Muscles of Back, Abdomen & Inguinal Canal PDF

Muscles of the back, anterior abdominal wall and inguinal canal  The muscles of the back are divided into superficial and deep muscles. superficial muscles are also known as the muscles which connect the upper extremitu with the vertebral column - Trapezius muscle - Latissimu...

Muscles of the back, anterior abdominal wall and inguinal canal  The muscles of the back are divided into superficial and deep muscles. superficial muscles are also known as the muscles which connect the upper extremitu with the vertebral column - Trapezius muscle - Latissimus dorsi muscle - Rhomboideus major and minor - Levator scapulae Trapezius muscle Origin: external occipital protuberance and the medial part of the superior nuchal line of the occipital bone, from the ligamentum nuchæ (which covers the spinous processes of first 6 cervical vertebrae), the spinous process of the seventh cervical, and the spinous processes of all the thoracic vertebræ Insertion: posterior border of the lateral third of the clavicle; the acromion, the superior lip of the spine of the scapula Innervation: accessory nerve and cervical nerves Actions: superior fibers elevate the shoulder middle fibers, project the shoulder back inferior fibers depress the shoulder If the shoulders are fixed, the Trapezii, acting together, will draw the head directly backward; or if only one act, the head is drawn to the corresponding side. Latissimus dorsi muscle Origin: the spinous processes of the lower six thoracic vertebræ, of the lumbar and sacral vertebræ (middle sacral crest); the external lip of the crest of the ilium ; the inferior angle of scapula; the three or four lower ribs Insertion: intertubercular groove of the humerus Innervation: thoracodorsal nerve Actions: extension, adduction and medial rotation of the arm Elevates the last ribs, helps in climbing Rhomboideus major and minor Rhomboideus major Origin: spinous processes of the second, third, fourth, and fifth thoracic vertebræ T2-T5 Insertion:medial border of scapula Rhomboideus minor Origin: spinous processes of the sixth, seventh cervical and first thoracic vertebræ C6-T1 Insertion: medial border of the scapula Innervation: dorsal scapular nerve Actions: retract the scapula towards the vertebral column Levator scapulae muscle Origin: the transverse processesC1-C4 Insertion: superior angle of scapula Innervation: dorsal scapular nerve Actions: elevates the superior angle of scapula Serrati posteriores muscles Serratus posterior superior Origin: spinous processes C6-T2 Insertion: ribs 2-5 Innervation: first 5 intercostal nerves Action: elevates the ribs (inspiration) Serratus posterior inferior Origin: spinous processes T10-L2 Insertion: lower four ribs Innervation: last 4 intercostal nerves Action: lowers the ribs (expiratory) Anterior muscles of the abdomen Obiquus externus Obliquus internus Transversus abdominis Rectus abdominis Obliquus externus/External oblique The Obliquus externus abdominis situated on the lateral and anterior parts of the abdomen, is the largest and the most superficial of the three flat muscles in this region. Origin: the external surfaces and inferior borders of the lower eight ribs Insertion: Those from the lower 2 ribs are inserted into the external lip of the iliac crest; the middle and upper fibers end in an aponeurosis (the tendon of the ) which inserts on linea alba (between xyphoid process and pubic symphysis, formed at the intersection of all the aponeuroses of the 3 muscles) and the anterior border of coxal bone, between anterior superior iliac spine and pubic tubercle (this part of the external oblique aponeurosis is called inguinal ligament). Innervation: intercostal nerves 5-11, the subcostal nerve. Iliohypogastric, ilioinguinal Actions: flexion of the trunk on the same side and rotation on the opposite side; expiration Obliquus internus/internal oblique The Obliquus internus abdominis is thinner and smaller than the Obliquus externus, beneath which it lies Origin: the lateral half of the inguinal ligament, the middle lip of the iliac crest, the thoracolumbar fascia. Insertion : fibers from the inguinal ligament, together with those of the Transversus, into the crest of the pubis, pubic tubercle and pectineal line behind the lacunar ligament, forming what is known as the inguinal aponeurotic falx (conjoined tendon); the 3-4 lower ribs; the rest of the fibers are inserted into the linea alba Innervation: intercostal nerves 8-11, subcostal nerve, iliohypogastric, ilioinguinal Actions: flexion and rotation of the trunk on the same side, expiration Transversus abdominis The Transversus abdominis is the most internal of the flat muscles of the abdomen, being placed immediately beneath the Obliquus internus. Origin: the lateral half the inguinal ligament, the inner lip of the iliac crest, the inner surfaces of the lower six ribs, interdigitating with the diaphragm, and from the thoracolumbar fascia. Insertion: the fibers from inguinal ligament, together with those of the Obliquus internus,through conjoined tendon; the rest of it through anterior aponeurosis into the linea alba Innervation: intercostal nerves 6-11, subcostal nerve, iliohypogastric, ilioinguinal Actions : increases the pressure in the abdominal cavity Rectus abdominis The Rectus abdominis is a long flat muscle and is separated from its fellow of the opposite side by the linea alba. Origin: ribs 5,6,7 Insertion: two tendons: a lateral tendon on the pubic tubercle and a medial tendon in front of the pubic symphysis. The Rectus is crossed by fibrous bands, three in number, which are named the tendinous inscriptions Innervation: intercostal nerves 5-111, subcostal nerve, iliohypogastric, ilioinguinal Actions: flexion of the trunk, flexion of the pelvis, expiration  All the abdominal muscles compress the abdominal viscera by constricting the cavity of the abdomen, in which action they are assisted by the descent of the diaphragm. By these means assistance is given in expelling the feces from the rectum (defecation), the urine from the bladder (micturition), the fetus from the uterus (childbirth), and the contents of the stomach in vomiting. The sheath of rectus abdominis The Rectus is enclosed in a sheath formed by the aponeuroses of the Obliqui and Transversus, which are arranged in a different manner in the upper 2 thids of the muscle and in the lower third. Upper 2 thirds. At the lateral border of the Rectus, the aponeurosis of the Obliquus internus divides into two lamellæ, one of which passes in front of the Rectus, blending with the aponeurosis of the Obliquus externus, the other, behind it, blending with the aponeurosis of the Transversus, and these, joining again at the medial border of the Rectus, are inserted into the linea alba. So, the anterior lamina of the Rectus sheath is formed by the aponeurosis of external oblique and the anterior lamella of the internal oblique, and the posterior lamina is formed by the posterior lamella of the internal oblique, the anterior aponeurosis of transversus, and fascia transversalis Lower one third, the aponeuroses of all three muscles pass in front of the Rectus, forming the anterior lamina, and the posterior lamina is only formed by fascia transversalis. Since the tendons of the Obliquus internus and Transversus only reach as high as the costal margin, it follows that above this level the sheath of the Rectus is deficient behind. The limit on the posterior lamina of the sheath is called linea semicircularis or arcuate line of Douglas, the concavity of which is directed downward.