Muscles of back
Superficial layer:
trapezius
latissimus dorsi
levator scapulae
rhomboid muscle
Deep layer:
eretor spinae
Superficial group
Trapezius
a large, triangular m. lying on the back of the neck and thorax;
Origin:
external occipital protuberance, superior nuchal line, ligamentum nuchae, the spinous processes of 7th cervical vertebrae and all thoracic vertebrae;
Insertion:
lateral 1/3 of clavicle, acromion and spine of scapula.
Action:
raises, descends, and rotates the scapula and extends the head.
superficial group
Latissimus Dorsi
It is a largest and triangular m. lying the back and lateral wall of thorax;
Origins: the spinous processes of lower 6 thoracic vertebrae and all lumbar vertebrae;
Insertion: inserted into the floor of the intertubercular sulcus
Action:
Extend, adduct, and rotate the shoulder joint medially
superficial group
Levator scapulae
Origin : the transverse processes of the upper 4 cervical vertebrae;
Insertion : superior angle of scapula.
Action : raise the scapula.
rhomboideus
Lies deep to the trapezius. Adduct the scapular by pulling it medially toward the vertebral column.
The deep group
Position :
It lies in the vertebral groove on each side of vertebral spines.
Action : extend the spinal column and head.
Thoracolumbar fascia
Wrap the surrounding of erector muscle of spine. It can be divided into three layers:
Superficial layer:posterior to the erector spinae;
Middle layer :separate the erector spinae and the quadratus lumborum
Deep layer:anterior to the quadratus lumborum
Muscles of thorax
Extrinsic muscles
Pectoralis major
Pectoralis minor
Serratus anterior
Pectoralis major
Origin: medial half of clavicle, sternum, 1th-6th costal cartilages.
Insertion: crest of greater tubercle of humerus.
Action: flexes, adducts and rotates arm medially; arm fixed, elevates trunk; elevates ribs 1-6, aidding in forced inspiration.
Pectoralis minor
Deep to the pectoralis major
Origin: 3rd-5th ribs
Insertion: coracoid process of scapula
Action:
Draw the scapula forwards and downwards, when the scapula is fixed it helps the inspiration (by elevation the ribs)
Serratus anterior
It overlies the lateral wall of thorax
Origin: external surfaces of the upper 8~9 ribs
Insertion: medial border of scapula
Action: holds the scapula against the chest wall;Pulls the scapula forwards in throwing and pushing.
Intrinsic muscles
External Intercostale muscles
Origin: lower border of rib
Insertion: upper border of rib below origin
external intercostals membrane.
Action: elevate ribs adding in forced inspiration
Internal Intercostale muscles
Origin: upper border of rib;
Insertion: lower border of rib above origin
Replaced posteriorly by internal intercostals membrane.
Action: depress ribs for forced expiration
Diaphragm
Position and division:
dome-shaped between thorax and abdomen, consists of
Central tendon
muscular part
Sternal part:
Costal part:
Lumbar part: arises by left and right crus from upper 2-3 lumbar vertebrae
Insertion: central tendon
Openings of diaphragm:
Aortic hiatus
at the level of 12th thoracic vertebra, the thoracic aorta and thoracic duct pass through it.
Esophageal hiatus
at the level of 10th thoracic vertebra, the esophagus and vagus n. pass throught it.
Vena caval foramen
at the level of 8th thoracic vertebra, inferior vena cava through it.
Action:
Contraction: the dome moving downward, increases the volume of thoracic cavity which results in inspiration.
Relaxation: the dome returns to the former position, reduces the volume of the thoracic cavity, resulting in expiration.
Weak areas:
triangular spaces without muscular tissue
Lumbocostal triangle: between costal and lumbar parts.
Sternocostal triangle: between costal and sternal parts.
Muscles of abdomen
Anterolateral group
Obliquus externus abdominis
Obliquus internus abdominis
Transversus abdominis
Rectus abdominis
Obliquus externus abdominis
Origin:
Arises from the lower 8 ribs, and the muscular fibers run obliquely from the superolateal
to the inferomedial, the anterior part of the m. change gradually into aponeurosis, which pass over the rectus Abdominis;
Insertion: Linea alba
Structures
formed by aponeurosis of this m. include:
Inguinal ligament
Superficial inguinal ring - triangular-shaped hiatus above pubic tubercle
Lacunar ligament
Obliquus internus abdominis
Origin: thoracolumbar fascia, iliac crest and the lateral half of the ingunal lig.
Insertion: Linea alba
The muscular fibers run upwards and forwards, and become the aponeurosis close the lateral border of the rectus abdominis. Its aponeurosis divided into two layers to inclose the rectus abdominis.
Transversels abdominis:
is the deepest one of the three flat abdominal m.
Origin:
it arises from the costal cartilages of the lower 6 ribs,the thoracolumbar fascia , the iliac crest and the lateral 1/3 of the ingunal lig.
Insertion: Linea alba
The muscular fibers run transversly, and pass deep to rectus abdominis.
Inguinal falx (conjoined tendon) :
is a common aponeurosis joined by obliquus internus abdominis and transverse abdominis, it turns downwards to insert the pubic crest and pecten pubis.
Cremaster : around the spermatic cord and testis
Rectus abdominis:
is a long, broad, strap m. and the principal vertical one of the anterior abdominal wall.
Origin: it arises from pubic symphysis and pubic crest.
Insertion: xiphoid process and 5th to 7th costal cartilages.
The two muscles are separated by the linea alba and enclosed in the rectus sheath.
The Sheath of rectus abdominis
Anterior layer:
formed by the aponeurosis of obliquus externus abdominis ; anterior leaf of aponeurosis
of obliquus internus abdominis
Posterior layer: formed byposterion leaf of aponeurosis of obliquus internusabdominis;
aponeurosis of transverses abdominis
The Sheath of rectus abdominis
arcuate line or semicircular line
at about 4-5cm below the umbilicus, the lower free border of the posterior layer of the sheath present arcuated.
Below this line the rectus abdominis in contact with transverse fascia directly.
Linea alba
tendinous raphe between right and left rectus abdominis from xiphoid process to pubic symphysis.
The functions of the four pairs of muscles
Support and protect the abdominal viscera
Maintain and increase intra-abdominal pressure, aid in vomiting, coughing, sneezing, defecation, urination and childbirth.
Flex, lateral flex, and rotate vertebral column
Inguinal canal
Position:
oblique passage about 4cm long, and passes downwards and medially, it lies parallel to, and immediately above medial half of inguinal lig. It has two openings and four walls.
Four walls
Anterior wall
Aponeurosis of obliquus externus abdominis
Obliquus internus abdominis (lateral third of wall)
Post wall
—Transverse fascia
— Inguinal flax medially
Roof- lower fibers of obliquus internus and transversus abdominis
Floor-inguinal ligament.
Two openings
Superficial inguinal ring
Deep inguinal ring
-defect in transverse fascia,lies at about 1.5cm above midpoint of inguinal ligament
Structures passing through the inguinal canal
Male: Spermatic cord
Female: Round ligament of uterus
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