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Anterior Abdominal Wall: Anatomy

The anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen is anatomically delineated as a hexagonal area defined superiorly by the xiphoid process Xiphoid process Chest Wall: Anatomy, laterally by the midaxillary lines, and inferiorly by the pubic symphysis Pubic Symphysis A slightly movable cartilaginous joint which occurs between the pubic bones. Vagina, Vulva, and Pelvic Floor: Anatomy. From the superficial to deep order, the anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen consists of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, subcutaneous tissue Subcutaneous tissue Loose connective tissue lying under the dermis, which binds skin loosely to subjacent tissues. It may contain a pad of adipocytes, which vary in number according to the area of the body and vary in size according to the nutritional state. Soft Tissue Abscess, muscle, transversalis fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis, and peritoneum Peritoneum The peritoneum is a serous membrane lining the abdominopelvic cavity. This lining is formed by connective tissue and originates from the mesoderm. The membrane lines both the abdominal walls (as parietal peritoneum) and all of the visceral organs (as visceral peritoneum). Peritoneum: Anatomy. The lateral abdominal muscles include the external and internal obliques and the transversus abdominis. Anterior abdominal muscles include the rectus abdominis and pyramidalis muscles. The abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen is primarily supplied by epigastric arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology and innervated by thoracoabdominal nerves.

Last updated: 9 Mar, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Introduction

Surface landmarks

Abdominal planes

The abdomen can be divided into 4 quadrants with the transverse and sagittal Sagittal Computed Tomography (CT) planes.

  • Transverse (transumbilical) plane: crosses the abdomen at the level of the umbilicus
  • Sagittal Sagittal Computed Tomography (CT) (vertical) plane: crosses the body at the level of the umbilicus
  • The intersection of these 2 planes defines 4 quadrants:
    • RUQ
    • LUQ
    • RLQ
    • LLQ

The abdomen can also be divided into 9 regions using the following planes:

  • Midclavicular planes: vertical planes extending from the midclavicular lines to the midinguinal points
  • Upper horizontal (subcostal) plane: inferior to the costal margin at the level of L3
  • Lower horizontal (transtubercular) plane: courses between the 2 tubercles of the iliac crest at the level of L5
  • The planes define 9 regions:
    • On the left and right sides (superior to inferior):
      • Hypochondrium
      • Lateral abdominal region
      • Inguinal region
    • Centrally (superior to inferior):
The 9 regions of the abdomen

The 9 regions of the abdomen created by the vertical midclavicular and horizontal subcostal and transtubercular planes:
Note that the hypochondrium, lateral abdominal region, and inguinal region are present on both the left and right sides of the abdomen.

Image by Lecturio.

Muscles

Layers of the abdomen

The layers of the anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen from superficial to deep are:

  • Skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions
  • Superficial fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis:
    • External layer of adipose tissue Adipose tissue Adipose tissue is a specialized type of connective tissue that has both structural and highly complex metabolic functions, including energy storage, glucose homeostasis, and a multitude of endocrine capabilities. There are three types of adipose tissue, white adipose tissue, brown adipose tissue, and beige or “brite” adipose tissue, which is a transitional form. Adipose Tissue: Histology (Camper fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis):
      • Contains superficial epigastric veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology that drain the anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen
      • Superficial epigastric veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology drain into the femoral and paraumbilical veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology.
    • Internal layer of dense connective tissue Dense connective tissue Connective Tissue: Histology (Scarpa fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis)
  • Muscles:
    • Lateral abdominal muscles:
      • External oblique
      • Internal oblique
      • Transversus abdominis
    • Anterior abdominal muscles:
      • Rectus abdominis
      • Pyramidalis muscle
  • Transversalis fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis
  • Extraperitoneal fat
  • Peritoneum Peritoneum The peritoneum is a serous membrane lining the abdominopelvic cavity. This lining is formed by connective tissue and originates from the mesoderm. The membrane lines both the abdominal walls (as parietal peritoneum) and all of the visceral organs (as visceral peritoneum). Peritoneum: Anatomy
Layers of anterolateral abdominal wall

Layers of the anterolateral abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen

Image by Lecturio.

