neck Posterior triangle Anteriorly- SCM Posteriorly- trapezius Inferiorly –clavicle Anterior triangle Anteriorly- midline of the neck Posteriorly- SCM Inferiorly- inferior margin of the mandible Internal jugular vein Occipital bone Carotid arteries Submandibular gland Accessory nerve (XI) Suprahyoid muscles Infrahyoid muscles Phrenic nerve External jugular vein Cervical plexus Brachial plexus Subclavian artery Contents of the anterior and posterior triangles External Carotid Pulse Ask the patient to sit upright. Locate the carotid artery medial to the sternomastoid muscle (between the muscle and the trachea at the level of the cricoid cartilage, which is in the middle third of the neck). With the pads of your three fingers, gently palpate the Carotid arteries Internal Jugular Vein Puncture Muscles of the Neck- Head Movements The head is moved by muscles that originate on the axial skeleton inf Flexion of the head is mainly brought about by the sternocleidomastoid muscles, with some help from the suprahyoid and infrahyoid muscles. Extension of the head is aided by the trapezius muscle of the back, but the main extensors of the head are the splenius muscles (splenius capitis and splenius cervicis of the spinotransversales muscle group). Lateral flexion and rotation of the head and neck result when muscles contract on one side of the neck only. These actions are performed by the sternocleidomastiods and the deeper neck muscles, the scalenes.