Human Anatomy & Physiology Marieb Hoehn Ninth Edition

Human Anatomy & Physiology ISBN 978-1-29202-649-7

Elaine N. Marieb Katja N. Hoehn

9 781292 026497 Ninth Edition ISBN 10: 1-292-02649-9 ISBN 13: 978-1-292-02649-7

Pearson Education Limited Edinburgh Gate Harlow Essex CM20 2JE England and Associated Companies throughout the world

Visit us on the World Wide Web at: www.pearsoned.co.uk

© Pearson Education Limited 2014

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without either the prior written permission of the publisher or a licence permitting restricted copying in the United Kingdom issued by the Copyright Licensing Agency Ltd, Saffron House, 6–10 Kirby Street, London EC1N 8TS.

All trademarks used herein are the property of their respective owners. The use of any trademark in this text does not vest in the author or publisher any trademark ownership rights in such trademarks, nor does the use of such trademarks imply any affi liation with or endorsement of this book by such owners.

ISBN 10: 1-292-02649-9 ISBN 13: 978-1-292-02649-7

British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library

Printed in the United States of America The Muscular System

MUSCLE GALLERY Table 1 Muscles of the Head, Part I: Facial Expression (Figure 7 )

The muscles that promote facial expression lie in the and smile. The tremendous importance of in nonverbal face just deep to the skin. They are thin and variable in shape and communication becomes especially clear when they are paralyzed, strength, and adjacent muscles tend to be fused. They are unusual as in some stroke victims and in the expressionless “mask” of muscles in that they insert into skin (or other muscles), not bones. patients with Parkinson’s disease. In the scalp, the main muscle is the epicranius, which has Cranial nerve VII, the facial nerve, innervates all muscles listed distinct anterior and posterior parts. The lateral scalp muscles in this table. are vestigial in humans. Muscles clothing the facial bones lift the The external muscles of the eyes direct the eyeballs, and the eyebrows, fl are the nostrils, open and close the eyes and mouth, levator palpebrae superioris muscles raise the . and provide one of the best tools for infl uencing others—the

ORIGIN (O) AND NERVE MUSCLE DESCRIPTION INSERTION (I) ACTION SUPPLY MUSCLES OF THE SCALP Epicranius (occipitofrontalis) Bipartite muscle consisting of the frontal and occipital bellies connected by the epicranial . The (epı˘-krane-us; alternate actions of these two muscles pull scalp forward and backward. ok-sipı˘-to-fron-talis) (epi over; cran ) ■ Frontal belly Covers forehead and O—epicranial aponeurosis With aponeurosis fi xed, Facial nerve (cranial VII) (frontal) dome of skull; no bony I—skin of eyebrows and raises the eyebrows (as (front forehead) attachments root of nose in surprise). Wrinkles forehead skin horizontally ■ Occipital belly Overlies posterior occiput; O—occipital and Fixes aponeurosis and Facial nerve (ok-sipı˘-tal) by pulling on the epicranial temporal bones pulls scalp posteriorly ( occipito base of skull) aponeurosis, fi xes origin of I—epicranial aponeurosis frontal belly MUSCLES OF THE FACE Corrugator supercilii Small muscle; activity O—arch of frontal bone Draws eyebrows together Facial nerve (korah-ga-ter sooper-sı˘le-i) associated with that of above nasal bone and inferiorly; wrinkles (corrugo wrinkle; orbicularis oculi I—skin of eyebrow skin of forehead vertically supercilium eyebrow) (as in frowning)

Epicranial aponeurosis

Frontal belly of epicranius

Occipital belly Corrugator of epicranius supercilli

Sternocleidomastoid (covered by )

Platysma

(a)

Figure 7 Lateral view of muscles of the scalp, face, and neck. (a) Photograph. David Bassett ➤

369 The Muscular System

MUSCLE GALLERY Table 1 Muscles of the Head, Part I: Facial Expression (Figure 7) (continued)

