Lecture 8: Muscular System - Muscles of Trunk, Hip, and Limbs PDF

Because learning changes everything. ® Lecture 8 Outline Muscular Sys...

Because learning changes everything. ® Lecture 8 Outline Muscular System (2) Muscles of Trunk, Hip and limbs 1-1 Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  10.3 Muscles of the Trunk Expected Learning Outcomes: Name and locate the muscles of respiration and explain how they affect airflow and abdominal pressure. Name and locate the muscles of the abdominal wall, back, and pelvic floor. Identify the skeletal attachments, action, and innervation of these muscles. © McGraw Hill, LLC 2  10.3a Muscles of Respiration 1 Breathing requires the use of muscles enclosing thoracic cavity—the diaphragm and muscles between ribs Diaphragm—muscular dome between thoracic and abdominal cavities; its fibers converge toward a central tendon Contraction causes diaphragm to flatten and enlarge thoracic cavity, causing air intake Muscles between the ribs: External intercostal muscles—most superficial layer; elevate ribs Internal intercostal muscles—deep to external intercostals; each is divided into intercartilaginous and interosseous parts; depress ribs Innermost intercostal muscles—vary in number; same function as internal intercostals © McGraw Hill, LLC 3  Muscles of Respiration 2 Access the text alternative for slide images. Figure 10.14a © McGraw Hill, LLC 4  Muscles of Respiration 3 Access the text alternative for slide images. Figure 10.14b © McGraw Hill, LLC 5  Table 10.04 TABLE 10.4 Muscles of Respiration Name Action Skeletal Attachments Innervation Diaphragm48 Prime mover of inspiration (responsible for about Xiphoid process of sternum; ribs Phrenic nerves (DY-ah-fram) two-thirds of air intake); contracts in preparation for and costal cartilages 7–12; sneezing, coughing, crying, laughing, and weight lumbar lifting; contraction compresses abdominal viscera vertebrae Central tendon of diaphragm and aids in childbirth and expulsion of urine and feces. External intercostals49 When scalenes fix rib 1, external intercostals elevate Inferior margins of ribs 1– Intercostal nerves (IN-tur-COSS-tulz) and protract ribs 2–12, expanding the thoracic cavity 11Superior margin of next lower rib and creating a partial vacuum causing inflow of air; exercise a braking action during expiration so that expiration is not overly abrupt. Internal intercostals In inspiration, the intercartilaginous part aids in Superior margins and costal Intercostal nerves elevating the ribs and expanding the thoracic cavity; cartilages of ribs 2–12; margin of in expiration, the interosseous part depresses and sternum retracts the ribs, compressing the thoracic cavity Inferior margin of next higher rib and expelling air; the latter occurs only in forceful expiration, not in relaxed breathing. Innermost intercostals Presumed to have the same action as the internal Superomedial surface of ribs 2–12; Intercostal nerves intercostals may be absent from upper ribs Medial edge of costal groove of next higher rib 48 dia = across; phragm = partition linea = line; alba = white 50 49 inter = between; costa = rib linea = line; semilunar = half-moon 51 © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  10.3b Muscles of the Abdominal Wall 1 Three layers of muscle enclose lumbar region and extend halfway across anterior abdomen External oblique muscle—most superficial layer; fibers pass downward and anteriorly; rotation (twisting) of waist Internal oblique muscle—next deeper layer; fibers pass upward and anteriorly; rotation (twisting) of waist Transverse abdominal muscle (transversus abdominis)—deepest layer; fibers pass horizontally All abdominal muscles support viscera, stabilize spine, and compress abdominal contents © McGraw Hill, LLC 7  Muscles of the Abdominal Wall 2 Muscles of the abdomen (continued) Rectus abdominis muscles—paired muscles extending vertically from sternum to pubis; flexes waist Divided into segments by three tendinous intersections, giving them “six pack” appearance Tendons of oblique and transverse muscles are broad fibrous sheets called aponeuroses Enclose rectus abdominis as a vertical sleeve called the rectus sheath; meet at median line called linea alba More lateral linea semilunaris marks location where rectus sheeth meets the aponeurosis Aponeurosis of external oblique forms inguinal ligament © McGraw Hill, LLC 8  Cross Section of the Anterior Abdominal Wall Access the text alternative for slide images. Figure 10.15 © McGraw Hill, LLC 9  Thoracic and Abdominal Muscles 1 Access the text alternative for slide images. Figure 10.16a © McGraw Hill, LLC 10  Thoracic and Abdominal Muscles 2 Access the text alternative for slide images. Figure 10.16b © McGraw Hill, LLC 11  Thoracic and Abdominal Muscles of the Cadaver Christine Eckel/McGraw Hill Access the text alternative for slide images. Figure 10.17 © McGraw Hill, LLC 12  Table 10.05 TABLE 10.5 Muscles of the Abdominal Wall Name Action Skeletal Attachments Innervation External oblique Supports abdominal viscera against pull Ribs 5–12 Anterior rami of spinal of gravity; stabilizes vertebral column Anterior half of iliac crest; symphysis nerves T7–T12 during heavy lifting; maintains posture; and superior margin of pubis compresses abdominal organs, thus aiding in deep breathing, loud vocalizations such as singing and public speaking, and in expulsion of abdominopelvic contents during childbirth, urination, defecation, and vomiting; unilateral contraction causes contralateral rotation of the spine, as in twisting at the waist. Internal oblique Same as external oblique except that Inguinal ligament; iliac crest; Anterior rami of spinal unilateral contraction causes ipsilateral thoracolumbar fascia nerves T7–L1 rotation of waist Ribs 10–12; costal cartilages 7–10; pubis Transverse abdominal Compresses abdominal contents, with Inguinal ligament; iliac crest; thoracolum- Anterior rami of same effects as external oblique, but does bar fascia; costal cartilages 7–12 spinal nerves T7–L1 not contribute to movements of vertebral Linea alba; pubis; aponeurosis of column internal oblique Rectus52 abdominis Flexes waist, as in bending forward or Pubic symphysis and superior margin Anterior rami of spinal (REC-tus ab-DOM-ih-nis) doing sit-ups; stabilizes pelvic region of nerves T6–T12 during