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Muscles of the Neck and Vertebral Column: Trunk Extension

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Presentation on theme: "Muscles of the Neck and Vertebral Column: Trunk Extension"— Presentation transcript:

1 Muscles of the Neck and Vertebral Column: Trunk Extension
Deep (intrinsic) back muscles Erector spinae (sacrospinalis) group—prime movers of back extension and lateral bending Iliocostalis Longissimus Spinalis Semispinalis and quadratus lumborum—synergists in extension and rotation

2 Iliocostalis cervicis Semispinalis cervicis Longissimus cervicis
Ligamentum nuchae Mastoid process of temporal bone Semispinalis capitis Longissimus capitis Iliocostalis cervicis Semispinalis cervicis Longissimus cervicis Semispinalis thoracis Iliocostalis thoracis Longissimus thoracis Spinalis thoracis Iliocostalis Erector spinae Longissimus Spinalis Multifidus Iliocostalis lumborum Quadratus lumborum External oblique (d) Figure 10.9d

3 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

4 External intercostal (a) Internal intercostal Figure 10.10a

5 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

6 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

7 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

8 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

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

10 Muscles of the Pelvic Floor
Pelvic floor (pelvic diaphragm) is composed of two paired muscles Levator ani Coccygeus Both are innervated by sacral nerves

11 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

12 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)

13 Muscles of the Perineum
Muscles of superficial perineal space Ischiocavernosus Bulbospongiosus Superficial transverse perineal muscles External anal sphincter (in posterior half of perineum)

14 Urethral opening Clitoris Vaginal Anus opening Penis Midline raphe
Ischiocavernosus Bulbospongiosus Superficial transverse perineal muscle Levator ani Gluteus maximus Male Female (c) Figure 10.12c

15 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

16 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)

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

18 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)

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

20 Muscles Crossing the Shoulder Joint
Nine muscles cross the shoulder joint to insert on and move the humerus


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