Complete Macro Midterm 2 (rads, diagrams, lectures)

The autonomic nervous system is the portion of the peripheral nervous system that involves the transport of involuntary information to/from what three places?

• Smooth muscle

• Cardiac muscle

• Glands

What is the neuronal circuit of the ANS?

• Stimulus to sensory afferent neuron to CNS where it synapses on interneuron. Interneuron to preganglionic motor efferent neurons where it synapses on the postganglionic motor neuron in the ganglion. Postsynaptic neuron to effector organ.

What is a preganglionic motor neuron? Found where?

• Motor neuron that has its cell body located in the gray matter of the CNS with the axon extending part way to the target organ and synapses with the postganglionic neuron at a ganglion.

What is a postganglionic motor neuron? Found where?

• Motor neuron that synapses with the preganglionic motor neuron and has its cell body within the ganglion and extends its axon to the target organ completing its pathway.

What are the 2 main divisions of the ANS?

• Sympathetic (fight or flight)

• Parasympathetic (rest and digest)

Where do the PNS preganglionic motor neurons come from on the spine? Neurotransmitter? Do the pre and post ganglionic motor neurons differ in size?

• Craniosacral: cranial nerves III, VII, IX, X; sacral nerves S1-S3

• Acetylcholine at both synapses typically

• Long preganglionic efferent and short postganglionic efferent

Where do the SNS preganglionic motor neurons come from on the spine? Neurotransmitters? Do the pre and post ganglionic motor neurons differ in size?

• Thoracolumbar: T1-L5

• Acetylcholine at pre and typically norepinephrine at post.

• Short preganglionic efferent and long postganglionic efferent

What is the sympathetic trunk?

• A bilateral chain of pre and postganglionic visceral efferents and afferent located ventrolateral to the thoracolumbar vertebrae. A ganglion is located where each communicating branch joins the trunk.

From the ganglion, what are two paths that SNS motor neurons can take?

• Synapse with the postganglionic neuron in the sympathetic trunk where it leaves the spinal cord and return to a spinal nerve via the communicating branch to reach the periphery.

• Pass through the ganglion and travel to a peripherally located ganglion (collateral ganglion) where it synapses on the postganglionic neuron (specifically associated with abdominal and pelvic organs.

The sympathetic division of the ANS can be found in all regions of the body. What are some ganglia/nerves that can be seen grossly in the thorax and neck?

• Cervicothoracic ganglion- anglion located in the cranial thorax where the sympathetictrunk splits and courses around the subclavian artery (ansa subclavia). Cell bodies in this ganglion send branches to the heart. The vertebral nerve extends from this ganglion.

• Middle cervical ganglion- attaches to cervicothoracic but extends cranially to head.

• Ansa subclavia – loop between the middle cervical ganglion and the cervicothoracic ganglion

• Vertebral nerve- leaves the cervicothoracic ganglion to innervate the neck

• Cranial cervical ganglion – last chance to synapse before head, cranial to middle cervical ganglion.

What are three examples of collateral ganglia?

• Cranial mesenteric, caudal mesenteric, and celiac ganglia

What are the functions of the PNS?

• Think SLUDD

• Salivation, Lacrimation, Urination, Defecation, Digestion

What is the main nerve of the PNS that innervates the neck, thoracic, and abdominal viscera?

• Vagus Nerve

Describe the structure of the vagus nerve. How does it travel through the body?

• The nerve joins up with the cervical sympathetic ganglion to form the vagosympathetic trunk that runs down the neck within the carotid sheath. The vagus separates from the sympathetic trunk at the level of the middle cervical ganglion in the thorax and continues caudally where it splits into dorsal and ventral branches The right and left ventral branches unite to form the ventral vagal trunk along the esophagus; while the dorsal branches unite more caudally at the level of the diaphragm to form the dorsal vagal trunk along the esophagus. Both trunks continue into the abdomen to innervate the abdominal viscera.

What is the name of the somatic nerve that has fibres that run with the Vagus nerve?

• Recurrent laryngeal nerve

What are the body systems organized in the thorax?

• Musculoskeletal

• Respiratory

• Cardiovascular

• Lymphatic

• Digestive

What are the muscular parts of the thoracic body wall? What directions do their muscle fibres go in?

• External intercostals (caudoventral fibre direction)

• Internal intercostals (cranioventral fibre direction)

• Transversus thoracics (only in ventral region of thorax)

Describe the blood supply of the thoracic body wall?

• Ventral intercostal arteries which branch from the internal thoracic artery

• Dorsal intercostal arteries which branch from the aorta

What innervates the thoracic body wall? Where do the nerves lie?