walking; and compresses abdominal pubis viscera Xiphoid process; costal cartilages 5–7 52 rectus = straight © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  10.3d Muscles of the Pelvic Floor 1 Floor of pelvic cavity is a strong, multilayered muscular sheet Perineum—diamond-shaped region between the thighs Bordered by four bony landmarks: Pubic symphysis anteriorly Coccyx posteriorly Ischial tuberosities laterally Anal triangle—posterior half of perineum Urogenital triangle—anterior half of perineum Urogenital triangle divided into two muscle compartments separated by fibrous perineal membrane: Superficial perineal space between perineal membrane and skin Deep perineal space between perineal membrane and levator ani © McGraw Hill, LLC 14  Muscles of the Pelvic Floor 2 Superficial perineal space contains three pairs of muscles: Ischiocavernosus—converge like a V form ischial tuberosities toward penis or clitoris; maintains erection of penis or clitoris Bulbospongiosus (bulbocavernosus)—form sheath around root of penis in males; enclose vagina in females; expels residual urine after voiding and aids in erection of penis, clitoris Superficial transverse perineal muscles—extend from ischial tuberosities to median fibromuscular perineal body, and seam called the perineal raphe © McGraw Hill, LLC 15  Muscles of the Pelvic Floor 3 Deep perineal space contains: A pair of deep transverse perineal muscles—anchor perineal body to the median plane Compressor urethrae—in females only; aids in urine retention The anal triangle contains: External anal sphincter—tubular muscle surrounding lower anal canal; retains feces until voluntarily expelled Anococcygeal ligament—median attachment site for levator ani muscles The pelvic diaphragm is composed mainly of levator ani muscles © McGraw Hill, LLC 16  Muscles of the Pelvic Floor 4 Access the text alternative for slide images. Figure 10.21a © McGraw Hill, LLC 17  Muscles of the Pelvic Floor 5 Access the text alternative for slide images. Figure 10.21b © McGraw Hill, LLC 18  Muscles of the Pelvic Floor 6 Access the text alternative for slide images. Figure 10.21c © McGraw Hill, LLC 19  Table 10.07 TABLE 10.7 Muscles of the Pelvic Floor Name Action Skeletal Attachments Innervation Superficial Perineal Space Ischiocavernosus55 Maintains erection of the penis or clitoris by com- Ramus and tuberosity of Pudendal (ISS-kee-oh-CAV-er- pressing deep structures of the organ and forcing ischium nerve NO-sus) blood forward into its body Ensheaths internal structures of penis and clitoris Bulbospongiosus56 Expels residual urine from urethra after bladder has Perineal body and median raphe Pudendal nerve (BUL-bo-SPUN-jee- emptied. Aids in erection of penis or clitoris. In male, Male: ensheathes root of penis OH-sus) spasmodic contractions expel semen during ejacula- Female: pubic symphysis tion. In female, contractions constrict vaginal orifice and expel secretions of greater vestibular glands. Deep Perineal Space Deep transverse Anchors perineal body, which supports other pelvic Ischiopubic rami Pudendal nerve perineal muscles; supports vaginal and urethral canals Perineal body Compressor urethrae Aids in urine retention; found in females Ischiopubic rami Pudendal nerve; (yu-REE-three) only Right and left compressor urethrae spinal nerves S2–S4; meet each other inferior to exter- pelvic splanchnic nal urethral sphincter nerve Anal Triangle External anal Retains feces in rectum until voluntarily voided Coccyx, perineal body Pudendal nerve; spinal sphincter Encircles anal canal and nerves S2–S4; pelvic orifice splanchnic nerve Pelvic Diaphragm Levator ani57 Compresses anal canal and reinforces external Inner surface of lesser pelvis Pudendal nerve; (leh-VAY-tur AY-nye) anal and urethral sphincters; supports uterus and from spinal nerves S2–S3 other pelvic viscera; aids in falling away of the pubis through margin of obturator feces; vertical movements affect pressure internus to spine of ischium differences between abdominal and thoracic Coccyx via anococcygeal body; cavities and thus aid in deep breathing. walls of urethra, vagina, and anal canal 55 ischio = ischium of hip bone; cavernosus = corpus cavernosum of the penis or clitoris 57 levator = that which elevates; ani = of the anus 56 bulbo = bulb of the penis; spongiosus = corpus spongiosum of the penis © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Hernias A hernia is any condition in which the viscera protrudes through a weak point in the muscular wall of the abdominopelvic cavity Types of hernias: Inguinal hernia Most common type of hernia (rare in women) Viscera enter inguinal canal or even the scrotum Hiatal hernia Stomach protrudes through diaphragm into thorax Overweight people over 40 Umbilical hernia Viscera protrude through the navel © McGraw Hill, LLC 21  Inguinal Hernia Access the text alternative for slide images. Figure 10.22 © McGraw Hill, LLC 22  10.4 Muscles Acting on the Shoulder and Upper Limb 1 Expected Learning Outcomes: Name and locate the muscles that act on the pectoral girdle, shoulder, elbow, wrist, and hand. Relate the actions of these muscles to the joint movements described in chapter 9. Describe the skeletal attachments, action, and innervation of these muscles. © McGraw Hill, LLC 23  Muscles Acting on the Shoulder and Upper Limb 2 Upper limb is used for broad range of actions Climbing, grasping, throwing, writing, playing musical instruments, and manipulating small objects Functional groupings: Muscles that act on the scapula Muscles that act on the humerus and shoulder joint Muscles that act on the forearm and elbow joint Muscles that act on the wrist, hand, and fingers © McGraw Hill, LLC 24  10.4a Muscles Acting on the Shoulder 1 Muscles acting on pectoral girdle extend from axial skeleton to clavicle and scapula Scapula loosely attached to thoracic cage Capable of great movement Rotation, elevation, depression, protraction, retraction Clavicle braces the shoulder and moderates movements © McGraw Hill, LLC 25  Actions of Some Thoracic Muscles on the Scapula Access the text alternative for slide images. Figure 10.23 © McGraw Hill, LLC 26  Muscles Acting on the Shoulder 2 Muscles of pectoral girdle are divided into anterior and posterior groups Anterior group: Pectoralis minor—arises from ribs 3 to 5 and converges on coracoid process of