2. Objectives
• Distinguish between systemic anatomy, regional anatomy,
and clinical anatomy
• Describe relative locations, anatomical planes, and body
movements using proper anatomical terminology.
• Identify the organs and functions of organs from
undergraduate A&P, for each organ system, including
integumentary, skeletal, muscular, cardiovascular,
lymphatic, and nervous systems.
• Describe the importance of tension lines
• Describe the classification of burn severity & rules of 9
• List the events that occur in the process of fracture repair
• Understand the Salter-Harris classification system used to
classify pediatric fractures
Upon completion of this module
the student should be able to:
• Compare and contrast hydrostatic pressure
and oncotic pressure at the capillary beds.
• Classify the types of synovial joints
• Discuss dermatome & myotome formation
• Describe lymph formation
• Distinguish between isometric & isotonic
contractions
• Understand the mechanisms by which cancer
spreads
• Organize the divisions of the nervous system.
• Describe the organization and function of the
sympathetic & parasympathetic divisions of
the ANS
• Discuss the applications of imaging techniques
including radiography, MRI, ultrasound,
endoscopy, functional MRI, and CT scan.
4. Terminology
Regional Anatomy
• Anatomical study organized by body regions
• E.g. thorax, abdomen, upper limb, etc.
• Cooperative functions of multiple systems
• Surface anatomy: landmarks visible or
palpable from the surface
Example of surface anatomy: pain upon palpation of the
anatomical snuffbox may indicate a fracture scaphoid bone.
5. Terminology
Clinical Anatomy
• Emphasizes aspects of anatomy that are important
to the practice of medicine.
• Utilizes both systemic and regional anatomy
• Stresses clinical application
6. Clinical Anatomy: Reverses the typical thought process of systemic anatomy
Instead of being asked,
“Name one action of the trapezius”.
You may be asked,
“How would the absence of the ascending
part of the trapezius manifest clinically?
Terminology
7. Standard Anatomical Position (SAP)
Assumes patient is standing erect (regardless of actual position) with:
• Orientation from patient’s perspective (patient’s left and right)
• Body upright
• Head, eyes and toes directed anteriorly
• Upper limbs by sides with palms facing anteriorly, thumbs lateral
• Lower limbs close together with feet directed anteriorly
• Penis is erect
8. Standard Anatomical Position (SAP)
How would you describe the location of this stab wound?
A man who walked into a Michigan diner with a 5-inch knife
stuck in his chest ordered a coffee and complained only
about the cold weather.
9. Anatomical Planes
1. Median (Midsagittal) Plane 2. Frontal (Coronal) Plane
Vertical planes passing through the body
at right angles to the median plane
To study relations of structures, movements, etc., the body is divided using planes.
Divides into Front and Back (anterior and posterior)
Divides into Right and Left Sides
Sagittal, Parasagittal = Planes parallel to the median plane
Vertical plane passing longitudinally through
the midlines of the head, neck, and trunk.
10. Anatomical Planes
3. Transverse (Horizontal) Plane
Horizontal plane dividing the body into superior (upper)
and inferior (lower) parts.
12. 1. Longitudinal Section
Runs lengthwise or parallel
to the long axis of the body
Anatomic Sections
2. Transverse (Cross) Section
Cut at right angles to the
longitudinal axis
3. Oblique Section
Cut at any other angle
14. Terms of Relative Position
Terms are used to describe positions of structural elements relative to
one another all referenced to the Standard Anatomical Position (SAP)
Practice using these terms in lab!
15. Superior (cranial)
Inferior (caudal)
midline
medial lateral
proximal
distal
Superior – above (i.e. closer to head)
Inferior – below (i.e. closer to feet)
Medial – closer to midline
Lateral – away from midline
Proximal – closer to the trunk
*or point of origin
Distal – farther from the trunk
*or point of origin
proximal
distal
Relative Directions
16. Anterior
(ventral)
Posterior
(dorsal)
Anterior – closer to the front
Posterior – closer to the back
Superficial – closer to the surface
Intermediate – between superficial & deep
Deep – away from the surface
superficial
deep
Relative Directions
17. 1. The eyes are ___ to the chin.
