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Functions of nervous system (3 most basic)
- Sensation: has receptors (usu. dendrites, send to CNS) to monitor environmental changes (stimuli) inside and outside of the body.
- Integration: parallel processing and interpretation of sensory information to determine response
- Reaction: motor output. Activation of muscles or glands, usu with neurotransmitters
functions of nervous system (5)
- initiate/regulate movement of body parts
- regulate secretions of glands
- gather information about exernal environment and status of internal environment
- maintain an appropriate state of consciousness
- stimulate thirst, hunger, fear, rate and sexual behaviors appropriate for survival
Nervous vs. Endocrine system
- similarities: both monitor stimuli and react to maintain homeostasis
- differences: NS is rapid, fast-acting system. Effects do not always perservere. ES acts slower via blood-borne chemical signals called hormones and actions are usually much longer lasting
central nervous system
brain and spinal cord
peripheral nervous system
cranial and spinal nerves. Communication between the CNS and the rest of the body
Sensory (afferent) nerves
somatic and visceral sensory nerves conduct impulses from receptors to the CNS. Cell body outside CNS in ganglia
Motor (efferent) nerves
motor nerve fibers that conduct impulses from the CNS to effectors (muscles and glands). Cell body inside CNS
somatic nervous system
voluntary (skeletal) system. conducts impulses from the CNS to skeletal muscles. Controlled by cerebrum. Single efferent neuron. Axon terminals release acetylcholine. Always excitatory
Automatic nervous system (ANS)
visceral motor (involuntary). Consists of sympathetic and parasympathetic systems. Conducts impulses from the CNS to cardiac muscles, smooth muscles and glands. Multiple efferent neurons. Axon terminals release acetylcholine or norepinephrine. Can be excitatory or inhibitatory. Controlled by homeostatic centers in brain--pons, hypothalamus, medulla oblongata
sympathetic nervous system
part of autonomic. fight or flight response. "E" division. Exercise, excitement, emergency. Thoracolumbar. Form a chain on either side of spinal cord (sympathetic trunk or ganglion). Binds with vagus nerves. Preganglion is short , postganglion is long. Cell body in sympathetic ganglion. R and L bundles supply head
parasympathetic nervous system
- part of autonomic system. Conserves energy and promotes "housekeeping" functions during rest. Slow and steady. Homeostasis. "rest and digest". "D" division. Digestion defecation and diuresis. Craniosacral. Long preganglionic, almost to organ, and short postganglionic. Opposite sympathetic.
- Includes Cranial nerves III, VII, IX, X
3 types of nerves and direction of travel
- sensory (afferent), toward CNS
- interneuron, integrating function, within CNS
- motor (efferent), away from CNS
somatic motor neuron
1 efferent neuron. Conscious or voluntary. Skeletal muscle (sensory and motor)
automatic motor neuron
2 motor neurons (pre-ganglionic and post-ganglionic). Involuntary. Glands and smooth or cardiac muscle
basic functional unit of the nervous system. Initiates and conducts impulses. High oxygen levels. Can't reproduce, but can regenerate if the body is okay.
neuroglia or glial cells
- structurally and functionally support neurons. Helpers.
- Function as binding agents to maintain form of nervous system (myelin sheath).
- Provide metabolic support and play a role in repair of damaged nervous tissue.
- 50x more of them than nerves.
- Can divide.
- Oligodendryte and Astrocyte
parts of a neuron
- cell body (soma, perikaryon)
- dendrites (little branches off the body
- axons (long thin branch off body)
control center of neuron. Synthesizes enzymes and other molecules essential to normal function. If the body dies, the neuron dies. Contains lots of mitochondria, nuclei, golgi bodies, lots of rough ER called nissl bodies (makes a lot of proteins). No mitosis stuff. Also has myofibrils to support.
a group of nerve cell bodies in the CNS is called
a nuclei. Same as a ganglia in the PNS
a group of nerve cell bodies outside the brain in the PNS is called
ganglia. Same as nuclei in the CNS.
an arm-like extension emanating from every neuron. There are two kinds of processes: axons and dendrites.
the short branches off the cell body of a neuron. Recieve stimuli or impulses from other neurons and conduct stimulation to the cell body. Ends of dendrites are modified receptors. Lots of branches per neuron.
conducts nerve impulses away from the cell body toward another neuron or effector. SIngle long process, has neurofibrils but no nissl bodies. Contains axon hillock and telodendrian synaptic knobs (terminal bulbs)
"neck" from cell body leading into axon.
telodendrion synaptic knobs
terminal bulb of an axon, leading another nerve or to an effector organ.
bundles of nerve processes in the CNS are called
tracts or fasciculi. Like nerves in the PNS
bundles of nerve processes in the PNS are called
nerves. Like tracts/fasciculi in the CNS
axon plasma membrane
connecting neurons. Whole thing is contaned in the CNS
- function: to increase speed of impulse conducion along the axon and to insulate the nerve process
- a neuroglial cell wrapped around an axon or dendrite many times is a myelinate fiber.
a myelin sheath cell in the CNS is called a
oligodendrocyte. Like a schwann cell in the PNS.
a myelin sheath cell in the PNS is called a
schwann cell. Like an oligodendrocyte in the CNS.
Where cell is pushed to the outside by myelin sheath--assist in regeneration of injured axons.
creates myelin sheath in CNS
creates myelin sheath in PNS
medical specialty dealing with disorders of the heart and blood vessels
circulatory system components and function
heart, blood vessels and lymphatics. Function: provides for the metabolic requirements (nutrition, waste removal, protection) of the body's cells via the blood, the interstitial fluid and the lymph
lies in the mediastinum (area of thorax between the lungs). Between ribs 3 and 7 in cats and dogs. Between ribs 2 and 6 in horses and ruminants
base of heart
the wider, top part where the major vessels are
apex of heart
where the ventricles come to a point.
area of the thorax between the lungs
- fibrous pericardium: outer layer that covers heart.
- serous pericardium: two layers (visceral and parietal). Parietal lies just inside the fibrous, then pericardial space, then visceral serous layer directly on the outside of the heart.
layers of the heart and pericardium
- fibrous pericardium
- parietal serous pericardium
- pericardial cavity
- visceral serous pericardium/epicardium
number of chambers in the heart of a fish, amphibian, crocodile, reptile, bird, mammal
- fish - 2
- amphibian - 3
- crocodile - 4
- reptile - 3
- bird - 4
- mammal - 4
Circulation of blood through the heart
- Caudal/cranial vena cava
- right atrium
- right ventricle
- pulmonary trunk
- pulmonary arteries
- pulmonary veins
- left atrium
- left ventricle
- cranial/caudal vena cava
- right atrium
- right ventricle
- pulmonary trunk
- pulmonary arteries
- pulmonary veins
- left atrium
- left ventricle
- rest of body
Cardiac conduction cycle
- S-A node creates signal that contracts atria
- signal reaches A-V node and pauses.
- Signal spreads through His-Purkinje fibers, contracting ventricles.
modified muscle tissue that initiates the heart beat. Located in wall of RA, ventral to opening of cranial vena cava.
bridge between the atria and ventricles. Electric impulses travel from the atria down to the ventricles through the AV node. Interatrial septum, cranial to valve.
carries the electrical signal from the SA and AV nodes through the ventricles. Atrioventricular bundle (bundle of His), right bundle branch, left bundle branch, purkinje fibers.
fetal circulation shunts (3)
- shift blood away from unnecessary liver and lungs.
- ductus venosus (from umbilical vein through liver to vena cava, bypasses liver)
- foramen ovale (opening wall in wall separating atria, bypassing lungs)
- ductus arteriosus (shunt between pulmonary trunk and aorta, bypassing lungs).
duct between umbilical vein through liver to vena cava, bypassing liver in fetus.
fetal opening in the atrial septum, bypassing lungs in fetus. Adult remnant is fossa ovale.
adult remnant of foramen ovale
adult remnant of the ductus arteriosus between pulmonary trunk and aorta
fetal shunt between the pulmonary trunk and aorta bypassing lungs. Should close within 3 days of birth and be firmly closed by 7-10 days old.
base of heart
top, craniodorsal. Receives the great veins and sends out the great arteries
directed down, caudoventral. Always formed by left ventrical
arches caudally, comes from left ventricle
blind pocket off atria on top of heart. point to left with pulmonary trunk in between. Contain pectinate muscles that help open the valves
funnel-shaped end of right ventricle that leads into pulmonary trunk
partially encircles the heart, separating atria from ventricles. Contains coronary vessels. Band going around heart.
Paraconal interventricular groove
adjacent to conus. On exterior of heart, indicating the interventricular septum separating the ventricles. Carry vessels that feed the heart. Seen from front of heart.
Subsinuosal interventricular groove.
Right side of heart below coronary sinus. On exterior of heart, indicating the interventricular septum separating the ventricles. Carry vessels that feed the heart. Seen from back of heart.
where coronary veins empty into right atrium
top chamber on the right side of the heart. Cranial and caudal vena cava and coronary vein dump in. Contains the tricuspid valve
separates right atrium and ventricle. 2 cusps in a dog, three cusps in others
lower chamber on right side. Pumps into pulmonary trunk through pulmonic valve (semilunar). Wall on this side is thinner than the left.
top chamber on the left side of the heart. pulmonary veins pump in, leaves through bicuspid or mitral valve.
lower chamber on left side. Pumps into aorta through aortic semilunar valve.
attach to chordae tendinae, keeping valves from everting into atria
chords that link valves to papillary muscles, keeping valves from everting.
2 cusps, between left atrium and ventricle
skeleton of heart
connective tissue that separates atria from ventricles and attaches heart valves. Contains cartilage and bones (ossa cordis) in ox and older horses.
- great artery learving left ventricle and arching caudally. Oxygenated blood from heart to body.
- 3 parts: ascending aorta, aortic arch (brachiocephalic, subclavian, common carotid), descending aorta (thoracic and abdominal)
pockets between the aortic valve's cusps and the vessel wall. Right and left coronary arteries arise from the right and left sinuses, respectively.
contraction of ventricles. Occurs between the 1st and 2nd heart sounds (lub to dub).
relaxation of the ventricles. Occurs between 2nd and 1st heart sound (dub to lub)
right coronary artery goes around heart, branches to form subsinuosal interventricular bridge, which turns into paraconal interventricular bridge, which connects to left cornary artery. Also runs in coronary groove straight from right to left coronary arteries, becoming circumflex bridge in between.
- sound of heart valves closing.
- 1st: "lub", AV valves (tricuspid and bicuspid)
- 2nd: "dub", semilunar valves (aortic and pulmonic)
location of heart
second to third intercostal space to sixth or seventh. 2/3 of the way up thorax.
PMI (pulmonic, aortic, mitral)
- point of maximum intesity. The point on the thoracic wall where the valve sound is loudest.
- Pulmonic-left 3rd intercostal space at level of olecranon
- aortic valve-left 4th intercostal space at level of the shoulder
- mitral valve-left 5th intercostal space at level of olecranon
- PAM 3 4 5
abnormal sounds caused by blood flow turbulence, due to vavular or nonvalvular problems
PDA (patent ductus arteriosus) murmur
continuous (systolic and diastolic) "washing machine" sound. PDA still open.
VSD (ventricular septal defect) murmur
hole in ventricular septum. Loud systolic murmur
Where to take a pulse in cat, dog and horse
- Cat and dog: femoral or digital arteries
- horse: facial artery (by jaw, just rostral to curve), transverse facial artery (by eye), median artery (medial forearm), digital arteries
- consists of heart, blood vessels and lymphatics. Provides for metabolic requirements (nutrition, waste removal, protection) of the body's cells
- Consists of blood vascular system and lymph vascular system
blood vascular system
heart, arteries, capillaries, veins
lymph vascular system
- consists of lymph, lymph vessels, lymph nodes and lymphatic organs. Filter waste and bacteria from interstitial fluid.
- maintains fluid balance between vessels and tissues
- immunity and absorption of digested fats in small intestine
- Primary and Secondary organs
artery is away from heart, vein is toward, capillaries are tiny vessels connecting smallest veins and arteries
- carry blood away from heart. Tend to be twisty or in protected areas. Higher-pressure portion of the circulatory system.
- Systemic: oxygenated blood from heart to body
- pulmonary: deoxygenated blood from heart to lungs
- Contain elastic fibers more than muscle--can carry a lot of blood and snap back, helping with blood pressure
when blood vessels connect to form a region of diffuse vascular supply. Critical alternative routes in case of a blockage (collateral circulation)
when an area of tissue or an organ has a number of different pathways for blood to reach it. (anastomoses)
vessel that shunts blood from an artery to a vein in order to bypass a capillary under certain conditions--temperature regulation or to allow tissue/gland to rest
singular rete. Refers to a network of anastomoses or blood vessels, connective. Example renal glomerulus
layers of artery and vein
- tunica intima (endothelium) - most internal. Epithelial, connective and elastic
- tunica media (middle) - elastic and smooth muscle
- tunic adventitia (outer) - tough fibrous layer
- Capillaries only have tunica intima (endothelium)
- pores in the endothelial cells that allow small molecules and limited amounts of protein to diffuse
- endocrine glands, intestines, pancreas, glomeruli of kidney
sinusoidal capillaries (discontinuous)
- special fenestrated capillaries with larger openings to allow red and white blood cells and serum proteins to pass through--very leaky.
- liver, spleen, bone marrow, lymph nodes and adrenal gland
- carry blood back to the heart (usually deoxygenated except pulmonary)
- blood flows slowly with no pulse and at low pressure
- thinner walls, same three layers
- greater size and capacity than arteries (not aorta).
- blood squeezed along veins by skeletal muscles.
- Valves to prevent backward flow of blood.
Primary organs of lymph system
- thymus gland and bone marrow
- regulates the production and differentiation of lymphocytes--the cells that make up the immune system.
Secondary organs of the lymphatic system
- include the lymphatic vessels, lymph nodes, aggregated lymphoid tissue and spleen.
- involved in all three lymphatic functions
- Tissue fluid enters lymphatic capillaries, becoming lymph
- Contains lots of WBCs, protein, cellular debris, foreign particles and bacteria. GI lymph contains digested fat from the small intestine
lymphatic vs veins
- similarities: thin walled and return fluid to right side of heart, fluid moved by muscle contraction, valves to prevent backflow
- differences: lymph passes through lymph nodes before blood to filter out cell parts, cancer cells and bacteria
- firm and smooth. Consist of lymph tissue surrounded by a fibrous sheath. Comprised of primitive cells and macrophages
- Reactive: swollen secondary to activity
Palpable lymph nodes in cat and dog
- cat: prescapular, submandibular, sometimes popliteal
- dog: parotid, submandibular, prescapular, axillary, superficial inguinal, popliteal
cavernous tissue. Closely-packed spaces continuous with blood vessels. Engorge when fed by arterioles. Found in genital tissue and (modified) in teat and nasal mucosa
- "vessels of the vessels". network of small blood vessels that supply large blood vessels.
- These small arteries are distributed to the outer and middle coats of the larger blood vessels--provide nutrients
get afferent and efferent innervations. Mostly sympathetic nervous system
sensory nerve terminal that is found in blood vessel walls and is stimulated by changes in pressure (carotid sinus)
a baroreceptor. Dilation of the proximal portion of the internal carotid or distal portion of the common carotid artery, containing in its wall pressoreceptors (baroreceptors) that are stimulated by changes in blood pressure
found in the large arteries of the thorax and neck. Responsive to changes in the oxygen, carbon dioxide and hydrogen ion concentration in the blood. (ex. carotid and aortic bodies)
a chemoreceptor. A small neurovacular structure lying in the bifurcation of the common carotid arteries, containing chemoreceptors that monitor oxygen content in blood and help to regulate respiration.
where coronary arteries come off
the first branch off aorta arch, present in all domestic species. Gives rise to the common carotid arthery and the right subclavian artery
right and left common carotid arteries
ascend the neck to supply the head, face and brain. Ascend neck with the vagosympathetic trunk to terminate near the larynx into the internal and external carotid arteries. Separate or together (bicarotid trunk)
External/common carotid artery
the large direct continuation of the common carotid artery supplying the head and face. Becomes the maxillary artery.
internal carotid artery
smaller terminal branch of common carotid goes to brain.
direct continuation of external carotid artery to the space below the orbit. Its branches supply orbit, teeth, chin, nose, nasal cavity and palate.
Right and left subclavian arteries
- supply neck, thoracic limb and cranial portion of thoracic wall.
- Right subclavian comes off brachiocephalic artery in all species.
- In carnivores and pig left subclavian comes directly off aortic arch after brachiocephalic
axillary arteries (L and R)
direct continuation of subclavian artery past the first rib to the thoracic limb. Caudal to humerus, medial surface of limb. Passes through cat's supercondyloid foramen.
brachial arteries (R and L)
- direct continuation of axillary on medial surface of leg. In cat, passes through supracondylar foramen making it dangerous if humerous if broken.
- Has multiple branches. Common interosseus artery has cranial and caudal interosseous branches.
- Becomes the median artery in the forearm
path of brachiocephalic
continuation of brachial artery (after axillary after subclavian after brachiocephalic). largest artery supply to manus in all but cat (radial)
arises from aorta or from one of the dorsal intercostal arteries. Its bronchial branch is the nutritional supply to tisues of the lungs
dorsal intercostals arteries
- Splits into two branches after coming off thoracic aorta.
- Main branch courses ventrally on caudal ribs to anastomosis with ventral intercostal artery.
- Dorsal branch courses dorsally to vertebral column. Runs with azygous vein and thoracic duct.
ventral intercostal arteries
arises from the internal thoracic artery and courses between the ribs supplying the ventral thoracic wall eventually forming an anastomoses with the dorsal intercostal arteries
part of descending aorta caudal to diaphragm. Along roof of abdomen between caudal vena cava and psoas muscle. Caudal to last lumbar vertebra branches to internal iliac (to pelvis) and external iliac (to pelvic limb)
main branches off abdominal aorta
- celiac (unpaired)
- cranial mesenteric (unpaired)
- renal (paired)
- gonadal (testicular or ovarian--paired)
- caudal mesenteric (unpaired)
first unpaired branch off the abdominal aorta after passing through diaphragm. Contains hepatic, splenic and left gastric
supplies liver and gall bladder, as well as stomach and cranial small intestine. Off of celiac aftery
off of celiac. Supplies spleen and stomach
left gastric artery
off of celiac. Supplies left side of the lesser curvature of the stomach.
- the largest visceral branch off the abdominal aorta arising caudal to celiac artery.
- Branches to ileocolic, with jejunal and ileal branches
- Courses caudoventrally in the mesentery to supply most of intestine.
tissue on edge of GI tract.
paired arteries originating from aorta caudal to the cranial mesenteric artery. Pass to each kidney.
Caudal mesenteric artery
the smallest unpaired major branch of the abdominal aorta. Arises near termination of abdominal aorta. Supplies colon and rectum
external pudential artery
(branch off deep femoral artery) supplies scrotum and vulva respectively
the larger branch of the abdominal aorta. Primary supply to the hindlimb. Gives off deep femoral artery then penetrates abdominal wall.
the continuation of the external iliac artery through the femoral triangle, passing distally to continue as the popliteal artery caudal to the stifle
branch of the femoral artery on the medial surface of leg
caudal femoral artery
supplies caudal thigh.
the continuation of the femoral artery after the caudal femoral artery branches off passing between the two heads of the gastrocnemius muscle, it branches into cranial and caudal (small) tibial arteries
the area bounded by the sartorius muscle cranially, the pectineus muscle caudally, and the body wall dorsally.
the terminal branch of the aorta that enters pelvic cavity. It branches into caudal gluteal artery and internal pudendal artery
caudal gluteal artery
supplies muscles of lumbosacral junction, gluteal muscles and hamstrings
Internal pudendal artery
terminates as the ventral perineal artery and the artery of penis or clitoris
prostatic or vaginal artery
supplies the urogenital organs in the pelvic cavity.
arises from internal iliac or internal pudendal and passes to apex of bladder
external jugular vein
the large vein in the neck returning blood from the head
vessel returning blood from thoracic limb to heart (upper forelimb). Brachial vein to axillary vein to subclavian vein
found only in the carnivore and pig, formed by the intersection of the external jugular and the subclavian veins. Empties into the cranial vena cava.
cranial vena cava
runs through mediastinum into heart.
draws from lingofacial vein and maxillary vein. Runs between brachiocephalicus and sternocephalicus muscles
arising in the abdomen, passes through diaphragm and runs with aorta into chest. Empties into cranial vena cava or directly into right atrium. Drains the dorsal intercostal veins. Carnivores lack a left azygous.
runs up cranial surface of arm crossing the flexor surface of elbow. Joined by accessory cephalic vein. Drains distal forelimb, empties into external jugular
median cubital vein
connects the superficially located cephalic vein with the deeply located brachial vein over the flexor surface of elbow
Internal iliac vein
drains pelvic wall and cavity
external iliac vein
drains pelvic limb. Becomes femoral.
continuation of external iliac vein.
Common iliac vein
internal and external iliac veins join to become the common iliac. It then joins the caudal vena cava
medial and lateral saphenous veins
hind limb. medial empties into femoral and lateral empties into distal caudal femoral.
drain kidney and feed caudal vena cava
drain liver sinusoids directly into caudal vena cava without leaving liver
combines with cranial and caudal mesenteric vein, and gastroduodenal vein to form portal vein
hepatic portal vein
large vein coming from intestinal mass into hilus of the liver. Drains spleen, digestive organs, caudal thoracic esophagus and (distantly) rectum. Drains into the liver sinusoids of liver so intestinal blood can be cleaned before entering general circulation
where aren't there lymph vessels?
brain, spinal cord and bone marrow
groups of lymph nodes draining the same region of the body in all species
where ducts or trunks empty into the large veins in the thoracic inlet.
lymph nodes that drain the head
parotid, mandibular and medial and lateral retropharyngeal
Nodes of Ranvier
Gaps between the cells of the myelin sheath--impluse jumps from node to node, allowing for more rapid conduction of nerve impulses
An unmyelinated nerve is
still surrounded by schwann cells but not myelin sheath.
myelinated axons in the CNS.
neuron cell bodies in CNS.
Basic nerve types (4)`
- unipolar: 1 process, only seen in development
- bipolar: 1 axon and 1 dendrite
- multipolar: number of dentrites and one axon. Most nerves
- Pseudounipolar: 1 dendrite and 1 axon, fused together to look like 1 process. Sensory
Brain parts (4, 7)
- brain stem:Medulla oblongata
- largest part of brain in most animals, usually more dorsorostral. Telencephalon
- Responsible for "higher order" functions (learning, intelligence, awareness).
- Interprets sensory info, initiates conscious voluntary nerve impulses to skeletal muscles.
- Integrates nerves for communication and memory.
- R and L hemispheres are divided by longitudinal fissure and connected by corpus callosum. Sulci divide into lobes--frontal, parietal, temporal, occipital, etc.
- Grey matter on the outside, white matter on the inside, basal nuclei (initiation and maintinence of normal motor activity)
- Contralateral (opposite). Damage R cerebrum, damage L side of body.
Arrangement of grey and white matter in the brain
white matter on the inside (medulla) , grey matter on the outside (cortex)
gyrus, sulcus, fissure
folds and lines in the brain, a very deep fold
separates the brain into R and L hemispheres
ventricles of brain
air-filled spaces in the brain that develop from lumen of embryonic neural tube. Lateral (2, interventricular foramen), third (mesencephalic aqueduct) and fourth (communicates with subarachnoid space surrounding the CNS through two lateral apertures. .
Cerebellum receives impulses from:
- proprioceptors in joints, muscles and pressure areas (foot pads)
- Equilibrium apparatus in inner ear
- Visual cortex
- Motor cortex
center-top of cerebellum separating R and L hemispheres.
Tree of life--pattern of medulla in cerebellum.
- coordinating voluntary movement. Allows body to have smooth, coordinated movement, posture, balance and complex reflexes. Has sensors to see if orders are being carried out.
- Acts as a collecting house for info reguarding the instantaneous physical status of body.
- Ipsilateral (R cerebellum damage = right body damage)
meaning "between brain". Serves as nervous system passageway between the primitive brain stem and the cerebrum. Contains Thalamus, epithalamus, hypothalamus, hypophysis, third ventricle.
- most primitive part of brain, maintains basic support functions, operates on a subconscious level. Consists of medulla oblongata, pons and midbrain (mesencephalon). Connection between the rest of brain and the spinal cord.
- Origin of many cranial nerves. Involved in autonomic control related to heart, respiration (cough, sneeze, hiccup), blood vessel diameter (vasomotor control), swallowing, vomiting.
important in initiation and maintinence of normal motor activity.
white part in center of brain that connects the right and left cerebral hemispheres
relay station for regulating sensory input to the brain. In Diancephalon
Part of Diancephalon. Contains an olfactory correlation center and the pineal gland. Pineal gland is an endocrine gland in mammals that secretes melatonin, important to circadian rhythms and sleep cycles.
part of diencephalon that links nervous and endocrine systems. Function in autonomic activities and behavior. Plays role in hunger, thirst, temp control and component of rage and anger response
Pituitary gland. part of diencephalon. One of the most important endocrine glands. "master gland" that regulates hormone production and release throughout the body
Midbrain. Auditory and Visual reflex center, the nuceli of two cranial nerves and several descending tracts.
Contents of Medulla and Pons
- Many ascending and descending pathways
- sensory and motor nuclei for most of cranial nerves originating in the brain stem
- a large part of central mechanism of the postural reflexes
- Several reflex centers associated with autonomic visceral functions (heart rate, blood vessels, muscle tone, respiration, and motor and sensory activities of the GI tract
Associated with olfaction, autonomic functions and certain aspects of emotion and behavior. It si regulated centrally by the hypothalamus. Defense and procreation (where telencephalon meets brainstem)
White and grey matter in Cerebrum, Cerebellum, diencephalon, spinal cord and brain stem
- Cerebellum, Cerebrum: white on inside, grey on outside
- Diencephalon, brain stem, spinal cord: grey on inside and white on outside
a tuft of capillaries that protrudes into the lumen of each ventricle. It is responsible for forming the bulk of the cerebrospinal fluid (CSF)
fills the ventricles and surrounds the CNS. Continuously formed, circulated, and reabsorbed in the spaces of the nervous system. Has arachnoid granulations. Cushioning effect for the brain and spinal cord. Chemical composition may be involved in regulation of some autonomic functions such as respiration and vomiting
tiny structure that protrudes into blood filled dura sinus and act as one way valves for return of CSF from subarachnoid space to venous blood
certain nerurological disorders can be diagnosed by taking a sample of CSF and analyzing its content for changes in protein, cell type and other specific changes in composition. Take CSF from subarachnoid space
water on the head. Condition in which excessive is found within and around the brain. The body may form too much fluid or the fluid is not drained.
- connective tissue coverings of brain and spinal cord. From superficial to deep:
- dura mater
- pia mater
- House a rich supply of blood vessels that supply nutrients and oxygen to superficial tissue of brain and spinal cord. The fluid, fat and connective tissue also provide cushioning and distribution of nutrients for the CNS
tough fibrous outer covering of CNS. Intimately attached to inside of cranial bones. Forms inner periosteum. Splits into two layers (Dural sinuses). Venous space formed filled with blood. Empty into jugular vein to go back to the heart. CSF retrned to the general circulation from subarachnoid space to dural space.
an artifical space created by a separation between the dura mater and the arachnoid as a result of trauma, pathologic processes, or absense of CSF seen in cadavers
delicate spider web-like middle layer. (subarachnoid space is the space between arachnoid and pia mater, filled with CSF)
an expansion of the subarachnoid space located between the caudal surface of the cerebellum and the dorsal surface of the medulla, just inside the foramen magnum. CSF tap site
deepest layer over brain. Delicate membrane. Sheath around blood vessels==follows into CNS
refers to the pia and the arachnoid together
blood brain barrier
A functional barrier separating the capillaries in the brain from the nervous tissue. Stops foreign chemicals from getting into brain. Glials cover capillaries and capillaries have no holes. Need drugs that can pass through barrier
Where spinal cord ends right after sacrum. Looks like a horse tail
conducts sensory information and motor instructions between the brain and periphery of the body. A considerable amount of processing and modification of nerve impulses between brain and the peripheral nerves takes place in spinal cord. Grey matter inside (butterfly! Neuron cell bodies), white matter outside (myelinated tracts)
Spinal cord segment
area of cord defined by the presence of a pair of spinal nerves
dorsal root ganglion
where sensory neuronal cell bodies are present. Meets up with ventral root to make spinal nerve (mixed afferent and efferent)
spinal grey matter, sensory (afferent) nerve. Meets ventral horn to make spinal nerve
spinal cord grey matter; motor (efferent) nerve. Meets dorsal horn to make spinal nerve
Spinal cord tracts
a bundle of functionally related axons in the CNS. Descending (motor) and ascending (sensory). Found in the white matter of the spinal cord.
Peripheral nervous system
includes the nerves and ganglion outside the CNS. Convey sensory information to the brain and spinal cord and to produce movement of muscles and secretion from glands via its motor nerves. Includes cranial nerves.
- 12 pairs of cranial nerves arising from brain. Each pair numbered in roman numerals. May contain motor axons, sensory axons or combination of both.
- I-Olfactory -- sensory -- smell
- II-Optic -- sensory -- vision
- III-Oculomotor -- motor -- eye movement, pupil size, focusing lens
- IV-Trochlear -- motor -- eye movement
- V-Trigeminal -- sensory/motor -- sensations from head and teeth, chewing
- VI-Abducent -- motor -- eye movement
- VII-Facial -- sensory/motor -- face and scalp movement, salivation, tears, taste
- VIII-Vestibulocochlear -- sensory -- balance and hearing
- IX-Glossopharyngeal -- sensory/motor -- tongue movement, swallowing, salivation, taste
- X-Vagus -- sensory/motor -- sensory from GI tract and respiratory tract, motor to the larynx, pharynx, parasympathetic to abdominal and thoracic organs
- XI-Accessory -- motor -- Head and neck movement, swallowing and vocalizing
- XII-Hypoglossal -- motor -- tongue movement
Cranial nerve sensory/motor mneumonic
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cranial nerve function mneumonic
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- dorsal and ventral branch (both mixed nerves).
- With exception of cranial and caudal nerves a pair of spinal nerves (R and L) emerges caudal to the vertebrae of the same number and name.
- Same number thoracic, lumbar, and sacral nerves as vertebrae.
- first pair of cervical nerves emerges through lateral vertebral foramina of atlas and axis. (8 pair cervical nerves, though 7 cervial vertebrae). Usually fewer caudal nerves than vertebrae.
an area of skin supplied by a single spinal nerve
- Plexus: interlacing of the ventral branches of spinal nerves adjacent to vertebral column in every region except thorax.
- Cervical, Brachial and Lumbosacral Plexus
Intercostal thoracic nerves
do not form plexus. Supply the intercostal muscles and overlying skin. Pass into intercostal spaces, so no plexus.
axillary (armpit) region. Last few cervical to first few thoracic. Supplies most muscles of thoracic limb. Same organization and distance in all domestics, but not same by digits. Innervate intrinsic and some extrinsic muscle of the thoracic limb and vial the phrenic nerve, the diaphragm
- Largest branch from brachial plexus. Motor impulses to extensor muscles of the elbow, carpus and digits. Sensory impulses to brain from craniolateral forearm in all species and dorsal surface of paw in all but the horse. Helps extend.
- Extends from brachial plexus into triceps brachii, then around caudal aspect of humerus to lateral side of arm. Continues distally into superficial and deep branches to forearm.
Sign of radial nerve damage
- Motor: high: inability to bear weight because animal can't extend the elbow
- low: knuckling over. Paw can't be extended.
- Sensory: analgesia to dorsal surface of paw and forelimb (only to carpus in horses)
Median and ulna nerve
- Median gives motor impulses to most flexors of the forearm. Runs with the brachial vessels and ulna nerve in arm.
- Ulna gives motor to some flexors of forearm and muscle of manus. Most caudal of the three brachial plexus nerves. Medial side of arm. Funny bone.
- Both carry sensory impulses to brain from palmer manus (foot pads). Ulna is also sensory to caudal forearm and is the sensory innervation of fifth digit in dogs
- Carpus and fetlock will sink if both nerves are damaged. Gait will not change with either.
innervates the flexors of elbow (biceps brachii and brachialis). Damage causes motor inability to flex elbow and sensory--medial side of limb
innervates infraspinatus and supraspinatus muscles. Damage causes sweeny--atrophy of supra- and infraspinatus muscles
motor latissimus dorsi. No sensory
motor to the shoulder flexors (deltoid, teres major and minor). Sensory to cranial arm and forearm.
Equine nerve blocks
- median, ulnar and median cutaneous antebrachial (branch of musculocutaneous) are the three sensory nerves that extend past the carpus.
- Nerve blocks can determine which is damaged and localize the problem causing lameness
consist of ventral branches of the lumbar and sacral nerves. Nerves supply to pelvic limb, external genitalia, rump and perineum
pelvic. Found on medial surface of the thigh running with the femoral artery and vein. Motor function to muscles of the thigh (extensors of stifle--quads) and sensory from skin, hips, thigh, leg and knee. Inability of stifle to bear weight.
superficial branch of femoral nerve, cutaneous innervation to medial side limb, motor to sartorious.
motor to medial adductor muscles of thigh. Damage is lateral slipping on a slick surface due to loss of adductor muscle control
Becomes ischiatic nerve. Cranial gluteal, caudal gluteal, and caudal cutaneous femoral nerve.
part of lumbosacral trunk, which becomes ischiatic nerve. Flexor and extensor of hip (tensor fascia latae, deep and middle gluteal and sometimes superficial)
part of lumbosacral trunk which becomes ischiatic nerve. Extensor of hip (superficial gluteal and proximal part of hamstring)
Caudal cutaneous femoral nerve
part of lumbosacral trunk which becomes ischiatic nerve. Sensory innervation caudal thigh.
- splits into tibial and common fibular (peroneal) nerves. Supplies the caudal thigh muscle and by its terminal branches the muscle of crus and pex (ankle, bottom leg).
- Continues the lumbosacral trunk caudal to hip joint, to run distally caudal to femur and deep to biceps femoris muscle.
Ischiatic nerve damage
results in knuckling over (peroneal nerve) but can bear weight (intact femoral nerve). Loss of sensation below stifle, except on medial side (saphenous nerve), Not bearing weight is femoral.
- one of the terminal branches of the ischiatic nerve (with common peroneal)
- Runs between the two heads of gastrocnemius muscle
- supplies caudal muscle of caudal leg
- splits into medial and lateral plantar nerves that supply mainly sensation to plantar aspect of pes
- Damage is minimal motor effect, dropping of hock and analgesia to plantar side of paw
Common Peroneal (fibular) nerve
- other terminal branch of ischiatic nerve (with tibial).
- Courses around lateral side of crus (over fibula).
- Supplies craniolateral muscles of crus (deep peroneal branch) and the skin of the craniolateral crus and dorsal foot (superficial peroneal branch).
- Damage results in knuckling over dur to inability to extend digits. Cutaneous sensation is lost to the dorsal surface of the leg and pes
arises from ventral branch of sacral nerves and supplies genitalia, rectum, perineum. A branch of this is responsible for parasympathetic supply to the pelvis.
Caudal rectal nerve
nerve supply to anus.
damage to: radial nerve, median and ulnar, musculocutaneous, suprascapular, thoracodorsal, axillary, femoral, obdurator, ischiatic, tibial, peroneal
- radial: knuckling over or inability to bear weight (can't extend elbow), analgesia to dorsal paw/forelimb/equine carpus
- Median and Ulnar: both sinks fetlock and carpus
- musculocutaneous: inability to flex elbow
- suprascapular: atrophy of supra- and infraspinatus (sweeny)
- thoracodorsal: latissimus dorsi
- axillary: shoulder flexor (deltoid, teres major and minor)femoral:inability to extend stifle to support weight
- obdurator: lateral slipping on slick surface (adductors)
- Ischiatic: knuckling over but can bear weight
- Tibial: dropping hock
- Peroneal: knuckling over due to inability to extend digits
- one speeds up, one slows down. Most internal organs are innervated by both branches of the ANS which exhibit antagonistic control. (heart rate).
- Sweat glands and blood vessel smooth muscle are only innervated by sympathetic. Strictly up-down control.
- Sympathetic and Parasympathetic work together for sexual function.