scapula; protracts scapula Serratus anterior—arises from nearly all ribs to medial border of scapula; protracts scapula © McGraw Hill, LLC 27  Muscles Acting on the Shoulder 3 Muscles of pectoral girdle (continued) Posterior group: Trapezius—large superficial muscle capable of causing elevation, depression, and retraction of scapula depending on which portion contracts Levator scapulae—elevates scapula along with superior fibers of trapezius Rhomboid major and minor—extend from vertebrae to medial border of scapula; cause retraction of scapula © McGraw Hill, LLC 28  Thoracic and Abdominal Muscles 3 Access the text alternative for slide images. Figure 10.16a © McGraw Hill, LLC 29  Thoracic and Abdominal Muscles 4 Access the text alternative for slide images. Figure 10.16b © McGraw Hill, LLC 30  Table 10.08 TABLE 10.8 Muscles Acting on the Shoulder Name Action Skeletal Attachments Innervation Anterior Group Pectoralis minor With serratus anterior, draws scapula laterally and Ribs 3–5 and overlying fascia Medial and lateral pec- (PECK-toe-RAY-liss) forward around chest wall; with other muscles, Coracoid process of scapula toral nerves rotates scapula and depresses apex of shoulder, as in reaching down to pick up a suitcase Serratus58 anterior With pectoralis minor, draws scapula laterally and All or nearly all ribs Long thoracic nerve (serr-AY-tus) forward around chest wall; protracts scapula, and is Medial border of scapula the prime mover in all forward-reaching and push- ing actions; aids in rotating scapula to elevate apex of shoulder; fixes scapula during abduction of arm Posterior Group Trapezius Stabilizes scapula and shoulder during arm External occipital protuberance; Accessory nerve (tra-PEE-zee-us) movements; elevates and depresses apex of medial one-third of superior nuchal shoulder; acts with other muscles to rotate and line; nuchal ligament; spinous pro- retract scapula (see also roles in head and neck cesses of vertebrae C7–T12 movements in table 10.3) Acromion and spine of scapula; lateral one-third of clavicle Levator scapulae Elevates scapula if cervical vertebrae are fixed; Transverse processes of vertebrae Spinal nerves C3–C4, (leh-VAY-tur SCAP- flexes neck laterally if scapula is fixed; retracts C1–C4 and C5 via posterior you-lee) scapula and braces shoulder; rotates scapula and Superior angle to medial border of scapular nerve depresses apex of shoulder scapula Rhomboid minor Retracts scapula and braces shoulder; fixes Spinous processes of vertebrae Posterior scapular (ROM-boyd) scapula during arm movements C7–T1; nuchal ligament nerve Medial border of scapula Rhomboid major Same as rhomboid minor Spinous processes of vertebrae T2–T5 Posterior scapular Medial border of scapula nerve serrate = scalloped, zigzag 58 © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  10.4b Muscles Acting on the Arm 1 Nine muscles cross the shoulder joint and attach to the humerus Seven are scapular muscles—arise from scapula Two are axial muscles—arise primarily from axial skeleton © McGraw Hill, LLC 32  Muscles Acting on the Arm 2 Rotator cuff muscles Tendons of four scapular muscles form the rotator cuff Acronym “SITS muscles” Supraspinatus Infraspinatus Teres minor Subscapularis Tendons of these muscles merge with the joint capsule of the shoulder as they cross it in route to the humerus Holds head of humerus into glenoid cavity Supraspinatus tendon easily damaged © McGraw Hill, LLC 33  Rotator Cuff Muscles in Relation to the Scapula (Lateral View) Access the text alternative for slide images. Figure 10.24 © McGraw Hill, LLC 34  Muscles Acting on the Arm 3 Other scapular muscles Deltoid—triangular muscle capping shoulder; common site of intramuscular drug injections Capable of flexion, extension, abduction, medial and lateral rotation of arm, depending on region that contracts Teres major—extension and medial rotation of arm Coracobrachialis—flexes and medially rotates arm © McGraw Hill, LLC 35  Muscles Acting on the Arm 4 Axial muscles Pectoralis major—large superficial muscle of chest; flexes, adducts, and medially rotates arm Latissimus dorsi—large superficial muscle of mid and lower back; extends, adducts, and medially rotates arm © McGraw Hill, LLC 36  Pectoral and Brachial Muscles 1 Access the text alternative for slide images. Figure 10.25a © McGraw Hill, LLC 37  Pectoral and Brachial Muscles 2 Access the text alternative for slide images. Figure 10.25b © McGraw Hill, LLC 38  Pectoral and Brachial Muscles 3 Access the text alternative for slide images. Figure 10.25c © McGraw Hill, LLC 39  Pectoral and Brachial Muscles 4 Access the text alternative for slide images. Figure 10.25d © McGraw Hill, LLC 40  Pectoral, Brachial, and Upper Back Muscles of the Cadaver 1 Rebecca Gray/McGraw-Hill Access the text alternative for slide images. Figure 10.26a © McGraw Hill, LLC 41  Pectoral, Brachial, and Upper Back Muscles of the Cadaver 2 Rebecca Gray/McGraw-Hill Access the text alternative for slide images. Figure 10.26b © McGraw Hill, LLC 42  Table 10.09 TABLE 10.9 Muscles Acting on the Arm Name Action Skeletal Attachments Innervation Rotator Cuff Muscles Supraspinatus59 Aids deltoid in abduction of arm; resists downward slippage Supraspinous fossa of scapula Suprascapular (SOO-pra-spy- of humeral head when arm is relaxed or when carrying Greater tubercle of humerus nerve NAY-tus) weight Infraspinatus60 Modulates action of deltoid, preventing humeral head from Infraspinous fossa of scapula Suprascapular (IN-fra-spy-NAY-tus) sliding upward; rotates humerus laterally Greater tubercle of humerus nerve Teres minor Modulates action of deltoid, preventing humeral head from Lateral border and adjacent Axillary nerve (TERR-eez) sliding upward as arm is abducted; rotates humerus laterally posterior surface of scapula Greater tubercle of humerus; posterior surface of joint capsule Subscapularis61 Modulates action of deltoid, preventing humeral head from Subscapular fossa of scapula Upper and lower (SUB-SCAP- sliding upward as arm is abducted; rotates humerus medially Lesser tubercle of humerus; subscapular nerves you-LERR-iss) anterior surface of joint capsule Other Scapular Muscles Deltoid Anterior fibers flex and medially rotate arm; lateral fibers Acromion and spine of scapula; Axillary nerve abduct arm; posterior fibers extend and laterally rotate