• Intercostal nerves which are ventral branches of the spinal nerves which run along the caudal borders of the ribs

What are the two pleura membranes and where are they found?

• Visceral pleura covers the surface of the lungs

• Parietal pleura forms the outer layer of each pleural cavity

What is the name of the parietal pleura that cover the thoracic wall? The diaphragm?

• Costal pleura

• Diaphragmatic pleura

What is the area called where the parietal pleura of one cavity meets the parietal pleura of the other pleural cavity?

• Mediastinal pleura

What is the caudal extent of the pleural cavity marked by?

• Diaphragmatic line of pleural reflection at the 8th costochondral junction to the middle of the last rib

• It is where the costal pleura reflects on itself to become the diaphragmatic pleura

What is the cranial extent of the pleural cavity?

• Cupula pleurae, cranial to the first pair of ribs

What is the costodiaphragmatic recess?

• The potential space between the caudal border of the lungs and the diaphragmatic line of pleural reflection. (where the lungs don’t fully fill the pleural cavities).

How is the mediastinum divided? What things are found in each section?

• Cranial- esophagus, trachea, great vessels, lymph nodes, thoracic duct, nerves, thymus

• Middle- heart, esophagus, trachea, bronchi, pulmonary vessels, thoracic duct, lymph nodes, and nerves.

• Caudal- esophagus, aorta, thoracic duct and nerves

In what section of the mediastinum does the trachea stop?

• Middle

What are the lobes found in each lung?

• Right- cranial, middle, caudal and accessory

• Left- cranial and caudal

Where does the trachea bifurcate into the bronchi?

• Carina

What is the region called where the lobes of the lungs converge?

• Hilus

What are the major veins of the thorax?

• Cranial and caudal vena cava

• Azygous vein (drains blood from the dorsal body wall)

What is the plica vena cava?

• Fold of mediastinal pleura that supports the vena cave (right side)

What is the main artery from the heart?

• Aorta

What is the first branch off the aorta? What branches come off of it?

• Brachiocephalic trunk

• Right and left common carotid arteries (then name changes to right subclavian)

What is the second branch off the aorta?

• Left subclavian artery

What is are the four branches of the subclavian arteries?

• Vertebral artery- blood for vertebrae and brain

• Costocervical trunk- gives off 1st 3 dorsal intercostal arteries

• Internal thoracic artery- gives rise to ventral intercostal arteries

• Superficial cervical artery- courses cranial to supply blood to the structures at the base of the neck

What are the lymph nodes draining the body wall? The viscera?

• Sternal and intercostal lymph nodes

• Tracheobronchial and mediastinal lymph nodes

What is the thoracic duct?

• Lymphatic drainage duct, draining lymph from the abdominal viscera and returning it to the circulatory system.

• Enters the thoracic cavity at the aortic hiatus and is located near esophagus

What nerves are closely associated with the esophagus?

• Dorsal and ventral vagal trunks

What are the three grooves of the heart? What do the grooves contain?

• Subsinuosal interventricular groove (dorsal side of heart)

• Paraconal interventricular groove (ventral side of heart)

• Coronary groove (separates atria from ventricles)

• Grooves contain coronary vessels to supply blood to the heart

What valves in the heart are semilunar? What do they look like? When are they open?

• Pulmonic and aortic valves

• Three pockets of endothelium with apical fibrous nodule to prevent back flow of blood at the arteries when leaving the heart

• Open during ventricular contraction

What is the structure of the atrioventricular valves? When are they open?

• Cusps attached via chordae tendinae to papillary muscles

• Open during ventricular filling

What are auricles?

• Blind outpouchings of each atrium. Inner walls have ridges called pectinate muscles.

What are the ridges called in the ventricles?

• Trabeculae carnae

What is the puncta maxima for the pulmonic valve? Aortic valve? Mitral valve? Right A-V?

• Pulmonic: low left ICS 3

• Aortic: high, left ICS 4

• Mitral: low left ICS 5

• Righ AV: right ICS 4

What are the two types of pericardia?

• Visceral pericardium (epicardium) that covers the surface of the heart

• Parietal pericardium forms and outer layer of the pericardial cavity

What are the two layers of the parietal pericardium?

• Inner serous and outer inelastic fibrous layer

What are two pieces of anatomy in the canine thorax that are remnants of the fetal circulatory system?

• Fossa ovalis- caudal to intervenous tubercle—was a shunt to connect the atria called the foramen ovale

• Ligamentum arteriosum- fibrous band between the pulmonary trunk and aorta which was the ductus arteriosus which acted to bypass the lungs

What does the phrenic nerves innervate?

