MUSCULAR SYSTEM : MUSCLES OF ABDOMINAL,THORACIC AND PELVIC CAVITY IN ENGLISH
watch my youtube video to understand this topic in easy way-
https://www.youtube.com/watch?v=uTSfVijwe0A
MUSCLES OF ABDOMINAL CAVITY
Rectus
abdominis- This muscle arises from
pubic crest and pubic symphysis and inserts into Cartilage of fifth to seventh
ribs and xiphoid process. These muscles help in flexion of vertebral column.
this muscle is innervated by T7-T12 spinal nerves.
Transversus
abdominis- This muscle arises from
iliac crest, inguinal ligament , lumber fascia and cartilage of 5th
to 10th ribs. This muscle inserts into xiphoid process, linea alba
and pubis. These muscles compresses the abdomen. this muscle is innervated by
T8-T12 spinal nerves.
External
oblique- This muscle arises from 5th
to 10th ribs and inserts into iliac crest and linea alba. Working
unilaterally it laterally flexes/rotates the vertebral column and hen both
moucles act together the compress the abdomen and flex vertebral column. These muscles are innervated by T7-T12 spinal
nerves.
Internal
oblique- This muscle arises from
iliac crest, inguinal ligament & lumber fascia and inserts into linea alba and cartilage of 7th to
10th ribs. Working unilaterally it laterally flexes/rotates the
vertebral column and when both muscles act together they compress the abdomen
and flex vertebral column. These muscles
are innervated by T7-T12 spinal nerves.
The anterolateral abdominal wall is composed of
skin, fascia, and four pairs of muscles that we have discussed just now. The
external oblique is the superficial muscle. Its fascicles extend inferiorly and
medially. The internal oblique is the intermediate flat muscle. Its fascicles
extend at right angles to those of the external oblique. The transversus
abdominis is the deep muscle, with most of its fascicles directed transversely
around the abdominal wall.
The rectus
abdominis muscle is a long muscle that extends the entire length
of the anterior abdominal wall. The aponeuroses (sheath like tendons) of the
external oblique, internal oblique, and transversus abdominis muscles form the rectus sheaths, which enclose
the rectus abdominis muscles. The sheaths meet at the midline to form the linea
alba ( white line), a tough, fibrous band that extends from the xiphoid
process of the sternum to the pubic symphysis.
Quadratus
lumborum- This muscle arises from iliac crest and ilio-lumber ligament and
inserts into Inferior border of twelfth rib and first four lumbar vertebrae.
This muscle forms the posterior abdominal wall. Working unilaterally it
laterally flexes the vertebral column and when both muscles act together they
extend vertebral column. These muscles are innervated by T12,L1-L3 spinal
nerves
MUSCLES OF THORACIC CAVITY
Diaphragm-
This is a dome shaped muscle and have a central tendon and separates chest
cavity from abdominal cavity. It arises
from xiphoid process, costal cartilages of lower 6 ribs and lumber vertebrae.
Diaphragm help in respiration. This muscle is innervated by phrenic nerve.
(formed by C3-C5 spinal nerves)
External
intercostals- The 11 pairs of external intercostal muscles lies superficial
to internal intercostals, and their fibers run in an oblique direction
inferiorly and anteriorly from the rib above to the rib below. They elevate the
ribs during inhalation to help expand the thoracic cavity. These muscles are
innervated by T2–T12 spinal nerves.
Internal
intercostals- The 11 pairs of internal intercostal muscles lies deep to
external intercostal, and their fibers run in an oblique direction opposite to
external intercostal They elevate the ribs during inhalation to help decrease
the volume of the thoracic cavity. These muscles are innervated by T2–T12
spinal nerves.
Subclavius-
This muscle arises from first rib and inserts into clavicle. These muscles
Depresses and moves clavicle anteriorly and helps stabilize scapula. These
muscles are innervated by subclavian nerve.
Pectoralis
minor- This muscle arises from 3rd 4th and 5th
rib and inserts into coracoid process of scapula. These muscles abduct scapula
and rotate it downwards. These muscles are innervated by medial pectoral nerve.
Serratus
anterior- This muscle arises from
first eight ribs and inserts into medial border and angle of scapula. These
muscles abduct scapula and rotate it upwards. It is also known as boxer’s
muscle. These muscles are innervated by long thoracic nerve.
Trapezius-
This muscle arises from superior nuchal
line of occipital bone and spines of C7-T12 vertebrae and inserts into clavicle
and acromion process of spine of scapula. These muscles abduct scapula and
rotate it upwards and stabilizes the scapula. These muscles are innervated by
11th cranial and C3-C5 spinal nerves.
