Body Wall Flashcards
Body Wall
Refers to the external surface of the organism
What is the body wall derived from?
Ectoderm and mesoderm surrounding the dorsal and ventral body cavities
The body wall is subdivided into what regions?
Thoracic and abdominal body wall
Intercostal muscles
Muscles that occupy the intercostal spaces
What are the 3 groups of intercostal muscles? What is their function?
External
Internal
Innermost
Elevates and depresses the ribs
Diaphragm
The chief respiratory muscle
External
Elevate rib cage
Internal
Depress rib cage
Innermost
Discontinuous- Expiratory, decrease volume of the rib cage, and weak
What does the external layer do during forced inspiration?
Stabilizes ribs, and elevates the ribs
What do the internal and innermost layers do during forced expiration?
Stabilize ribs, and different parts depress and elevate ribs
Serratus Posterior Superior
Elevates ribs, mostly proprioceptive in function
Serratus Posterior Inferior
Depresses ribs, mostly proprioceptive in function
What upper limb muscles are responsible for moving the scapula and humerus? What are they all innervated by?
Pectoralis major, pectorals minor, and serrates anterior, they’re all innervated by branches of the brachial plexus
What 4 muscles flex the vertebral column and compress abdominal contents?
External oblique
Internal oblique
Transversus abdominis
Rectus abdominis
Superficial Layers of the Abdominal Body Wall
Skin
Subcutaneous tissue
- Camper’s fascia, fatty
- Scarpa’s fascia, membranous
Deep Layers of the Abdominal Body Wall
Muscles enclosed in investing fascia
Transversalis fascia- situated deep to abdominal muscles
Extraperitoneal fat- variable amount
Parietal peritoneum
External oblique (2)
Fibers run supero-medially
Flexes and rotates the trunk; works with internal oblique
Internal oblique (2)
Fibers run perpendicular to those of external oblique
Flexes and rotates the trunk; works with external oblique
Transversus Abdominus (2)
Fibers run horizontally
No skeletal movement
Horizontal orientation does not permit flexion or lateral bending
Primarily raises intra-abdominal pressure
Rectus Abdominis (2)
Paired muscles separated by linea alba
Attachments on pubic symphysis inferiorly and xiphoid process and costal cartilages 5-7 superiorly
Contained within rectus sheath = fused aponeuroses of 3 flat abdominal muscles
Arcuate line
Abrupt termination of posterior rectus sheath
Inferiorly, where does the rectus abdominis lie directly on?
Transversalis fascia
What is the function of the sheath?
Encloses the rectus abdominis muscle, and heavily assists in the compression of viscera by compound the contraction of the rectus muscle
Abdominal Muscle Functions
Support abdominopelvic contents
Protect abdominal viscera
Compress viscera to maintain or increase intra-abdominal pressure (assisting diaphragm)
Generate force necessary for defecation, micturition, vomiting, and parturition
Produce anterior and lateral flexion + rotation of the trunk; help with posture maintenance
Inguinal Canal
Passage formed in relation to gonadal descent during fetal development
Where does the inguinal canal extend from?
The deep inguinal ring (entrance) to superficial inguinal ring (exit)
What is the deep ring formed by?
An evagination of transversals fascia
Superficial Ring
External oblique aponeurosis
Contents of Inguinal Canal
Spermatic cord in males/ round ligament of uterus in females, blood and lymphatic vessels, and ilioinguinal nerve
What is crucial for understanding the inguinal canal?
Fetal development and gonadal relocation
Gonads in both sexes originate where?
The dorsal body wall of lumbar region
The testes must pass through what?
Body wall via the inguinal canal to the scrotum, which is guided by a gubernaculum
Where do testes descend from?
Behind an evagination of peritoneum: Processus vaginalis
What is guided by its gubernaculum in females?
Ovaries which descend during fetal development
What does the gubernaculum become in females?
A round ligament of uterus and ovarian ligament
What does the female inguinal canal contain?
A round ligament of uterus + ilioinguinal nerve
Hernia
A protrusion of abdominal contents out of abdominal cavity through a weak point in muscles of abdominal wall
What are the most commonly herniated elements?
Parietal peritoneum
Parts of small intestine
Greater omentum
What are the typical sites for hernias to develop?
Inguinal (above inguinal ligament)
Femoral (femoral canal)
Diaphragmatic
Lumbar (lumbar triangle)
Umbilical (omphalocele)
What is the frequency for indirect (congenital) inguinal hernia’s?
more common (2/3 to 3/4 of inguinal hernias)
What is the frequency for direct (acquired) inguinal hernia’s?
Less common (1/3 to 1/4 of inguinal hernias)
Where are the breasts located?
Situated superficially to the underlying skeletal muscle
Nipple
Opening in the body wall through which milk is excreted
Areola
Pigmented skin surrounding the nipple
Suspensory ligaments
CT that run from the underlying skeletal muscle to the overlying skin and support the breasts (breast tissue)
Lobules
Tissue composed of simple cuboidal epithelial, milk secreting cells
Lactiferous ducts
Milk passes from alveoli in the lobules thru larger and larger ducts until it reaches the lactiferous ducts
Lactiferous Sinus
Milk accumulates here during nursing
Scrotum
An out pouching of the body wall with the same layers (just renamed)
Layers of the scrotum
Skin
Dartos Muscle and Fascia
External spermatic fascia
Cremasteric muscle and fascia
Internal spermatic fascia
Tunica vaginalis
Tunia albuginea
How does the scrotum develop?
From an embryological feature called the labioscrotal swelling
Dartos muscle
Corrugates and wrinkles the skin of the scrotum
Cremaster muscle
Elevates the testes, the testes relax and move away from the body when hot and move closer to the body when cold