arm; clavicle involved in arm swinging during such actions as walking or Deltoid tuberosity of humerus bowling, and in adjustment of hand height for various manual tasks Teres major Extends and medially rotates humerus; contributes to arm Inferior angle of scapula Lower subscapular (TERR-eez) swinging Medial lip of intertubercular nerve sulcus of humerus Coracobrachialis Flexes and medially rotates arm; resists deviation of arm Coracoid process Musculocutaneous (COR-uh-co- from frontal plane during abduction Medial aspect of humeral shaft nerve BRAY-kee-AY-lis) Axial Muscles Pectoralis major Flexes, adducts, and medially rotates humerus, as in climbing Medial half of clavicle; lateral Medial and lateral (PECK-toe-RAY-liss) or hugging; aids in deep inspiration margin of sternum; costal carti- pectoral nerves lages 1–7; aponeurosis of exter- nal oblique Lateral lip of intertubercular sul- cus of humerus Latissimus dorsi62 Adducts and medially rotates humerus; extends the shoulder Vertebrae T7–L5; lower three Thoracodorsal (la-TISS-ih-mus joint as in pulling on the oars of a rowboat; produces back- or four ribs; iliac crest; thora- nerve DOR-sye) ward swing of arm in such actions as walking and bowling; columbar fascia with hands grasping overhead objects, pulls body forward Floor of intertubercular sulcus and upward, as in climbing; aids in deep inspiration, sudden of humerus expiration such as sneezing and coughing, and prolonged forceful expiration as in singing or blowing a sustained note on a wind instrument supra = above; spin = spine of scapula 60infra 59 61 sub = below, under = below, under; spin = spine of scapula 62 latissimus = broadest; dorsi = of the back © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  10.4c Muscles Acting on the Elbow and Forearm 1 Muscles that act on the elbow and forearm are located in both brachium (arm) and antebrachium (forearm) Four motions: Flexion Extension Pronation Supination © McGraw Hill, LLC 44  Muscles Acting on the Elbow and Forearm 2 Muscles of the brachial region Elbow flexors are in anterior compartment Brachialis—principal elbow flexor Biceps brachii and brachioradialis are synergistic flexors Elbow extensors are in posterior compartment Triceps brachii—three heads; prime mover of elbow extension © McGraw Hill, LLC 45  Pectoral and Brachial Muscles 5 Access the text alternative for slide images. Figure 10.25a © McGraw Hill, LLC 46  Pectoral and Brachial Muscles 6 Access the text alternative for slide images. Figure 10.25b © McGraw Hill, LLC 47  Muscles Acting on the Elbow and Forearm 3 Muscles of the antebrachial region Brachioradialis—on radial side of forearm, extending from distal end of humerus to distal end of radius; elbow flexor Anconeus—posterior side of elbow; weak elbow extensor Pronator quadratus—prime mover in forearm pronation Pronator teres—assists pronator quadratus in pronation Supinator—supinates the forearm © McGraw Hill, LLC 48  Actions of the Rotator Muscles on the Forearm Access the text alternative for slide images. Figure 10.27 © McGraw Hill, LLC 49  Table 10.10 TABLE 10.10 Muscles Acting on the Elbow and Forearm Name Action Skeletal Attachments Innervation Muscles of the Brachial Region Brachialis Prime mover of elbow flexion Anterior surface of distal half of humerus Musculocutaneous (BRAY-kee-AY-lis) Coronoid process and tuberosity of ulna nerve; radial nerve Biceps brachii Rapid or forceful supination of forearm; Long head: superior margin of glenoid Musculocutaneous (BY-seps BRAY-kee-eye) synergist in elbow flexion; slight shoul- cavity nerve der flexion; tendon of long head stabi- Short head: coracoid process lizes shoulder by holding humeral head Tuberosity of radius; fascia of forearm against glenoid cavity Triceps brachii Extends elbow; long head extends and Long head: inferior margin of glenoid Radial nerve (TRI-seps BRAY-kee-eye) adducts humerus cavity and joint capsule Lateral head: posterior surface of proximal end of humerus Medial head: posterior surface of entire humeral shaft Olecranon; fascia of forearm Muscles of the Antebrachial Region Brachioradialis Flexes elbow Lateral supracondylar ridge of humerus Radial nerve (BRAY-kee-oh-RAY-dee-AY-lis) Lateral surface of radius near styloid process Anconeus63 Extends elbow; may help to control Lateral epicondyle of humerus Radial nerve (an-CO-nee-us) ulnar movement during pronation Olecranon and posterior surface of ulna Pronator quadratus Prime mover of forearm pronation; Anterior surface of distal ulna Median nerve (PRO-nay-tur quad-RAY-tus) also resists separation of radius and Anterior surface of distal radius ulna when force is applied to forearm through wrist, as in doing push-ups Pronator teres Assists pronator quadratus in prona- Humeral shaft near medial epicondyle; Median nerve (PRO-nay-tur TERR-eez) tion, but only in rapid or forceful action; coronoid process of ulna weakly flexes elbow Lateral surface of radial shaft Supinator Supinates forearm Lateral epicondyle of humerus; Radial nerve (SOO-pih-NAY-tur) supinator crest and fossa of ulna just distal to radial notch; anular and radial collateral ligaments of elbow Proximal one-third of radius 63 anconeus = elbow © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  10.4d Muscles Acting on the Wrist and Hand 1 Intrinsic muscles are in the hand itself Extrinsic muscles arise in the forearm Extrinsic muscle actions: Flexion and extension of wrist and digits Radial and ulnar flexion Finger abduction and adduction Thumb opposition Fasciae divide forearm muscles into anterior and posterior compartments, each with superficial and deep layers © McGraw Hill, LLC 51  Serial Cross Sections Through the Upper Limb 1 Access the text alternative for slide images. Figure 10.28a © McGraw Hill, LLC 52  Serial Cross Sections Through the Upper Limb 2 Access the text alternative for slide images. Figure 10.28b © McGraw Hill, LLC 53  Serial Cross Sections Through the Upper Limb 3 Access the text alternative for slide images. Figure 10.28c © McGraw Hill, LLC 54  Muscles Acting on the Wrist and Hand 2 Anterior (flexor) compartment, superficial layer Flexor carpi radialis—flexion and radial flexion of wrist Flexor carpi ulnaris—flexion and ulnar flexion of wrist Flexor digitorum superficialis—flexion of wrist, MP, and IP joints Palmaris longus—anchors skin, fascia of