ORIGIN (O) AND NERVE MUSCLE DESCRIPTION INSERTION (I) ACTION SUPPLY Orbicularis oculi Thin, fl at sphincter muscle O—frontal and maxillary Closes eye ; various Facial nerve (cranial VII) (or-biku-lar-is oku-li) of ; surrounds rim of bones and ligaments parts can be activated (orb circular; ocul eye) the orbit around orbit individually; produces I—tissue of eyelid blinking and squinting; draws eyebrows inferiorly Zygomaticus —major and Muscle pair extending O—zygomatic bone Raises lateral corners of Facial nerve minor (zi-go-matı˘-kus) diagonally from cheekbone I—skin and muscle at mouth upward (smiling (zygomatic cheekbone) to corner of mouth corner of mouth muscle) (ri-zore-us) Slender muscle inferior and O—lateral fascia Draws corner of lip Facial nerve (risor laughter) lateral to zygomaticus associated with masseter laterally ; tenses lips; muscle synergist of zygomaticus I—skin at angle of mouth Thin muscle between O—zygomatic bone and Opens lips ; raises and Facial nerve (le-˘ vator labe-i orbicularis oris and inferior infraorbital margin of furrows upper lip soo-pere-oris) eye margin maxilla 10 (leva raise; labi lip; I—skin and muscle of superior above, over) upper lip Depressor labii inferioris Small muscle running from O—body of mandible Draws lower lip inferiorly Facial nerve (de-presor labe-i mandible to lower lip lateral to its midline (as in a pout) in-fere-oris) I—skin and muscle of (depressor depresses; lower lip infer below) Depressor anguli oris Small muscle lateral to O—body of mandible Draws corners of mouth Facial nerve (anggu-li or-is) depressor labii inferioris below incisors down and laterally (a (angul angle, corner; I—skin and muscle at “tragedy mask” grimace); or mouth) angle of mouth below zygomaticus antagonist insertion of zygomaticus Orbicularis oris Complicated, multilayered O—arises indirectly from Closes lips ; purses and Facial nerve muscle of the lips with maxilla and mandible; protrudes lips; kissing and fi bers that run in many fi bers blend with fi bers whistling muscle different directions; most of other facial muscles run circularly associated with the lips I—encircles mouth; inserts into muscle and skin at angles of mouth (men-talis) One of the muscle pair O—mandible below Wrinkles chin ; protrudes Facial nerve (ment chin) forming a V-shaped muscle incisors lower lip mass on chin I—skin of chin Buccinator Thin, horizontal cheek O—molar region of Compresses cheek (as in Facial nerve (busı˘-nater) muscle; principal muscle of maxilla and mandible whistling and sucking); (bucc cheek or cheek; deep to masseter I—orbicularis oris trampoline-like action “trumpeter”) (see also Figure 8 ) holds food between teeth during chewing; draws corner of mouth laterally; well developed in nursing infants Platysma (plah-tizmah) Unpaired, thin, sheetlike O—fascia of chest (over Tenses skin of neck (as Facial nerve (platy broad, fl at) superfi cial neck muscle; pectoral muscles and during shaving); helps not strictly a head muscle, deltoid) depress mandible; pulls but plays a role in facial I—lower margin of lower lip back and down, expression mandible, and skin and producing downward sag muscle at corner of mouth of mouth

370 The Muscular System

MUSCLE GALLERY Table 1 (continued)

Epicranial aponeurosis

Frontal Epicranius belly

Corrugator supercilii Occipital belly Orbicularis oculi

Levator labii superioris Temporalis

Zygomaticus minor and major

Buccinator Masseter Risorius Sternocleidomastoid Orbicularis oris Mentalis Trapezius Depressor labii inferioris Splenius capitis Depressor anguli oris

Platysma

(b)

Figure 7 (continued) Lateral view of muscles of the scalp, face, and neck. (b) Superfi cial muscles. Imagineering STA Media Services

371 The Muscular System

MUSCLE GALLERY Table 2 Muscles of the Head, Part II: Mastication and Movement ( Figure 8 )

Four pairs of muscles are involved in mastication (chewing). All are The tongue is composed of muscle fi bers that curl, squeeze, innervated by the mandibular branch of cranial nerve V. and fold the tongue during speaking and chewing. These intrinsic The prime movers of jaw closure (and biting) are the powerful tongue muscles change the shape of the tongue and contribute to masseter and temporalis muscles, which are easily palpated when its exceptional nimbleness, but they do not really move the tongue. the teeth are clenched (Figure 8a ). The pterygoid muscles In this table, we consider only the extrinsic tongue muscles, produce side-to-side grinding (Figure 8b ). The buccinator which anchor and move the tongue (Figure 8c ). Cranial nerve XII, muscles (see Table 1 ) also play a role in chewing. Normally, the hypoglossal nerve, innervates all extrinsic tongue muscles. gravity is suffi cient to depress the mandible, but if there is resistance to jaw opening, neck muscles such as the digastric and mylohyoid muscles (see Table 3 ) are activated.

