Vasculature and Nerves Flashcards
How many cervical spinal nerves in the dog?
Eight
Where does the first cervical spinal nerve pass through?
Lateral vertebral foramen of the atlas (Transverse foramen in wing of the caudal vertebral body of the atlas)
Where does the eight cervical spinal nerve pass through?
The intervertebral foramen between the 7th cervical vertebra and 1st thoracic vertebra.
Which are larger - dorsal or ventral branches of the spinal nerves?
Ventral
What do dorsal branches of the spinal nerves innervate?
Structures dorsal to the vertebrae.
Where will you find the 2nd cervical nerve?
Between: Mastoid part of the cleidocephalicus Omotransversarius Deep to platysma Dorsal to external jugular vein
What does the 2nd cervical nerve innervate?
Branches into two:
Great auricular nerve: skin of the neck, the ear, and back of the head.
Transverse cervical nerve: Skin of the cranioventral part of the neck
What vessels is the external jugular vein formed by?
Facial components: Linguofacial (ventral) and maxillary (dorsal) veins. Maxillary can be distinguished by mandibular lymph nodes lying on either side.
Brachial components: Omobrachaial (dorsal) and cephalic (ventral) veins
Mandibular salivary gland
Dorsal to the mandibular LNs.
Mandibular lymph nodes
Receive lymph drainage from the cutaneous areas of the head, neck, and thoracic limb
Ventral to the mandibular salivary gland, deep to the cleidocephalicus and omotransversarius.
Where do you find the accessory cranial nerve?
Also called the 11th cranial nerve
Emerges below the sternocephalicus, runs along the dorsal border of the omotransversarius, terminates in the trapezius
What does the accessory cranial nerve innervate?
Only motor nerve of the trapezius. Also supplies: Omotransversarius Cleidocephalicus (mastoid and cervical parts) Sternocephalicus
Third, Fourth, and Fifth cervical spinal nerves
Distributed segmentally to the muscles and skin of the neck
Vagosympathetic nerve trunk
Within the carotid sheath, medial to the common carotid artery.
Medial retropharyngeal lymph node
Lies ventrolateral to the carotid sheath
Opposite the larynx
Branching pattern of the dorsal intercostal arteries
Do not confuse with dorsal branch of the artery
First three dorsal arteries: from branch of the costocervical trunk
Last 9 dorsal arteries: from aorta
Two lateral cutaneous branches (one dorsal, one ventral) that perforate both intercostal muscles
Ventral intercostal arteries
Ventral intercostal artery anastomoses with the dorsal intercostal artery
Perforating branch that perforates just the internal intercostal muscles near the sternum.
Dorsal branch of the arteries of the intercostal space
Supplies the epaxial muscles
Do not confuse with dorsal intercostal arteries.
Ventral branch of the arteries of the intercostal space
Anastomoses with the dorsal intercostal artery.
Veins of the intercostal spaces
Will follow in the same pattern as the arteries of the intercostal spaces.
What do the lateral branches of the dorsal intercostal arteries supply?
Cutaneous structures
Example: thoracic mammae
What do the perforating branches of the ventral intercostal arteries supply?
Cutaneous structures
Example: thoracic mammae
Branching pattern of the intercostal nerves
Dorsal, lateral, and ventral branches
Dorsal: innervates epaxial muscles.
Lateral: Becomes the dorsal lateral cutaneous branch
Ventral: A lateral branch that perforates both intercostal muscles and a ventral cutaneous branch that perforates just the internal intercostal near the sternum.
What are the cranial thoracic mammae supplied by?
Fourth, fifth, and sixth ventral and lateral cutaneous vessels and nerves (from the intercostals)
Branches of the lateral thoracic vessesls (from the axillary vessels)
What are the caudal thoracic mammae supplied by?
Sixth and seventh cutaneous nerves and vessels
Cranial superficial epigastric vessels
What do the intercostal vessels and nerves become after they pass through the intercostals?
Cutaneous vessels and nerves.
Axilla
Armpit.
Bounded by: Pectorals and serattus ventralis.
Contains: brachial plexus
Where do you find the lateral thoracic vessels and nerve?
In the axilla
Between the latissiumus dorsi and deep pectorals
What does the lateral thoracic nerve innervate?
Motor to the cutaneus trunci.
What does the lateral thoracic nerve consist of?
Branches of the 8th cervical and 1st thoracic spinal nerves.
What do the lateral thoracic vessels consist of?
Branches of the axillary artery and vein.
What do the lateral thoracic vessels supply?
Muscle, skin, subcutaneous tissue, and cranial thoracic mama.
Axillary lymph node
Drains the afferent lymph vessels of the thoracic wall and deep structures of the limb.
Dorsal to the deep pectoral
Cranial epigastric artery
Terminal branch of the internal thoracic artery
Emerges from costal arch
Runs caudally on the deep surface of the rectus abdominis
Gives rise to cranial superficial epigastric artery
Cranial superficial epigastric artery
From the cranial epigastric artery
Perforates the rectus abdominis
Runs caudally over external surface of rectus abdominis
Branches terminate in rectus abdominus.
What does the cranial superficial epigastic artery supply?
Skin over the rectus abdominis
Caudal thoracic mammae
Cranial abdominal mammae
Transversus thoracis
Flat muscle on deep ventral surface of costal cartilage 2-8.
Attachments: chostochondral junctions and sternum
Internal thoracic artery
3rd lateral branch off the brachiocephalic artery.
Supplies the phrenic nerve, the thymus, the mediastinal pleurae and the dorsal intercostal spaces.
Branch from the subclavian artery
Runs ventrocaudally through the cranial mediastinum
Anastomoses with ventral intercostal arteries on the medioventral surface of the thoracic cavity.
Terminatees in the musculophrenic and cranial epigastric arteries.
Pleurae
Serous membranes that cover the lungs and line the walls of the thorax.
Visceral pleura
Also called pulmonary pleura
Closely attach to the surfaces of the lungs and separate the two lobes.
Parietal pleura
Attached to the thoracic wall by endothoracic fascia
Three contiguous parts: costal, diaphragmatic, and mediastinal
Costal pleura
Covers inner surface of the ribs and associated intercostal and transverses thoracis muscles.
Diaphragmatic pleura
Covers cranial surface of the diaphragm.
Mediastinal pleura
Covers the sides of the partition between the two pleural cavities
Mediastinum
Two mediastinal pleurae and the space between them
Encloses the heart, lymph nodes, thymus, heart, aorta, trachea, and esophagus, as well as the vagus nerve and other nerves/vessels.
Can be divided into cranial, middle, dorsal, ventral, and caudal parts with the middle covering the heart and the others in relation to the heart.
Pericardial mediastinal pleura
Portion of the mediastinal pleura covering the heart.
Esophageal hiatus
Where the esophagus passes through the diaphragm
Connected by connective tissue, pleura, and peritoneum.
Plica venae cavae
Loose fold of pleura from the right caudal mediastinal portion of the pleural sac.
Surrounds the caudal vena cava.
Root of the lung
Also called the hilus of the lung.
The pleura, bronchi, vessels, and nerves that are all entering into the lung.
Pulmonary ligament
Between the caudal lung lobe and the mediastinum at the level of the esophagus.
Thymus
Bilobed compressed structure in the cranial mediastinum, over the surface of the pericardium when large.
Largest in young animals and atrophies with age.
Musculophrenic artery
Runs caudodorsally in the angle formed by the diaphragm and the lateral thoracic wall.
What artery supplies the thymus?
Internal thoracic artery.
What nerve innervates the trapezius?
Accessory cranial nerve.
Left lung lobes
Two:
Cranial lobe with cranial and caudal parts
Caudal lobe
Right lung lobes
Four: Cranial lobe Middle lobe (most lateral) Caudal lobe Accessory lobe (most medial)
Cardiac notch
On the right lung
Between the cranial and middle lobes of the lung
The fourth and fifth intercostal space
Principal bronchi
Bifurcation of the trachea to supply each lung.
Carina
Partition between the principal bronchi in the trachea.
Lobar bronchi
Divisions of the principal bronchi to supply the lobes of the lungs.
What is the clinical significance of the cardiac notch?
Heart is accessible for cardiac puncture here.
Aortic impression on the left lung
Most marked on the accessory lobe.
Tracheobronchial lymph nodes
Located at the bifurcation of the trachea and further down on the bronchi.
Do not confuse with mediastinal lymph nodes.
Where do the pulmonary veins drain? Do they carry oxygenated or deoxygenated blood?