2. The patellar region is ____ to the femoral region.
4. The carpal region is ____ to the antecubital region.
5. The gallbladder is on the _________ side of the liver.
6. The spleen is on the ___________ side of the liver.
Unilateral – one side vs. Bilateral – both sides
Ipsilateral – same side vs. Contralateral – opposite side
Relative Directions
Practice
19. Movement at a joint occurs when a muscle contracts and its fibers pull its
moveable end (insertion) towards its fixed end (origin).
Abduction = movement away from the midline
Adduction = movement towards the midline
Joint movements
21. Flexion = decreases the angle of a joint
Extension = increases the angle of a joint
Hyperextension = extension beyond the normal
range
Joint movements
22. Rotation = movement around a central axis
Circumduction = movement so the end
follows a circular path
Joint movements
23. Elevation = raising a part
• Shrugging the shoulders
Depression = lowering a part
• Drooping the shoulders
Protraction (protrusion) = moving a part forward
• thrusting head forward
Retraction (retrusion) = moving a part backward
• pulling the head backward
Joint movements
24. Supination = turning the hand so the palm faces
upward or anteriorly
Pronation = turning the hand so the palm faces
downward or posteriorly
Dorsiflexion = movement at the ankles that points
toes towards the sky
Plantar flexion = movement at the ankles that
points toes towards the ground
Joint movements
25. Eversion = turning the foot so the planter surface
faces laterally
Inversion = turning the foot so the plantar surface
faces medially
Joint movements
28. Anatomical Variations
• Structural Variation ranges from normal to
incompatible with life.
• E.g., congenital anomalies (birth defects),
variations in bone size, shape, and muscle
attachments
• Most images demonstrate the most
commonly observed pattern.
Expect anatomical variations during your dissections!
34. Skin Ligaments
Numerous small band extending through the subcutaneous tissue and
attach the deep surface of the dermis to the underlying deep fascia
35. Skin Ligaments in subcutaneous tissue
• The thickness of subcutaneous tissue can be estimated as being approximately
½ that of a pinched fold of skin.
• Long, sparse skin ligaments on dorsum of hand.
• Short, abundant skin ligaments on palm of hand.
36. Superficial Fascia
Superficial fascia (subcutaneous layer)
Lies deep to skin and connects it to deep fascia (thicker in ♀ than ♂)
Supports blood vessels, cut. nerves and lymphatics
Some places (face) have sheets of muscle
37. Deep Fascia
Extensions of deep fascia form:
• Investing fascia (invest individual muscles or neurovascular bundles)
• Intermuscular septa (divide muscles into compartments or groups)
• Subserous fascia ( between muscular walls and serous membranes)
• retinacula to hold tendons in place during joint movement
• Bursa:
• Fluid-filled sac in synovial joint
• Cushion between bone and tendon and bone or muscle.
Dense regular connective tissue deep to the subcutaneous layer
38. Necrotizing fasciitis
• Commonly called a "flesh-eating infection“
• Caused by several types of bacteria
• Group A strep is considered the most common cause of necrotizing fasciitis.
Travels along fascial planes
Integumentary System: Clinical Impact
39. Basic structures of the appendages
• Skin (epidermis/dermis)
• Subcutaneous Tissue (superficial fascia)
• Deep fascia
• Bone
• Muscles
• Investing Fascia of muscle
• Neurovascular Sheath:
– Blood vessels
– Lymphatic vessels
– Nerves
40. Tension Lines
Tension Lines (Cleavage Lines or Langer lines)
• Appear as folds in the skin during movement
• Alert to orientation of collagen fibers
• Incisions parallel to the tension lines will gape less, disrupt
fewer collagen fibers, and will heal better with less scaring.
• Tend to spiral longitudinally in the limbs
• Runs transversely in the neck and trunk
• In elbows, knees, ankles, and wrists they run parallel to
the transvers creases that appear when limbs are flexed.
41. Burns
• Tissue damage due to thermal, electrical, radioactive, or
chemical agents.
• Superficial (1st degree): damage to superficial epidermis.
• Partial thickness (2nd degree): damage limited to superficial
part of the dermis.
