Body Walls Flashcards by Fares Ahmed

Thoracic wall boundaries

Anterior: sternum and costal cartilage
Posterior: vertebral column
Lateral: ribs and intercostal spaces

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Thoracic cage superior appreture

Posteriorly: body of first thoracic vertebra
Anteriorly: manubrium
Medial margin of first rib on each side

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Thoracic inferior appreture

Closed by diaphragm
Posteriorly: body if the 12th vertebra
Anteriorly: Xiphoid process
Posterio-lateral: 12th rib and distal end of 11th rib
Anterio-lateral: Distal cartilaginous ends of ribs 7 to 10

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External intercostal muscle 
Origin
Insertion
Direction 
Extension
Action

Inferior margin of the ribs above
Superior margin of the rib below
Fibres run obliquley anteroinferiorly (downward and forward)
from the tubercles of the ribs to the costal cartilage then continues as external intercostal membrane
Most active during inspiration

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Internal intercostal muscle 
Origin
Insertion
Direction 
Extension
Action

Inferior lateral edge of the costal groove of rib above
Superior margin of the rib below
Fibres pass obliquely posterioinferiorly (downward and to the back)
From the parasternal region to the angle of the ribs where it continues as internal intercostal membrane
Mostly active during forced respiration

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Sternocostalis muscle
Origin
Insertion
Direction

Lower 1/3 of posterior surface of the body of the sternum and the xiphoid process
To the lower border of the 2nd to the 6th (3rd to 6th) costal cartilage
Pass superiorly and laterally

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Subcostalis muscle
Origin
Insertion
Extension

From inner surface of the rib above
to the superior surface of the 2nd or 3rd rib below
Lies in the inner aspect of the posterior thoracic wall medial to the angle of ribs

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Intercostalis intimis muscle 
Origin
Insertion
Direction 
Action

From inner surface of the rib above
to the superior surface of the 2nd or 3rd rib below
Pass posterioinferiorly
Exporation

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Posterior intercostal arteries

1st and 2nd arteries origin is from the supeior intercostal artery which arise from the costo-cervical trunk of the sub-clavian artey
The remaining 9 posterior intercostal arteries arise from the descending aorta

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Internal thoracic artery origin and termination

Origin: A major branch of the sub-clavian artery

Ends at the level of the 6th intercostal space when it divides to musclo-phrenic artery and Superior epigastric artery

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Anterior Intercostal arteries

In the upper 6 spaces arise from the internal thoracic artery
In the 7th,8th and 9th space, it arise from the musculo-phrenic artery
In the 10th and 11th space there is no anterior intercostal arteries

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Venous drainage of the posterior and anterior

Posterior thoracic veins drain into the azygos and hemiazygous veins
Anterior thoracic arteries drain into the musculo-phrenic and internal thoracic veins

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Nerve supply of the thoracic wall (generally)

Innervation of the thoracic wall is mainly by the intercostal nerves which are the anterior rami of spibal nerves T1 to T11. The anterior ramus of T12 is called the subcostal nerve

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Typical intercostal nerves

From 3rd to the 6th

The intercostal nerve gives a lateral and anterior cutaneous branches to supply the skin above the intercostal space

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Atypical intercostal nerves

Anterior ramus of T1 contributes to the brachial plexus to supply the upper limb
Lateral cutaneous branch of T2 (intercostobrachial) contributes to the innervation of the medial surface of the upper arm
Lower 5 intercostal nerve supply muscles, skin and peritoneum of the abdominal wall

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Superficial fascia divisions in the anterior abdominal wall

Above the umbilicus it is one layer
Below the umbilicus it differentiates into:
-Superficial fatty layer (Camper’s fascia)
- Deep membranous layer (Scarpa’s fascia) loosely attacted to the aponeurosis of the external oblique muscles

External Oblique Muscle
Origin
Insertion
Direction

It arises by 8 fleshy digitations from the outer surfaces of the lower 8 ribs
It inserts into -the anterior half of the outer lip of the iliac crest
-The pubic crest
-the pubic tubercle
-Xiphoid process
-Linea alba
Muscle fibres run downward, forward medially and fan out

Inguinal ligament attatchment

The lower part of the aponeurosis of the external oblique muscle is attatched laterally to the ASIS (anterior superior iliac spine) and medially to the pubic crest and tubercle It folds back on itself to form the inguinal liagment

Internal Oblique Muscle
Origin
Insertion
Direction

It arises from : Lumbar fascia, the anterior 2/3 of the intermediate area of the iliac crest and the lateral 2/3 of the upper surface of the inguinal liagment
It is inserted into the lower border of the 7th,8th and 9th costal cartilage, middle part is split into 2 laminaae which enclose the rectus abdominis and form the linea alba and main part of the rectus sheath
Most lower part arches upwards, medially and downwards to be inserted into the pubic crest