Levator
scapulae- This muscle arises from transverse process of C1-C4 cervical
vertebrae and inserts into upper medial border of scapula. These muscles
elevate the scapula and rotate it downwards. These muscles are innervated by
dorsal scapular nerve and C3-C5 spinal nerves.
Rhomboid
major- This muscle arises from
Spines of T2–T5 thoracic vertebrae and
inserts into medial border of scapula. These muscles elevate & adduct
scapula and rotate it downwards and stabilizes the scapula. These muscles are
innervated by dorsal scapular nerve.
Rhomboid
minor- This muscle arises from
Spines of C7–T1 vertebrae and inserts into medial border of scapula. These
muscles elevate & adduct scapula and rotate it downwards and stabilizes the
scapula. These muscles are innervated by dorsal scapular nerve.
MUSCLES OF PELVIC CAVITY-
Levator
ani- This muscle have three components, and these are pubococcygeus iliococcygeus and puborectalis.
The Pubococcygeus arises from
Pubis and ischial spine and inserts into Coccyx, urethra, anal canal, perineal
body of the perineum and anococcygeal
raphe. The iliococcygeus
arises from ischial spine and inserts
into Coccyx.
Puborectalis is a thick narrow,
medial part of the levator ani. It forms a U-shaped muscular sling around and
behind the rectum, just cephalad to the external sphincter
Levator ani muscles supports and maintains
position of pelvic viscera; constricts anus, urethra, and vagina. This muscle
is included in pelvic floor muscles. These muscles are innervated by sacral
spinal nerve (S2-S4).
Ischiococcygeus-
This muscle arises from ischial spine
and inserts into sacrum and coccyx. These muscles supports and maintains
position of pelvic viscera. This muscle is also included in pelvic floor
muscles. These muscles are innervated by sacral spinal nerve (S4-S5).
MUSCLES OF PERINEUM-
The
perineum is the region of the trunk inferior to the pelvic floor. It is a
diamond-shaped area that extends from the pubic symphysis anteriorly, to the
coccyx posteriorly, and to the ischial tuberosities laterally. Several perineal
muscles insert into the perineal body of the perineum. Perineal body is a
fibro-muscular structure or central tendon located in the midline of the
perineum
Ø
Superficial
transverse perineal- This muscle
arises from ischial tuberosity and inserts into perineal body of
perineum. These muscles supports and maintains position of perineal body of
perineum. These muscles are innervated by perineal branch of pudendle nerves of
sacral plexus
Ø
Bulbospongiosus-
This muscle arises from perineal body
and inserts into corpus spongiosum of penis, deep fascia on dorsum of penis in
male and root and dorsum of clitoris in female. These muscles help in expelling
urine and semen through urethra in male and constricting vagina and erection of
clitoris in females. These muscles are innervated by perineal branch of
pudendle nerves of sacral plexus
Ø
Ischiocavernosus-
This muscle arises from ischial
tuberosity and ramus of ischium and pubis and inserts into corpus cavernosum of
penis in male and clitoris in female. These muscles help in maintaining
erection of penis in male and erection of clitoris in females. These muscles
are innervated by perineal branch of pudendle nerves of sacral plexus
Ø
Deep
transverse perineal- This muscle
arises from ramus of ischium and
inserts into perineal body of perineum. These muscles help to expel last drops
of urine and semen in male and urine in female. These muscles are innervated by
perineal branch of pudendle nerves of sacral plexus
Ø
External
urethral sphincter- This muscle
arises from ramus of ischium and pubis and inserts into neck of urethra
in male and vaginal wall in female. These muscles help to expel last drops of
urine and semen in male and urine in female. These muscles are innervated
by pudendle nerves of sacral plexus
Ø
Compressor
urethrae- This muscle arises from
ramus of ischium and pubis and inserts into compressor urethrae of other side,
anterior to urethra. These muscles act as accessory sphincter of urethra. These
muscles are innervated by pudendle
nerves of sacral plexus
Ø
Sphincter
urethro-vaginalis- This muscle
arises from perineal body and inserts into Sphincter urethrovaginalis of
other side, anterior to urethra. These muscles act as accessory sphincter of
urethra and compressing vagina in females. These muscles are innervated by pudendle nerves of sacral plexus
Ø
External
anal sphincter- This muscle arises
from anococcygeal ligament and inserts into perineal body. These muscles keep
anal opening closed. These muscles are innervated by inferior rectal branch of
pudendle nerves of sacral plexus
No comments:
Post a Comment