palmar region Anterior (flexor) compartment, deep layer Flexor digitorum profundus—flexion of wrist, MP, and IP joints; sole flexor of distal IP joints Flexor pollicis longus—flexion of phalanges of thumb © McGraw Hill, LLC 55  Flexors of the Wrist and Hand Access the text alternative for slide images. Figure 10.29 © McGraw Hill, LLC 56  Muscles Acting on the Wrist and Hand 3 Posterior (extensor) compartment, superficial layer Extensor carpi radialis longus—extension and radial flexion of wrist Extensor carpi radialis brevis—extension and radial flexion of wrist Extensor digitorum—extension of wrist, MP, and IP joints Extensor digiti minimi—extension of wrist and joints of little finger Extensor carpi ulnaris—extension and ulnar flexion of wrist © McGraw Hill, LLC 57  Muscles Acting on the Wrist and Hand 4 Posterior (extensor) compartment, deep layer Abductor pollicis longus—abduction and extension of thumb Extensor pollicis brevis—extends proximal phalanx of thumb Extensor pollicis longus—extends distal phalanx of thumb Extensor indicis—extends index finger and wrist © McGraw Hill, LLC 58  Extensors of the Wrist and Hand Access the text alternative for slide images. Figure 10.30 © McGraw Hill, LLC 59  Table 10.11 TABLE 10.11 Muscles Acting on the Wrist and Hand Name Action Skeletal Attachments Innervation The Anterior (Flexor) Compartment, Superficial Layer Flexor carpi radialis64 Flexes wrist anteriorly; aids in radial flexion of wrist Medial epicondyle of humerus Median nerve (FLEX-ur CAR-pye RAY-dee- Base of metacarpals II–III AY-lis) Flexor carpi ulnaris65 Flexes wrist anteriorly; aids in ulnar flexion of wrist Medial epicondyle of humerus; Ulnar nerve (ul-NAY-ris) medial margin of olecranon; posterior surface of ulna Metacarpal V; pisiform; hamate Flexor digitorum superficialis66 Flexes wrist, metacarpophalangeal, and inter- Medial epicondyle of humerus; Median nerve (DIDJ-ih-TOE-rum SOO-per- phalangeal joints depending on action of other ulnar collateral ligament; FISH-ee-AY-lis) muscles coronoid process; superior half of radius Middle phalanges II–V Palmaris longus Anchors skin and fascia of palmar region; resists Medial epicondyle of humerus Median nerve (pal-MERR-iss) shearing forces when stress is applied to skin by Flexor retinaculum, palmar such actions as climbing and tool use. Weakly aponeurosis developed and sometimes absent. (continued ) 64 carpi = of the wrist; radialis = of the radius digitorum = of the digits; superficialis = shallow, near the surface 66 65 ulnaris = of the ulna © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Table 10.11 Contd. TABLE 10.11 Muscles Acting on the Wrist and Hand (continued) Name Action Skeletal Attachments Innervation Anterior (Flexor) Compartment, Deep Layer Flexor digitorum profundus67 Flexes wrist, metacarpophalangeal, and interphalan- Proximal three-quarters of ulna; Median nerve; geal joints; sole flexor of the distal interphalangeal coronoid process; interosseous ulnar nerve joints membrane Distal phalanges II–V Flexor pollicis68 longus Flexes phalanges of thumb Radius; interosseous membrane Median nerve (PAHL-ih-sis) Distal phalanx I Posterior (Extensor) Compartment, Superficial Layer Extensor carpi radialis Extends wrist; aids in radial flexion of wrist Lateral supracondylar ridge of Radial nerve longus humerus Base of metacarpal II Extensor carpi radialis brevis Extends wrist; aids in radial flexion of wrist Lateral epicondyle of humerus Radial nerve (BREV-iss) Base of metacarpal III Extensor digitorum Extends wrist, metacarpophalangeal, and Lateral epicondyle of humerus Radial nerve interphalangeal joints; tends to spread digits apart Dorsal surfaces of phalanges II–V when extending metacarpophalangeal joints Extensor digiti minimi69 Extends wrist and all joints of little finger Lateral epicondyle of humerus Radial nerve (DIDJ-ih-ty MIN-ih-my) Proximal phalanx V Extensor carpi ulnaris Extends and fixes wrist when fist is clenched Lateral epicondyle of humerus; Radial nerve or hand grips an object; aids in ulnar flexion posterior surface of ulnar shaft of wrist Base of metacarpal V Posterior (Extensor) Compartment, Deep Layer Abductor pollicis longus Abducts thumb in frontal (palmar) plane (radial Posterior surfaces of radius Radial nerve abduction); extends thumb at carpometacarpal and ulna; interosseous membrane joint Trapezium; base of metacarpal I Extensor pollicis brevis Extends metacarpal I and proximal phalanx of Shaft of radius; interosseous mem- Radial nerve thumb brane Proximal phalanx I Extensor pollicis longus Extends distal phalanx I; aids in extending proximal Posterior surface of ulna; Radial nerve phalanx I and metacarpal I; adducts and laterally interosseous membrane rotates thumb Distal phalanx I Extensor indicis Extends wrist and index finger Posterior surface of ulna; interosse- Radial nerve (IN-dih-sis) ous membrane Middle and distal phalanges of index finger 67 profundus = deep 68 pollicis = of the thumb 69 digit = finger; minim = smallest © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Carpal Tunnel Syndrome 1 Flexor retinaculum—bracelet-like fibrous sheet, passed under by flexor tendons crossing the wrist Carpal tunnel—tight space between the flexor retinaculum and the carpal bones Flexor tendons passing through the tunnel are enclosed in tendon sheaths Enable tendons to slide back and forth quite easily © McGraw Hill, LLC 62  Carpal Tunnel Syndrome 2 Carpal tunnel syndrome—prolonged, repetitive motions of wrist and fingers cause tissues in the carpal tunnel to become inflamed, swollen, or fibrotic Puts pressure on median nerve of wrist that passes through the carpal tunnel along with flexor tendons Tingling and muscular weakness in the palm and medial side of the hand Pain may radiate to arm and shoulder Treatment: anti-inflammatory drugs, immobilization of the wrist, and sometimes surgery to remove part or all of flexor retinaculum © McGraw Hill, LLC 63  The Carpal Tunnel 1 Access the text alternative for slide images. Figure 10.31a © McGraw Hill, LLC 64  The Carpal Tunnel 2 Access the text alternative for slide images. Figure 10.31b © McGraw Hill, LLC 65  10.4e Intrinsic Muscles of the Hand 1 Intrinsic muscles of hand—assist muscles of forearm to make finger movements more precise Thenar group—fleshy mass at base of thumb Adductor pollicis—forms web