Abdominal Arthrology & Myology Flashcards
Location of Abdominal Cavity
- Inferior to Thoracic Diaphragm
- Superior to Pelvic Cavity
Walls of the abdomen are mostly:
Soft Tissue (muscle)
What lines the Abdominal Cavity?
Serous Membrane called the Peritoneum
Role of the Peritoneum:
Allows the tightly packed organs of the abdomen to work next to each other without interfering or impeding
Camper Fascia (Superficial Fatty Layer)
- Superficial layer of adipose tissue found below the skin
- In males the accumulation of this type of fat is often called “beer belly”
Scarpa Fascia (Deep Membranous Layer of Subcutaneous Tissue)
- Layer of thick tissue that runs deep to the Camper Fascia
Scarpa Fascia runs inferior to the ____ to become continuous with the ___ ___ fascia
- Perineum (genitoanal area)
- Superficial Perineal (Colles)
Importance of the Scarpa Fascia becoming continuous with the Superficial Perineal Fascia:
This connection allows fluid to travel from the abdomen into the perineum
Scarpa Fascia fuses with the ___ __, preventing abdominal fluid from traveling into the leg
Fascia Lata
Deep Fascia
- Cover the anterior wall muscle layers
- Intimately associated with anterior wall muscle fascial layers
Transversalis Fascia (Endoabdominal Fascia)
- Deepest layer of the abdominal wall
- Made up of membranous and areolar tissue that varies in thickness depending on location
What separates the Transversalis Fascia from the peritoneum of the abdominal cavity?
Thin layer of fat (Extraperitoneal Fat)
Parietal Peritoneum
- Serous lining of the abdominal cavity
- Two layers: Parietal, Visceral
Parietal Layer of Parietal Peritoneum
- Located next to the Transversalis Fascia and the abdominal walls
- Innervated and vascularized by same supply as abdominal wall
Visceral Layer of Parietal Peritoneum
- Covers abdominal organs
What is between the Parietal and Visceral Layers of the Peritoneum?
A space with serous fluid
External Oblique Muscle
- Paired muscle
- Largest and most external of the anterolateral abdominal muscles
- Majority of the fibers run in an inferomedial direction (down towards midline)
External Oblique Muscle: Origin & Insertion
- Origin: external surfaces of ribs 5-12
- Insertion: Linea alba, pubic tubercle, anterior iliac crest
External Oblique Muscle: Innervation
- Thoracoabdominal Nerves (T7-T11)
- Subcostal Nerve
External Oblique Muscle: Action
- Compresses and supports abdominal organs
- Flexes and rotates the trunk
External Oblique Aponeurosis
- Anterior tendinous aspect of external oblique muscles
- Right and left fuse together along the Linea Alba
- Create rectus sheath
Linea Semilunaris
- Demarcates where the abdominal muscles transition to aponeurosis
- Located on the lateral border of the rectus abdominis muscle
Linea Alba
- Where aponeurosis from the left and right abdominal muscles come together and interweave with each other forming a raphe
- Runs vertically along the midline of the body
- Separates the two rectus abdominis muscle bodies
Inguinal Ligament (Poupart Ligament)
- Inferior, fibrous edge (aponeurosis) of the external oblique muscle folds under itself creating this ligament
- Runs between the ASIS and the pubic tubercle
- Located right below this ligament is the Subinguinal Space (hip flexors and neurovascular structures pass thru that space)
Internal Oblique Muscle
- Second muscle layer of the anterolateral abdominal wall
- Majority of fibers run in superolateral direction, opposite the external oblique fibers
Internal Oblique Aponeurosis
- Anterior tendinous aspect of the internal oblique muscles
- Right and left fuse together along the Linea Alba
- Creates rectus sheath
Inferiorly the Internal Oblique Aponeurosis fuses with the Transversus Abdominis Aponeurosis, creating the:
Conjoint Tendon
Internal Oblique Muscle: Origin & Insertion
- Origin: Thoracolumbar fascia, anterior iliac crest, lateral inguinal ligament
- Insertion: Inferior portion of ribs 10-12, linea alba, pectin pubis (conjoint tendon)
Internal Oblique Muscle: Innervation
- Thoracoabdominal Nerves (T6-T11)
- Subcostal N
- Ilioinguinal N
- Iliohypogastric N
Internal Oblique Muscle: Action
- Compresses and supports abdominal organs
- Flexes and rotates the trunk
Formation of Cremaster Muscle
- Internal Oblique muscle fibers are pulled into the spermatic cord as male gonads travel outside the body, which leads to formation of this muscle
Function of Cremaster Muscle
Thermoregulation of testes
Innervation of Cremaster Muscle
Genital branch of Genitofemoral N
Conjoint Tendon (Inguinal Flax)
- Aponeurosis of the Internal Oblique Muscle and Transversus Abdominis Muscle fuse together before inserting on the Pectin Pubis and Pubic Crest
- Serves as a posterior boundary for the Inguinal Canal
Transversus Abdominis Muscle
- Deepest of the 3 anterolateral abdominal wall muscles