Lateral abdominal muscles

External oblique:

  • Origin: outer surface of ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy 5–12
  • Insertion: linea alba (rectus sheath), pubic tubercle, and iliac crest
  • Nerve supply:
    • Intercostal nerves (T7–T11)
    • Subcostal nerve (T12)
    • Iliohypogastric nerve
  • Action:
External oblique muscle

External oblique muscle

Image by BioDigital, edited by Lecturio

Internal oblique:

Internal oblique muscle

Internal oblique muscle

Image by BioDigital, edited by Lecturio

Transversus abdominis:

  • Deepest of the 3 lateral abdominal muscles
  • Fibers run horizontally.
  • Transversalis fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis lies underneath the transversus abdominis.
  • Origin: inner surface of costal cartilages of ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy 7–12, iliac crest, thoracolumbar fascia Thoracolumbar fascia Posterior Abdominal Wall: Anatomy, and lateral 3rd of the inguinal ligament Inguinal Ligament Femoral Region and Hernias: Anatomy
  • Insertion: linea alba (rectus sheath)
  • Nerve supply:
    • Intercostal nerves (T7–T11)
    • Subcostal nerve (T12)
  • Action:
Transversus abdominis

Transversus abdominis

Image by BioDigital, edited by Lecturio

Anterior abdominal muscles

Rectus abdominis:

  • Pair of long, straight muscles running vertically
  • Left and right parts are separated by the central linea alba.
  • Each muscle consists of 4 parts separated by 3 bands of tendon → tendinous intersections
  • Origin: pubic symphysis Pubic Symphysis A slightly movable cartilaginous joint which occurs between the pubic bones. Vagina, Vulva, and Pelvic Floor: Anatomy and crest
  • Insertion: xiphoid process Xiphoid process Chest Wall: Anatomy and costal cartilage Cartilage Cartilage is a type of connective tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Perichondrium (connective tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. Cartilage: Histology of ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy 5–7
  • Nerve supply:
    • Intercostal nerves (T7–T11)
    • Subcostal nerve (T12)
  • Action:
  • Enveloped by the rectus abdominis sheath:
    • Created by the aponeurosis of the 3 lateral abdominal muscles
    • Above the arcuate line, the rectus abdominis is enclosed within the sheath.
    • Below the arcuate line, the sheath is entirely anterior to the muscle, placing the muscle in direct contact with the transversalis fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis.
Rectus abdominis muscle

Rectus abdominis muscle

Image by BioDigital, edited by Lecturio

Pyramidalis muscle:

  • Small muscle contained within the rectus abdominis sheath
  • May be absent in 20% of the population
  • Origin: pubic symphysis Pubic Symphysis A slightly movable cartilaginous joint which occurs between the pubic bones. Vagina, Vulva, and Pelvic Floor: Anatomy and pubic crest
  • Insertion: linea alba
  • Nerve supply: subcostal nerve (T12)
  • Action: tenses linea alba
Pyramidalis muscle

Pyramidalis muscle

Image by BioDigital, edited by Lecturio

Inguinal Canal

The inguinal canals are bilateral canals in the lower lateral anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen that run obliquely and superolaterally to inferomedially. Each inguinal canal Inguinal canal The tunnel in the lower anterior abdominal wall through which the spermatic cord, in the male; round ligament, in the female; nerves; and vessels pass. Its internal end is at the deep inguinal ring and its external end is at the superficial inguinal ring. Inguinal Canal: Anatomy and Hernias has 4 walls and 2 openings (inguinal rings), 1 at each end.

Inguinal canal

Schematic representation of the location of the inguinal canal Inguinal canal The tunnel in the lower anterior abdominal wall through which the spermatic cord, in the male; round ligament, in the female; nerves; and vessels pass. Its internal end is at the deep inguinal ring and its external end is at the superficial inguinal ring. Inguinal Canal: Anatomy and Hernias in the anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen

Image by Lecturio.

Neurovasculature

Arterial supply

The arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology of the anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen are divided into superficial and deep layers.