between thumb and palm; draws thumb toward palm Abductor pollicis brevis—abducts thumb in sagittal plane Flexor pollicis brevis—flexes metacarpophalangeal thumb joint Opponens pollicis—flexes metacarpal 1 Hypothenar group—fleshy base of the little finger Abductor digiti minimi—abducts little finger Flexor digiti minimi brevis—flexes little finger at metacarpophalangeal joint Opponens digiti minimi—flexes metacarpal 5 © McGraw Hill, LLC 66  Intrinsic Muscles of the Hand 2 Intrinsic muscles of hand (continued) Midpalmar group—occupies hollow of palm; 11 small muscles divided into three groups: Four dorsal interosseous muscles—abduct fingers; flex metacarpophalangeal joints and extend interphalangeal joints Three palmar interosseous muscles—adduct fingers; other actions same as dorsal interosseous muscles Four lumbricals muscles—extend interphalangeal joints © McGraw Hill, LLC 67  Intrinsic Muscles of the Right Hand 1 Access the text alternative for slide images. Figure 10.32a © McGraw Hill, LLC 68  Intrinsic Muscles of the Right Hand 2 b: Rebecca Gray/Don Kincaid/McGraw Hill Access the text alternative for slide images. Figure 10.32b © McGraw Hill, LLC 69  Intrinsic Muscles of the Right Hand 3 Access the text alternative for slide images. Figure 10.32c © McGraw Hill, LLC 70  Intrinsic Muscles of the Right Hand 4 Access the text alternative for slide images. Figure 10.32d © McGraw Hill, LLC 71  Table 10.12 TABLE 10.12 Intrinsic Muscles of the Hand Name Action Skeletal Attachments Innervation Thenar Group Adductor pollicis Draws thumb toward palm as in gripping a tool Capitate; bases of metacarpals II–III; Ulnar nerve anterior ligaments of wrist; tendon sheath of flexor carpi radialis Medial surface of proximal phalanx I Abductor pollicis brevis Abducts thumb in sagittal plane Mainly flexor retinaculum; also scaph- Median nerve oid, trapezium, and abductor pollicis longus tendon Lateral surface of proximal phalanx I Flexor pollicis brevis Flexes metacarpophalangeal joint of thumb Trapezium; trapezoid; capitate; Median nerve; anterior ligaments of wrist; flexor ulnar nerve retinaculum Proximal phalanx I Opponens pollicis Flexes metacarpal I to oppose thumb to fingertips Trapezium; flexor retinaculum Median nerve (op-PO-nenz) Metacarpal I Hypothenar Group Abductor digiti minimi Abducts little finger, as in spreading fingers apart Pisiform; tendon of flexor carpi ulnaris Ulnar nerve Medial surface of proximal phalanx V Flexor digiti minimi brevis Flexes little finger at metacarpophalangeal joint Hamulus of hamate bone; flexor Ulnar nerve retinaculum Medial surface of proximal phalanx V Opponens digiti minimi Flexes metacarpal V at carpometacarpal joint when Hamulus of hamate bone; flexor Ulnar nerve little finger is moved into opposition with tip of retinaculum thumb; deepens palm of hand Medial surface of metacarpal V Midpalmar Group Four dorsal interosseous70 Abduct fingers; strongly flex metacarpophalangeal Each with two heads arising from fac- Ulnar nerve muscles joints but extend interphalangeal joints, depending ing surfaces of adjacent metacarpals (IN-tur-OSS-ee-us) on action of other muscles; important in grip Proximal phalanges II–IV strength Three palmar interosseous Adduct fingers; other actions same as for dorsal Metacarpals I, II, IV, V Ulnar nerve muscles interosseous muscles Proximal phalanges II, IV, V Four lumbrical71 muscles Extend interphalangeal joints; contribute to ability Tendons of flexor digitorum profundus Median nerve; (LUM-brih-cul) to pinch objects between fleshy pulp of thumb and Proximal phalanges II–V ulnar nerve finger, instead of these digits meeting by the edges of their nails 70 inter = between; osse = bones 71 lumbrical = resembling an earthworm © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  10.5 Muscles Acting on the Hip and Lower Limb Expected Learning Outcomes: Name and locate the muscles that act on the hip, knee, ankle, and toe joints. Relate the actions of these muscles to the joint movements described in chapter 9. Describe the skeletal attachments, action, and innervation of these muscles. © McGraw Hill, LLC 73  10.5 Introduction Body’s largest muscles found in lower limb Less for precision, more for strength needed to stand, maintain balance, walk, and run Several cross and act on two or more joints Leg—the part of the limb between the knee and ankle Foot—includes tarsal region (ankle), metatarsal region, and the toes © McGraw Hill, LLC 74  10.5a Muscles Acting on the Hip and Thigh 1 Anterior muscles of the hip: Iliopsoas—flexes thigh at hip; collective term for two muscles that share a common tendon to the femur Iliacus—arises from iliac crest and fossa Psoas major—arises from lumbar vertebrae © McGraw Hill, LLC 75  Muscles that Act on the Hip and Femur (Anterior View) Access the text alternative for slide images. Figure 10.33 © McGraw Hill, LLC 76  Muscles Acting on the Hip and Thigh 2 Lateral and posterior muscles of the hip: Tensor fasciae latae—extends knee, laterally rotates tibia Fascia lata—fibrous sheath encircling thigh Laterally, fascia lata combines with tendons of gluteus maximus and tensor fasciae latae to form the iliotibial tract Tensor fasciae latae tightens iliotibial tract to brace knee Gluteus maximus—extends thigh at hip as in stair climbing; abducts thigh; forms mass of the buttock Gluteus medius and gluteus minimus—abduct and medially rotate thigh; shift weight of trunk to load-bearing limb during walking © McGraw Hill, LLC 77  Muscles Acting on the Hip and Thigh 3 Medial (adductor) compartment of the thigh—muscles function as adductors: Adductor brevis Adductor longus Adductor magnus Gracilis Pectineus © McGraw Hill, LLC 78  Muscles Acting on the Hip and Thigh 4 Lateral rotators—named for their action on the femur; six muscles inferior to gluteus minimus and deep to the two other gluteal muscles Gemellus superior Gemellus inferior Obturator externus Obturator internus Piriformis Quadratus femoris © McGraw Hill, LLC 79  Posterior Gluteal and Thigh Muscles 1 Access the text alternative for slide images. Figure 10.34 © McGraw Hill, LLC 80  Table 10.13 TABLE 10.13 Muscles Acting on the Hip and Thigh Name Action Skeletal Attachments Innervation Anterior Muscles of the Hip Iliacus72 Flexes thigh at hip when trunk is fixed; flexes Iliac crest and fossa; superolateral region of