ANATOMICAL DEFINITIONS Flashcards
What components make up the CNS?
- Brain & Spinal Cord
What makes up the Peripheral Nervous System? (PNS)
- Cranial Nerves (Originate from brain)
- Spinal Nerves (Originate from spinal cord)
- Sensory & Motor nerves (Voluntary)
Somatic Nervous System (SoNS)
- Voluntary muscle response
Autonomic Nervous System (ANS)
- Involuntary responses to stimuli from muscle (smooth and Cardiac) & glands
2 Divisions:
* Sympathetic Nervous System (SNS)
* Parasympathetic (PSNS)
Axon / nerve fibers
- Conduct nerve impulses away from the cell body toward another neuron or an effector cell (a cell that does something well stimulated, such as a muscle or gland cell)
- Can be called efferent processes because:
ex means “away”
ferre means “to carry”
Efferent processes conduct impulses away from the cell body
- nerve fibers refers to bundles of axons
Cell Body/Soma/Perikaryon
Contains the nucleus, which maintains the life of the neuron
Myelin sheath
- Speeds up conduction
- Made up of the cell membrane of specialized glial cells called oligodendrocytes in the brain and spinal cord, and Schwann cells in the nerves outside of the brain and spinal cord
Neuroglia/glial cells
glia means glue
- Structurally and functionally support and protect the neurons
White matter
Nervous tissue containing many myelinated axons
(Myelin appears white grossly (without magnification)
Dendrites
Receive stimuli, or impulses from other neurons and conduct this stimulation to the cell body
- Can be referred to as afferent processes because:
ad means “toward”
ferre means “to carry”
Afferent processes conduct impulses towards the cell body
Afferent nerve fibers
- Conduct nerve impulses toward the CNS
- Referred to as sensory nerve fibers b/c afferent nerve fibers conduct sensations from the sensory receptors in the skin and other locations in the body to the CNS
Efferent nerve fibers
- Carry nerve impulses away from the CNS
- Referred to as motor nerve fibers b/c the efferent nerve impulses cause skeletal muscle contractions and movement
Myelin
- A sheath of fatty substance that covers each axon
- Appears white without magnification
Gray matter
Nervous tissue made up largely of neuron cell bodies appears darker
Nodes of Ranvier
- Small gaps in the myelin sheath between each adjacent glial cell
- Myelin sheath and nodes of Ranvier work together to enhance the speed of conduction of nerve impulses along the axon
T/F - Myelinated axons conduct nerve impulses faster than unmyelinated axons?
True
Terminal end fibers
- Takes messages to the synapse
Sensory nerve
- A nerve that contains only sensory nerve fibers
Motor nerve
- A nerve that contains only motor nerve fibers
Mixed nerve
- A nerve that contains both sensory and motor nerve fibers
- Most nerves in the PNS are mixed
Synapse
- Space between 2 neurons OR neuron and muscle/gland/target cell
- Requires a neurotransmitter (carries the message)
What muscles in the nervous systems are voluntary?
- Skeletal muscle
- (SoNS)
Resting State
- When a neuron is not being stimulated
What muscles in the nervous systems are involuntary?
- Smooth & cardiac
(ANS)
Sodium-potassium pump
- A specialized molecule located in the neurons cell membrane that pumps sodium ions (Na+) from the inside of the neuron to the outside and pumps potassium ions (K+) from the outside to the inside.
Action potential
- Significant change in electric charge from negative to positive
Synaptic cleft
- Gap between two neurons or a neuron and its target cell
Presynaptic neuron
- The neuron bringing the nerve impulse to the synapse and releasing the chemical to stimulate the next cell
Neurotransmitter
- The chemical released by the synaptic neuron
Postsynaptic neuron
- The neuron that contains the receptors that receive the neurotransmitter
Telodendron
- The branched end of an axon; each branch terminates in a neurotransmitter-filled synaptic end bulb/knob, terminal bouton (The bulbs contain many mitochondria)
- Bouton meaning “button”
Excitatory neurotransmitters
- Chemicals released by neurons at the synapse that tend to cause excitation or depolarization of other neurons or target tissues
- Cause an influx of sodium so that the postsynaptic membrane moves toward threshold
Inhibitory neurotransmitters
- Tend to hyperpolarize the postsynaptic membrane, making the inside of the cell more negative than positive and moving the charge within the postsynaptic cell farther away from threshold
Acetylcholine
- Both an excitatory and an inhibitory neurotransmitter depending on its location in the body
- At the junction between somatic motor neurons and the muscles they supply, acetylcholine stimulates muscle fibers to contract
- At the site where parasympathetic nerves synapse with the heart, acetylcholine has an inhibitory effect that slows the heart rate
Norepinephrine
- A neurotransmitter that belongs to the Catecholamine group
- Associated with arousal or fight-or-flight reactions of the sympathetic nervous system
Epinephrine
- A neurotransmitter that belongs to the Catecholamine group
- Is released primarily from the adrenal medulla (center of the adrenal gland)
- Plays more of a role in the fight-or-flight reactions of the sympathetic nervous system
Dopamine
- A neurotransmitter that belongs to the Catecholamine group
- Found in the brain, where it is involved in autonomic functions and muscle control
Gamma-aminobutyric acid (GABA) & Glycine
- Both are inhibitory neurotransmitters
- GABA is found in the brain
- Glycine is found in the spinal cord
Gray matter of the CNS
- Contains most of the neuron cell bodies, and appears a dark brownish-gray colour grossly
- Thought to be the “thinking” part of the brain
White matter
- Contains most of the myelinated nerve fibers and appears white because of all the myelin
- It is the “wiring” that connects the various components of the brain
Cerebrum
- Made up of gray matter in the cerebral cortex and white matter beneath the cortex, including the corpus callosum
- Largest part of the brain
- Responsible for higher-order behaviours such as learning, reasoning, and intelligence
- Receives and interprets sensory information, initiates conscious (Voluntary) nerve impulses to skeletal muscle, and is associated with memory, recall, and conscious activity
- Surface is covered by “wrinkles”
Cerebral cortex
- The outer most superficial layer of the brain
Corpus callosum
- A set of fibers that connects the two halves of the cerebral cortex
Gyrus
- Wrinkled appearance/ folds on the surface of the cerebral hemispheres
- Plural form is gyri
Sulcus
- Shallow grooves in the cerebral cortex
- Pleural form is sulci
Fissures
- Deep grooves found in the cerebral cortex
Longitudinal fissure
- Most prominent groove which divides the cerebrum into left and right cerebral hemispheres
(Each hemisphere is divided by sulci into lobes; frontal, parietal, temporal, and occipital)
Cerebellum
- Located caudal to the cerebrum
- Second largest component of the brain
- Wrinkled appearance with a gray matter cortex with white matter beneath it
- Coordinated movement, balance, posture, and complex reflexes
Hypermetria
- A condition in which voluntary movements become exaggerated and jerky
(Pigs with cerebellar disease)
Diencephalon
- Serves as a nervous system passageway between the primitive brainstem and the cerebrum
- “the between brain”
- Does not have clear visible layers of gray and white matter
3 layers:
* Thalamus
* Hypothalamus
* Pituitary
Thalamus
- Acts as a relay station for regulating sensory inputs to the cerebrum
Hypothalamus
- Is an interface between the nervous system and the endocrine system
- Plays a major roles in temperature regulation, hunger, thirst, and components of rage and anger responses
Pituitary
- The endocrine “master gland” that regulates production and release of hormones throughout the body
Brainstem
The connection between the rest of the brain and the spinal cord
- Most primitive part of the brain composed of the medulla oblongata , the pons, and the midbrain
- Does not have clear visible layers of gray and white matter
- Role is to maintain basic support functions of the body, so it operates at the subconscious level
- Involved in the autonomic control functions of the heart, respiration (including coughing, sneezing, hiccupping), blood vessel diameter (vasomotor control), vomiting, swallowing
- Many of the cranial nerves originate here
Meninges
- A set of connective tissue layers that surround the brain and spinal cord
3 layers: - Dura mater - outside tough, fibrous layer
- Arachnoid - Delicate, spiderweb-like layer
- Pia mater - Very thin innermost layer that lies directly of the surface of the brain and spinal cord
- These connective tissue layers contain a rich network of blood vessels that supply nutrients and oxygen to the superficial tissues of the brain and spinal cord
Cerebral Spinal Fluid (CSF)
- Cushions and nourishes the CNS
- Clear, slippery, colourless fluid
- May be involved in certain autonomic functions such as respiration and vomiting
Blood-brain barrier
- Functional barrier separating the capillaries in the brain from the nervous tissue itself
- The cells that make up the capillary walls in the brain are aligned tightly without opening or fenestrations; they are covered by glial cells
Cranial Nerve I
- Olfactory
- Sensory
- Smell
Cranial Nerve II
- Optic Nerve
- Sensory
- Vision
Cranial Nerve III
- Oculomotor
- Motor
- Eye movement, pupil size, focusing lens
Cranial Nerve IV
- Trochlear Nerve
- Motor
- Eye movement
Cranial Nerve V
- Trigeminal Nerve
- Both Sensory & Motor
- Sensations from the head and teeth, chewing
Cranial Nerve VI
- Abducent
- Motor
- Eye movement
Cranial Nerve VII
- Facial
- Both Sensory & Motor
- Face and scalp movement, salivation, tears, taste
Cranial Nerve VIII
- Vestibulocochlear
- Sensory
- Balance, hearing
Cranial Nerve IX
- Glossopharyngeal
- Both sensory & Motor
- Tongue movement, swallowing, salivation, taste
Cranial Nerve X
- Vagus (Wanderer)
- Both Sensory & Motor
- Sensory from the gastrointestinal tract and respiratory tree
- Motor to the larynx, pharynx, parasympathetic
- Motor to the abdominal and thoracic organs
Cranial Nerve XI
- Accessory
- Motor
- Head movement, accessory motor with vagus
Cranial Nerve XII
- Hypoglossal
- Motor
- Tongue movement
Nociception
- The process of experiencing pain
(Transduction, transmission, modulation, perception)
External ear
- Acts as a funnel to collect sound wave vibrations and direct them to the eardrum
- Main parts are the pinna, the external auditory canal, and the tympanic membrane (eardrum)
Middle ear
- Amplifies and transmits the vibrations from the ear drum to the inner ear
- Hollowed-out cavity of the temporal bone that is lined by soft tissue membranes
- Contains 3 small bones known as ossicles & the opening of the Eustachian tube, which connects it to the pharynx (throat)
Inner ear
- Made up of structures that contribute to hearing and equilibrium
Hearing portion:
* Snail-shaped spiral cavity in the temporal bone called the cochlea
* Within the cochlea is a soft, multilayered, fluid-dilled portion that contains the receptor organ of hearing - organ of Corti which runs the length of the cochlea in a long tube called the cochlear duct - filled with fluid called endolymph
Transduction
The conversion of the painful stimulus to a nerve impulse, which occurs at the sensory nerve ending
Transmission
Modulation
Perception
Anesthesia
- Loss of esthesia (the capacity for sensation or feeling)
- The complete loss of sensation
General Anesthesia
- Involves a complete loss of sensory perception accompanied by loss of consciousness
Local Anesthesia
- Loss of sensation from a specific, localized area of the body without affecting consciousness
Analgesia
- A related state in which perception of pain is decreased by not completely absent
Pinna
- Part of the ear that we can see from the outside
- Funnel-like structure composed mainly of elastic cartilage and skin
- Collects sound wave vibrations and directs them into the external auditory canal
External auditory canal
- Soft, membrane-lined tube that begins at the base of the pinna and carries sound waves to the tympanic membrane
- L-shaped in most domestic species
Tympanic membrane (Eardrum)
- Paper-thin connective tissue membrane that is tightly stretched across the opening between the external auditory canal and the middle ear cavity
- When sound wave vibrations strike it, the eardrum vibrates at the same frequency through sympathetic vibration
Ossicles
Malleus (hammer) -
* Outermost bone attached to the tympanic membrane.
* Forms a complete synovial joint with the middle bone, the incus
Incus (Anvil)
* Forms a joint with the medial-most bone, the stapes
Stapes (Stirrup)
* Other end of the stapes is attached to the membrane that covers the oval window of the cochlea
- All 3 act as a system of levers, transmitting sound wave vibrations from the tympanic membrane to the cochlea - They reduce the amplitude (size) of the vibrations but amplify their force
Stapedius
- Tiny muscle that assists the damage-control process by restricting the movement of the stapes in response to loud sounds
Tensor tympani
- Tiny muscle attached to the malleus
- It adjusts tension of the tympanic membrane and helps deaden the transmission of extremely loud vibrations to the cochlea
Eustachian tube (Auditory tube)
- Connects the middle ear cavity with the pharynx
- It equalizes the air pressure on the two sides of the tympanic membrane
- Slit-like opening of the tube opens when the animal yawns or swallows, allowing air to enter or leave as necessary to equalize the pressure on the outside of the tympanic membrane
Ear Hematomas
- An abnormal accumulation of free blood between the cartilage and skin of the pinna
- Especially in dogs with floppy ears, irritation in the ear can cause the animal to shake its head vigorously - this ruptures small blood vessels under the skin of the pinna
Otitis Externa
- An inflammation of the skin of the external ear canal
- Occurs most commonly in dogs, cats, and rabbits
- Often caused by parasites, mites, yeast, bacteria
- Causes irritation, fluid accumulation, redness, pain, pungent odor, swelling
U-shaped tube
- Lies on either end of the cochlear duct
- Filled with a fluid called perilymph
- Membrane-covered openings at the ends of the “U” are called round window and oval window - located at the base of the cochlea
- Bottom of the “U” is located at the tip of the cochlea
Vestibule
- Portion of the inner ear that is located between the cochlea and the semicircular canals
- 2 sac-like spaces called utricle and the saccule - they are continuous with the cochlear duct of the cochlea and filled with endolymph fluid
Semicircular canals
- Located on the other side of the vestibule from the cochlea
- They sense rotary motion of the head
Macula
- Patch of sensory epithelium in each utricle and saccule
- Consists of hair cells and supporting cells covered by a gelatinous matrix that contains tiny crystals of calcium carbonate called otoliths (ear stone)
- The hair cells give the brain information about the position of the head
Ampulla
- An enlargement in each semicircular canal that contains the receptor structure called the crista/crista ampullaris
Cupula
- The gelatinous structure that sits on top of the receptor hairs in the crista ampullaris of the semicircular canals
Cornea
- The transparent “window” that admits light to the interior of the eye
- Contains collagen fibers and no
blood vessels
Transparency is maintained by careful control of the amount of water it contains:
* Too much water - corneal edema
* Too little water - corneal dehydration (cloudy, opaque)
Sclera
- The “white” of the eye
- Made up of collagen fibers and makes up most of the outer fibrous layer if the eye
Limbus
- The junction of the cornea and the sclera
Fibrous Layer
- Admits light to its interior and gives strength and shape to the eyeball
- Cornea and Sclera
Vascular Layer
- Also called the Uvea
- Choroid, iris, ciliary body
Choroid
- Sandwiched between the sclera and the retina
- Pigment and blood vessels that supply blood to the retina (Most of the pigment is dark melanin)
- In most domestic species, except for swine, the choroid forms a highly reflective area in the rear of the eye called the tapetum lucidum (tapetum)
Tapetum lucidum/ tapetum
- Responsible for the bright light that seems to shine from and animal’s eyes in the dark, when a light is directed into them
- Acts as a light amplifier to aid low-light vision. After light has passed through the photoreceptors (the rods & cones in the retina), it reflects off the tapetum and passes through the photoreceptors again
Iris
- Coloured part of the eye
- Pigmented, muscular diaphragm that controls the amount of light that enters the posterior part of the eyeball
- The opening at its centre is called the pupil
- Has 2 sets of multiunit smooth muscle fibers -
1) Radially arranged fibers (oriented like the spokes of a wheel) enlarge the pupil when they contract
2) Circularly arranged fibers constrict the pupil when they contract
(Nerve supply comes from the ANS)
Pupil
- Enlarges in low-light conditions and gets smaller in bright light
- Enlarged by the radially arranged fibers when they contract
- Constricts by the circularly arranged fibers when they contract
Ciliary body
- Ring-shaped structure located immediately behind the iris
- Has tiny muscles that adjust the shape of the lens to allow near and far vision and the cells that produce aqueous humor
Nervous Layer
- Inner nervous layer is the retina which lines the back of the eye
- Fundus is sometimes used to describe the caudal interior surface of the eye (retina and the optic disc)
Aqueous compartment
- In front of the lens and ciliary body
- Contains clear, watery fluid called aqueous humor
Vitreous compartment
- Behind the lens and the ciliary body
- Contains a clear fluid with the consistency of soft gelatin, called vitreous humor
- Larger than the aqueous compartment
Canal of Schlemm
- Structure that drains aqueous from the anterior chamber of the eye
- Located at the edge of the anterior chamber where the iris and the cornea meet
Lens
- Soft, transparent structure made up of layers of microscopic fibers
- Main role is to help focus a clear image on the retina regardless of it being close or far away
- Front rostral surface is in contact with the aqueous humor
- Back caudal surface is in contact with vitreous humor
Accomodation
- The process whereby the shape of the eye is changed to allow close-up and distant vision
Glaucoma
- A group of diseases characterized by increased ocular pressure
- Causes pain and can lead to blindness
Cataracts
- An abnormal condition of the eye whereby the lens become opaque
- Senior patients
- Genetically inherited
- Secondary conditions such as diabetes mellitus, infection, excessive exposure of the eyes to ionizing radiation
- Surgical removal of the lens
Retina
- Where the visual image is formed, sensed, and converted to nerve impulses that are decoded in the brain to re-form the image in the conscious mind
- “Camera”
- Multilayered structure that lines the vitreous compartment
From outside in: - thin piment layer
- the photoreceptor layer
- the the bipolar layer
- the ganglion layer
- a nerve layer that proceeds to the optic nerve
Rods
- Thin shaped receptors
- More sensitive to light
- Produce a somewhat coarse image in shades of gray
- Low-light vision
Cones
- Thicker shaped receptor
- More sensitive to colour and detail, but do not function well in dim light
- Perceive colour and detail
Conjunctiva
- Thin, transparent membrane that converts the front portion of the eyeball and lines the interior surfaces of the eyelids
Bulbar conjunctiva
- The portion covering the front of the eyeball
- Bulbar refers to the eyeball
Palpebral conjunctiva
- The portion lining the eyelids
- Palpebral refers to eyelids
Conjunctival sac
- Space between the bulbar and palpebral portions of the conjunctiva (between the eyelid and the eyeball)
Canthi (Plural: Canthus)
- The lateral and medial corners, where the eyelids come together
Tarsal glands/ meibomian glands
- Tiny openings along the margin of each eyelid
- Produce a waxy substance that helps prevent tears from overflowing onto the face
Nictitating membrane
- Third eyelid in domestic animals
- Located medially between the eyelids and the eyeball
- Movements are passive - no muscles attach to the third eyelid
Conjunctivitis
- Inflammation of the conjunctiva of the eye
- Common is all domestic species
- Redness (hyperemia)
- Swelling (chemosis)
- Ocular discharge & discomfort
The ocular discharge can be:
* Watery (serous)
* Bloody (Sanguineous)
* Pus-like (Purulent)
Lacrimal apparatus
- Includes structures that produce and secrete tears and the structures that drain them away from the surface of the eye
Lacrimal glands
- Primary source of tears
- Located dorsally and lateral to each eye inside the bony orbits that protect the eyeballs
Lacrimal puncta
- Drain the tears away from the surface of the eye
- Located near the medial canthus of each eye
- Two small openings (one each in the upper and lower eyelid margins
- Tears then flow down 2 small ducts known as lacrimal sacs and then singular ducts called nasolacrimal ducts, to the nasal cavity
Ecdysis
Shedding of the skin of reptiles
Dysecdysis
Abnormal shedding of a reptile, usually leading to skin buildup
Ptosis
- Symptom of Horner’s Syndrome
- Drooping of the upper eyelid
Enophthalmos
- ” Sunken Eye”
- A condition in which the animal’s eyeball is displaced backwards in the eye socket
Catalepsy
Epidydymis
- Ribbon-like structure that lies along the surface of the testes
*One long, convoluted tube that links the efferent ducts with the Vas Deferens
- Stores spermatozoa until ejaculated
Vas Deferens
- The muscular tube that carries spermatozoa and the fluid they are suspended in from the epididymis to the urethra
Prostate Gland
- The male accessory reproductive gland that generally surrounds the urethra
- Lies just distal to urinary bladder
- The only accessory reproductive gland in a dog, so it is quite large in that species
Lumpectomy
- A surgical procedure that removes a lump or mass from the body
Mastectomy
- A surgical procedure that removes one or more mammary glands to treat mammary tumors
Comedones
Blackhead
Sclerosis /Lenticular & Nuclear Sclerosis
- Bluish, transparent haze that develops in the lens of the eye in middle-aged to senior pets
Enteric Coatings
- A polymer applied to oral medication
- Serves as a protective barrier to prevent gastric acid in the stomach from degrading/dissolving the drugs after being swallowed
- Designed to dissolve in the basic pH of the small intestine
Fomite
- An inanimate object, such as a blanket that can transmit disease to a new host if contaminated with infectious agents
Hemoptysis
- A rare, yet serious symptom in which blood or bloody mucus is coughed up from the respiratory tract
Joint Laxity
- Carpal laxity, hip dysplasia
- Joints are looser / more unstable than normal
Ptyalism
- Excessive drooling in animals
(Examples, Stress, oral tumors, toxicity, oral or esophageal inflammation)
Paraphimosis
- The inability to completely reduce the penis into the preputial cavity
Intussusception
- One part of the intestines slides into another part
- Can cause a blockage in the intestine, preventing food to pass through
Eructation
The process of belching or burping
Uveal Tract
- Layer of tissue in the eye
- Iris, ciliary body, and choroid
Trichobezoar
- Ball of swallowed hair that collects in the stomach and can fail to pass through the intestines
Hypertrophic Cardiomyopathy (HCM)
- More common in cats
- Thickening of the heart muscle, making it harder to pump blood
Dilated Cardiomyopathy (DCM)
- Very common in dogs
- The heart muscle becomes weak and reduced the heart’s ability to pump blood effectively
Nosocomial Infections
- An infection that patients may acquire in connection with medical care in Veterinary clinics and hospitals
- Always wash your hands
Orf/ Contagious ecthyma/ “Sore mouth”
- Viral infection primarily in sheep and goats
- Highly contagious and be spread to humans
- Caused by poxvirus called Orf virus
Melena
- Dark, sticky, tar-like stool caused by digested or swallowed blood in a pet’s upper GI tract
Meconium
- A newborn’s first stool
- Thick, sticky, and dark green
Lochia
- Vaginal discharge that occurs after giving birth
Pyuria
- High levels of white blood cells or pus in the urine
Aplastic Anemia
- Occurs when your bone marrow cannot make enough new blood cells for your body to work normally
Septicemia
- Life-threatening condition
- Occurs when bacteria enters the bloodstream and spreads, resulting in blood poisoning
Diphtheria
- An acute cutaneous infection caused mainly by toxigenic strains of the gram-positive bacillus Corynebacterium diphtheriae
Ileitis
- Inflammation of the ileum
- Classically caused by Crohn’s disease
Petechia
- Red or purple spots that appear on the skin or mucous membranes
- Due to broken blood vessels
Ecchymosis
- Bruising
- Ecchymoses are larger lesions caused by arteriolar and venular bleeding
Erythema
- Increased supply of blood to the skin
- Redness of the skin or mucous membranes
Papillomas
- Benign tumors caused by viruses - commonly known as warts
- Small, round, cauliflower-like growths on the skin or in the mouth of animals
Precocious
- Animals born or hatched having hair, feathers, eyes open, and the ability to move around
Anisocoria
- Pupils of the eyes are different sizes
Urticaria
- Hives
- Localized patches of red, swollen, itchy skin
Pemphigus
- An autoimmune skin disease
- Immune system attacks the connections between skin cells
Buphthalmos
- A condition that causes the eyeball to enlarge
- Usually due to glaucoma
Mydriasis
- Abnormally dilated pupils in an animal
Miosis
- Smaller than normal pupil size
Dystocia
- Difficult or abnormal birth
Ortolani
- Identifying hip laxity to diagnose hip dysplasia
Syncope
- Fainting
- Temporary loss of consciousness
- Brain doesn’t receive enough oxygen
Diphtheritic Membrane
- Respiratory disease characterized by the formation of a pseudomembrane consisting of necrotic tissue and bacteria
*Diphtheria produce toxins that cause an abnormal membrane to grow in the throat which can lead to suffocation
Anhidrosis
- A condition that prevents horses from sweating properly