Class 6

Question 1

What are the regions of the abdomen?

Answer 1

• 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

Question 2

Muscles of the abdomen anteriorly, they are…

Answer 2

• rectus abdominis
• external oblique
• internal oblique
• transversus abdominis

Question 3

Muscles of the abdomen posteriorly, they are…

Answer 3

• psoas major
• quadratus lumborum

Question 4

What are the attachments of Rectus Abdominis?

Answer 4

• superior attachment: costal cartilages of ribs 5-7, xiphoid process
• inferior attachment: pubic symphysis & pubic crest
• right & left sides separated by linea alba

Question 5

What are the actions of Rectus Abdominis?

Answer 5

• action: flexes vertebral column (trunk)
• action: stabilizes pelvis during leg-lowering
• action: compresses viscera

Question 6

Where is the External Oblique muscle & what is the fibre direction?

Answer 6

• 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

Question 7

What are the actions of External Oblique muscle?

Answer 7

• 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

Question 8

Where is the Internal Oblique muscle & what is the fibre direction?

Answer 8

• 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

Question 9

What are the actions of Internal Oblique muscle?

Answer 9

• 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

Question 10

What is the Cremaster muscle?

Answer 10

• 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

Question 11

What are the attachments and fiber direction of Transversus Abdominis?

Answer 11

• 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

Question 12

What is the action of Transversus Abdominis?

Answer 12

• action (bilateral contraction): compress & support viscera

Question 13

What are key features of the anterior wall of the abdomen?

Answer 13

• 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.

Question 14

What are the fascia of the abdomen?

Answer 14

• The rectus sheath
• The linea alba
• The linea semilunaris

Question 15

What is the rectus sheath?

Answer 15

• 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

Question 16

What is the linea alba?

Answer 16

• runs vertically from xiphoid process to symphysis pubis
• 2 rectus abdominis muscles are separated by linea alba

Question 17

What is the linea semilunaris?

Answer 17

• lateral border of rectus abdominis & its sheath

Question 18

What are the attachments of Quadratus Lumborum (QL)?

Answer 18

• superior attachment: medial ½ of rib 12, TVPs of lumbar vertebrae
• inferior attachment: iliac crest, iliolumbar ligament

Question 19

What are the actions of Quadratus lumborum (QL)?

Answer 19

• 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’

Question 20

What are the Intercostalsmuscles?

Answer 20

• 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

Question 21

What are the Internal Intercostals?

Answer 21

• superior attachment: ribs 1-11
• inferior attachment: ribs 2-12 (inferior att. fixed)
• fibre direction: (right angles (90o) to the external intercostals

Question 22

What are the Innermost Intercostals?

Answer 22

• same as internal intercostals
• separated from internal intercostals by neurovascular bundle

Question 23

What are the actions of the Intercostals?

Answer 23

• external intercostals: quiet & forced inspiration (through elevation of the ribs)
• internal/innermost intercostals: forced expiration
• all intercostals: keep intercostal spaces rigid

Question 24

What are the attachments of Levator Costarum?

Answer 24

• 12 pairs
• superior attachment: TVPs of C7-T11
• inferior attachment: ribs (immediately inferior)

Question 25

What are the actions of Levator Costarum?

Answer 25

• action: elevate the ribs during inspiration

Question 26

What are the attachments of Subclavius?

Answer 26

• medial attachment: 1st rib & its costal cartilage • lateral attachment: middle 1/3rd of inferior surface of clavicle

Question 27

What are the actions of Subclavius?

Answer 27

• action: anchors, depresses and draws the clavicle medially

Question 28

What is the thoracic diaphragm?

Answer 28

• 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

Question 29

Thoracic diaphragm (Muscular Component) the muscle attaches inferiorly onto the…

Answer 29

• 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)

Question 30

What is the Central Tendon (thoracic diaphragm)?

Answer 30

• muscular fibres converge radially into strong aponeurotic tendon called central tendon • has C-shaped appearance with a central, left & right ‘leaflet’

Question 31

What is the action & innervation of the diaphragm?

Answer 31

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

Question 32

What is inspiration?

Answer 32

• 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

Question 33

What is the the pump-handle movement?

Answer 33

• 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

Question 34

What is “bucket-handle movement”?

Answer 34

• 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”

Question 35

What is Expiration?

Answer 35

• 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

Question 36

What is Apical Breathing?

Answer 36

• diaphragm remains relatively relaxed • accessory muscles of respiration lift chest up & out • this is an inefficient means of respiration

Question 37

Singultus = _______________

Answer 37

hiccup

Question 38

What is the Perineum?

Answer 38

• region below pelvic cavity • floor: skin • roof: pelvic diaphragm

Question 39

What are the muscles of the Pelvic Diaphragm?

Answer 39

• levator ani muscles (two) • coccygeus muscles (two)

Question 40

What are attachments of levator ani?

Answer 40

• anterior attachment: back of pubis, spine of ischium • posterior attachment: anococcygeal ligament, lower sacrum & coccyx

Question 41

What are attachments of coccygeus?

Answer 41

• lateral attachment: pelvic surface of ischial spine & sacrospinous ligament • medial attachment: lateral margin of coccyx & S5

Question 42

What are the actions of the pelvic diaphragm?

Answer 42

supports pelvic viscera, helps maintain control of bodily functions