Femoral nerve (ih-LY-uh-cus) trunk at hip when thigh is fixed, as in bending sacrum; anterior sacroiliac and iliolumbar ligaments forward in a chair or sitting up in bed; balances Lesser trochanter and nearby shaft of femur trunk during sitting Psoas73 major Same as iliacus Bodies and intervertebral discs of vertebrae Anterior rami of (SO-ass) T12–L5; transverse processes of lumbar vertebrae lumbar spinal Lesser trochanter and nearby shaft of femur nerves Lateral and Posterior Muscles of the Hip Tensor fasciae Extends knee, laterally rotates tibia, aids in Iliac crest; anterior superior spine; deep surface of Superior gluteal latae74 abduction and medial rotation of femur; during fascia lata nerve (TEN-sur FASH- standing, steadies pelvis on femoral head and Lateral condyle of tibia via iliotibial tract ee-ee LAY-tee) steadies femoral condyles on tibia Gluteus Extends thigh at hip as in stair climbing (rising to Posterior gluteal line of ilium, on posterior surface Inferior gluteal maximus75 next step) or running and walking (backswing of from iliac crest to posterior superior spine; nerve limb); abducts thigh; elevates trunk after stoop- coccyx; ing; prevents trunk from pitching forward during posterior surface of lower sacrum; aponeurosis of walking and running; helps stabilize femur on erector tuberosity Gluteal spinae of femur; lateral condyle of tibia tibia via iliotibial tract Gluteus medius Abduct and medially rotate thigh; during walking, Most of lateral surface of ilium between crest and Superior gluteal and gluteus mini- shift weight of trunk toward limb with foot on the acetabulum nerve mus ground as other foot is lifted Greater trochanter of femur Medial (Adductor) Compartment of the Thigh Adductor brevis Adducts thigh Body and inferior ramus of pubis Obturator nerve Linea aspera and spiral line of femur Adductor longus Adducts and medially rotates thigh; flexes thigh Body and inferior ramus of pubis Obturator nerve at hip Linea aspera of femur Adductor Adducts and medially rotates thigh; extends Inferior ramus of pubis; ramus and tuberosity of Obturator magnus thigh at hip ischium nerve; tibial Linea aspera, gluteal tuberosity, and medial supra- nerve condylar line of femur Gracilis76 Flexes and medially rotates tibia at knee Body and inferior ramus of pubis; ramus of ischium Obturator nerve (GRASS-ih-lis) Medial surface of tibia just below condyle Pectineus77 Flexes and adducts thigh Superior ramus of pubis Femoral nerve (pec-TIN-ee-us) Spiral line of femur Lateral Rotators Gemellus78 Laterally rotates extended thigh; abducts flexed Ischial spine Nerve to obtu- superior thigh; sometimes absent Greater trochanter of femur rator internus (jeh-MEL-us) Gemellus inferior Same actions as gemellus superior Ischial tuberosity Nerve to Greater trochanter of femur quadratus femoris Obturator79 Not well understood; thought to laterally rotate External surface of obturator membrane; rami of Obturator nerve externus thigh in climbing pubis and ischium (OB-too-RAY-tur) Femur between head and greater trochanter 72 ili = loin, flank 76 gracil = slender 73 psoa = loin 77 pectin = comb 74 fasc = band; lat = broad 78 gemellus = twin 75 glut = buttock; maxim = largest 79 obtur = to close, stop up © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Table 10.13 Contd. TABLE 10.13 Muscles Acting on the Hip and Thigh (continued) Name Action Skeletal Attachments Innervation Lateral Rotators (continued) Obturator Not well understood; thought to laterally rotate Ramus of ischium; inferior ramus of pubis; antero- Nerve to obtu- internus extended thigh and abduct flexed thigh medial surface of lesser pelvis rator internus Greater trochanter of femur Piriformis80 Laterally rotates extended thigh; abducts flexed Anterior surface of sacrum; gluteal surface of ilium; Spinal nerves (PIR-ih-FOR-mis) thigh capsule of sacroiliac joint L5–S2 Greater trochanter of femur Quadratus femo- Laterally rotates thigh Ischial tuberosity Nerve to ris81 (quad-RAY- Intertrochanteric crest of femur quadratus tus FEM-oh-ris) femoris 80 piri = pear; form = shaped 81 quadrat = four-sided; femoris = of the thigh or femur © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  10.5b Muscles Acting on the Knee and Leg 1 Anterior (extensor) compartment of the thigh: Quadriceps femoris—prime mover of knee extension and most powerful muscle of body; has four heads Has four heads—rectus femoris, vastus lateralis, vastus medialis, vastus intermedius All converge on single quadriceps (patellar) tendon that extends to patella, then continues as patellar ligament to tibial tuberosity Sartorius—straplike muscle that flexes hip and knee joints; laterally rotates thigh Longest muscle in the body “Tailor’s muscle” © McGraw Hill, LLC 83  Superficial Muscles of the Right Thigh Rebecca Gray/McGraw Hill Access the text alternative for slide images. Figure 10.35 © McGraw Hill, LLC 84  Anterior Muscles of the Right Thigh Access the text alternative for slide images. Figure 10.36 © McGraw Hill, LLC 85  Muscles Acting on the Knee and Leg 2 Posterior (flexor) compartment of the thigh: Hamstring muscles—group of three muscles that flex the knee and extend the hip From lateral to medial: Biceps femoris Semitendinosus Semimembranosus © McGraw Hill, LLC 86  Posterior Gluteal and Thigh Muscles 2 Access the text alternative for slide images. Figure 10.34 © McGraw Hill, LLC 87  Table 10.14 TABLE 10.14 Muscles Acting on the Knee and Leg Name Action Skeletal Attachments Innervation Anterior (Extensor) Compartment of the Thigh Quadriceps femoris Extends the knee, in addition to the Varies; see individual heads Femoral nerve (QUAD-rih-seps FEM-oh-ris) actions of individual heads noted Patella; tibial tuberosity; lateral and subsequently medial condyles of tibia Rectus femoris Extends knee; flexes thigh at hip; Ilium at anterior inferior spine and supe- Femoral nerve flexes trunk on hip if thigh is fixed rior margin of acetabulum; capsule of hip joint See quadriceps femoris Vastus82 lateralis Extends knee; retains patella in Femur at greater trochanter and Femoral nerve groove on femur during knee intertrochanteric line, gluteal tuberosity, movements and linea aspera See quadriceps femoris Vastus medialis Same as vastus lateralis Femur at intertrochanteric line, Femoral nerve spiral line, linea aspera, and medial supracondylar