Drain into the left atrium of the heart
Carry oxygenated blood
Pulmonary trunk
Supplies each lung with a pulmonary artery. Right pulmonary artery will be ventral to right principal bronchus.
Cranial vena cava
Drains into the right atrium
Formed by the union of the left and right brachiocephalic veins, and the right azygos vein.
Thoracic inlet
Union of the left and right brachiocephalic veins draining into the cranial vena cava.
Brachiocephalic veins
Formed by external jugular and subclavian veins
Azygos vein
Only the right vein develops in the dog
The last branch entering the cranial vena cava
Winds ventrocranially around the right lung
Collects blood from all of the dorsal intercostal veins as far cranially as the 3rd/4th intercostal space
Thoracic duct
Drainage from: lymphatic capillaries ducts to the venous system left thoracic limb left tracheal trunk Drains into the left brachiocephalic vein
Cisterna chyli
Dilated structure that receives lymph drainage from the abdominal and pelvic viscera and the pelvic limbs.
Caudal to the thoracic duct and the thoracic duct continues from it.
Left tracheal trunk
Lymph drainage from the left side of the head and neck
Drains into the thoracic duct
Right tracheal trunk
Lymph drainage from the right side of the head and neck
Drains into the venous system at the right brachiocephalic vein.
Aorta
Large unpaired vessel from left ventricle
Two main parts:
Cranial aorta (to the diaphragm): Ascending aorta, aortic arch, and descending aorta
Caudal aorta (to the diaphragm
Coronary arteries
Branches of the ascending aorta that supply the heart muscle
Vessels from the ascending aorta
Coronary arteries
Vessels from the aortic arch
Brachiocephalic trunk
Left subclavian artery
Vessels from the descending aorta
8-9 dorsal intercostal arteries (first 3 from the costocervical trunk)
Brachiocephalic trunk
First branch from the aortic arch
Gives rise to left carotid artery and then terminates as the right carotid artery and the right subclavian artery.
Common carotid arteries
Both left and right come from the brachiocephalic trunk
Subclavian arteries
Right comes from the brachiocephalic trunk
Left is the second branch of the aortic arch
Both have similar branching after this point.
Vertebral artery
1st branch off of the subclavian artery
Supplies the cervical muscles and spinal branches spinal cord and its coverings via intervertebral foramina.
Costocervical trunk
2nd branch off the subclavian artery
Supplies the 1st/2nd/3rd intercostal spaces, muscles at the base of the neck, and muscles dorsal to the first few thoracic vertebrae.
Superficial cervical artery
3rd medial branch of the subclavian artery.
Supplies the base of the neck and the scapular region.
Bronchoesophageal artery
Supplies the esophagus
Arises from the 5th intercostal artery
Terminates in the bronchial arteries
Bronchial arteries
Supply the lungs
Phrenic nerves
Arises from the ventral branches of the 5th/6th/poss.7th cervical nerves
Innervate the diaphragm
Have both sensory and motor functions.
Central Nervous System
Brain and spinal cord
Peripheral Nervous System
Anything outside of the CNS
Cranial nerves, spinal nerves, and what they become.
Sensory nerves
Afferent nerves
Always pseudounipolar
Motor nerves
Efferent nerves Somatic efferents (conscious, to skeletal muscle) are pseudounipolar Visceral/autonomic efferents (unconscious, to smooth muscle) parasympathetic (rest and digest) or sympathetic (fight or flight) are multipolar and need two to reach the effector tissue
Ganglion
Gross enlargement of a nerve
Contains neuronal cell bodies
What are groups of neuronal cell bodies within the CNS called?
Nuclei
What are the two autonomic efferent neurons called as they travel to the effector tissue?
Preganglionic and postganglionic neurons.
What is another name for the sympathetic nervous system?
Thoracolumbar system
What is another name for the parasympathetic nervous system?
Craniosacral system
What humoral transmitter substance is released at sympathetic nerve endings?
Norepinephrine
What humoral transmitter substance is released at parasympathetic nerve endings?
Acetylcholine
Where are parasympathetic ganglia typically located?
In the wall of the structure being innervated.
Where are sympathetic ganglia typically located?
A short distance from the spinal cord.
Ventral root of the spinal cord
Efferent neurons
Dorsal root of the spinal cord
Afferent neurons
Spinal nerve
Joining of the ventral and dorsal roots of the spinal cord just at the edge of the vertebra at the level of the intervertebral foramen.
Ramus communicans
Also called the communicating branch
Leaves the ventral branch of the spinal nerve just after it starts
Joins the sympathetic trunk
Like all other nerves, multiple types of nerves. Mostly pre and post ganglionic sympathetic GVEs in these branches but may be others.
Sympathetic trunk ganglion
Peripheral nerve just lateral to the spinal column
A sympathetic trunk ganglion located at each point where a ramus communicants joins with the trunk, with cell bodies of postganglionic sympathetic neruons.
Splanchic nerves
Run through the sympathetic trunk
Form plexuses around the main blood vessels of the abdominal organs
Additional sympathetic ganglion within the plexuses (postganglionic cell bodies of the neurons that formed these nerves located here)
Describe the movement of a pair of sympathetic GVE neurons that innervate smooth muscles, sweat glands, and other strucutures located above the spinal cord.
- Run down the ramus communicans
- Synapse either with the first sympathetic trunk ganglion that they come across or move one or two ganglia cranially or caudally.
- Postganglionic neuron runs back over through the ramus comminicans in the segment where the synapse occurred
- Runs with a spinal nerve to the structures to be innervated.
What verterbrae have spinal nerves that feed into the sympathetic nervous system?
T1 - L4 or L5
Cranial cervical ganglion
Synapses of the preganglionic sympathetic neurons that supply the head.
Cervicothoracic ganglion
Enlargement of the sympathetic trunk lateral to the longus colli at the first intercostal space
Fusion of the caudal cervical ganglion and the first two or three thoracic ganglion.
Brachial plexus
Pathway through the axilla for the postganglionic axons to reach the thoracic limb.
Formed by the ventral branches of the (sometimes 5th)/6th/7th/8th cervical and 1st/2nd thoracic spinal nerves.
These intermix and differently named intermixed nerves leave from the plexus.
Vertebral nerve
From the cervicothoracic ganglion through transverse foramina to the heart and other thoracic structures.
Ansa subclavia
Division of the sympathetic trunk for it to loop around the subclavian artery. Unite at the middle cervical ganglion.
Many nerves leave this to supply the heart.
Middle cervical ganglion
Junction of the nasa and the vagosympathetic trunk. Many nerves leave this to supply the heart.
Cardiac nerves
Numerous
Leave the ansa subclavia and middle cervical ganglion to course to the heart.
Vagosympathetic trunk
Lies in the carotid sheath
Cranial cervical ganglion at its cranial end.
Combines with the vagus nerve (tenth cranial nerve).
Left and right recurrent laryngeal nerves
Left curves around the arch of the aorta
Right curves around the right subclavian artery
Both then run up the trachea and supply the larynx
Innervate the heart, esophagus, and trachea.
Longest peripheral nerves in the body, so early peripheral neuropathy is typically seen with trouble barking or swallowing.
Caudal laryngeal nerve
Termination of the recurrent laryngeal nerves in the larynx.
Ventral vagal trunk
Cranial termination of the dorsal and ventral vagus nerves on the esophagus, cranial to the heart.
Dorsal vagal trunk
Caudal termination of the dorsal and ventral vagus nerves dorsal to the esophagus near the diaphragm.
Dorsal and ventral vagus nerves
Division of each vagus nerve near the base of the heart.
Pericardium
Fibroserous covering of the heart Three layers: Outer: Pericardial mediastinal pleura Fibrous pericardium Inner: Parietal serous pericardium
Serous pericardium
Two layers
parietal layer - adheres to the fibrous pericardium (forms part of the pericardium)
visceral layer - adheres to the heart (considered part of the heart)
Pericardial cavity
Contains pericardial fluid between the parietal serous pericardium and visceral serous pericardium.
Phrenicopericardial ligament
Continuation of the fibrous pericardium to the sternum and the diaphragm.
Usually associated with adipose tissue.
Located in the ventral mediastinum.
Epicardium
Another name for visceral serous pericardium.
Auricular surface of the heart
Left side of the heart, can see both auricles from this side.
Atrial surface of the heart
Right side of the heart. Can generally only see the right auricle here.
Dorsal surface of the heart
Attachments of the great vessels
Apex of the heart
Ventrocaudal and slightly to the left in most hearts, part of the left ventricle.