• Full thickness (3rd degree): entire epidermis and dermis and
maybe underlying tissue are damaged.
Stratum basale damaged = Requires grafting.
• More important: the percent of body surface affected is the
more important indicator of patient outcome.
Integumentary System: Clinical Impact
42. Rule of Nines
Body is divided into areas that are approximately 9%
(or multiples of 9%) of the total body surface.
3 factors that increase burn mortality:
1. Age over 60
2. Partial-thickness & full-thickness burns over
40% body surface area.
3. Presence of inhalation injury
Integumentary System: Clinical Impact
44. Bone (Skeletal system)
Specialized C.T. with mineralized extracellular component
Functions:
• Protection
• Support
• Movement (rigid levers at synovial joints)
• Stores and releases calcium (calcium-phosphate salts)
• Hematopoiesis (in red bone marrow)
45. By Location:
Axial Skeleton – along central axis
Skull (cranium & facial bones)
Vertebral column
Thoracic cage
Hyoid Bone
Appendicular Skeleton – attaches to axial skeleton
Pectoral girdle & upper limbs
Pelvic girdle & lower limbs
By Shape:
Long- Femur
Short-Carpals
Flat-Cranial vault
Irregular-vertebrae
Sesamoid-patella
Skeletal System:Classification
46. Skeletal System
Compact (Cortical) Bone
• Dense arrangement of the bone matrix
• Prevents compression
• All bones have an outer layer of compact bone.
Spongy (Trabecular) Bone
• Open arrangement of bone matrix in trabeculae
• In the center of all bones except those with a medullary cavity.
• Blood cells and platelets made in open spaces (hematopoietic
tissue)
47. Vasculature and Innervation of Bones
Bones have a dual blood supply:
1. nutrient artery supplies medullary cavity; bone marrow, spongy
bone, and deeper portions of compact bone
2. periosteal arteries supplies cortical bone
• Periosteal supply is important in elderly: stripping of the
periosteum in trauma or surgery may result in bone necrosis
Periosteal nerves
• Carry pain fibers from periosteum
• Especially sensitive to tearing or tension
• Source of the acute pain of a broken bone
Bone itself has very few sensory fibers
49. Bone Development
Intramembranous Ossification
• Bones form from embryonic connective tissue (CT), called
mesenchyme.
• Forms flat bones of the skull, most cranial bones, and clavicle
Ossification of cartilage begins during the embryonic
period (8 weeks) and is complete in the early 20s.
50. Bone Growth
Endochondral Ossification
• Cartilage model of the bones form during the fetal
period
• Bone subsequently replaces most of the cartilage
• Primary ossification center – forms diaphysis
• Secondary ossification centers – form the epiphyses
51. Two areas of endochondral bone retain
cartilage after ossification.
1. Articular cartilage
• surrounds the epiphyses for joints
2. Epiphyseal plates
• retain cartilage for bone growth
Bone Growth
52. Skeletal System: Clinical Impact
Accessory Bones
• Extra bones
• Os Trigonum: Accessory bone to the talus.
Osteoporosis (porous bone)
• Reduction in bone mass making bones brittle
• Risk factors include age, sex, smoking
Osteoarthritis/ Degenerative Joint Disease
• Irreversible degeneration of the articular cartilage
• Older patients, joints that support weight
Healthy Bone Osteoporosis Bone
53. Bone is living tissue “plastic” – continually being remodeled
• As ligaments and tendons pull on the bone, new bone is
laid down for reinforcement (or removed)
• osteophytes (bone spurs)
• Pathological bone formation
• osteophytes often form where joints are affected by
osteoarthritis
osteophytes of spondylosis (age-
related changes) of the lumbar spine.
Bone Remodeling
55. Bone Fractures in Children
Salter-Harris Fracture – fracture in epiphyseal plate of children
By James Heilman, MD - Own work, CC BY-SA 3.0,
https://commons.wikimedia.org/w/index.php?curid=10379649
An X-ray of the left ankle showing a Salter–Harris type III fracture of medial malleolus.
Black arrow demonstrates fracture line while the white arrow marks the growth plate.