line See quadriceps femoris Vastus intermedius Extends knee Anterior and lateral surfaces of femoral Femoral nerve shaft See quadriceps femoris Sartorius83 Aids in knee and hip flexion, as in On and near anterior superior spine of Femoral nerve sitting or climbing; abducts and ilium laterally rotates thigh Medial surface of proximal end of tibia Posterior (Flexor) Compartment of the Thigh Biceps femoris Flexes knee; extends hip; elevates Long head: ischial tuberosity Tibial nerve; common trunk from stooping posture; laterally Short head: linea aspera and lateral fibular nerve rotates tibia on femur when knee is supracondylar line of femur flexed; laterally rotates femur when Head of fibula hip is extended; counteracts forward bending at hips Semitendinosus84 Flexes knee; medially rotates tibia on Ischial tuberosity Tibial nerve (SEM-ee-TEN-din-OH-sus) femur when knee is flexed; medially Medial surface of upper tibia rotates femur when hip is extended; counteracts forward bending at hips Semimembranosus85 Same as semitendinosus Ischial tuberosity Tibial nerve (SEM-ee-MEM-bran-OH-sus) Medial condyle and nearby margin of tibia; intercondylar line and lateral condyle of femur; ligament of popliteal region Posterior Compartment of the Leg Popliteus86 Rotates tibia medially on femur if Lateral condyle of femur; lateral Tibial nerve (pop-LIT-ee-us) femur is fixed (as in sitting down), or meniscus and joint capsule rotates femur laterally on tibia if tibia is Posterior surface of upper tibia fixed (as in standing up); unlocks knee to allow flexion; may prevent forward dislocation of femur during crouching 82 vastus = large, extensive semi = half; membranosus = membranous 85 83 sartor = tailor poplit = ham (pit) of the knee 86 84 semi = half; tendinosus = tendinous © McGraw Hill, LLC © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  10.5c Muscles Acting on the Foot 1 Anterior (extensor) compartment of the leg: Fibularis tertius—dorsiflexes and everts foot Extensor digitorum longus—extends toes; dorsiflexes foot Extensor hallucis longus—extends great toe; dorsiflexes foot Tibialis anterior—dorsiflexes and inverts foot Muscle tendons held against ankle by two extensor retinacula © McGraw Hill, LLC 89  Muscles of the Right Leg, Anterior Compartment Access the text alternative for slide images. Figure 10.38 © McGraw Hill, LLC 90  Muscles Acting on the Foot 2 Posterior (flexor) compartment of the leg, superficial group: Gastrocnemius—plantar flexes foot; flexes knee Soleus—plantar flexes foot Plantaris—weak synergist of gastrocnemius and soleus; absent in many people Triceps surae is a collective name for gastrocnemius and soleus Attach to the calcaneus via calcaneal (Achilles) tendon Strongest tendon in the body © McGraw Hill, LLC 91  Superficial Muscles of the Right Leg, Posterior Compartment Access the text alternative for slide images. Figure 10.39 © McGraw Hill, LLC 92  Muscles Acting on the Foot 3 Posterior (flexor) compartment of the leg, deep group: Flexor digitorum longus—flexes phalanges of digits 2-5 Flexor hallucis longus—flexes great toe Tibialis posterior—inverts foot Popliteus also located here, but acts on knee (not the foot) © McGraw Hill, LLC 93  Deep Muscles of the Right Leg, Posterior and Lateral Compartments 1 Access the text alternative for slide images. Figure 10.40a © McGraw Hill, LLC 94  Table 10.15 TABLE 10.15 Muscles Acting on the Ankle and Foot Name Action Skeletal Attachments Innervation Anterior (Extensor) Compartment of the Leg Fibularis (peroneus88) Dorsiflexes and everts foot during Medial surface of lower one-third of fibula; Deep fibular tertius89 walking; helps toes clear the ground interosseous membrane (peroneal) nerve (FIB-you-LERR-iss TUR- during forward swing of leg Metatarsal V she-us) Extensor digitorum longus Extends toes; dorsiflexes foot; tautens Lateral condyle of tibia; shaft of fibula; Deep fibular (DIDJ-ih-TOE-rum) plantar aponeurosis interosseous membrane (peroneal) nerve Middle and distal phalanges II–V Extensor hallucis longus Extends great toe; dorsiflexes foot Anterior surface of middle of fibula, Deep fibular (ha-LOO-sis) interosseous membrane (peroneal) nerve Distal phalanx I Tibialis90 anterior Dorsiflexes and inverts foot; resists Lateral condyle and lateral margin of Deep fibular (TIB-ee-AY-lis) backward tipping of body (as when stand- proximal half of tibia; interosseous (peroneal) nerve ing on a moving boat deck); helps support membrane medial longitudinal arch of foot Medial cuneiform, metatarsal I Posterior (Flexor) Compartment of the Leg, Superficial Group Gastrocnemius91 Plantar flexes foot, flexes knee; active in Condyles, popliteal surface, and lateral Tibial nerve (GAS-trock-NEE-me-us) walking, running, and jumping supracondylar line of femur; capsule of knee joint Calcaneus Soleus92 Plantar flexes foot; steadies leg on ankle Posterior surface of head and proximal one- Tibial nerve (SO-lee-us) during standing fourth of fibula; middle one-third of tibia; interosseous membrane Calcaneus Posterior (Flexor) Compartment of the Leg, Deep Group Flexor digitorum longus Flexes phalanges of digits II–V as foot is Posterior surface of tibial shaft Tibial nerve raised from ground; stabilizes metatarsal Distal phalanges II–V heads and keeps distal pads of toes in contact with ground in toe-off and tiptoe movements Flexor hallucis longus Same actions as flexor digitorum longus, Distal two-thirds of fibula and interosseous Tibial nerve but for great toe (digit I) membrane Distal phalanx I Tibialis posterior Inverts foot; may assist in strong plantar Posterior surface of proximal half of tibia, Tibial nerve flexion or control pronation of foot during fibula, and interosseous membrane walking Navicular, medial cuneiform, metatarsals II–IV Lateral (Fibular) Compartment of the Leg Fibularis (peroneus) brevis Maintains concavity of sole during toe-off Lateral surface of distal two-thirds of fibula Superficial and tiptoeing; may evert foot and limit Base of metatarsal V fibular (peroneal) inversion and help steady leg on foot nerve Fibularis (peroneus) longus Maintains concavity of sole during toe-off Head and lateral surface of proximal Superficial and tiptoeing; everts and plantar flexes two-thirds of fibula fibular (peroneal) foot Medial cuneiform, metatarsal I nerve 88 perone = pinlike (fibula) 91