- Muscle fibers run mostly horizontally across the abdomen
- Between this muscle and the Internal Oblique muscle is a neurovascular pathway for the nerves and vessels to travel before piercing the surface
- Forms the Transversus Abdominis Aponeurosis near the Linea Semilunaris
Transversus Abdominis Muscle: Origin & Insertion
- Origin: Costal cartilages of ribs 7-12, thoracolumbar fascia, iliac crest, lateral inguinal ligament
- Insertion: linea alba, pubic crest, pectin pubis (conjoint tendon)
Transversus Abdominis Muscle: Innervation
- Thoracoabdominal Nerves (T6-T11)
- Subcostal N
- Ilioinguinal N
- Iliohypogastric N
Transversus Abdominis Muscle: Action
Compresses and supports abdominal organs
Rectus Abdominis Muscle
- Strap-like muscle that lies on either side of the anterior midline (Linea Alba), running vertically
- Muscle belly tapers as it moves inferiorly
- Surrounded by the rectus sheath (created by the aponeurosis of the external oblique, internal oblique, transversus abdominis)
Rectus Abdominis Muscle: Origin & Insertion
- Origin: pubic symphysis, pubic crest
- Insertion: xiphoid process, costal cartilages of ribs 5-7
Rectus Abdominis Muscle: Innervation
- Thoracoabdominal Nerves (T6-T11)
- Subcostal N
Rectus Abdominis Muscle: Action
- Flexes trunk (lumbar vertebrae)
- Compresses abdominal contents
- Aids in pelvic stabilization
Tendinous Intersections
- Horizontal tendons amongst rectus abdominis muscle – break it into smaller sections
- Create 6 pack appearance of muscle
Tendinous Intersections fuse with the:
Anterior Rectus Sheath
Pyramidalis Muscle
- Small, triangular-shaped muscle lying anterior to the rectus abdominis muscle (under the rectus sheath)
- Runs from the pubic crest (widest point) and inserts into the Linea Alba
Pyramidalis Muscle: Action
Tenses the Linea Alba
Pyramidalis Muscle: Innervation
Subcostal Nerve
What structure is absent in 20% of the population?
Pyramidalis Muscle
Rectus Sheath
- Fibrous structure made out of the aponeuroses of the anterolateral abdominal wall muscles (external and internal oblique, and transversus abdominis muscles)
Rectus Sheath incompletely surrounds the:
- Rectus Abdominis
- Pyramidalis
- Superior & Inferior Epigastric vessels
- Lymphatics
- Distal portions of the Thoracoabdominal nerves
Above the Umbilicus, the External Oblique Aponeurosis is the:
- Most superficial to the Rectus Abdominis Muscle
- Creates outer layer of rectus sheath
Above the Umbilicus, the Internal Oblique Aponeurosis:
- Splits – part of the aponeurosis is superficial to the Rectus abdominis muscle and the other part goes posterior to the rectus abdominis muscle
Above the Umbilicus, the Transversus Abdominis Muscle creates the:
Deepest part of the rectus sheath behind the rectus abdominis muscle
Arcuate Line
- Crescent shaped line that demarcates the switch in the pattern of how the rectus sheath is created
- Located below the umbilicus
Below the Arcuate Line, all anterolateral muscle aponeuroses move:
Anterior to the Rectus Abdominis
Below the Arcuate Line, the only thing posterior to the Rectus Abdominis is the:
Transversalis Fascia (the deepest layer of the abdominal wall before the peritoneum)
Is the abdominal wall more translucent above or below the Arcuate Line?
Wall is more translucent below the line than above the Arcuate Line
Psoas Major Muscle
- Long, thick muscle located lateral to the lumbar vertebrae
- Runs under the inguinal ligament to insert onto the femur (lesser trochanter)
- Joins with the Iliacus muscle to form the Iliopsoas muscle
- Lumbar plexus is intimately associated with this muscle
What nerve pierces the Psoas Major Muscle belly?
Genitofemoral Nerve
Psoas Major Muscle: Origin & Insertion
- Origin: T12, Lumbar vertebrae (body and transverse processes)
- Insertion: Lesser Trochanter of the femur
Psoas Major Muscle: Innervation
Muscular branches of Lumbar Plexus (L2-L4)
Psoas Major Muscle: Action
- Alone: Helps in laterally flexing the vertebral column, helps balance the trunk
- With the Iliacus: flexes the thigh
Psoas Minor Muscle
- Lies on top of the psoas major
- May not be present in all people
- Medial Arcuate Ligament of the diaphragm is located near its superior aspect
Psoas Minor Muscle: Origin & Insertion
- Origin: T12 and L1
- Insertion: Pubis’s Iliopectineal eminence and Pectineal Line
Psoas Minor Muscle: Action
- Laterally flexes the vertebral column
- Balances the trunk
Psoas Minor Muscle: Innervation
Muscular branches of Lumbar Plexus (L1-L2)
Iliacus Muscle
- Triangular-shaped muscle on the lateral abdominal (upper pelvic) wall
- Runs with the Psoas Major out of the abdomen and inserts onto the femur
Iliacus Muscle: Origin & Insertion
- Origin: Superior Iliac Fossa, Sacrum, Anterior Sacroiliac Ligament
- Insertion: Lesser Trochanter of the Femur, Femoral Shaft
Iliacus Muscle: Innervation
Femoral N