Gross Anatomy
Background Review
Anatomical Position, terminology
• Nomina Anatomica (Latin)
– Normal anatomical position
– upright, arms at side, forearm + hand supine
Planes
• imaginary lines separating the body at different
angles
• 1. Median - longitudinal - separates left and right
(hit surface at anterior, posterior median lines)
• 2. Coronal also referred as Frontal - vertical,
right angle to median - separate anterior and
post (front, back)
• 3. Horizontal - (often = transverse, not always) separate superior & inferior (upper /lower)
(transverse of hand is horizontal but the foot is
coronal)
• 4. Sagittal - vertical off-center, parallel to median
(include midsagittal & parasagittal)
Sections / slices
• 1. Longitudinal
– lengthwise through body or an appendage (direction
of its long axis)
– can be in median, coronal or sagittal planes
• 2. Vertical - same as longitudinal but referring to
body in anatomical position
• 3. Transverse - cross sections - at right angles to
long axis (often horizontal)
• 4. Oblique - slanted, at an angle, not in
longitudinal or transverse
Relational terms
• to localize different structures on the body in anatomical
position
– 1. Anterior = ventral - toward front (chest, palms, soles); also =
rostral in brain
– 2. Posterior = dorsal - toward back (dorsum)
– 3. Superior = cranial = cephalic - toward head
– 4. Inferior = caudal - below, toward feet (tail)
– 5. Medial - toward midline or median plane
– 6. Lateral - toward side, away from median (little toe = lateral;
little finger = *medial)
– 7. Intermediate - between 2 structures
– 8. visceral
– 9. parietal
Relative / Comparison
• Terms to describe relative positions of & to
compare 2 structures
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1. Proximal - nearer trunk or point of origin
2. Distal - farther from trunk or point of origin
3. Superficial - to surface
4. Deep - away from surface
5. External - toward exterior, especially of an organ
6. Internal - to the interior of an organ or inner surface
7. Ipsilateral - same side of body
8. Contralateral - opposite side ( Right vs. Left )
9. Central - near or towards the center
10. Peripheral - father, away from the center
Movements - of body parts
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1. Abduction - away from midline
2. Adduction - toward midline
3. Flexion - bend - decrease angle of a joint
4. Extension - straighten - increase angle of a
joint (hyperextension = beyond straight point)
5. Lateral rotation - rotate outward (e.g. leg)
6. Medial rotation - rotate inward
7. Circumduction - circular motion (involves 1-4)
8. Inversion - sole of foot toward median plane
Movements - of body parts
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9. Eversion - sole of foot laterally - outward to side
10. Pronation - rotate hand so palm faces posterior
11. Supination - rotate hand so palm is anterior
12. Protrusion - move anteriorly - stick out (e.g. chin)
13. Retraction / Retrusion - move posteriorly - pull, tuck
in (shoulders, chin)
14. Elevation - lifting
15. Depression - lowering to a more inferior position
16. Opposition - move thumb towards the other digits
17. Reposition - move thumb away from other digits
Systems
• 1. Integumentary - skin + accessory
structures
• 2. Skeletal - bones, cartilages
• 3. Articular - joints (+ bones, ligaments at
each)
• 4. Muscular - muscles (part of
musculoskeletal)
• 5. Nervous - brain, spinal cord, nerves
• 6. Circulatory - vascular - heart + arteries,
veins, capillaries + lymphatic (nodes,
vessels)
Systems
• 7. Respiratory - lungs, diaphragm, airways
• 8. Digestive - alimentary canal (mouth to anus) +
accessory organs (liver, pancreas etc)
• 9. Renal / Urinary - kidneys, bladder, excretory
tubule system
• 10. Endocrine - endocrine glands (pituitary,
hypothalamus, adrenals, reproductive glands)
• 11. Reproductive - ovaries or testes (a.k.a.
urogenital system, esp. in males)
Muscular System
• function in movement, support (posture),
heat generation
Skeletal Muscle
• 1. striated, voluntary
• 2. moves bones, skin (facial muscles) - typically, origin &
insertion are attached across a joint
– - most are under our control, although many movements are
reflexes - eg stretch reflex
• 3. attachments:
– each has an Origin = proximal attachment & Insertion = distal
attachment
• 4. structure:
a. muscle fiber = muscle cell = structural unit
b. motor unit = one motor neuron + all muscle fibers
under its control
– size varies inversely with precision, delicacy of control
Skeletal muscle
• 5. movements:
a. agonists = prime movers - carry out the main
movement
• b. antagonists - oppose action of agonists - relax
as agonist contracts for smooth movement
• c. synergists - complement/ work with/ support
prime movers - especially to support the joint
• d. fixators - steady proximal part of limb while
distal part is moved (e.g. forearm vs. hand)
Smooth muscle
• 1. non-striated, involuntary - controlled by
ANS
• 2. propels foodstuffs thru alimentary canal;
blood thru vessels
a. undergoes peristalsis - rhythmic waves
of contraction
• b. maintains a constant level of tone (esp.
important in vasculature)
Cardiac muscle
• 1. striated, but involuntary - spontaneous
excitation; under control of ANS
• 2. pumps blood through heart
Nervous System
• Major Functions of the Nervous System
• 1. Sensory - many receptor types in body sense,
detect changes in body or surroundings
• 2. Integration - of information received thru
sensory system to arrive at a proper response
• 3. Motor - nerve impulses trigger responses by
the body’s effectors = muscles, glands etc
Nervous System
• Divisions
• 1. CNS = the brain & spinal cord - nerves
do NOT regenerate after injury
• 2. PNS = peripheral nerves that
communicate between the CNS and the
rest of the body
- nerves MAY regenerate after injury
Structures
• 1. Neurons = the functional cells of the NS transmit electrical impulses
a. dendrites = receptive processes; receive
impulses from receptors & other neurons
b. axon = single transmitting process, sends
impulse to other neurons or to effectors
- myelin sheath - insulates axon - speeds
transmission
- nodes of Ranvier - spaces between sections of
myelin
Structures
• 2. Neuroglial cells
– a. supportive accessory cells - insulate, connect
neurons, attach neurons with surrounding tissue
– b. provide nutritive support - to provide energy,
provide central nervous system with blood
• 3. Types of Neurons - Classified by Function:
– a. Motor
– b. Sensory
– c. Interneurons
depends on how information flows
Basic terminology
• 1. Nucleus - a group of neuronal cell bodies within the
CNS
• 2. Ganglion (ganglia, pl) - group of cell bodies outside
the CNS
• 3. Nerve - collection of axons (fibers) in PNS ; fasciculus
- a bundle of nerves
- plexus = network of nerves in one area
• 4. Tract - bundle of axons/fibers in the CNS
• 5. Gray matter - concentrations of cell bodies in CNS,
e.g.. cerebral cortex
• 6. White matter - axons, processes in the CNS
Connective tissue meninges
• 1. CNS = meninges:
– connective tissue surround, protect the nervous
sytem
– a. pia mater - immediately next to the nervous tissue
– b. arachnoid - middle layer
– the 2 inner layers, leptomeninges, thin & delicate
– c. dura mater - outermost meninges, thicker & very
tough
– d. cerebrospinal fluid fills space between arachnoid
and pia mater
PNS
• a. endoneurium: thin collagenous layer,
immediately surrounds a myelinated n fiber
• b. perineurium: CT covering surrounding a
fascicle of nerve fibers
• c. epineurium: thick CT layer surrounding many
fascicles wh make up a nerve trunk
• * the 3 CNS meningial layers are continuous
with the CT layers around PNS nerves
The Peripheral Nervous System
• 1. Cranial nerves: 12 pair transmit from brain to head,
neck, trunk (mixed, motor & sensory, more in Neuro)
• 2. Spinal nerves: 31 pair communicate btw spinal cord &
neck, trunk, arms, legs (mixed)
– a. Dorsal roots - sensory/afferent fibers into cord, dorsal root
ganglia contain cell bodies of sensory neurons
– b. Ventral roots - motor/efferent ff from cord to periphery, branch
once outside cord
– c. dorsal & ventral roots combine, form spinal nerve, which
branches again:
– dorsal primary rami: supply fibers to dorsum (back)
– ventral primary rami: supply fibers to anterolateral trunk, limbs
Somatic Nervous System
• 1. nerves that communicate w skin &
skeletal muscles
• 2. functions are under conscious control
Autonomic Nervous System
• 1. concerned with automatic/ visceral
functions, homeostatic mechanisms (CVS,
digestion)
• 2. function without conscious control
• 3. control the function of visceral organs heart, smooth muscle, vessels, glands
D. ANS has 2 Divisions
Sympathetic Division
• concerned primarily w survival, emergency, stressful
situations – “Fight or flight system”
– a. connects with thoracic & lumbar segments: T1 - L2
or 3
– b. many connect with Peripheral NS efferent/motor
neuron in ganglia:
• paravertebral ganglia (sympathetic trunk)
• prevertebral ganglia (visceral ganglia., e.g. celiac
ganglia.)
• the adrenal medulla (exception, innervated by
preganglionic fiber directly)
– c. route: spinal cord lateral horn - sympathetic axons
(preganglionic) => through ventral root => through
white ramus communicante (branch to ganglion) => to
paravertebral ganglia
Sympathetic Division
• then either:
1) passes through ganglia (without synapse)
directly to viscera (as a splanchnic nerve)
• 2) ascends or descends through trunk to another
level, then postganglionic fibers innervate
organs like heart, lungs, glands
• 3) synapses in ganglia with excitor neurons =>
postganglionic go back through gray ramus
communicante => then blend in with spinal
nerve > effectors
Parasympathetic system
• “Breed and Feed”
• a. concerned w normal functions: eating,
sleeping, procreation, conserving energy
• b. connects with cranial & sacral
segments: cranial = III, VII, IX, X & spinal
= S2 - S4
Spinal cord
• 1. continuation of the CNS from the brain, out of
the skull into the vertebral column
• 2. composed of 31 segments - a pair of spinal
nerve exits each segment, to the periphery
• 3. gray matter localized to central core: mostly
cell bodies, proximal unmyelinated process’
• 4. white matter surrounds central area:
composed of primarily myelinated axons, fibers
Spinal cord
• 5. Function - spinal cord communicates to
& from the brain & the remainder of the
body
– a. ascending tracts carry sensory input to
CNS (some to spinal cord, some to brain)
– b. descending tracts leaving the brain & spinal
cord carry motor output to effectors
– c. most fiber tracts cross to contralateral side
at some point in spinal cord or brain
• mixed nerves
• 31 pairs
• 8 cervical (C1 to C8)
• 12 thoracic (T1 to T12)
• 5 lumbar (L1 to L5)
• 5 sacral (S1 to S5)
• 1 coccygeal (Co)
Dermatome
• an area of skin that the sensory nerve
fibers of a particular spinal nerve
innervate