Coronary Groove
Separates the ventricles from the atria on the atrial side of the heart.
Interventricular grooves
Paraconal interventraicular groove (auricular surface, oblique)
Subsinuosal interventricular groove (atrial surface)
Cranial surface of the heart
Right ventricle covers the left ventricle here.
Parts of the right atrium
Sinus venarum (main) right auricle
How many openings into the right atrium? What are they?
Four.
- Caudal vena cava
- Coronary sinus
- Cranial vena cava
- Right atrioventricular orifice (holds the valve)
Interatrial septum
Medial wall of the heart separating the left and right atria.
Intervenous tubercle
Transverse ridge between the two caval openings in the right atrium
Serves to channel blood towards the right atrioventricular orifice.
Fossa ovalis
Slitlike depression caudal to the intervenous tubercle
Formed the foramen ovale between the right and left atria in the fetus (no need to send blood to the lungs)
Pectinate muscles
Interlacing muscular bands in the auricles and atria
Endocardium
Grossly: glistening surface on the inner surface of the heat
Microscopically: Simple squamous epithelium lining the inner part of the vessel.
Crista terminalis
Thick, semilunar smooth portion of the right atria at the entrance into the auricle. Pectinate muscles radiate from this band.
Pulmonary trunk
Leaves the right ventricle at the conus arteriosus to continue to the lungs.
At the left craniodorsal aspect of the heart.
Will then bifurcate into the left and the right pulmonary arteries.
Atrioventricular valve
Right and left
Both have two cusps, a septal and a parietal cusp.
Subsidiary leaflets found at the end of both cusps in the left and just the septal cusp in the right.
Chordae tendineae
Connect the cusps of the atrioventricular valves with the walls of the ventricles via the papillary muscles.
Papillary muscles
Conical muscle projections in the ventricles
Usually three or four
Attachments for the chordae tendineae.
Trabeculae carnae
Muscular irregularities of the interior of the ventricular walls.
More numerous in the right ventricle than in the left.
Trabecula septomarginalis
Muscular strand extending across the lumen of the right ventricle from the septal to the parietal wall, also anchored by a papillary muscle.
Pulmonary valve
Between the conus arteriosus and the pulmonary trunk
three semilunar cusps, each with a small fibrous nodule in the middle of them.
Valve of the foramen ovale
Remnant of the foramen oval
In the left atrium, directly across from the fossa ovalis in the right atrium.
ligamentum arteriosum
Fibrous connection between the pulmonary trunk and the aorta
Remnant of the patent ductus arteriosus to bypass the lungs in the fetus (funneled blood straight into the aorta).
Aortic valve
Between the left ventricle and the aorta.
Three semilunar cusps with fibrous nodules like the pulmonary valve.
Sinus of the aorta
Slight expansion of the aorta just cranial to the aortic valve.
Right coronary artery
Leaves the right sinus of the aorta.
Passes through coronary groove and often part of the subsinuosal interventricular groove.
Left coronary artery
Twice as large as the right coronary artery.
Leaves the left sinus of the aorta.
Two branches: circumflex branch and paraconal inter ventricular branch.
Circumflex branch of the left coronary artery
Passes through the subsinuosal interventricular groove and in the coronary sulcus.
Paraconal interventricular branch of the left coronary artery.
Passes through the paraconal interventricular groove.
Sends large rami over the surface of the left ventricle.
Septal branch that runs into the interventricular septum and supplies this.
Coronary sinus
Dilated terminal end of the great cardiac vein.
Great cardiac vein
Drains the coronary vessels back to the heart.
Starts in the paraconal interventricular sulcus.
Subclavian artery branches
- Vertebral artery
- Costocervical artey
- Internal thoracic artery and superficial cervical artery
- Continues as the axillary artery
What does the superficial cervical artery supply?
Superficial muscles of the base of the neck, superficial cervical lymph nodes, and the muscles of the scapula and shoulder.
What is the function of the superficial cervical lymph nodes?
Drain the afferent lymph vessels from the superficial part of the neck, caudal surface of the head, ear, and pharynx, and the thoracic limb.
What are the branches off the axillary artery?
External thoracic artery
Lateral thoracic artery
Subscapular artery
Cranial circumflex artery
What are the nerves that come out of the brachial plexus?
Suprascapular nerve Subscapular nerve Axillary nerve Musculocutaneous nerve Radial nerve Median nerve Ulnar nerve Thoracodorsal nerve Lateral thoracic nerve Pectoral nerve
External thoracic artery
1st branch off the axillary artery.
(normal variation: may be off the same trunk as the lateral thoracic artery or superficial cervical artery)
Supplies the superficial pectorals.
Lateral thoracic artery
2nd branch off the axillary artery.
(normal variation: may be distal to the subscapular artery).
Supplies the latissimus dorsi, deep pectorals, cutaneus trunk, and thoracic mammae.
Subscapular artery
3rd branch off the axillary artery. Three branches: Thoracodorsal artery Caudal circumflex humeral artery Continuation of the subscapular artery (supplies the scapula).
Cranial circumflex artery
4th branch off the axillary artery.
(normal variation: may be distal or proximal to the subscapular artery).
Supplies the biceps brachia and the joint capsule of the shoulder
Thoracodorsal artery
Supplies the trees major and latissimus dorsi
Caudal circumflex humeral artery
Wraps around the cranial side of the humerus (can be seen under the deltoideus on the lateral side).
Supplies the triceps, deltoids, coracobrachialis, infraspinatus, and shoulder joint capsule.
Brachial artery
Continuation of the axillary artery over the humerus. Terminates in the median artery after the branch off of the common interosseous artery. Branches into: Collateral ulnar artery Superficial brachial artery Transverse cubital artery Common interosseous artery
Collateral ulnar artery
1st branch off the brachial artery (across from a smaller bicipital artery)
Supplies the triceps, ulnar nerve, and the elbow
Superficial brachial artery
2nd branch off the brachial artery
More distally will anastomose with the cranial superficial antebrachial artery.
Supplies the dorsum of the forepaw
Transverse cubital artery
3rd branch off the brachial artery.
Supplies the elbow.
Cranial pectoral nerves
Derived from branches of the 6th/7th/8th cervical spinal nerves
Innervate superficial pectoral muscle.
Suprascapular nerve
Derived from 6th/7th cervical spinal nerves (Brachial plexus)
Passes directly across the scapular notch and so very susceptible to injury (sweeny in horses)
Innervates supraspinatus and infraspinatus
Subscapular nerve
Derived from 6th/7th cervical spinal nerves (Brachial plexus)
Innervates the subscapularis
Musculocutaneous nerve
Derived from 6th/7th/8th cervical spinal nerves (Brachial plexus)
Innervates coracobrachialis, biceps brachii, brachialis.
A branch off the musculocutaneous joins with the median nerve.
Axillary nerve
Derived from 7th/8th cervical spinal nerves (Brachial plexus)
Innervates
Thoracodorsal nerve
Derived from 8th cervical spinal nerve (Brachial plexus)
Innervates the latissimus dorsi
Radial nerve
Derived from 7th/8th cervical and 1st/2nd thoracic spinal nerves (Brachial plexus)
Innervates all the extensor muscles of the elbow, carpal, phalangeal joints, triceps, tensor fasciae antebrachii, and anconeus.
Terminates as a deep and superficial branch.
Median nerve
Derived from 8th cervical and 1st/2nd thoracic spinal nerves. (Brachial plexus) Common trunk with the ulnar nerve.
Receives a branch from the musculocutaneous nerve.
Innervates most of the muscles of the forearm and skin of the palmar surface of the paw -
Pronator teres
Pronator quadratus
Flexor carpi radialis
Superficial digital flexor
Parts of deep digital flexor
Ulnar nerve
Derived from 8th cervical and 1st/2nd thoracic spinal nerves (Brachial plexus) Common trunk with the median nerve.
Innervates the skin of the distal medial aspect of the brachium and the caudal aspect of the antebrachium -
Flexor carpi ulnaris
Parts of deep digital flexor
Caudal pectoral nerves
Derived from 8th cervical and 1st and 2nd thoracic spinal nerves.
Innervates the deep pectoral muscle.
Lateral thoracic nerve
Derived from from 8th cervical and 1st thoracic spinal nerves. (Brachial plexus)
Innervates the cutaneus trunci.
Cephalic vein
Begins on palmar surface of paw and runs over the cranial surface of the antebrachium.
Enters the external jugular vein near the thoracic inlet.
