The Muscular System Part B Chapter 10 The Muscular System Part B

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

Xiphoid process of sternum Foramen for inferior vena cava Foramen for esophagus Costal cartilage Central tendon of diaphragm Diaphragm Foramen for aorta Lumbar vertebra 12th rib Quadratus lumborum (b) Psoas major Figure 10.10b

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

Transversus abdominis Pectoralis major Serratus anterior Linea alba Tendinous intersection Transversus abdominis Internal oblique Rectus abdominis External oblique Aponeurosis of the external oblique Inguinal ligament (formed by free inferior border of the external oblique aponeurosis) (a) Figure 10.11a

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

Rectus abdominis Internal External oblique oblique Lumbar fascia IIiac crest Pubic tubercle Lumbar fascia Transversus abdominis Inguinal ligament (b) Figure 10.11b

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

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)

Sternocleido- mastoid Subclavius Clavicle Subscapularis Deltoid Pectoralis minor Pectoralis major Coracobrachialis Sternum Serratus anterior Biceps brachii Humerus (a) Figure 10.13a

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)

Levator scapulae Trapezius Supraspinatus Clavicle Deltoid Spine of Rhomboid minor Infraspinatus Rhomboid major Teres minor Teres major Humerus Latissimus dorsi (c) Figure 10.13c