The container - lesson 20

Trunk

Thoracic cage, vertebral column, and pelvic girdle

Lower limb

Pelvic girdle and femur

Perineum

Inferior external region of the pelvis

Abdominopelvic cavity

Located between the thoracic cavity and perineum; contains the abdominal and pelvic cavities and houses the alimentary and urogenital systems

Inferior thoracic aperture

Superior boundary of the abdominopelvic cavity

Superior anterior aspect of pelvic girdle

Forms part of the boundary of the abdominal cavity

Pelvic inlet

Separates the greater or false pelvis superiorly from the lesser or true pelvis inferiorly

Lesser pelvis

Region between the pelvic inlet and pelvic outlet

Inguinal ligament

Thick fibrous band running from the anterior superior iliac spine to the pubic tubercle

Container boundaries of the abdominopelvic cavity

Resembles a pop can, with the respiratory diaphragm as the roof, pelvic diaphragm as the floor, lumbar vertebrae and posterior abdominal wall posteriorly, and anterolateral abdominal wall anteriorly and laterally

Abdominopelvic wall muscle contraction

Increases intra abdominal pressure to assist forced expiration and expulsion of urine, feces, and fetuses

Abdominopelvic muscles

Important for locomotion and posture

Thoracic cage functions

Protects viscera, supports upper limbs, provides muscle attachment sites, and assists respiration

Sternum

Consists of the manubrium, body, and xiphoid process

True ribs

Ribs 1 to 7; articulate directly with the sternum through their costal cartilages

False ribs

Ribs 8 to 10; articulate indirectly with the sternum through the costal cartilage of rib 7

Floating ribs

Ribs 11 and 12; do not articulate with the sternum

Costal margin

Formed by the joined costal cartilages of ribs 7 to 10

Inferior thoracic aperture boundaries

Anteriorly, xiphisternal joint; anterolaterally, costal margins; posterolaterally, floating ribs; posteriorly, T12 vertebra

Xiphisternal joint

Joint between the xiphoid process and body of the sternum

Lumbar lordosis

Inward curvature of the lumbar vertebral column

Respiratory diaphragm

Muscular roof of the abdominopelvic cavity that closes the inferior thoracic aperture and separates the thoracic and abdominopelvic cavities; attaches to the aperture boundaries and vertebrae

Pelvic girdle

Complete bony ring adapted to support more weight than the pectoral girdle

Bony pelvis

Consists of the hip bones, sacrum, coccyx, and pubic symphysis

Pubic symphysis

Slightly movable cartilaginous joint between the pubic bones; mobility increases during pregnancy

Hip bone

Formed by fusion of the ilium, pubis anteriorly, and ischium posteriorly

Acetabulum

Bowl shaped socket formed by the fused hip bone components that articulates with the head of the femur

Iliac fossa

Depression on the ilium

Anterior superior iliac spine

Prominent projection on the anterior aspect of the ilium

Lesser trochanter

Bony projection on the proximal femur visible in posterior view

Posterior abdominal wall exposure

Requires reflecting the anterolateral abdominal wall and abdominal organs

Psoas major

Travels inferolaterally from the lumbar vertebral bodies and transverse processes to the lesser trochanter as part of the iliopsoas; flexes the hip unilaterally and flexes the trunk when both sides contract with the thighs fixed; innervated by anterior rami of L1 to L3

Iliacus

Arises from the iliac fossa and iliac crest and converges with psoas major to insert on the lesser trochanter; flexes the hip as part of the iliopsoas; innervated by the femoral nerve, L2 to L4

Iliopsoas

Combination of psoas major and iliacus and the strongest hip flexor; unilateral contraction flexes the hip, while bilateral contraction flexes the trunk when the thighs are fixed and helps maintain posture

Quadratus lumborum

Square shaped muscle that extends from the iliac crest to rib 12 and the lumbar transverse processes; unilateral contraction laterally flexes the trunk, while bilateral contraction extends the lumbar vertebral column; innervated by anterior rami of T12 to L4

Lumbar plexus

Formed by anterior rami of L1 to L4

Iliohypogastric nerve

L1; passes anterior to quadratus lumborum toward the iliac crest and supplies muscles of the anterolateral abdominal wall

Ilioinguinal nerve

L1; follows a path similar to the iliohypogastric nerve and travels medially toward the external genitalia

Lateral cutaneous nerve of the thigh

L2 to L3; travels lateral to iliacus and carries sensory information from the lateral thigh

Genitofemoral nerve

L1 to L2; pierces psoas major and divides into femoral and genital branches

Femoral branch of genitofemoral nerve

Travels toward the upper thigh

Genital branch of genitofemoral nerve

Travels medially toward the genital region

Femoral nerve

L2 to L4; travels lateral to psoas major, deep to the inguinal ligament, alongside iliopsoas

Obturator nerve

L2 to L4; travels medial to psoas major and enters the thigh through the obturator foramen