PART 2 Muscles of the Body

Go to http://getbodysmart.com Click on muscular system Excellent resource for quizzing on muscles Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Characteristics Used to Name Muscles Direction- orientation of fascicles relative to the midline. Rectus abdominis. Size- based on relative size of the muscle. Maximus, brevis, major. Shape- based on the relative form of the muscle. Deltoid, trapezius, serratus. Action- principal action of the muscle. Flexor, levator. Number of origins- number of tendons of origin. Biceps brachii. Location- structure near which a muscle is found. Temporalis, frontalis. Origin and Insertion- site where muscle originates and inserts. Sternocleidomastoid. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Fascicle Arrangements Fascicle- a bundle of skeletal muscle fibers. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

How Skeletal Muscle are Named Direction the muscle fibers run Size, shape, action, number of origins or locations Examples from Table 11.2 triceps brachii -- 3 sites of origin quadratus femoris -- square shape serratus anterior -- saw-toothed edge Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Coordination Within Muscle Groups Most movement is the result of several muscles working at the same time. Most muscles are arranged in opposing pairs at joints (antagonistic). Agonist (prime mover)- muscle that contracts to cause the desired action. Antagonist- muscle that stretches and yields to the prime mover. Synergist- muscle that contracts to stabilize nearby joints. Fixator- muscle that stabilizes the origin of the prime mover; it allows for more efficient contraction. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Superficial Muscles of the Body – Anterior View Figure 11.7a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Superficial Muscles of the Body – Posterior View Figure 11.7b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Head – Facial Expression Muscles of facial expression Lie in the face and scalp Thin and variable in shape Often insert in the skin – not on bones Innervated by cranial nerve VII – the facial nerve Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Head – Facial Expression Figure 11.8 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Mastication and Tongue Movement Four main pairs of muscles involved in mastication Innervated by mandibular division of the trigeminal nerve (cranial nerve V) Prime movers of jaw closure Masseter and temporalis Side-to-side movement Pterygoid muscles Compression of cheeks Buccinator muscles Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of Mastication and Tongue Movement Figure 11.9a, b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Mastication and Tongue Movement Extrinsic muscles of the tongue Move tongue Laterally Anteriorly Posteriorly All innervated by cranial nerve XII – the hypoglossal nerve Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of Mastication and Tongue Movement Figure 11.9c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Anterior Neck and Throat – Swallowing The neck is divided into anterior and posterior triangles Anterior triangle Divided into suprahyoid and infrahyoid muscles Participate in swallowing Pharyngeal constrictors Squeeze food into the esophagus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Anterior Neck and Throat – Swallowing Figure 11.10a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Anterior Neck and Throat – Swallowing Figure 11.10b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Neck and Vertebral Column Head movement Sternocleidomastoid Splenius capitis and splenius cervicis Figure 11.11a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Neck and Vertebral Column Figure 11.11b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Neck and Vertebral Column Trunk extension Deep muscles of the back Maintain normal curvatures of the spine Form a column from sacrum to the skull Erector spinae group Largest of the deep back muscles Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Neck and Vertebral Column Figure 11.11d Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Deep Muscles of the Thorax – Breathing Deep muscles provide movements for breathing External intercostal muscles Lift the ribcage Internal intercostal muscles Aid expiration during heavy breathing Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Deep Muscles of the Thorax – Breathing Diaphragm Most important muscle of respiration Flattens as it contracts Increases the volume of the thoracic cavity Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Deep Muscles of the Thorax – Breathing Figure 11.12a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Deep Muscles of the Thorax – Breathing The diaphragm Figure 11.12b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Abdominal Wall Lateral and anterior abdominal wall Formed from three flat muscle sheets External oblique Internal oblique Transversus abdominis Fourth muscle pair Rectus abdominis Inserts at the linea alba Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Abdominal Wall Figure 11.13a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Abdominal Wall Figure 11.13b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Pelvic Floor Pelvic floor (pelvic diaphragm) Sheet of two muscles Both support pelvic organs Levator ani Formed from iliococcygeus, puborectalis, and pubococcygeus Coccygeus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Pelvic Floor Figure 11.14a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Perineum Inferior to the muscles of the pelvic floor Urogenital diaphragm formed from Sphincter urethrae and the deep transverse perineus Figure 11.14b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Perineum Muscles of the superficial perineal space Ischiocavernosus Bulbospongiosus Superficial transverse perineus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Perineum Figure 11.14c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Superficial Muscles of the Anterior Thorax Movements of the scapula Pectoralis major Pectoralis minor Serratus anterior Subclavius Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Superficial Muscles of the Anterior Thorax Figure 11.15a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Superficial Muscles of the Posterior Thorax Movements of the scapula Trapezius Levator scapulae Rhomboid major Rhomboid minor Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Superficial Muscles of the Posterior Thorax PLAY Rotator cuff muscles: an overview (a) PLAY Rotator cuff muscles: an overview (b) Figure 11.15b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Crossing the Shoulder Joint Movements of the arm Deltoid Pectoralis major Figure 11.16a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Crossing the Shoulder Joint Movements of the arm Latissimus dorsi Supraspinatus Infraspinatus Teres minor Teres major Coracobrachialis Subscapularis PLAY Movement at the glenohumeral joint: an overview Figure 11.16b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Crossing the Elbow Joint Figure 11.16a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Crossing