Innervation of the APP Flashcards
More APP Lecture
What is the somatic nervous system?
- innervates structures derived from the somites, namely skeletal muscle and skin
- responds to information from the external environment
What is the visceral nervous system?
- innervates the viscera: namely smooth muscle, cardiac muscle and glands (mainly mesoderm/endoderm derived)
- responds to information from the internal environment
What is the innervation of the viscera like?
- sensory and motor innervation of the viscera
- motor element = autonomic nervous system (AKA visceral efferent)
- autonomic nervous system can be divided into sympathetic and parasympathetic
- visceral afferents follow the course of the visceral efferents
What are the functions of the sympathetic nervous system?
- increases heart rate
- bronchodilation
- vasodilation of skeletal muscle
- vasodilation of skin
- piloerection of hairs on skin
- sweating
- dilation of pupils
- ejaculation (shoot)
What are the functions of the parasympathetic nervous system?
- decreases heart rate
- bronchoconstriction
- increase blood flow to viscera
- increase peristalsis of GIT
- secretion from accessory glands of GIT
- constriction of pupils (miosis)
- erection (point)
What is the sympathetic outflow like?
- AKA thoracolumbar outflow
- originates from T1-L2
- forms sympathetic chain to reach cervical and sacral areas of the body
- flight or flight visceral efferent
What is the parasympathetic outflow like?
- AKA craniosacral outflow
- originates from CN III, CN VII, CN IX, CN X and S2-S4 (pelvic splanchnic nerve)
- the vagus nerve (CN X) is the major parasympathetic nerve of the body
- rest and digest visceral efferent
Which spinal segments do the abdomen, pelvis and perineum get sympathetic input from?
Sympathetic input from T5-L2
(T1-T4 is thoracic sympathetic outflow)
Which spinal segments do the abdomen, pelvis and perineum get parasympathetic input from?
Parasympathetic input from vagus (CN X) and S2-S4
What is the prevertebral plexus?
- combined visceral nerves of abdomen and pelvis
- sympathetic
- parasympathetic
- visceral afferents (sensory)
- lies over abdominal aorta and lumbar/sacral vertebrae
What parts does the prevertebral plexus consist of?
- abdominal part
- pelvic part
- abdominal and pelvic parts linked by the hypogastric nerve
What plexuses are in the abdominal part of the prevertebral plexus?
- coeliac plexus
- aortic plexus
- superior hypogastric plexus
What plexuses are in the pelvic part of the prevertebral plexus?
Inferior hypogastric plexus
What are the associated ganglia of the coeliac plexus?
Coeliac, aorticorenal and superior mesenteric ganglia
What are the associated ganglia of the aortic plexus?
Inferior mesenteric ganglion
What are the associated ganglia of the superior and inferior hypogastric plexuses?
Numerous smaller ganglia
What spinal segments provide sympathetic innervation to the prevertebral plexus?
T5-L2
What are the sympathetic inputs (and vertebral levels) of the prevertebral plexus?
- thoracic splanchnics
- greater splanchnic (T5-T9)
- lesser splanchnic (T10-T11)
- least splanchnic (T12)
- lumbar splanchnic nerves (L1-L2)
- sacral splanchnic nerves (T12-L2)
- (NB named lumbar and sacral due to position in sympathetic chain, not vertebral level)
What are the parasympathetic inputs (and vertebral levels) of the prevertebral plexus?
- vagus nerve (CN X)
- pelvic splanchnic nerves (S2-S4)
- NB these are the only splanchnic nerves that are parasympathetic
- think Pelvic = Parasympathetic
What nerves innervate the foregut?
- greater splanchnic (sympathetic)
- vagus (parasympathetic)
What ganglion innervates the foregut?
Coeliac ganglion
What plexus innervates the foregut?
Coeliac plexus
What nerves innervate the midgut?
- lesser splanchnic (sympathetic)
- vagus (parasympathetic)
What ganglion innervates the midgut?
Superior mesenteric ganglion
What plexus innervates the midgut?
Coeliac plexus
What nerves innervate the hindgut?
- lumbar splanchnic (sympathetic)
- sacral splanchnic (sympathetic)
- pelvic splanchnic (parasympathetic)
What ganglion innervates the hindgut?
Inferior mesenteric ganglion
What plexus innervates the hindgut?
Aortic plexus
What nerves innervate the pelvic part of the abdomen?
- lumbar splanchnic (sympathetic)
- sacral splanchnic (sympathetic)
- pelvic splanchnic (parasympathetic)
What plexuses innervate the pelvic part of the abdomen?
Superior and inferior hypogastric plexuses (connected by hypogastric nerve)
What do the least splanchnic nerves supply?
Kidneys
Which nervous system supplies the parietal peritoneum, and how localised is the pain?
- parietal peritoneum (lines abdominal walls) is innervated by the somatic nervous system
- detects well-localised pain
Which nervous system supplies the visceral peritoneum, and how localised is the pain?
- visceral peritoneum innervated by visceral afferents
- gives rise to dull, referred pain over the epigastrium (foregut), umbilicus (midgut) or suprapubic (hindgut) region of the abdomen
Where does pain from the foregut refer to on the abdomen?
Epigastric region
Where does pain from the midgut refer to on the abdomen?
Umbilical region
Where does pain from the hindgut refer to on the abdomen?
Suprapubic region
What plexuses and nerves give visceral input to the viscera of the perineum?
- superior and inferior hypogastric plexuses
- lumbar splanchnic, sacral splanchnic and pelvic splanchnic nerves
What nerve gives somatic input to the skeletal muscle (e.g. pelvic floor muscles) and skin of the perineum?
- pudendal nerve - arises from S2-S4
- NB pelvic splanchnic nerves also arise S2-S4 but these are parasympathetic fibres not somatic fibres
What artery supplies the perineum?
Anterior iliac artery (branch of internal iliac artery)
What branches off the anterior iliac artery?
- umbilical artery
- superior vesicular artery
- obturator artery
- uterine artery (females) & interior vesicular artery in males
- prostatic artery (males)
- internal pudendal artery (blood to perineum e.g. for erections)