Accessory cephalic vein
Arises from small veins on the dorsum of the paw and joins the cephalic on the distal third of the antebrachium.
Median cubital vein
Forms connection between the cephalic and brachial veins over the flexor surface of the elbow.
Axillobrachial vein
Leaves the cephalic vein at the middle of the antebrachium.
Joins the axillary vein near the deltoideus.
Omobrachial vein
Arises from the axillobrachial vein and enters the external jugular vein cranial to the cephalic vein.
Median artery
Termination of the brachial artery after the branch of the common interosseous artery. Runs with the median vein.
Extends to the superficial palmar arch in the paw.
Branches:
Deep antebrachial artery
Radial artery
Common interosseous artery
Short branch off the brachial artery. Branches into: Ulnar artery Caudal interosseous artery Cranial interosseous artery
Ulnar artery
Courses caudally from the common interosseous artery and continues with the ulnar nerve.
Supplies the ulnar and humeral heads of the deep digital flexor and flexor carpi ulnaris.
Caudal interosseous artery
Course distally from the common interosseous artery between the radius and ulna under the pronator quadratus.
Supplies many structures around the radius and ulna with small branches then joins with radial and median arteries to supply the palmar surface of the forepaw.
Cranial interosseous artery
Third branch off of the common interosseous artery, difficult to visualize.
Superficial palmar arch
Formed by the anastomosis of the median artery and caudal interosseous artery.
Gives rise to the palmar common digital arteries that supply the palmar surface of the forepaw.
Radial artery
Arises from the median artery in the middle of the leg and follows medial border of the radius.
Deep antebrachial artery
Caudal branch of the median artery just under the common interosseous artery.
Supplies the flexor carpi radialis, deep digital flexor, flexor carpi ulnaris, and superficial digital flexor.
Radial nerve
Supplies the extensors of the elbow, carpus, and digital joints.
Divides into superficial and deep branches, superficial divides again to medial, lateral, and lateral cutaneous branches.
Deep branch of the radial nerve
Courses with the brachial into the forearm.
Innervates the extensor carpi radialis, common digital extensor, supinator, lateral digital extensor, the abductor digiti I longus, and the ulnaris lateralis.
Medial and lateral branches of the radial nerve
Follow the medial and lateral sides of the cephalic vein.
Innervate (sensory to) the skin on the cranial and lateral surface of the forepaw and dorsal surface of the carpus, metacarpus and digits.
Terminate in the dorsal common digital nerves.
Palmar branch of the ulnar nerve
Sensory to the palmar surface of the forepaw and motor to the intrinsic muscles of the forepaw.
Dorsal and palmar common digital vessels and nerves
Superficial nerves and vessels of the forepaw
Each common trunk divides to branches medial and lateral to each digit.
Dorsal and palmar metacarpal vessels and nerves
Deep nerves and vessels of the forepaw
Each common trunk divides to branches medial and lateral to each digit.
Cutaneous area of a nerve
Entire area of skin innervated by a nerve. May overlap with the cutaneous area of other nerves.
Autonomous zone of a nerve
The area of skin innervated solely by one nerve with no overlap by the adjacent nerves.
External pudendal artery
Emerges from the superficial inguinal ring. Courses caudally near the gracialis.
Caudal superficial epigastric artery
Continuation of the external pudendal artery that courses cranially over the rectus abdominus.
Supplies the prepuce, caudal abdominal mammae, inguinal mammae, labia, and scrotum.
Superficial inguinal lymph nodes
Drain the mammae, prepuce, scrotum, and the ventral abdominal wall as far cranially as the umbilicus
Cranial abdominal arteries
Arises with the caudal phrenic artery off the aorta
Perforate abdominal musculature and supply the skin.
What are the four main arteries that supply the abdominal wall?
Cranial abdominal artery
Cranial epigastric artery
Caudal epigastric artery
Deep circumflex iliac artery
Patterning of the ventral branches of the first four lumbar nerves
Run ventrocaudally from their vertebra of origin to the area of skin innervated. (Names: T1: Cranial iliohypogastric T2: Caudal iliohypogastric T3: Ilioinguinal T4: Lateral cutaneous femoral nerves)
Genitofemoral nerve
Arises from the 3rd and 4th lumbar nerves
Bound to external pudendal vein
Innervates cremaster, prepuce, and skin of inguinal thigh in both sexes.
Spermatic fascia
Continuation of abdominal and transversus fascia
Surrounds the structures coming through the superficial inguinal ring including the vaginal tunic, spermatic cord, and cremaster muscle.
Vaginal process
Diverticulum of the peritoneum present in both sexes
Called the vaginal tunic in males and covers the testes, and spermatic parts.
Consists of parietal, visceral, and connecting parts.
Parietal vaginal tunic
Outer layer of the peritoneal diverticulum. Surrounds a portion of the peritoneal cavity between the parietal and visceral tunics. Joins with the visceral layer at the caudal end of the testis.
Visceral vaginal tunic
Inner layer of the peritoneal diverticulum, closely fused to the testis, epididymus, and ductus deferens. Joins with the parietal layer at the caudal end of the testis.
Mesorchium
Connecting mesentery of the testis that contains nerves and vessels
Mesoductus deferens
Fold of the peritoneum that attaches the ductus deferens to the body wall and mesorchium. Contains the artery, vein, and nerve of the ductus deferens.
Spermatic cord
The ductus deferens and spermatic artery and vein (everything above the testes)
Ductus deferens
Carries the sperm from the tail of the epididymus to the urethra.
Deferens artery and vein
Accompany the ductus deferens
Patterning of the testicular artery and vein
Veins and nerves are woven around the artery. Important for temperature control of the testes.
Cremaster muscle
Arises from the free border of the internal abdominal oblique and attaches to the vaginal tunic near the testes. Comes through the superficial inguinal ring.
Pampiniform plexus
Venous plexus of the testicular veins, interwoven with nerves and wrapped around the artery, important for temperature control of the testes.
Epididymus
Head: cranial, least mature sperm.
Middle
Tail: caudal, most mature sperm.
Ligament of the tail of the epididymus
Connects the tail of the epididymus to the vaginal process.
Forms the round ligament of the uterus in females.
Proper ligament of the testis
Connects the tail of the epididymus to the testis.
Scrotum
Skin over the testes divided by an external raphe and an internal median septum.
Round ligament of the uterus
Runs with the peritoneal diverticulum out of the superficial inguinal ring in the female. May
extend as far as the fascia.
Nerve types in the plexus of the testes
Both autonomic and sensory
sympathetic axons from the third to 5th lumbar sympathetic ganglia.
Inguinal canal
Short fissure filled with connective tissue, bounded by the four abdominal muscles and the superficial and deep inguinal rings. Vaginal tunic/process and spermatic cord/round ligament of the uterus travel through this canal.
Abdominal cavity
Formed by the muscles of the abdominal wall, ribs, and the diaphragm. Lined by the peritoneum. Contains all of the abdominal organs.
Peritoneal cavity
Closed space lined by a serous membrane, between the parietal and visceral peritoneum. No organs within the cavity.
Derived from somatic and splanchnic mesodermal layers of the embryonic coelom.
Parietal peritoneum
Lines the body cavity of the abdomen and scrotum.
Visceral peritoneum
Lines the organs of the abdominal cavity and scrotum.
Connecting peritoneum
Double sheet of peritoneum that extends between the parietal and visceral peritoneums. Forms the mesentery that suspends the organs, as well as containing their nerves and vessels.
Its folds can form the mesenteries, omenta, or ligaments of the abdominal cavity.
Transversalis fascia
Reinforces the parietal peritoneum and attaches it to the abdominal muscles and diaphragm.
Falciform ligament
Fold of peritoneum that passes from the umbilicus to the diaphragm.
Connects to the liver between the medial and quadrate lobes.
Accumulation of fat inside this ligament in adults.
Umbilical vein ran through this - may find remnants of the embryonic ventral mesentery here in young animals.
Round ligament of the liver
Attached to the free border of the falciform ligament, more prominent in young animals.
Median ligament of the bladder
Caudal to the umbilicus, fold of the peritoneum running caudally to the urinary bladder. Umbilical artery and urachus ran through this structure.
Vaginal ring
Opening in the parietal peritoneum as it leaves the abdomen and enters the inguinal canal. Contains the spermatic cord and vaginal tunic/process.
Deep inguinal ring
Fatty structure formed by the folds of the transversalis fascia and associated adipose tissue on the superficial side of the vaginal ring.
Caudal epigastric artery
Course cranially on the deep face of the caudal part of the rectus abdominis.
Origin from the pudendoepigastric trunk.
Greater omentum
Also called the epiploon
Extension of the connecting peritoneum, with two layers.
Extends caudoventrally to many of the abdominal organs. (outside of the liver)
Superficial leaf of the greater omentum
Lacelike. Layer closer to the peritoneum. Encloses the spleen.
Deep leaf of the greater omentum
Layer closer to the viscera. Encloses the left lobe of the pancreas.
Omental bursa
Space between the deep and superficial leaf of the greater omentums.
Can cause colic in horses if a loop of intestine becomes entrapped in this sac. May occasionally happen in the small animal but rare (epiploic entrapment).
Urinary bladder
Empty: lies on the floor of the abdomen.
Full: Displaces freely moving viscera, frequently reaching a transverse plane through the umbilicus.
Uterus
Short cevix
Two long horns.
How does the uterus change shape during pregnancy?
Lies on the floor of the abdomen.
As pregnancy develops, middle parts of the horns move ventrocranially, causing the uterus to bend on itself.
Round ligament of the uterus
May pass through the inguinal canal.
Fold of the peritoneum from the mesometrium which surrounds the uterus.
Remnant of fetal gubernaculum.
Becomes the ligament of the tail of the epididymus in males.
Spleen
Left side of the abdomen Shape variable (HUGE in our dogs as a result of the barbiturates they were given).
Gastrosplenic ligament
The part of the greater omentum that attaches to the spleen.
Muscular parts of the diaphragm plus their attachments?
Tendinous center: V shaped and small, in the center of the diaphragm, runs between the costal and lumbar parts on each side.
Lumbar part: Left and right crura: attach to the bodies of L3 and L4 by large tendons.
Costal part: Arises from the medial surface of ribs 8-13, interdigitating with the transversus abdominis.
Sternal part: Narrow, from sternum to xyphoid cartilage.
Cupula of the diaphragm
Most cranial part of the diaphragm, bulges into the thorax.
Where does the aorta pass through the diaphragm?
Aortic hiatus. Dorsal diaphragm.
Where does the caudal vena cava pass through the diaphragm?
Caval foramen.
Where does the esophagus pass through the diaphragm?
Esophageal hiatus. Right crus of the diaphragm.
Where does the thoracic duct pass through the diaphragm?
Aortic hiatus. Dorsal diaphragm.
Where does the azygous vein pass through the diaphragm?
Aortic hiatus. Dorsal diaphragm.
Liver (lobes)
- Caudate lobe
- Right lateral lobe
- Right medial lobe
Gallbladder! - Quadrate lobe
- Left medial lobe
- Left lateral lobe
What are the two sides of the liver?
Visceral surface (caudal) and parietal surface (cranial).
Which lobe of the liver does the right kidney contact?
Caudate lobe, forming the renal impression on the caudate process.
Which lobe of the liver does the lesser curvature of the stomach contact?
Caudate lobe, contacting the papillary process of the caudate lobe.
Lesser omentum
The omentum that is hidden under the liver and viscera rather than padding the ventral side of the viscera.
Hepatoduodenal ligament
Right free edge of the lesser omentum, attaching the liver to the duodenum.
Contains the portal vein, hepatic artery, and the bile duct.
Epiploic foramen
Formed by the omenta. Opens in the main peritoneal cavity.
Mesoduodenum
Originates at the dorsal abdominal wall and root of the mesentery and attaches to the duodenum. Continuous with the mesentery of the jejunum.
Duodenocolic fold
Attachment of the ascending duodenum to the mesocolon of the descending colon.
Mesentery
Passageway for nerves and vessels to supply the small intestines. Continuous with the mesocolon of the ascending colon.
Root of the mesentary
Attachment of the mesentery to the abdominal wall at the second lumbar vertebra.
Mesocolon (parts and function)
Ascending, transverse, and descending parts.
Right and left triangular ligaments
Extend from the right and left crus of the diaphragm to the right and left lateral lobes of the liver.
Coronary ligament
Sheet of peritoneum continuous with both the right and left triangular ligaments on the dorsal side.
Hepatic ducts
Carries bile from microscopic structures out of the liver from each lobe. Joins with the cystic duct to form the bile duct.
Variable arrangements.
Gallbladder
Between the quadrate and right medial lobes of the liver
Storage for bile
Neck is continuous with the cystic duct.
Cystic Duct
Carries bile to and from the gallbladder.
Joins with the hepatic ducts to form the bile duct.
Bile duct
Ductus choldochus
Created by the joining of the hepatic and cystic ducts
No valves = flow in two directions
Empties into the duodenum at the major duodenal papilla.
Major duodenal papilla
Termination of the bile duct and the pancreatic duct.
Most cranial papilla in the descending duodenum.
Parts of the Stomach
- Cardiac part (near esophagus)
- Fundus (left side)
- Body (middle)
- Pyloric part (right side)
Parts of the pylorus
- Pyloric antrum (initial and thin walled)
- Pyloric canal (narrower and thicker)
- Pylorus (sphincter)
Lesser curvature of the stomach
Faces mainly to the right
Greater curvature of the stomach
Faces mainly to the left
How does the position of the empty stomach differ from that of the full stomach?
Empty stomach: Hidden under the liver, strongly curved around the papillary process of the liver.
Full stomach: In contact with the ventral abdominal wall, displacing the intestinal mass.
Duodenum and its parts.
Most fixed part of the small intestine, suspended by mesoduodenum.
- Cranial duodenal flexure near the pylorus
- Descending part
- Caudal duodenal flexure
- Ascending part.
Where does the duodenum turn into the jejunum?
Duodenojejunal flexure
At the root of the mesentary
Jejunum
The coils of the small intestine, supplied by the cranial mesenteric artery.
Root of the mesentery attaches the jejunum to the dorsal body wall.
Mesenteric lymph nodes
Near the vessels in the mesentery.
Ileum
Continuous with the jejunum, recognized by the anti mesenteric iliac artery.
Ileocolic orifice
Junction between the ileum and the colon. Sphincter.
Cecum
S-shaped blind tube off of the colon.
Lies to the right of the colon.
Cecocolic orifice
Junction between the cecum and the colon.
Parts of the colon
- Ascending colon
- Right colic flexure
- Transverse colon
- Left colic flexure
- Descending colon
Rectum
Continuous with the descending colon
Parts of the pancreas
Body: at the pylorus
Left lobe: between the peritoneal layers that form the deep leaf of the greater omentum.
Right lobe: dorsomedial to the descending duodenum.
Pancreatic duct
Terminates in the descending duodenum with the bile duct at the major duodenal papilla
Accessory pancreatic duct
Terminates in the descending duodenum at the minor duodenal papilla (caudal to the major papilla).
Major pancreatic duct in the dog.
Adrenal glands
Light cortex and dark medulla
Crossed by the common trunk of the caudal phrenic and cranial abdominal veins.
What are the locations of the two kidneys?
Right kidney: L1-L3 (cranial)
Left kidney: L2-L4 (caudal)
What are the kidneys considered to be?
Retroperitoneal organs.
What passes through the hilus of the kidney?
Renal vessels and nerves and the ureter.
Renal pelvis
Expansion of the ureter to collect urine.
Renal sinus
Fat filled space that surrounds the renal pelvis and contains the renal vessels.
Renal cortex
Light, granular region on the periphery of the kidneys. Contains renal corpuscles and tubules.
Renal medulla
Darker, striated central portion of the kidneys that contains collecting ducts.
Arcuate branches
Branches of the renal vessels that appear at the corticomedullary junction
Renal crest
Ridge of the medulla projecting into the renal pelvis. Collecting tubules of the medulla end here.
Renal pyramids
Formed by the medulla and the intersections of the pelvic recesses.
Pelvic recesses
Projections of the renal pelvis outwards between the renal pyramids.
Where are the ovaries located?
Near the caudal poles of the kidneys.
Ovarian bursa
Thin walled peritoneal sac that encloses the ovary.
Slitlike orifice on the medial surface opens to the peritoneal cavity.
Formed by the mesovarium and the mesosalpinx.
Uterine tube
Oviduct. Runs through the lateral wall of the bursa from the ovary to the uterine horn.
Infundibulum
Dilated ovarian end of the uterine tube.
Fimbriated margin to catch eggs as they leave the ovary
Many fimbriae project through the orifice of the bursa into the peritoneum.
Abdominal ostium
The entrance of the infundibulum into the uterus, where fertilization takes place.
Tubouterine junction
Junction between the uterine horn and uterine tube.
Here the transit of sperm and ova are regulated.
Broad ligaments of the uterus
Peritoneal folds that attach the uterus to the lateral sublumbar region.
Three parts: mesometrium, mesovarium, and mesosalpinx.
Mesometrium
Attaches to cranial end of the vagina, uterine cervix, uterine body, and uterine horn.
Uterine horn
Long part of the uterus from the uterine body and cervix to the uterine tube.
Mesovarium
Cranial portion of the broad ligament and helps to create the ovarian bursa.
Mesosalpinx
Helps create the ovarian bursa and attaches the uterine tube to the mesovarium.
Suspensory ligament of the ovary
Holds the ovary in a relatively fixed position by connecting with the transversalis fascia.
Proper ligament of the ovary
Attaches the ovary to the cranial end of the uterine horn
Round ligament of the uterus
The free border of the mesometrium.
Homologue to the embryonic gubernaculum, which becomes the ligament of the tail of the epididymus in the male. Passes through the inguinal canal.
Patterning of the vagus nerve
Travels through the neck in the vagosympathetic trunk (GVE, GVA)
Separates from the sympathetic trunk at the thoracic inlet
RLNs branch off
Branches into dorsal vagal trunk and ventral vagal trunk caudal to the heart
Passes through the esophageal hiatus
Gives off a celiac branch
What do the dorsal and ventral branches of the vagus innervate?
The esophagus
Where does cranial nerve ten pass through the diaphragm
Vagus nerve; through esophageal hiatus
Dorsal vagal trunk
Uniting of the right and left dorsal vagal branches near the diaphragm
Ventral vagal trunk
Uniting of the right and left ventral vagal branches caudal to the root of the lung
What does the dorsal vagal trunk innervate in the abdomen?
Lesser curvature of the stomach, pylorus, small intestines, and adrenal glands.
What does the ventral vagal trunk innervate in the abdomen?
Liver, parietal surface of the stomach, and the pylorus.
Psoas minor
Cranial to the psoas major, running along the lumbar vertebrae within the abdomen.
Attachments: Fascia of the quadratus lumborum to T13 and L1-5, inserts on the arcuate line of the ilium.
What type of nerves are the splanchnic nerves? What are the types of splanchic nerves?
GVE sympathetics. Branch off of the sympathetic trunk. Major = First branch off at T12/13 Minor = before the adrenals Lumbar = after the adrenals
What does the major splanchnic nerve run towards?
Courses to celiacomesenteric ganglia and plexus.
What do the minor splanchnic nerves innervate?
Adrenal glands.
Terminates in celiacomesenteric ganglia and plexus.
How are the lumbar splanchnic nerves distributed?
To aorticorenal, cranial mesentaric, and caudal mesenteric ganglia and plexuses.
What does the celiacomesenteric ganglion and plexus consist of?
Celiac ganglia
Cranial mesenteric ganglion
Terminal plexus of celiac artery
What do the nerves of the caudal mesenteric ganglion innervate?
A portion of the colon
Right and left hypogastric nerves
Leave the caudal mesenteric ganglion and run caudally near the ureters, then enter the pelvic canal.
Lumbar arteries
Paired
Penetrated the dura and arachnoid to join with the ventral spinal artery and supply the spinal cord
Also supply muscles and skin above lumbar vertebrae.
Celiac artery
From the aorta between the diaphragmatic crura.
Three branches: hepatic, left gastric, and splenic.
Often covered by the celiac plexus.
Hepatic artery
First branch off the celiac, directed cranially towards the liver.
Branches into the hepatic branches (1-5), cystic artery, right gastric artery, and gastroduodenal artery.
Hepatic branches
Leave the hepatic artery
Supply the liver
One to five branches
Cystic artery
Leaves hepatic artery
Supplies the gallbladder
Right gastric artery
Leaves the hepatic artery.
Small artery that passes dorsal to the stomach and then supplies the lesser curvature of the stomach.
Anastomoses with the left gastric artery.
Gastroduodenal artery
Leaves the hepatic artery.
Supplies the pylorus.
Terminates with right gastroepiploic artery.
Right gastroepiploic artery
Terminal branch of the gastroduodenal artery.
Anastomoses with the left gastroepiploic artery and supplies the greater curvature of the stomach.
Cranial pancreaticoduodenal artery
Terminal branch of the gastroduodenal artery, follows the descending duodenum.
Supplies the duodenum and right lobe of the pancreas.
Anastomoses with the caudal pacreaticoduodenal artery.
Left gastric artery
Branch off of the celiac artery
Runs to the lesser curvature of the stomach and supplies both sides of the stomach.
Anastamoses with the right gastric artery near the pylorus.
Splenic artery
Branch off of the celiac artery
Crosses and supplies the left lobe of the pancreas
Enters the hilus of the spleen
Gives rise to the short gastric arteries and left gastroepiploic artery.
Short gastric arteries
Branches of the splenic artery
Supply the greater curvarture of the left side of the stomach.
Left gastroepiploic artery
Branch of the splenic artery.
Supplies the greater curvature of the stomach.
Anastomoses with the right gastroepiploic artery.
Cranial mesenteric artery
Unpaired, leaves the abdominal aorta just caudal to the celiac branch.
Branches into the common trunk of the middle and right colic arteries, the ileocolic artery, the caudal pancreaticoduodenal artery, the jejunal arteries, then terminates in the branches of the ileal arteries.
Middle colic artery
Arises from a common trunk with the right colic artery off the cranial mesenteric.
One branch supplies the descending colon and anastamoses with the left colic artery.
Other branch supplies the left colic flexure and transverse colon and anastomoses with the right colic artery.
Right colic artery
Arises from a common trunk with the middle colic artery off the cranial mesenteric.
Supplies the ascending colon, right colic flexure, and the transverse colon (anastomosing with the middle colic artery and colic branch of the ileocolic artery)
Ileocolic artery
Branch off of the cranial mesenteric artery.
Branches into the colic branch and the cecal artery, then continues as the mesenteric ileal branch.
Colic branch of the ileocolic artery
Supplies the ascending colon, anastomoses with the right colic artery.
Cecal artery
Branch off of the ileocolic artery.
Supplies the cecum
Then terminates as the antimesenteric ileal artery supplying the ileum.
Mesenteric ileal branch of the ileocolic artery
Termination of the ileocolic branch.
Supplies the ileum.
Anastomoses with the ileal arteries.
Caudal pancreaticoduodenal artery
Branch of the cranial mesenteric artery.
Supplies descending duodenum and right lobe of the pancreas.
Anastamoses with the cranial pancreaticoduodenal artery.
Jejunal arteries
Branches of the cranial mesenteric artery.
Form cascades in the mesentery and supply the jejunum.
Ileal arteries
Termination of the cranial mesenteric artery.
Supply the ileum, run through the mesentery.
Last branch anastamoses with the ileocolic artery.
Common trunk of the caudal phrenic and cranial abdominal arteries
Paired, arise from the abdominal aorta caudal to the cranial mesenteric and cranial to the renal arteries.
Caudal phrenic artery
Runs cranially to supply the diaphragm.
Cranial abdominal artery
Runs into the abdominal wall through the internal abdominal obliques, can be seen superficially.
Renal arteries
Paired, leave the aorta at different levels (right cranial to the left)
Right is longer than the left.
Supply the kidneys.
Ovarian arteries
Homologous to the testicular arteries.
Paired, caudal to the renal arteries.
Varies in size, position, and tortuosity depending on the size and the development of the uterus.
Supplies the ovary, ovarian bursa, uterine tube, and uterine horn.
Anastomoses with the uterine artery.
Testicular arteries
Homologous to the ovarian arteries.
Also paired, caudal to the renal artery.
Crosses the ventral surface of the ureter.
Lies in the mesorchium with the vein and nerve plexus, then through the vaginal ring.
Caudal mesenteric artery
Unpaired, arises from the abdominal aorta near its termination as the iliac arteries.
Runs in descending mesoduodenum and branches to the left colic artery and cranial rectal artery.
Left colic artery
Supplies the left colic flexure and anastomoses with the middle colic artery.
Cranial rectal artery
Descends along rectum and supplies.
Anastamoses with the middle rectal artery.
Deep circumflex iliac artery
Paired, arises from the abdominal aorta near the external iliac.
Crosses the psoas minor, perforates abdominal wall and supplies skin of the caudal abdomen, flank, and cranial thigh.
Portal vein
Returns blood from the GI tract to the liver and then to the caudal vena cava
Gastroduodenal vein: drains pancreas, stomach, duodenum, and greater omentum
Splenic vein: Drains lesser curvature of the stomach, spleen, pancreas, and greater omentum
Cranial and caudal mesenteric veins: drain the small intestine
Separates into a right and left branch as it enters the liver, to right and left three lobes each.
Levator ani muscles
Broad thin muscle lying dorsal to the internal obturator on the wing of the ileum.
Attachments: Medial edge of the body of the ileum and caudal vertebrae 3-7.
Coccygeus muscle
Lateral to the levator ani - can be seen on the medial surface of the leg next to the internal obturator.
Attachments: ischiatic spine and transverse processes of caudal verterbrae 2-4.
Pelvic diaphragm
Formed by the coccygeus and levator ani muscles.
Contract with the abdominal muscles to keep the viscera from moving into the pelvic canal.
In older dogs can become weak and may see perianal hernias.
Pelvic plexus
Lies near the colon, dorsal to the prostate, and near the vaginal/prostatic artery.
Joining of the hypogastric nerve (sympathetic) and pelvic nerve (parasympathetic).
Pelvic nerve
Parasympathetic preganglionic axons.
Very small, runs from the bladder to the pelvic plexus
Supplies: urogenital organs, rectum, descending colon.
Pararectal fossa
Extension of the peritoneal cavity dorsal to the rectum on either side of the mesorectum.
Extends to second caudal vertebra.
Rectogenital pouch
Continuous with pararectal fossa, ventral to this. Communicates with the uterus in the female.
Vesicogenital pouch
In the female, the pouch between the uterus and the bladder.
Iliac artery patterning
External iliac becomes the femoral artery.
Internal iliac branches into the caudal gluteal artery and internal pudendal artery. Also gives off the round ligament of the bladder, the remnant of the umbilical artery.
Small unpaired median sacral artery between the internal iliac.
Vascular lacuna
Where the external iliac exits the abdominal cavity and becomes the femoral artery.
Pubovesical pouch
Communication of the rectogenital (male) or vesicogenital (female) pouch between the bladder and the ventral body wall and pubis. Divided by the median ligament of the bladder.
Caudal gluteal artery
Branch of the internal iliac artery.
Supplies the muscles on the outside of the pelvis and the caudal thigh.
Internal pudendal artery
Branch of the internal iliac artery.
Vaginal/prostatic artery branches off here.
Supplies the pelvic viscera and external genitalia at the ischial arch.
Vaginal/prostatic artery
Branch off of the internal pudendal artery.
Termination = uterine artery or artery of the ductus deferens.
Uterine artery
Supplies the uterus, and branches into a caudal vesical artery and middle rectal artery.
Caudal vesical artery
Branch off of the uterine or artery of the ductus deferens.
Supplies bladder, urethra (both sexes)
Female - also runs in round ligament of the uterus to supply the uterine body and horn, anastomoses with the uterine branch of the ovarian artery.
Middle rectal artery
Branch off of the uterine or the artery of the ductus deferens.
Female: supplies rectum and vagina.
Male: supplies rectum, prostate, and urethra.
Artery of the ductus deferens
Branch off the prostatic artery.
Gives off caudal vesicle and middle rectal arteries.
Supplies the ductus deferens.
Ventral perineal artery
Termination of the internal pudendal artery after it passes the ischiatic notch with a variable urethral artery and artery of the penis/clitoris.
Branch here for the caudal rectal artery to the rectum and anus.
Artery of the penis
Terminates as three branches at the ischial arch:
Artery of the bulb of the penis
Deep artery of the penis
Dorsal artery of the penis
Surrounded by veins that will assist with erection.
Artery of the bulb of the penis
Arborizes in the bulb of the penis
Supplies corpus spongiosum and penile urethra.
Deep artery of the penis
Enters the corpus cavernous at the crus.
Dorsal artery of the penis
Supplies the prepuce and pars long glandis.
Artery of the clitoris
Supplies clitoris and vestibular bulb.
Cranial vesical arteries
Remnant artery of the umbilical artery that has not closed all the way to the round ligament of the bladder. Supply bladder.
Parts of the urinary bladder
Apex
Body
Neck: no gross sphincter but smooth muscle innervation makes a physiological sphincter
Lateral ligament of the bladder
Attaches the bladder to the pelvic wall, often contains adipose tissue.
Urethral muscle
Serves as a voluntary sphincter for the urethra
In the pelvic canal and surrounds the urethra.
Innervated by the pudendal nerve
Trigone of the bladder
Triangle formed by the urethra and the entrance of the ureters into the bladder.
What are the infoldings of the empty bladder called?
Rugae
Where is the rectum
Within the pelvic canal. Continuous with the colon and the anal canal.
Three zones of the anal canal
Columnar zone: (Mucosa forms longitudinal ridges/anal columns)
Cutaneous zone: Fine hairs, cirucumanal glands, and paranal sinus).
Anus: After the external sphincter muscle.
Paranal sinus
Anal sac
Opens into the cutaneous zone of the anal canal.
Where is the external sphincter muscle and what kind of muscle does it contain? What supplies the external sphincter muscle?
Surrounds the anal sac external to the cutaneous zone of the anal canal
Striated muscle
Innervated by the caudal rectal branch of the pudendal nerve
Supplied by the caudal rectal branch of the pudendal artery. `
Where is the internal sphincter muscle and what kind of muscle does it contain?
Enlargement of the smooth muscle coat of the anal canal near the anus.
Rectococcygeus muscle
Lies between the levator ani and the coccygeus to connect the anus with the tail
Attachments: dorsal surface of the rectum and sphincter muscles to caudal vertebrae.
Prostate gland (male)
Surrounds the neck of the bladder, varies in size.
Thick capsule that is partially divided into right and left lobes by a septum.
Uretral parts (male)
Pelvic part
Penile part
Based on location
Colliculus seminalis (male)
Hillock into the lumen of the urethra where the ductus deferens opens.
Parts of the penis (male)
Root (crura and bulb)
Body (fibrous region that “locks” by bending).
Glans (pars longa glandis and bulbis glandis)
Preputial orifice (male)
Opening of the prepuce
Haired region and smooth region of the prepuce meet here.
Fornix (male)
Deepest recess of the prepuce, pocketlike. Eliminated in erection.
Urethral crest (male)
Widening of the prostate into the pelvic urethra.
What are the crura of the root of the penis formed by? (male)
Corpus cavernosum penis
Vascular cavernous tissue
Extends from the ischiatic tuberosities on each side.
What is the corpus cavernosum penis supplied by? (male)
Deep artery of the penis
Tunica albuginea (male)
Thick fibrous white tunic surrounding the corpus cavernosum.
Ischiocavernosus muscle (male)
Arises from the ischiatic tuberosity and covers the origin of the crus, then inserts on the crus.
Retractor penis muscle (male)
Very long and skinny cordlike muscle. Mix of smooth and striated muscle.
Attachments: ventral surface of the sacrum, first 2-3 caudal vertebrae, and anal sphincters to the glans of the penis.
Bulbospongiosus muscle (male)
Bulges between the ischiocavernosus and covers the bulb of the penis.
Bulb of the penis (male)
Dorsal expansion of the corpus spongiosum.
Part of the root of the penis between the left and right crura and covered by the bubospongiosus m.
Corpus spongiousum (male)
Surrounds the urethra over its entire length.
Supplied by the artery of the bulb of the penis.
Ischiourethralis muscle (male)
Transverse muscle from ischial tuberosity to pelvic symphysis. Encircles the left and right dorsal veins of the penis, helping maintain erection.
Bulbis glandis (male)
Expansive vascular structure that surrounds the proximal end of the os penis
Helps retain the penis in the vagina during copulation.
Separated from the pars longa glandis by connective tissue.
Pars longa glandis (male)
Overlaps with the bulbis glands and continues to the distal end. Separated from the bulbis glands by connective tissue.
Os penis (male)
Forms about 1mo after birth from ossification of corpora cavernosa.
Ends in a pointed cartilagenous tip dorsal to urethral opening.
Deep V in the center of the os penis is called?
Which surface is it on?
(male)
The urethral groove
Surrounds the urethra and corpus spongiosum on 3 sides.
Ventral surface
Cervix (female)
Constricted caudal portion of the uterus. Small palpable enlargement grossly.
Cervical canal (female)
Vertical opening through the cervix.