  • Superficial layer:
    • Musculophrenic artery:
      • Branch of the internal thoracic artery
      • Supplies the superior anterolateral abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen
    • Superficial epigastric artery:
      • Branch of the femoral artery Femoral Artery The main artery of the thigh, a continuation of the external iliac artery. Femoral Region and Hernias: Anatomy
      • Supplies the inferior anterolateral abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen
    • Superficial circumflex iliac artery:
      • Branch of the femoral artery Femoral Artery The main artery of the thigh, a continuation of the external iliac artery. Femoral Region and Hernias: Anatomy
      • Supplies the inferior anterolateral abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen
  • Deep layer:
    • Superior epigastric artery:
      • Direct continuation of the internal thoracic artery
      • Runs inside the rectus sheath behind the rectus muscle
      • Supplies the superior part of the abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen
    • Inferior epigastric artery:
      • Branch of the external iliac artery
      • Courses through the rectus sheath and anastomoses with the superior epigastric artery
      • Supplies the inferior part of the abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen
    • The 10th and 11th intercostal arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology and the subcostal artery supply the lateral abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen.
Arteries of anterior and lateral abdominal wall

Arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology of the anterior and lateral abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen

Image by Lecturio.

Venous drainage

  • Venous drainage follows the arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology of the same name.
  • The superficial veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology around the umbilicus anastomose with the deep veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology through the paraumbilical veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology.

Innervation

  • The skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, abdominal muscles, and peritoneum Peritoneum The peritoneum is a serous membrane lining the abdominopelvic cavity. This lining is formed by connective tissue and originates from the mesoderm. The membrane lines both the abdominal walls (as parietal peritoneum) and all of the visceral organs (as visceral peritoneum). Peritoneum: Anatomy are innervated by:
  • Sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology distribution:
    • Series of transverse dermatomal Dermatomal Dermatologic Examination bands from T7 to L1
    • Skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions around the umbilicus is innervated by T10.
Innervation of abdominal wall

Innervation of the abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen

Image by Lecturio.

Clinical Relevance

  • Inguinal hernias: The superficial and deep inguinal rings represent 2 weak points in the abdominal wall and create a pathway for inguinal hernias. Several risk factors have been implicated in the development of inguinal hernias, including obesity, pregnancy, and aging. Affected individuals will present with a burning sensation or dull ache at the groin, and a mass that may fluctuate in size based on time of the day and preceding activity. Classically, coughing or straining leads to the appearance of the hernia. Treatment is surgical and usually performed on an outpatient basis with excellent results.
  • Caput medusae: a sign of portal hypertension that manifests by the appearance of dilated superficial epigastric veins radiating from the umbilicus. The name caput medusae (Latin for “head of Medusa”) originates from the apparent similarity to Medusa’s head, who, according to Greek Mythology, had venomous snakes instead of hair. Treatment is geared toward controlling portal hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension.
  • Cullen sign: hemorrhagic discoloration and edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions around the umbilicus. A similar finding involving the flank is called Grey Turner sign. Both signs are due to intraperitoneal hemorrhage Intraperitoneal hemorrhage Hepatocellular Carcinoma (HCC) and Liver Metastases due to acute hemorrhagic pancreatitis Pancreatitis Inflammation of the pancreas. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of chronic pancreatitis. The two most common forms of acute pancreatitis are alcoholic pancreatitis and gallstone pancreatitis. Acute Pancreatitis, intra-abdominal trauma, or conditions that lead to hemorrhage into the abdominal cavity. Discoloration of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions is due to blood collection in the subcutaneous fascial planes.

References

  1. Cheuck, L. (2017). Inguinal region anatomy. Medscape. Retrieved September 8, 2021, from https://reference.medscape.com/article/2075362-overview
  2. Flynn, W., Vickerton, P. (2021). Anatomy, Abdomen and Pelvis, Abdominal Wall. StatPearls. Treasure Island (FL). https://pubmed.ncbi.nlm.nih.gov/31869113/
  3. Rather, A.A. (2021). Abdominal hernias. Medscape. Retrieved September 8, 2021, from https://reference.medscape.com/article/189563-overview

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