62. • Articular disc - divides some synovial joints (eg TMJ) into 2 cavities
• Menisci (sing. Meniscus) – pad of fibrocartilage that separates
some joints.
• Bursa – sac filled with synovial fluid.
* Bursitis = inflammation of bursa
• Ligaments – reinforce the joint and protect the joint
Synovial Joints (cont.)
63. Joint Vasculature and Innervation
Joints receive blood from articular arteries that arise
from vessels around the joint.
• Arteries usually form anastomoses (networks)
around the joint – provides collateral circulation
• Articular veins accompany articular arteries
• Articular arteries and veins are located within the
joint capsule
Hilton “law” (rule of thumb)
• Nerves innervate muscles and skin crossing over a joint
also innervate that joint. Anterior innervation of the shoulder joint. The suprascapular nerve and
axillary nerve are the primary nerves supplying the capsule and the
glenohumeral joint
64. pivot
hinge
Condylar (oval)
gliding
saddle
Ball-and-socket
Types of Synovial Joints
Ball-and-socket = multiaxial (movement in all planes)
• Hip joint, glenohumeral joint
Condylar = biaxial (movement in two planes) (no rotation)
• Metacarpophalangeal joints (knuckle joints)
Hinge – uniaxial (flexion & extension only)
• Elbow, interphalangeal joints, Knee (modified hinge)
Pivot – rotation
• Atlantoaxial joint
• Proximal radioulnar joint
Gliding (plane) – nonaxial (glides across surfaces)
• Intercarpal joints, intertarsal joints
• Acromioclavicular joint
Saddle – 2 planes + opposition/reposition
• Carpometacarpal joint of the 1st digit (thumb)
66. Muscular System
Skeletal muscle (40% of body)
• Striated cells under voluntary control
• Moves bones and other structures, warmth,
posture, support
• Fatigable
Cardiac Muscle
• Striated cells under involuntary control
• Forms myocardium of the heart
• Regulated by ANS
Smooth muscle
• Non-striated, involuntary control
• Walls of vessels and hollow organs
• Vessel constriction, GI peristalsis, pupillary
constriction, ureter peristalsis
• Regulated by ANS
67. Skeletal Muscle
Skeletal muscle joined to bones by dense connective tissue (tendons)
For a muscle to have an action on a joint it must cross over joint
Note how biceps brachii & brachialis cross over the elbow joint, inserting
onto the forearm bones.
Insertions (Distal attachments)
Origins (Proximal attachments)
68. Fascia - Dense connective tissue surrounding skeletal muscles
• Superficial fascia – beneath skin
• Deep fascia – covers muscles
• Serous fascia – surrounds serous membranes
Tendons – anchor muscles to bone
• Continuation of muscle fascia and bone periosteum
Aponeurosis - broad sheet of connective tissue attaching flat muscle to another flat muscle
Skeletal Muscle Coverings
epicranial aponeurosis
69. Classification of muscles by shape
• Flat/strap: Abdominal oblique
• Pennate “feather-like” (uni-, bi-, multi-) Deltoid
• Fusiform “spindle-shaped” with thick belly Biceps
• Quadrate “4 equal sides” Rectus abdominis
• Circular or sphincteral “surrounds and opening”
Oribicularis Oculi
• Multiheaded/multibellied – more than one head or
belly biceps brachii
70. Phasic Contraction
Isotonic contraction – muscle changes length while
force (muscle tension) remains the same
• Concentric – muscle shortens
• Eccentric – muscle lengthens
Isometric contraction – muscle changes force
(muscle tension) while the length remains the same
71. Motor Unit
All skeletal muscles requires motor neuron
innervation to contract
CNS constantly adjusts muscle fiber tension
(muscle tone) to maintain optimal tension
Motor unit=Functional unit consisting of a motor
neuron and the muscle fiber it controls
• Size of M.U. is highly variable
• Large M.U. generate power (posture)
• Small M.U. produce precise control
72. Prime Mover (agonist) = responsible for movement
i.e. Biceps brachii = forearm flexion
Antagonists = resists movement of prime mover
i.e. Triceps brachii = forearm extension
Synergists = Aid prime movers
i.e. Brachioradialis for forearm flexion
Skeletal muscle actions
Fixator(s)- muscle pair that act together to prevent unwanted
motion in a joint during movements
75. Pulmonary Circuit – Delivers Deoxygenated blood to the lungs
• From the right ventricle through the lungs to the left
atrium.
Vascular Circuits
Systemic Circuit – Delivers oxygenated blood to tissues
• From the left ventricle through systemic circulation to
the right atrium.
76. Arteries
Convey blood AWAY from the heart
Classification:
• Large Elastic Arteries:
• Walls have many layers of elastic fibers
• Receive cardiac output
• Elasticity minimizes the pressure change
• Medium Muscular (distributing) Arteries
• Walls mostly of smooth muscle
• Pulsatile contractions propel blood to various body
parts
• Small arteries and arterioles
• Narrow lumen and thick muscular walls
77. Capillaries
• Thin endothelial tubes connecting arteries and veins
• Arranged in networks “capillary beds”
• Location of exchange between blood and interstitial fluid (IF)
• Types
• Continuous
• Fenestrated
• Sinusoid
78. Veins
Convey blood Towards the heart
• Systemic circuit – deoxygenated blood
• Pulmonary circuit – oxygenated blood
• One-way valves may be present
• Classification:
• Large Vein (vena cava, jugular, pulmonary veins)
• Medium Vein (e.g., cephalic, renal, hepatic vein, etc.)
• Venule
79. Accompanying Veins
• Veins in the limbs occur as two or more smaller vessels that
accompany an artery in a common vascular sheath.
• Veins are stretched and flattened as artery expands, driving
blood towards the heart – arteriovenous pump
80. Musculovenous pump
• Muscular contractions in the limbs move blood
towards the heart.
• One-way valves prevent retrograde flow of blood.
81. Cardiovascular System: Clinical Impact
Arteriosclerosis “hardening of the arteries”
• Commonly caused by atherosclerosis “buildup of fat
(mostly cholesterol) in the arterial wall.
• Atheromatous plaque (atheroma) – hardened yellow
areas formed by calcium deposits
• Thrombus – local intravascular clot
E.g. deep vein thrombosis
• Embolus – a circulating blood clot
• E.g., pulmonary embolisms
82. Cardiovascular System: Clinical Impact
Varicose Veins
Abnormally swollen, twisted veins
• Veins lose elasticity and dilate
• Venous valves are incompetent, allowing more
pooling of blood.
• Typically in legs
• Relief – exercise, compression stockings,
elevate legs
84. Lymphatic System Functions
• Returns excess interstitial fluid to circulation
(preventing edema)
• Removes old, worn-out cells and debris
• Pathogen surveillance and defense
• Absorbs fats from intestines
85. Fluid Filtration Across Capillaries
As blood passes through capillaries:
Hydrostatic pressure moves fluid out of
blood capillaries into the interstitial space.
H2O
H2O
H2O
Plasma proteins (e.g. albumin)
From
arteriole
To
venule
Blood capillary
oncotic pressure reabsorbs 90% of the lost
fluid from the interstitial space.
H2O
H2O
H2O
H2O
H2O
H2O
Interstitial fluid
H2O
The remaining 10% is returned
to circulation through the
lymphatic system.
Hydrostatic pressure oncotic pressure
(due to colloids in blood)
plasma
86. Components of Lymphatic System
• Lymphatic Plexuses (network of capillaries) –
originate in ECF near blood capillaries.
• Lymphatic vessels – similar to veins but thinner
• Lymphatic trunks – larger lymphatic vessels
• Lymph – tissue fluid within the vessels
• Lymph nodes – contain lymphocytes
• Lymphocytes (B-cells & T-cells)
• Lymphoid Organs: Produce Lymphocytes
• Spleen, tonsils, Peyer’s patches, appendix,
Thymus, Red Bone Marrow
87. Lymphatic Vessels
• Superficial lymphatic Vessels
• Drains the skin and follow the venous drainage.
• Drain into deep lymphatic vessels
• Deep lymphatic vessels
• Accompany the arteries
• Receives the drainage of internal organs
• Lymph nodes are located along both
superficial and deep lymphatic vessels
Lymphatic Nodes
88. Lymphatic Vessels
• Larger lymphatic vessels drain into lymphatic trunks
• Lymphatic trunks unite to form Collecting Ducts
89. Collecting Ducts
Right lymphatic duct
• drains lymph from upper right quadrant (right
head, neck, thorax, plus right upper limb)
• enters the right venous angle (junction of right
internal jugular and right subclavian vein).
Thoracic duct
• drains entire lower body, plus the left upper quadrant
(left side of face, neck, thorax, and left upper limb)
• enters the left venous angle (junction of left internal
jugular and left subclavian vein).
90. Cisterna chyli
• A dilated collecting sac.
• Located in the abdomen in front of the bodies of
the 1st & 2nd lumbar vertebrae
• Drain lymphatic trunks of the lower part of the
body
• Gives rise to the thoracic duct, which ascends
through the aortic opening of the diaphragm into
the thorax.
91. Lymphatic System: Clinical Impact
Lymphangitis – secondary inflammation of lymphatic vessels
Lymphadenitis – secondary inflammation of lymph nodes
Lymphedema – localized type of edema when lymph does not
drain from an area of the body.
After an insect bite, this patient developed an
erythematous streak on the arm consistent with
lymphangitis.
This photo shows swollen lymph
nodes (lymphadenitis) in a child.
Lower extremity lymphedema
92. Lymphatic System: Clinical Impact
Spread of Cancer
Contiguity – growing into adjacent tissue
Metastasis – dissemination of tumor cells to sites
distant from original or primary tumor
Lymphogenous spread of lung cancer
1. Direct seeding of serous membranes of body cavities
2. Lymphogenous spread (via lymphatic vessels)
• Common site of metastasis due to permeability of
lymphatic capillaries
• Most common route for the metastasis of carcinomas
(epithelial tumors).
3. Hematogenous spread (via blood vessels)
• Most common route for the metastasis of sarcomas
(CT cancers)
95. Neurons and Neuroglia
Nervous tissue
Neurons
• Functional units specialized for rapid communication
• Form synapses
• Release neurotransmitters
• Structure
• Dendrites – receive messages via graded potentials
• Excitatory
• Inhibitory
• Axon – sends messages via action potentials
• Myelination of the axon increases the speed of
action potentials
97. Organization
Nervous System
Central Nervous System (CNS)
Brain & Spinal Cord
• Nucleus – group of cell bodies (e.g. dentate nucleus)
• Tract – bundle of axons (e.g. spinothalamic tract)
Peripheral Nervous System (PNS)
Cranial Nerves & Spinal Nerves
• Ganglion – group of cell bodies (e.g. dorsal root ganglion)
• Nerve – bundle of axons + coverings
98. Brain and Spinal Cord
Central Nervous System
Gray Matter = unmyelinated
• Nuclei (neuron cell bodies)
• Cerebral and Cerebellar cortex in the brain
• H-shape region of the spinal cord (horns)
White Matter = myelinated axons
• Myelinated tracts (axons)
• Ex: corpus callosum and arbor vitae
Corpus callosum
99. Meninges
Central Nervous System
Dura Mater “tough mother”
• Cerebral meninges: dural folds
• Spinal meninges: epidural space
Arachnoid Mater “spider-web like”
• Cerebrospinal Fluid (CSF) flows through
the subarachnoid space
Pia Mater “gentle mother”
• Denticulate ligaments attach pia
mater to arachnoid and dura mater
100. Peripheral Nervous System
• 31 pairs of Spinal nerves arising from the spinal cord
• 12 pairs of Cranial nerves arising from the brain
Nerve – bundle of nerve fibers along with their CT coverings in the PNS
Ganglion – mass of nerve cell bodies in the periphery
• Motor ganglia (autonomic ganglia)
• Sensory ganglia
101. Peripheral Nervous System
Nerve Fiber – axon, its neurilemma and
surrounding connective tissues.
• Unmyelinated Nerve Fiber – Schwann Cells wrap
around a bundle of axons grouping them together
without producing myelin
• Myelinated Nerve Fiber – Schwann Cells continually
wrap around the axon forming a myelin sheath
102. Peripheral Nervous System
Peripheral nerves are strong due to
surrounding structures:
• Endoneurium – delicate layer surrounding the
axon and neurilemma
• Perineurium – dense connective tissue
surrounding fascicles of nerve fibers
• Epineurium – connective tissue sheath
surrounding bundles of fascicles.
• Outermost layer of nerve; contains blood
vessels, fat, and lymphatics
103. Nervous System: PNS Clinical Impact
Peripheral Nerve Degeneration
• Crushing Nerve Injury
• Distal axon is damaged
• Cell body and connective tissue covering axon are intact
• CT sheath guides growing axon to target
• Surgery typically not needed
• Cut Nerve Injury
• Distal axon and CT covering of axon are damaged
• Without axon guidance surgery is required
• Realign fascicles and secure with sutures through epineurium
104. Somatic Division
Somatic Sensory
• Touch
• Pain
• Temperature
• Position (e.g. proprioception)
Somatic Motor
• Skeletal muscles
Somatic Nervous System: provides sensory and motor to all parts
of the body, except the visceral organs, smooth muscle, and glands.
Most reach our conscious levels
(i.e. we are aware of them)
(voluntary & reflexive movements)
105. Somatic Reflex Arc
1. Receptor
2. Sensory (afferent) neuron
• Passes through posterior (dorsal) root
• Cell body within the dorsal root
ganglion (DRG)
3. Interneuron
4. Motor (efferent) neuron
• Cell body within anterior horn
• Passes through anterior (ventral) root
• Neurotransmitter = acetylcholine (Ach)
5. Effector = skeletal muscle
Anterior
(ventral) root
Posterior
(dorsal) root
106. Somatic Nervous System and Spinal Nerves
Spinal Nerves
• Anterior & Posterior roots unite
to form a spinal nerve
• Spinal Nerves exit through
intervertebral foramen
Spinal Nerves are Mixed (except C1): i.e.,
carry both sensory and motor fibers.
107. Somatic Nervous System: Clinical Impact
Rhizotomy
Surgical Sectioning of spinal nerve rootlet to
alleviate pain or spastic paralysis.
• Back and neck pain
• Trigeminal neuralgia
• Arthritic pain in hips & knee
• Spasticity (abnormal tightness & spasms)
108. Somatic Nervous System and Spinal Nerves
Nerves divide into 2 rami (branches):
• Posterior ramus – supplies nerve fibers to synovial
joints of the vertebral column, deep muscles of back,
and overlying skin
• Anterior ramus – supplies nerve fibers to the large,
remaining area of the trunk and the limbs.
111. Somite Formation
Somites:
• Are blocks of mesoderm
• Form on either side of neural tube
• Are laid down in sequence from head to tail
112. Somites give rise to striated muscle cells, the vertebrae, and the dermis
Each Somite differentiates into a:
1. sclerotome (medially)
• form vertebrae & base of cranium
2. dermatomyotomes (laterally) - Further
differentiates into a:
• Dermatome = dermis
• Myotome = skeletal muscle
113. Segmental distribution of myotomes in early
limb bud stage (approximately 5 weeks)
Migration of Dermatomyotome Cells
Cells that migrate posteriorly (Epimeres):
• Give rise to Epaxial or intrinsic (deep) muscles of the
back & overlying dermis
• Supplied by dorsal primary rami of spinal nerves
Cells that migrate anteriorly (hypomeres):
• Give rise to the hypaxial muscles of the anterolateral
trunk and limbs and associated dermis.
• Supplied by ventral primary rami of spinal nerves
114. Development of Myotome
• Myotome Cells differentiate into myoblasts
• Segmental spinal nerves from neural tube grow towards myotome
to provide motor and sensory innervation for each myotome
• Throughout life, severing a spinal nerve will denervate the area of
skin and mass of muscle it originally supplied.
115. Spinal Nerves
Dermatomes:
• Unilateral area of skin innervated by the somatic
sensory fibers of a single spinal nerve.
• Dermatome maps indicate the typical pattern of
innervation from the spinal nerves.