Conjoint tendon

Lower part of the internal oblique muscle arches upwards medially and downwards to be inserted into the pubic crest and the pectineal line forming the conjoint tendon

Cremastric muscle

Formed by a series of loops which descend to form a sac like fibres around the spermatic cord and the testis

Transversus abdominis muscle
Origin
Direction
Insertion

Inner surface of lower 6 costal cartilages, lumbar fascia, anterior 2/3 of the inner lip of the iliac crest and the lateral 1/3 of the inguinal ligament
Most fibres run medially in transverse direction
It is inserted by broad aponeurosis into the Xiphoid process, linea alba and the lowermost part joins the conjoint tendo to be inserted in the pubic crest and pectenial line

Rectus Abdominis Muscle
Origin
Insertion

It arises by 2 heads: Laterally, the pubic creast and medially the anterior pubic ligament
It is inserted by fleshy digitations into the xiphoid process and the 5th, 6th and 7th costal cartilages

Pyrimidalis Muscle
Origin
Insertion

Originates by attatchment of its base from the front of the symphysis pubis
Inserts by its apex into the linea alba midway between the umbilicus and the symphysis pubis

Rectus sheath contents

Rectus abdominis Pyrimidalis Lower 5 intercostal nerves and the subcostal nerve Superior and inferior epigastic arteries

Nerve supply of anterior abdominal wall muscles

The oblique and transversus abdominis muscles: By the lower 6 intercostal nerves and the L1 branches (Iliohypogastric and ilioinguinal nerves) The rectus abdominis muscle: By the lower 6 intercostal nerves The pyrimidalis muscle: By the Subcostal nerve (T12)

Arteries of the anterior abdominal wall and what they supply

- Superior epigastric artery: Arise from the internal thoracic artery and enters the rectus sheath to supply the upper central part of the abdominal walls - Inferior epigastric artery: It is a brach of the external iliac artery. It supplies the lower central part of the abdominal walls - Deep circumflex artery: It arises from the external iliac artery which runs upwards and laterally to supply lower lateral part of abdominal wall - Lateral part of the abdominal wall is supplied by the lower 2 thoracic arteries nd the 4 lumbar arteries arising form the posterior part of the descending aorta

Superficial veins of the anterior abdominal wall

Above umbilicus: The netwrok is drained into the axilary vein through the lateral thoracic vein Below umbilicus: The network is drained into the femoral veins via the superficial epigastric and great saphenous veins Around umbilicus: The paraumbilical veins connect the netwrok through the umbilicus and along ligamentum teres to the portal vein

Deep veins of the anterior abdominal wall

Superior epigastric vein, inferior epigastric vein and the deep circumflex iliac vein drain into the internal thoracic vein and the external iliac vein The posterior intercostal veins drain into the azygous The lumbar veins drain directly into the inferior vena cava

Inguinal canal definition and length

It is an oblique inter-muscular passage through the lower part of the abdominal wall It is 4cm in length

Superficial inguinal ring | Site, shape, formed from?

In the external oblique aponeurosis above and medial to the pubic tubercle Triangle in shape Fromed from the external oblique aponeurosis

Deep inguinal ring | Site, shape, formed from and its relations?

About 1/2 inch above the inguinal ligament at the mid-inguinal point Oval in shape Fromed from fascia transversalis Medial to it passes the inferior epigastric artery

Walls of the inguinal canal

Anterior wall: Aponeurosis of the external oblique muscle and internal oblique along its lateral 1/3 Posterior wall: Fascia transversalis along its whole length and conjoint tendon along its medial 1/2 Roof: By the arching fibers of the conjoint tendon Floor: Formed by the upper grooved surface of the inguinal ligament

Inguinal (Hasselbach's) triangle boundaries

Medially: Lateral border of the rectus abdominis Laterally: Inferior epigastric artery Inferiorly: medial 1/2 of the inguinal ligament Floor: Parietal perioneium and fascia transversalis

Psoas major Origin Insertion Nerve supply

From vertebral bodies of T12 to L5 Inserts into the lesser trochanter of the femur Branches of the lumbar plexus (L2-4)

Psoas minor Origin Insertion

Sides of T12 and L1 vertebra | Inserts into the iliopectenial eminence of the hip bone

Quadratus lamborum Origin Insertion Nerve supply

Iliolumbar ligament and adjoining part of iliac crest Inserts into the lower border of the12th rib and the tip of the transverse processes of upper 4 lumbar vertebrae Supplied by T12 and L1 to L4 (Lumbar plexus)

Iliacus muscle Origin Insertion Nerve supply

Iliac fossa of hip bone Joins the psoas major to form the iliopsoas tendon which inserts into the lesser trochanter of the femur Innervated by the femoral nerve (L2,3,4)