• Diaphragm

What do the recurrent laryngeal nerves innervate?

• Larynx

What does the vagus nerve innervate?

• Parasympathetic innervation to organs of the thorax and continues through the esophageal hiatus of the diaphragm as dorsal and ventral trunks.

What regions of spinal nerves is considered the brachial plexus?

• C6-T2

What are the five nerves that innervate the extrinsic muscles of the thoracic limb? What muscles do they innervate specifically?

• Pectoral n.- pectoral muscles

• Thoracodorsal n.- latissimus dorsi

• Long thoracic n.- serratus ventralis

• Lateral thoracic n.- cutaneous trunci

• Brachiocephalic n.- brachiocephalicus m.

What are the seven nerves that innervate the intrinsic thoracic limb muscles?

• Suprascapular nerve

• Subscapular nerve

• Musculocutaneous nerve

• Axillary nerve

• Radial nerve

• Median nerve

• Ulnar nerve

Where is the suprascapular nerve found? What muscles does it innervate?

• Between the supraspinatus and the subscapularis

• Supraspinatus and infraspinatus muscles

Where is the subscapular nerve found? What muscles does it innervate?

• Innervates directly into the subscapularis muscle

What muscles does the musculocutaneous nerve innervate? What areas does it supply sensory to? Via what nerve branch?

• BBC- biceps brachii + brachialis (flex elbow), coracobrachialis (flex shoulder)

• Medial antebrachium

• Medial cutaneous antebrachial nerve

Where is the axillary nerve found? What muscles does it innervate? Where does it provide sensory? Via what nerve branches?

• Between subscapularis and teres major

• Teres major and minor and deltoideus (flexors of the shoulder)

• Lateral brachium via the lateral cutaneous brachial nerve

• Cranial antebrachium via the cranial cutaneous antebrachial nerve

Where is the radial nerve found? What muscles does it innervate? Where does it supply sensory to?

• Between teres major and triceps brachii muscles

• Extensors of the elbow, carpus and digits

• Lateral antebrachium and dorsum of the paw excluding the 5th digit

Where do the median and ulnar nerve originate from? Where do they provide motor function?

• A common trunk

• Motor to flexors of the carpus and digits

Where does the median nerve provide sensory to?

• Palmar surface of the paw

Where does the ulnar nerve provide sensory to?

• Caudal surface of the antebrachium and the 5th digit

What is a dermatome?

• The entire area of the skin that is supplied by a nerve

What are autonomous zones of the distal extremities (define)?

• Areas of the skin where only one nerve supplies the skin

What nerve innervates the trapezius muscle?

• Accessory nerve

What are the muscles which form the body wall?

• the rectus abdominis, external oblique, internal oblique, and transversus abdominis.

What are the natural openings/gaps in the abdominal body wall?

• Superficial Inguinal Canal- gap in aponeurosis

• Vascular lacuna- passage way for femoral artery and vein located caudal to the aponeurosis of the external oblique.

What nerves are seen on the surface of the transversus abdominalis?

• Lumbar nerves

Ventral and lateral body walls have two distinct blood supplies. What are they?

• Ventrally: cranial and caudal epigastric arteries

• Dorsal: cranial abdominal artery and deep circumflex artery (more caudal)

What connects the deep inguinal ring and the superficial inguinal ring?

• Inguinal canal

What is the out pocketing of the peritoneum that protrudes out the abdominal wall during development? What happens to it in females? In males?

• Vaginal process

• In females it becomes filled with fat

• In males, it is called the vaginal tunic and is associated with testes and related structures.

In both sexes, what parts are seen travelling through the inguinal canal?

• External pudendal artery and vein, genitofemoral nerve, and vaginal process

What membrane lines the abdominal cavity?

• Peritoneum

What organs are found in each section of the gut?

• Foregut- pharynx, esophagus, stomach, liver, pancreas and part of the duodenum

• Midgut- duodenum, jejunum, ilium, cecum, ascending and transverse colon

• Hindgut- descending colon and rectum

What organ is immediately caudal to the diaphragm?

• Liver

What side of the abdomen is the descending duodenum found on?

• Right

What side is the spleen typically found on?

• Left

What is the general pathway of food through the digestive system?

• Food is taken in at the mouth, passes through the esophagus to the stomach then passes into the duodenum; the descending duodenum is located dorsally on the right side, it passes caudally and curves to the left and the ascending duodenum continues cranially; the jejunum is attached to the dorsal body wall by the root of the mesentery. The ileum passes to the right caudal to the root of the mesentery, and empties into the ascending colon; the cecum is a blind outpouching of the ascending colon, and it lies dorsally on the right side; The ascending colon to the transverse colon to the descending colon and terminates in the rectum.