the Elbow Joint Posterior muscles – extensors of the forearm Triceps brachii Anconeus Anterior muscles – flexors of the forearm Biceps brachii – also supinates the forearm Brachialis Brachioradialis Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Movements of the wrist, hand, and fingers Muscles of the Forearm Movements of the wrist, hand, and fingers Tendons are anchored by Flexor and extensor retinacula Most forearm muscles arise from the distal humerus Movements at the wrist include Flexion, extension, abduction, and adduction Wrist and fingers are “operated” by muscles in the forearm Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Originate from a common tendon Muscles of the Forearm Flexors Anterior flexor compartment Innervated by median and ulnar nerves Originate from a common tendon Medial epicondyle of the humerus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Superficial Anterior Muscles of the Forearm Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis Figure 11.17a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Deep Anterior Muscles of the Forearm Flexor pollicis longus Flexor digitorum profundus Pronator quadratus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Deep Anterior Muscles of the Forearm Figure 11.17b, c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Forearm Extensors Posterior compartment of the forearm Innervated by the radial nerve Originate at a common tendon Lateral epicondyle of the humerus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Superficial Posterior Muscles of the Forearm Brachioradialis – flexes forearm Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor carpi ulnaris Figure 11.18a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Deep Posterior Muscles of the Forearm Supinator Abductor pollicis longus Extensor pollicis brevis and longus Extensor indicus Figure 11.18b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Hand Fine movement of the fingers All located in the palm Control precise movements Include muscles of Adduction, abduction, and opposition Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Hand Thenar muscles – ball of thumb Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis Adductor pollicis Hypothenar muscles Abductor digiti minimi Flexor digiti minimi PLAY Muscles that act on the wrist and fingers: an overview Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Hand Figure 11.19a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Hand Midpalmar muscles Lumbricals Palmar interossei Dorsal interossei Figure 11.19b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Hand Figure 11.19c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Crossing the Hip and Knee Joints Thigh and leg movements Anterior muscles Flex the thigh and extend the leg at the knee Posterior muscles Extend the thigh and flex the leg Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Crossing the Hip and Knee Joints Thigh and leg movements Adductor muscles – on medial aspect of thigh Adduct the thigh only Deep fascia of the thigh Surrounds and encloses all three groups Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles Crossing the Hip and Knee Joints Movements at the hip joint Muscles that flex the thigh Originate on vertebral column or pelvis Muscles that extend the thigh Arise posterior to the hip joint Adductors originate medial to the hip joint Abductors originate lateral to the hip joint Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anterior and Medial Muscles Origin on pelvis or vertebral column Iliacus Psoas major Sartorius Muscles of the medial compartment Adductor longus Adductor brevis Adductor magnus Pectineus Gracilis Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Anterior and Medial Muscles Figure 11.20a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Anterior Compartment of the Thigh Quadriceps femoris Has four separate heads Has a common insertion at the quadriceps tendon Powerful knee extensors Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius Tensor fasciae latae Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Anterior Compartment of the Thigh Figure 11.20a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Posterior Muscles Origin on pelvis or sacrum Gluteus maximus Gluteus medius Gluteus minimus Lateral rotators Piriformis Obturator externus Obturator internus Superior and inferior gemellus Quadratus femoris PLAY Movement at the hip joint: an overview Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Posterior Muscles Figure 11.21b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Posterior Compartment of the Thigh Hamstrings Biceps femoris Semitendinosus Semimembranosus Figure 11.21a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Fascia lata of the leg surrounds muscles Muscles of the Leg Fascia lata of the leg surrounds muscles Tightly binds muscles Prevents swelling during exercise Aids venous return Divides leg into three compartments Tendons are held in place by Extensor, fibular, and flexor retinacula Muscle movement at ankle and intertarsal joints Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Anterior Compartment Tibialis anterior Extensor digitorum longus Fibularis (peroneus) tertius Extensor hallucis longus PLAY Muscles of the ankle and foot (b) Figure 11.22a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Lateral Compartment Fibularis (peroneus) longus Fibularis (peroneus) brevis Flexor hallucis longus Extensor hallucis longus Fibularis tertius PLAY Muscles of the ankle and foot (c) Figure 11.23a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Lateral Compartment Figure 11.23b, c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Posterior Compartment Superficial muscles Triceps surae Gastrocnemius Soleus Plantaris PLAY Muscles that act on the ankle and foot: an overview Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Posterior Compartment Figure 11.24a, b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Muscles of the Posterior Compartment Deep muscles Popliteus Flexor digitorum longus Flexor hallucis longus Tibialis posterior PLAY Muscles of the ankle and foot (a) PLAY Muscles of the ankle and foot (d) Figure 11.24c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Foot Toe movement and foot support Help to flex, extend, abduct, and adduct the toes Support the arches of the foot Single muscle on dorsal aspect of the foot Many muscles on the plantar aspect Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Foot Muscle on the dorsum of the foot Extensor digitorum brevis Muscles on the sole of the foot First layer Flexor digitorum brevis Abductor hallucis Abductor digiti minimi Figure 11.25a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Foot Second layer Flexor accessorius Lumbricals Figure 11.25b Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Foot Third layer Flexor hallucis brevis Adductor hallucis Flexor digiti minimi brevis Fourth layer Plantar and dorsal interossei Figure 11.25c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Intrinsic Muscles of the Foot Figure 11.25d, e Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings