Copyright © 2010 Pearson Education, Inc. THE MUSCULAR SYSTEM (ANATOMY) CHAPTER # 10(b)

Copyright © 2010 Pearson Education, Inc. Muscles of the Thorax Muscles of respiration External intercostals—more superficial muscles that elevate ribs for inspiration Internal intercostals—deeper muscles that aid forced expiration Diaphragm Partition between thoracic and abdominal cavities Most important muscle in inspiration Innervated by phrenic nerves

Copyright © 2010 Pearson Education, Inc. Figure 10.10a External intercostal (a) Internal intercostal

Copyright © 2010 Pearson Education, Inc. Muscles of the Thorax PLAY A&P Flix™: Internal intercostals PLAY A&P Flix™: External intercostals

Copyright © 2010 Pearson Education, Inc. Figure 10.10b Foramen for esophagus Costal cartilage Lumbar vertebra Xiphoid process of sternum Diaphragm Quadratus lumborum Psoas major Foramen for inferior vena cava Central tendon of diaphragm Foramen for aorta 12th rib (b)

Copyright © 2010 Pearson Education, Inc. Muscles of the Abdominal Wall Four paired muscles; their fasciae and aponeuroses form the lateral and anterior abdominal wall Internal obliques External obliques Transversus abdominis Rectus abdominis

Copyright © 2010 Pearson Education, Inc. Figure 10.11a Transversus abdominis Internal oblique External oblique Aponeurosis of the external oblique (a) Pectoralis major Linea alba Tendinous intersection Rectus abdominis Inguinal ligament (formed by free inferior border of the external oblique aponeurosis) Serratus anterior

Copyright © 2010 Pearson Education, Inc. Muscles of the Abdominal Wall Fascicles of these muscles run at angles to one another, providing added strength All are innervated by intercostal nerves Actions of these muscles Lateral flexion and rotation of the trunk Help promote urination, defecation, childbirth, vomiting, coughing, and screaming

Copyright © 2010 Pearson Education, Inc. Figure 10.11b Transversus abdominis Inguinal ligament Lumbar fascia Lumbar fascia Internal oblique Pubic tubercle Rectus abdominis External oblique (b) IIiac crest

Copyright © 2010 Pearson Education, Inc. Muscles of the Abdominal Wall PLAY A&P Flix™: Internal obliques PLAY A&P Flix™: External obliques PLAY A&P Flix™: Rectus abdominis PLAY A&P Flix™: Transversus abdominis

Copyright © 2010 Pearson Education, Inc. Muscles of the Pelvic Floor Pelvic floor (pelvic diaphragm) is composed of two paired muscles Levator ani Coccygeus Both are innervated by sacral nerves

Copyright © 2010 Pearson Education, Inc. Muscles of the Pelvic Floor Functions of the pelvic diaphragm Seals the inferior outlet of the pelvis Supports pelvic organs Lifts pelvic floor to help release feces Resists increased intra-abdominal pressure

Copyright © 2010 Pearson Education, Inc. Muscles of the Perineum Urogenital diaphragm Anterior half of perineum, inferior to pelvic floor Deep transverse perineal muscle External urethral sphincter (voluntary control of urination)

Copyright © 2010 Pearson Education, Inc. Figure 10.12a Pelvic diaphragm Symphysis pubis (a) Levator ani Piriformis Posterior Anterior Coccyx Coccygeus Obturator internus IIiococcygeus Levator ani Pubococcygeus Urogenital diaphragm Urethra Vagina Anal canal

Copyright © 2010 Pearson Education, Inc. Figure 10.12b Inferior pubic ramus External urethral sphincter Urethral opening Vaginal opening Deep transverse perineal muscle Central tendon Anus External anal sphincter Male (b) Female

Copyright © 2010 Pearson Education, Inc. Muscles of the Perineum Muscles of superficial perineal space Ischiocavernosus Bulbospongiosus Superficial transverse perineal muscles External anal sphincter (in posterior half of perineum)

Copyright © 2010 Pearson Education, Inc. Figure 10.12c Male Female Penis Midline raphe Ischiocavernosus Clitoris Urethral opening Anus Vaginal opening Bulbospongiosus Superficial transverse perineal muscle Levator ani (c) Gluteus maximus

Copyright © 2010 Pearson Education, Inc. PLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (b) PLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (a) Superficial Muscles of the Thorax Most are extrinsic shoulder muscles Act in combination to fix the shoulder girdle (mostly the scapula) and move it to increase range of arm movements Actions include elevation, depression, rotation, lateral and medial movements, protraction, and retraction Two groups of muscles: anterior and posterior

Copyright © 2010 Pearson Education, Inc. Superficial Muscles of the Thorax Anterior extrinsic shoulder muscles Pectoralis minor Serratus anterior Subclavius (Pectoralis major considered later with muscles that act on the humerus) PLAY A&P Flix™: Muscles of the pectoral girdle (b) PLAY A&P Flix™: Muscles of the pectoral girdle (a)

Copyright © 2010 Pearson Education, Inc. PLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview (b) Figure 10.13a Subclavius Clavicle Subscapularis Pectoralis minor Coracobrachialis Serratus anterior Humerus Sternocleido- mastoid Deltoid Pectoralis major Sternum Biceps brachii (a)

Copyright © 2010 Pearson Education, Inc. Superficial Muscles of the Thorax PLAY A&P Flix™: Serratus anterior PLAY A&P Flix™: Pectoralis minor

Copyright © 2010 Pearson Education, Inc. Superficial Muscles of the Posterior Thorax Posterior extrinsic shoulder muscles Trapezius Levator scpulae Rhomboids (major and minor) (Latissimus dorsi considered later with muscles that act on the humerus) PLAY A&P Flix™: Movement of the pectoral girdle PLAY A&P Flix™: Muscles of the pectoral girdle (c)

Copyright © 2010 Pearson Education, Inc. Figure 10.13c Trapezius (c) Levator scapulae Supraspinatus Clavicle Spine of scapula Infraspinatus Teres minor Humerus Deltoid Teres major Latissimus dorsi Rhomboid minor Rhomboid major

Copyright © 2010 Pearson Education, Inc. Superficial Muscles of the Posterior Thorax PLAY A&P Flix™: Levator scapula PLAY A&P Flix™: Trapezius PLAY A&P Flix™: Rhomboid major PLAY A&P Flix™: Rhomboid minor