Vagina (female)
Between the cervix and the vestibule. Mucosal lining has transverse folds so that it can expand.
Fornix (female)
s
Vestibule (female reproductive tract)
Continuous between the vagina and the vulva.
Contains the vestibular bulbs, fossa clitoris, and the urethral tubercle.
Urethral tubercle (female)
Projection of tissue where the vagina and urethra meet the wall of the vestibule.
Dorsal to the vulva.
Contains the external urethral orifice.
Vestibular bulbs (female)
Erectile tissue homologous to the bulb of the penis. Small and close to the clitoris in the vestibular walls.
Clitoris (female)
Female homologue of the penis. Located in the floor of the vestibule.
Glans clitoridis (female)
Two crura attached and a glans body. Very small erectile structure in the fossa clitoridis . May contain an os clitoridis.
Fossa clitoridis (female)
Contains the glans clitoridis, in the floor of the vestibule.
Do not mistake with the urethral opening (which is cranial and ventral farther into the vestibule).
Vulva parts (female)
Two labia that are joined by dorsal and ventral commissures.
Rima pudendi
Orifice formed by the parts of the vulva.
Neurons are? Axons are?
Excitable cells that are the functional unit of a nerve. Their axons move signals from one part of the body to another.
What are the layers of the meninges?
(Epidural/extradural space) The Dura mater (Subdural space - more spread out). The Arachnoid mater (subarachnoid space) The Pia mater
Cerebral spinal fluid cisterns
Cerebellomedullay (can access at the atlantoccipital joint).
Lumbosacral (can access at the end of L7).
What are the functions of cerebral spinal fluid?
Protect the central nervous system
Provide nutrients
Provide a sink for electrons
Provide buoyancy so the CNS weighs very little.
Brain epidural space
A potential space - not there unless something is wrong such as a hematoma. Its presence increases inter cranial pressure.
Spinal nerve formula for the dog?
C8 T13 L7 S3 Cd5 (36 pairs)
Caudal Equina
The combination of nerves L6-Cd5 that branch off of L5/6/7 (spp. dependent) like a horse’s tail.
Autonomic nervous system.
Synonym for visceral nervous system.
How do you test a reflex arc? What is going on in the nerves?
Often with skin pinching. Should see the cutaneus trunci twitch. This is from the afferent neuron communicating via a spinal cord interneuron in the spinal cord before the signal is sent to the brain.
How are the spinal nerves numbered in relation to vertebrae?
Cervical - for the vertebrae caudal to the nerve
Thoracic and beyond - for the vertebrae cranial to the nerve.
Nerve segments of the spinal cord starts to not match vertebrae at the lumbar portion.
Why can we breathe without thinking about it?
Strong reflex arcs of the diaphragm
Will cause us to pass out before we can suffocate ourselves.
What are some examples of SSAs?
Balance, Vision, Hearing
What are some examples of SVAs?
Taste, Olfaction
Cortical input
Conscious control
What do GVAs sense?
The internal environment mainly.
Chemical and physical status (temp, pressure, stretch, pH)
What do GSAs sense?
The external environment mainly.
Pressure temp and pain from bones, skin and CT.
Name some physiological responses to a sympathetic signal.
Increased:
HR, RR, airway diameter, urination
Decreased:
Pupil size (mydriasis), GI output and movement
Varied:
vascular smooth muscle depending on location
Name some physiological responses to a parasympathetic signal.
Decreased:
HR, RR, airway diameter, urination
Increased
Pupil size (miosis), GI output and motility.
What types of tissue only have connections to one type of GVE? What type?
Vascular smooth muscle
Piloerector muscles
Sweat glands
Have only sympathetic innervation. Other tissues normally always in flux state between the two.
What tissue within the heart carries electrical impulses from Purkinje fibers?
Trabeculae carnae.
“Right sided” circulation
Pulmonary, low pressure
“Left sided” circulation
Systematic, high pressure
What is the general venous return pathway for blood from:
- The head
- The front limbs
- Back/dorsum
- GI system
- Hind limbs and kidneys
- External jugular to cranial v.c.
- Cephalic vein to cranial v.c.
- Azygous to cranial v.c.
- Hepatic portal system to caudal v.c.
- Caudal v.c.
Ductus venosum
Normal fetal shunt for the umbilical artery through the liver.
What is the point of the FO and PDA?
To improve efficiency so that the fetal circulation does not have to go through the useless underdeveloped lungs.
S1 occurs in which phase of the cardiac cycle? What is it caused by?
Diastole
Closure of the aortic and pulmonary valves.
S2 occurs in which phase of the cardiac cycle? What is it caused by?
Systole
Closure of the atrioventricular valves
What are the stages of the cardiac cycle (5)?
- Atria contract (top off ventricles)
- Ventricles contract and pressure increases, AV valves close, Pul/Aortic valves open, and blood is ejected.
(1 and 2 are systole, shorter) - Ejection slows and ventricles relax.
- Aor/Pul valves close and AV valves open as pressure of ventricles drops
- Atria and ventricles fill (at the same time).
(3,4,and 5 are diastole, longer)
In which phase is the heart relaxed?
Diastole
What produces heart sounds?
Vibrations from the sudden increase in pressure on inelastic valvular tissue.
Puncta maxima localization scheme
P: Pulmonary valve, on the left 3rd intercostal space
A/M: Aortic/mitral valve, on left 4th intercostal space.
R: Right AV, on R 5th intercostal space.
L: Left AV on L 5th intercostal space.
Basal/Apical localization scheme
Combine P/A (basal) and R/L (apical)
Which heart sound can split? Why?
S2 in very athletic animals.
What would cause a murmur?
Turbulent blood flow due to stenosis or valvular insufficiency.
In what area can normal lung sounds be heard?
Around the large airways
Abnormal to hear sounds in smaller airways.
Which GVE has more broad coverage of the body?
The parasympathetic - into the brainstem as well.
How can you estimate the age of the animal from a thoracic radiograph?
Radiodensity of the thymus
Older animals have radiolucent (fattier) thymuses
What type of nerves is the brachial plexus primarily?
GSE and GSA
Some GVE for blood supply
What vessels supply the extensors of the antebrachium primarily?
Axillary and radial
What vessels supply the flexors of the antebrachium primarily?
Median and ulnar
What are the major sources of blood to the forepaw?
Median artery and caudal interosseous (radial branch).
Collateral circulation
If one blood supply is cut off the other can make up for it.
Is an open or closed castration technique preferred for small animals?
Open.
Peritoneal cavity is open but technique is aseptic so this is okay.
Vaginal cavity
Continuous with the peritoneal cavity. Around the testes.
Blood supply to the abdominal wall
Dorsal: Cranial abdominal artery and Deep circumflex iliac artery
Ventral: Cranial epigastric artery and caudal epigastric artery (and their superficial branches)
What does the diaphragm look like when the dog is in right lateral recumbency?
The right crus is pushed cranial to the left crus.
What is the main muscle of inspiration?
The diaphragm (others = muscles that pull the ribs laterally and cranially - external intercostals, serratis doornails, scalenus).
What is the main muscle of expiration
None - mainly the passive elastic recoil of the lungs and chest wall. Additional muscles recruited only with exertion.
Heave line
Mainly seen in horses.
Hypertrophy of the external abdominal obliques because of chronic effort to exhale due to an emphysema like condition caused by allergens.
How far does the abdominal cavity extend into the thorax via the cupula?
13th - 8th rib normally.
Name five structures on the left side of the abdomen?
Liver (both sides) L kidney Stomach Spleen Descending colon
Name five structures on the right side of the abdomen?
Liver (both sides) R kidney Descending duodenum Cecum Ascending colon
Name three structures in the dorsal abdomen?
Root of the mesentery
Transverse colon
Urinary bladder
What is found in the ventral abdomen?
The omentum
Spleen if enormously enlarged.
Functions of the omentum
Pads the organs
With damage forms adhesions with muscles to wall off areas of inflammation.
What is a sign of obesity in an abdominal radiograph?
A very clear falciform ligament in the ventral abdomen.
Where are the kidneys seen radiographically?
R kidney: L1-L3 (can only see the caudal pole in most radiographs)
L kidney: L2-L4
Name the unpaired arteries of the abdomen
Celiac
Cranial mesenteric
Caudal mesenteric
All supply the GI tract primarily
Why are splenectomies so time consuming?
Major branches of the splenic artery continue to the stomach and pancreas. Must ligate only the very small arteries next to the capsule of the spleen to avoid cutting off blood supply to those organs.