ORIGIN (O) AND NERVE MUSCLE DESCRIPTION INSERTION (I) ACTION SUPPLY Masseter (mah-seter) Powerful muscle that O— and Prime mover of jaw Trigeminal nerve (maseter chewer) covers lateral aspect of zygomatic bone closure ; elevates mandible (cranial V) mandibular ramus I—angle and ramus of 10 mandible Temporalis (tempor-a ˘ lis) Fan-shaped muscle O—temporal fossa Closes jaw ; elevates Trigeminal nerve (tempora time; pertaining that covers parts of the I—coronoid process of and retracts mandible; to the temporal bone) temporal, frontal, and mandible via a tendon maintains position of the parietal bones that passes deep to mandible at rest; deep zygomatic arch anterior part may help protract mandible Medial pterygoid Deep two-headed muscle O—medial surface of Acts with the lateral Trigeminal nerve (mede-ul terı˘-goid) that runs along internal lateral pterygoid plate of pterygoid muscle to (medial toward median surface of mandible and is sphenoid bone, maxilla, protrude (pull anteriorly) plane; pterygoid winglike) largely concealed by that and palatine bone the mandible and bone I—medial surface of promote side-to-side mandible near its angle (grinding) movements ; synergist of temporalis and masseter muscles in elevation of the mandible Lateral pterygoid Deep two-headed muscle; O—greater wing and Provides forward sliding Trigeminal nerve (lateral away from lies superior to medial lateral pterygoid plate of and side-to-side grinding median plane) pterygoid muscle sphenoid bone movements of the I—condylar process of lower teeth ; protrudes mandible and capsule mandible of temporomandibular joint Buccinator See Table 1 See Table 1 Compresses the cheek ; Facial nerve (cranial keeps food between VII) grinding surfaces of teeth during chewing MUSCLES PROMOTING TONGUE MOVEMENTS (EXTRINSIC TONGUE MUSCLES) Fan-shaped muscle; forms O—internal surface of Protracts tongue ; can Hypoglossal nerve (jene-o-glahsus) bulk of inferior part of mandible near symphysis depress or act in concert (cranial XII) (geni chin; tongue; its attachment to I—inferior aspect of the with other extrinsic glossus tongue) mandible prevents tongue tongue and body of muscles to retract tongue from falling backward and hyoid bone obstructing breathing (hio-glosus) Flat, quadrilateral muscle O—body and greater Depresses tongue and Hypoglossal nerve (hyo pertaining to hyoid horn of hyoid bone draws its sides inferiorly bone) I—inferolateral tongue Slender muscle running O—styloid process of Retracts and elevates Hypoglossal nerve (sti-lo-glahsus) superiorly to and at right temporal bone tongue (stylo pertaining to styloid angles to hyoglossus I—inferolateral tongue process)

372 The Muscular System

MUSCLE GALLERY Table 2 (continued)

Temporalis

Lateral pterygoid

Orbicularis Medial oris Masseter pterygoid Buccinator

Masseter pulled away

(a) (b)

Tongue Styloid process Styloglossus

Genioglossus Hyoglossus

Mandibular symphysis Stylohyoid Hyoid bone Geniohyoid Thyroid cartilage Thyrohyoid

(c)

Figure 8 Muscles promoting mastication and tongue movements. (a) Lateral view of superfi cial muscles of mastication (temporalis, masseter, and buccinator muscles). (b) Lateral view of the deep chewing muscles. (c) Extrinsic muscles of the tongue and associated suprahyoid muscles of the throat. Imagineering STA Media Services

373