What anchors the digestive system in place? What is it a passage way for?

• Mesentery- a double layer of peritoneum from the dorsal body wall

• Passage way for nerves and blood

Describe the mesentery of the jejunum. What makes up its lace-like structure?

• a double layer of peritoneum from the dorsal body wall

• neuromuscular bundles with fat deposited around them

What are the two layers of the peritoneum?

• Visceral peritoneal- covers the organs

• Parietal peritoneum- covers the body wall

Are the kidneys in the peritoneal cavity?

• No, they are retroperitoneal in position

What covers the small intestine when looking at the ventral side on the abdomen?

• Great omentum

Where does the greater omentum attach to? How many layers does it have?

• Greater curvature of the stomach

• The greater omentum consists of a deep and a superficial leaf, each of which is formed from two layers of serous membrane

What is the omental bursa?

• Space between the deep and superficial leaves of the greater omentum

What is the hole called which leads to the omental bursa? How do you find it?

• Epiploic foramen

• If you slide your finger along the caudate lobe of the liver, you will enter

• the epiploic foramen: the caudal vena cava will be dorsal to your finger, and three structures (the portal vein, hepatic artery, and common bile duct) will be ventral to your finger.

What is the ligament called that connects the liver to the ventral body wall? What was its original purpose?

• Falciform ligament

• Supported the umbilical vein in neonates but fills with fat when older

Where is the pancreas found?

• left lobe found in the deep leaf of the greater omentum, right lobe found in the mesoduodenum

What is the coronary ligament? What are the corners of this ligament called?

• Short ligament connecting the liver to the diaphragm

• Left and right triangular ligaments

What are the lobes of the liver?

• Left lateral, left medial, right medial, right lateral, quadrate lobe, caudal lobe (caudate process to the right with the renal fossa and papillary process more to the left)

What lobe is the renal fossa found on?

• Caudate process of the caudate lobe

How does blood get to and from the organs?

• The aorta branches into the root of mesentery so the mesentery can supply blood supply to the organs

• The mesenteric surface of the organs has large blood vessels compared to the antimesenteric surface due to additional branching to wrap around the organ.

What are the three arteries of the abdomen and what do they supply?

• Celiac artery supplies the mid foregut. Liver, stomach, spleen and part of the duodenum.

• Cranial mesenteric artery supplies the midgut. Duodenum, jejunum, ilium, ascending colon, cecum, transverse colon and part of the descending colon

• Caudal mesenteric artery supplies the hindgut. Transverse solon, descending colon and the rectum

What specific branches of the celiac artery supplies the different organs?

• The lesser curvature of the stomach is supplied by the right and left gastric arteries (which anastomose with each other).

• The greater curvature of the stomach is supplied by the right and left gastroepiploic arteries (which anastomose with each other).

• The hepatic artery supplies the liver

• The splenic artery supplies the spleen.

• The cranial pancreaticoduoudenal artery supplies the pancreas and duodenum, and anastomoses with the caudal pancreaticoduoudenal artery (which is a branch of the cranial mesenteric artery).

What specific branches of the cranial mesenteric artery supplies the different organs?

• The caudal pancreaticoduoudenal artery supplies the pancreas and duodenum, and anastomoses with the cranial pancreaticoduoudenal artery from the celiac artery.

• The ileocolic artery supplies the ileum, cecum, and part of the ascending colon. It anastomoses with the right colic artery, which supplies parts of the ascending and transverse colons.

• The right colic artery anastomoses with the middle colic artery, which supplies part of the transverse and descending colons.

• The middle colic artery anastomoses with the left colic artery (from the caudal mesenteric artery).

What specific branches of the caudal mesenteric artery supplies the different organs?

• The left colic artery supplies the transverse and descending colons, and anastomoses with the middle colic artery (from the cranial mesenteric artery). –

• The cranial rectal artery supplies the rectum, and anastomoses with a branch of the internal iliac artery.

How does the hepatic portal vein work?

• Blood from GI tract must go to liver via the hepatic portal vein before draining into the caudal vena cava.

What is the pathway of sperm?

• Sperm is formed in the testes and leaves the tests via efferent ductules which pass into the epididymis and enter the epididymal duct which becomes the ductus deferens. The ductus deferens passes through the inguinal canal and passes through the prostate before entering the urethra.

What male urogenital parts are not paired?

• Bladder, prostate, urethra

What surrounds and supports the ductus deferens?

• Visceral vaginal tunic surround the ductus deferens—mesoductus