Class 6 Flashcards
What are the regions of the abdomen?
• abdomen is area between diaphragm & pelvis
• abdomen typically divided into 4 quadrants
• dividing lines are based on mid-sagittal plane & transumbilical plane (transverse plane passing through umbilicus or belly button)
• the quadrants are:
RUQ: right upper quadrant
LUQ: left upper quadrant
RLQ: right lower quadrant
LLQ: left lower quadrant
Muscles of the abdomen anteriorly, they are…
• rectus abdominis
• external oblique
• internal oblique
• transversus abdominis
Muscles of the abdomen posteriorly, they are…
• psoas major
• quadratus lumborum
What are the attachments of Rectus Abdominis?
• superior attachment: costal cartilages of ribs 5-7, xiphoid process
• inferior attachment: pubic symphysis & pubic crest
• right & left sides separated by linea alba
What are the actions of Rectus Abdominis?
• action: flexes vertebral column (trunk)
• action: stabilizes pelvis during leg-lowering
• action: compresses viscera
Where is the External Oblique muscle & what is the fibre direction?
• most superficial
• superior/lateral attachment: ribs 5 – 12
• inferior/medial attachment: linea alba (via abdominal aponeurosis), pubic
tubercle, anterior ½ of iliac crest
• fibre direction: anteriorly & inferomedially
What are the actions of External Oblique muscle?
• action (unilateral contraction): rotates column to contralateral side
• action (unilateral contraction): ipsilateral lateral flexion
• action (bilateral contraction): trunk flexion
• action (bilateral contraction): stabilizes pelvis during leg-lowering
• action (bilateral contraction): compress & support viscera
Where is the Internal Oblique muscle & what is the fibre direction?
• inferior/lateral attachment: anterior ½ of iliac crest
• superior/medial attachment: linea alba (via abdominal aponeurosis), ribs 10-12
(inferior borders)
• deep to external oblique
• fibre direction: anteriorly & superomedially
What are the actions of Internal Oblique muscle?
• action (unilateral contraction): rotates column to ipsilateral side
• action (unilateral contraction): ipsilateral lateral flexion
• action (bilateral contraction): trunk flexion
• action: (bilateral contraction): stabilizes pelvis during leg lowering
• action (bilateral contraction): compress & support viscera
What is the Cremaster muscle?
• Cremaster muscle is an expansion of internal obliques
• Only developed in biological males.
• Contraction of muscle raises the testes.
• Light stroking on medial thigh can initiate cremaster reflex
What are the attachments and fiber direction of Transversus Abdominis?
• lateral attachment: inner iliac crest, lower 6 costal cartilages, thoracolumbar fascia
• medial attachment: linea alba (via abdominal aponeurosis)
• deep to internal oblique
• fibre direction: medial - late
What is the action of Transversus Abdominis?
• action (bilateral contraction): compress & support viscera
What are key features of the anterior wall of the abdomen?
• External obliques, internal obliques, & transversus abdominis overlap/cross each other in such a way that they protect & strengthen the abdominal wall
• they contract to compress the abdominal contents
• organs of upper thorax are protected by rib cage, while viscera of lower thorax rely on the 4 abdominal muscles for support & protection. The 4 abdominal muscles wrap the entire abdomen in vertical, horizontal, and diagonal directions.
What are the fascia of the abdomen?
• The rectus sheath
• The linea alba
• The linea semilunaris
What is the rectus sheath?
• Aponeurotic attachments of external oblique, internal oblique & transversus abdominis form a sheath of connective tissue which encases rectus abdominis muscle
• medially, they reconnect to form linea alba
What is the linea alba?
• runs vertically from xiphoid process to symphysis pubis
• 2 rectus abdominis muscles are separated by linea alba