Class 10 - THE MUSCLES OF THE THORAX, ABDOMEN, AND PELVIS Flashcards
The thoracic cavity increase in size during…
Inhalation
The thoracic cavity decreases in size during…
Exhalation
Muscles that act primarily during relaxed quiet breathing
Diaphragm
External intercostal
Internal intercostal
Diaphragm consists of two portions:
- Peripheral muscular portion
2. Central tendon
Three openings of diaphragm
- Aortic hiatus
- Esophageal hiatus
- Caval opening
Aortic hiatus consists of…
Aorta
Thoracic duct
Azygos veins
Esophageal hiatus consists of…
Esophagus
Vagus nerves
Caval opening consists of…
Foramen for the inferior vena cava
Diaphragm origin
Xiphoid process
Costal cartilages of ribs 7-12
Lumbar vertebrae and discs
Diaphragm insert
Central tendon
Diaphragm innervation
Phrenic nerve (which contains axons from cervical spinal nerves C3-C5)
Diaphragm actions
Exerts 75% of effort for the relaxed-quiet breathing
Helps return blood to the heart
The diaphragm with 5he anterolateral abdominal muscles help increase the intraabdominal pressure for…
Helps support the spine with weight lifting
Evacuation of contents of the organs (defection, urination, childbirth)
Pairs of intercostal muscles
11
Intercostal muscles occupy…
The intercostal space
Three layers of intercostal muscles
- External intercostals
- Internal intercostals
- Innermost intercostals
External intercostals occupy…
The superficial layer
External intercostals run…
Obliquely, inferiorly, anteriorly and medially (same direction of the external oblique muscles)
External intercostals origin
Inferior border of the rib above
External intercostals insertion
Superior border of the rib below
External intercostals action
Elevate the ribs (relaxation allows ribs to descend with gravity)
Exert 25% of the muscle effort in the relaxed-quiet breathing
Internal intercostals occupy…
The intermediate layer
Internal intercostals run…
Superiorly, anteriorly and medially (same direction as the internal oblique muscle)
Internal intercostals origin
Superior border of the rib below
Internal intercostals insertion
Inferior border of the rib above
Internal intercostals action
Forced exhalation
External intercostals innervation
Thoracic spinal nerves T2-T12
Internal intercostals innervation
Thoracic spinal nerves T2-T12
Anterolateral abdominal walls
Space between rib cage and the pelvis closed by the skin, fascia and four pairs of muscles
Four pairs of muscles of the anterolateral abdominal walls
- Rectus abdominis
- External oblique
- Internal oblique m
- Transverse abdominis
Recutus abdominis origin
Pubic crest and pubic symphysis
Rectus abdominis insertion
Costal cartilages of ribs 5-7 and xiphoid process
Three tendinous intersections that interrupt the rectus abdominis
One near the leaves of the navel
One near the xiphoid process
One in between those two intersections
(Sometimes a fourth below the level of the umbilicus)
Rectus sheath
Aponeurosis that encloses the rectus abdominis formed by the other three abdominal muscles
Linea alba
Where right and left rectus sheaths meet at the anterior midline from the xiphoid process to the public symphysis
(includes umbilicus)
Rectus abdominis action
Act bilaterally to flex the spine, antagonizing the erector spinae
Rectus abdominis RMA
Flexes the pelvis on the spine
External oblique muscle is…
Superficial
External oblique fascicles are extended…
Inferiorly, anteriorly and medially
External oblique origin
Ribs 5-12
External oblique insertion
Iliac crest and linea alba
Aponeurosis of the external oblique muscle forms…
Anterior layer of the rectus sheath
Inguinal ligament “jumping” between ASIS and pubic tubercle
Aponeurosis of the right and left external oblique muscle fuse at…
The linea alba
External oblique actions
Acting together: flex the spine
Acting unilaterally: laterally flex and rotate the spine
Internal oblique muscles is…
Intermediate
Internal oblique fascicles extend…
Superiorly, anteriorly and medially
At right angle to the external oblique
Internal oblique origin
Iliac crest
Inguinal ligament
Thoracolmbar fascia
Internal oblique insertion
Costal cartilages of ribs 7-10
Linea alba
Aponeurosis of the internal oblique muscle splits…
Into anterior and posterior layers where is reaches the side of the rectus abdominis, contributing to the anterior and posterior layers of the rectus sheath
Aponeurosis of the right and left internal oblique muscle fuses at…
The linea alba
Internal oblique action
Acting bilaterally: flex the spine
Acting unilaterally: laterally flex and rotate the spine
Transversus abdominis muscle is…
Deep
Transversus abdominis fascicles are divided…
Transversely around the abdominal walls
Transversus abdominis origin
- Iliac crest
- Inguinal ligament
- Lumbar fascia
- Costal cartilages of ribs 5-10
Aponeurosis of the transversus abdominis forms…
Part of the posterior layer of the rectus sheath
Aponeurosis of the right and left transversus abdominis fuse at…
The linea alba posterior to the rectus abdominis muscles
The aponeurosis of the transversus runs… to the rectus abdominis muscles and forms…
Anterior to form part of the anterior layer of the rectus sheath
Inguinal canal
Oblique passageway in the anterior abdominal wall
Location of inguinal canal
Superior and parallel to the medial half of the inguinal ligament
Inguinal canal measures…
4-5cm in length
Inguinal canal origin
Deep inguinal ring
Deep inguinal ring
Opening in the aponeurosis of the transverse abdominis
Inguinal canal ends…
Superficial inguinal ring
Superficial inguinal ring
Opening in the aponeurosis of the external oblique muscle
Inguinal canal in men contains…
The spermatic cord
Inguinal canal in women contains…
The round ligaments of the uterus
Posterior abdominal wall is formed by…
Muscles, lumbar vertebrae and the hip bone
Muscles of the posterior abdominal wall
Psoas major
Iliacus
Quadratus lumborum
Quadratus lumborum (QL) origin
Iliac crest and iliolumbar ligament
Quadratus lumborum (QL) insertion
12th rib and transverse process of L1-L4
Quadratus lumborum actions
Bilaterally: pull 12th rib down during forced exhalation, fix the 12th rib to prevent excessive elevation during forced inhalation md extend spine
Unilaterally: lateral flexion of spine
Pelvic diaphragm
Muscles of the pelvic floor
Pelvic diaphragm stretches from…to…
The pubis to the coccyx
Two muscles of the pelvic diaphragm
- Levator ani
2. Ischiococcygeus
Three parts of levator ani
- Puborectalis
- Iliococcygeus
- Pubococygeus
Ishiococcygeus form the…portion of the pelvic diaphragm
Posterior
Levator ani functions
Supports the pelvic viscera
Acts in conjuction with the intraabdominal pressure
Functions as the internal sphincter of the anus
Pelvic diaphragm piercings
Anal canal
Urethra
Vagina in females
Females pelvic diaphragm is…
Weaker
Perinium
Diamond-shaped area closing the pelvic cavity inferiorly
Line between the Ischial tuberosity divides perinium into two triangles
- Urogenital triangle (anterior)
2. Anal triangle (posterior)
Two layers of perinium
Superficial
Deep
Urogenital triangle muscle functions
Sphincter for the urethra
Play a role in the process of erection and ejaculation
Contribute in intercourse
Anal triangle muscle action
Include the external anal sphincter for the voluntary control of defecation