Respiratory Muscles

The diaphragm is the most important muscle of respiration (Fig. 12-21). This muscle arises from the lumbar vertebrae, from the lower ribs, and from the xiphoid process. The diaphragm arches up like a dome into the chest cavity. When the muscle fibers contract, they become less arched and thus cause the central tendinous part of the dome to descend. During contraction, the volume of the chest cavity increases (inspiration) and the volume of the abdominal cavity decreases.

The diaphragm also assists the abdominal muscles in increasing intra-abdominal pressure to reduce stress on the back when a person is lifting

TABLE 12-8 Layers and Groups in the Extensor Muscles of the Vertebral Column

Muscle Group

Splenius Muscle Erector Spinae

Transversospinalis Muscle

Suboccipital Muscle

Superficial layer

Splenius capitis Splenius cervicis

Intermediate layer —

Deep layer

Iliocostalis lumborum, iliocostalis thoracis, iliocostalis cervicis Longissimus thoracis, longissimus cervicis, longissimus capitis Spinalis thoracis, spinalis cervicis, spinalis capitis

Semispinalis thoracis, semispinalis cervicis, semispinalis capitis Multifidus Segmental muscles Interspinales Cervical intertransversarii:

anterior, posterior Lumbar intertransversarii:

lateral, medial Rotatores: longus, brevis

Rectus capitis posterior major and minor Obliquus capitis superior and inferior

TABLE 12-9 Abdominal Muscles*

Muscles

Origin

Insertion

Innervation

Action

External oblique

Internal oblique

Transverse abdominis

Rectus abdominis

External surface of 5th to 12th ribs

Thoracolumbar fascia, anterior two thirds of iliac crest, and lateral half of inguinal ligament Internal surfaces of 7th to 12th costal cartilages, thoracolumbar fascia, iliac crest, and lateral third of inguinal ligament Pubic symphysis and pubic crest

Linea alba, pubic tubercle, and anterior half of iliac crest

Inferior borders of 10th and 12th ribs, linea alba, and pubis via conjoint tendon

Linea alba with aponeurosis of internal oblique muscle, pubis crest, and pecten pubis via conjoint tendon

Xiphoid process and fifth to seventh costal cartilages

Interior six thoracic nerves and subcostal nerves

Ventral rami of inferior six thoracic and first lumbar nerves

Ventral rami of inferior six thoracic and first lumbar nerves

Ventral rami of inferior six thoracic nerves

Compresses abdominal viscera and supports abdominal visceral flexion and rotation of trunk Compresses abdominal viscera and supports abdominal visceral flexion and rotation of trunk Compresses and supports abdominal viscera

Flexes trunk and compresses abdominal viscera

Costoxiphoid ligaments

Serratus anterior

Rectus sheath, anterior layer

Rectus abdominis, tendinous intersection

Rectus abdominis

External oblique Umbilical ring

Linea alba

Anterior superior iliac spine

Intercrural fibres

Costoxiphoid ligaments

Serratus anterior

Rectus sheath, anterior layer

Rectus abdominis, tendinous intersection

Rectus abdominis

External oblique Umbilical ring

Linea alba

Anterior superior iliac spine

Intercrural fibres

Figure 12-20 Muscles of the abdominal wall

Superficial i Lateral crus inguinal ring \ Medial crus

Pyramidalis

Figure 12-20 Muscles of the abdominal wall

Pectoralis major, sternocostal head Pectoralis major, abdominal part

External oblique

Internal intercostal muscle Rectus abdominis

Internal oblique aponeurosis

External oblique Internal oblique

External oblique, aponeurosis

Spermatic cord; cremaster Reflected ligament

Sternal part Inferior phrenic veins Central tendon Caval opening: inferior vena cava Right phrenic nerve, phrenico-abdominal branch Costal part Median arcuate ligament Lumbar part, right bundle, (lateral part) Lateral arcuate ligament Rib XII Costal process of lumbar vertebrae I Medial arcuate ligament

Azygos vein

Figure 12-21 The diaphragm.

Xiphoid process

(Sternocostal trigangle): internal thoracic artery; vein, left phrenic nerve, phrenico-abdominal branch Oesophageul hiatus: oesophagus; anterior and posterior vagal trunk Left phrenic nerve, phrenico-abdominal branch Inferior phrenic artery Greater splanchnic nerve Hemi-azgos vein (Lumbocostal trigangle) Lesser splanchnic nerve Aortic hiatus: abdominal aorta; thoracic duct Quadratus lumborum Psoas major Sympathetic Trunk Lumbalar part, right bundle, (medial part)

Figure 12-21 The diaphragm.

heavy objects. The volume of the chest cavity can also be increased by raising the ribs with external intercostal muscles. A number of muscles (e.g., back, chest, neck) may exert an influence on the rib cage during forced breathing.

FUNCTIONAL ANATOMY AND PATHOMECHANICS OF THE UPPER LIMB

Dynamic Six Pack Abs

Dynamic Six Pack Abs

Reasonable care has been taken to ensure that the information presented in this book is accurate. However, the reader should understand that the information provided does not constitute legal, medical or professional advice of any kind.

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