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
What is the linea semilunaris?
• lateral border of rectus abdominis & its sheath
What are the attachments of Quadratus Lumborum (QL)?
• superior attachment: medial ½ of rib 12, TVPs of lumbar vertebrae
• inferior attachment: iliac crest, iliolumbar ligament
What are the actions of Quadratus lumborum (QL)?
• action (bilateral contraction): extends lumbar spine
• action (bilateral contraction): fixes 12th rib during forced expiration
• action (bilateral contraction): stabilizes lumbar spine
• action (unilateral contraction): ipsilateral lateral flexion or ‘hip hike’
What are the Intercostalsmuscles?
• arranged in 3 layers in spaces between adjacent ribs (intercostal space)
• from superficial to deep: external, internal, innermost
• each group (external, internal, innermost) has 11 pairs of muscles
• external intercostals (superior att. fixed)
• superior attachment: ribs 1-11
• inferior attachment: ribs 2-12
What are the Internal Intercostals?
• superior attachment: ribs 1-11
• inferior attachment: ribs 2-12 (inferior att. fixed)
• fibre direction: (right angles (90o) to the external intercostals
What are the Innermost Intercostals?
• same as internal intercostals
• separated from internal intercostals by neurovascular bundle
What are the actions of the Intercostals?
• external intercostals: quiet & forced inspiration (through elevation of the ribs)
• internal/innermost intercostals: forced expiration
• all intercostals: keep intercostal spaces rigid
What are the attachments of Levator Costarum?
• 12 pairs
• superior attachment: TVPs of C7-T11
• inferior attachment: ribs (immediately inferior)
What are the actions of Levator Costarum?
• action: elevate the ribs during inspiration
What are the attachments of Subclavius?
• medial attachment: 1st rib & its costal cartilage
• lateral attachment: middle 1/3rd of inferior surface of clavicle
What are the actions of Subclavius?
• action: anchors, depresses and draws the clavicle medially
What is the thoracic diaphragm?
• principle muscle of respiration
• dome-shaped muscle that divides thoracic cavity & abdominal cavity
• pierced by structures passing between thorax & abdomen
• top of dome sits at approximately 4th intercostal space (during expiration) & 6th intercostal space (during inspiration)
• divided into muscular component & tendinous component
Thoracic diaphragm (Muscular Component) the muscle attaches inferiorly onto the…
• posterior surface of xiphoid
• internal surfaces of lower 6 ribs (& costal cartilages)
• upper lumbar vertebrae via 2 muscular crura
• medial arcuate ligaments (upper lumbar vertebral bodies to TVPs – travels over psoas)
• lateral arcuate ligaments (L1 TVP to 12th rib – travels over QL)
What is the Central Tendon (thoracic diaphragm)?
• muscular fibres converge radially into strong aponeurotic tendon called central tendon
• has C-shaped appearance with a central, left & right ‘leaflet’
What is the action & innervation of the diaphragm?
Action:
• with contraction, the diaphragm moves inferiorly so that it is flattened
Innervation:
• phrenic nerve (C3, 4, 5)
• C3, C4, C5 keep the diaphragm alive
What is inspiration?
• contraction of diaphragm causes inferior movement of central tendon
• as it flattens it increases vertical dimension of thoracic cavity (increased thoracic volume)
• inspiration is assisted by contraction of intercostals
• ribs are raised & moved laterally which increases transverse dimension of thorax (increased thoracic volume)
• this is called “bucket-handle movement”
• as the ribs are raised, anterior parts of ribs & sternum move anteriorly which increases anterior-posterior dimension of the thorax (increased thoracic
volume) – this is called pump-handle movement
• these increases in vertical, transverse, and AP dimensions create negative pressure in lungs which results in air being drawn in (inspiration)
• this same contraction decreases vertical dimension of abdomen & increases pressure
• is important for normal blood and lymphatic circulation
• summary: with inspiration, thoracic volume increases which decreases thoracic
pressure AND the abdominal volume decreases which increases abdominal
pressure
What is the the pump-handle movement?
• as the ribs are raised, anterior parts of ribs & sternum move anteriorly which increases anterior-posterior dimension of the thorax (increased thoracic
volume) – this is called pump-handle movement
What is “bucket-handle movement”?
• contraction of diaphragm causes inferior movement of central tendon
• as it flattens it increases vertical dimension of thoracic cavity (increased thoracic volume)
• inspiration is assisted by contraction of intercostals
• ribs are raised & moved laterally which increases transverse dimension of thorax (increased thoracic volume)
• this is called “bucket-handle movement”
What is Expiration?
• diaphragm relaxes & moves superiorly
• this, with elastic recoil of lungs decreases thoracic volume & increases thoracic pressure
• air flows out
• normally, this is a passive process
What is Apical Breathing?
• diaphragm remains relatively relaxed
• accessory muscles of respiration lift chest up & out
• this is an inefficient means of respiration
Singultus = _______________
hiccup
What is the Perineum?
• region below pelvic cavity
• floor: skin
• roof: pelvic diaphragm
What are the muscles of the Pelvic Diaphragm?
• levator ani muscles (two)
• coccygeus muscles (two)
What are attachments of levator ani?
• anterior attachment: back of pubis, spine of ischium
• posterior attachment: anococcygeal ligament, lower sacrum & coccyx
What are attachments of coccygeus?
• lateral attachment: pelvic surface of ischial spine & sacrospinous ligament
• medial attachment: lateral margin of coccyx & S5
What are the actions of the pelvic diaphragm?
supports pelvic viscera, helps maintain control of
bodily functions