• Sensory testing (pin prick) can help determine if a
spinal nerve or spinal cord segment is functioning.
Note that in the Foerster map, C5–T1 and L3–S1 are distributed almost
entirely in the limbs (i.e., have little or no representation on the trunk).
116. Spinal Nerves
Myotomes:
• Unilateral muscle mass receiving innervation from the
somatic motor fibers of a single spinal nerve.
• Most skeletal muscles include multiple spinal nerves.
• Clinical testing: Myotomes grouped by joint movement
• Muscles that flex the shoulder: C5 spinal nerve
• Muscles that extend the knee: L3 & L4 spinal nerves
118. Autonomic Nervous System
• Two Divisions:
• Parasympathetic Nervous System
(craniosacral): rest-and-digest
• Sympathetic Nervous System
(thoracolumbar): Fight-or-Flight
• Effectors include cardiac muscle, smooth muscle, and glands
• Involuntary Control
• Visceral afferents (sensory) accompany the
efferent (motor) nerve fibers.
119. Autonomic Vs. Somatic Reflex Arc
Somatic efferent innervation
requires 1 efferent (motor) neuron
Autonomic efferent innervation requires 2 efferent
neurons & a ganglion located outside the CNS.
120. Autonomic Nervous System
• Presynaptic (preganglionic) fiber is in the
gray matter of the CNS
• Postsynaptic (postganglionic) fiber is in the
peripheral ganglion outside of the CNS
ANS Efferent Neurons:
121. Sympathetic (Thoracolumbar)
Division of ANS
• Begins in spinal cord – T1 through L2/L3
• Spreads out via sympathetic trunk, spinal
nerves, and cephalic arterial rami.
• Innervates all vascularized parts of the body =
widespread affects
122. • Cell bodies of presynaptic neurons are found in the
intermediolateral columns (IMLs) of the spinal cord.
Sympathetic (Thoracolumbar) Division of ANS
• T1 – T12 and L1 – L2 (or L3)
IMLs appear as Lateral Horns in spinal cord cross section
Presynaptic Neurons
123. • Cell bodies of presynaptic neurons are found in the
intermediolateral columns (IMLs) of the spinal cord.
Sympathetic (Thoracolumbar) Division of ANS
• T1 – T12 and L1 – L2 (or L3)
IMLs appear as Lateral Horns in spinal cord cross section
Presynaptic Neurons
124. occur in two locations:
Postsynaptic Neurons
1. Paravertebral ganglia
• Form right and left sympathetic trunks (chains)
on either side of the vertebral column.
• Extend the length of the vertebral column.
2. Prevertebral ganglia
• In the plexus surrounding the main branches of the
abdominal aorta.
• Ex. Celiac ganglia surround the celiac trunk, Superior
mesenteric ganglia, inferior mesenteric ganglia, and
aorticorenal ganglion
Sympathetic (Thoracolumbar) Division of ANS
125. occur in two locations:
2. Prevertebral ganglia
• In the plexus surrounding the main branches of the
abdominal aorta.
• Ex. Celiac ganglia surround the celiac trunk,
Superior mesenteric ganglia, inferior mesenteric
ganglia, and aorticorenal ganglion
1. Paravertebral ganglia
• Form right and left sympathetic trunks (chains)
on either side of the vertebral column.
• Extend the length of the vertebral column.
Postsynaptic Neurons
Sympathetic (Thoracolumbar) Division of ANS
126. • Axons of presynaptic neurons leave the spinal
cord via the anterior root (motor fibers)
• Axon enters the anterior rami of the spinal
nerves T1 – L2/L3
• Pass to the sympathetic trunks through white
rami communicans and….(next slide)
Sympathetic Pathway
Presynaptic Neuron
127. 1. Synapse at ganglion at level of entry to the chain
2. Ascend then synapse at a ganglion higher in the chain
3. Descend then synapse at a ganglion lower in the chain
4. Pass through the sympathetic trunk without synapsing.
• Passes through the abdominopelvic splanchnic nerves
• Synapses in prevertebral ganglia before innervating the
abdominopelvic viscera
• Sympathetic presynaptic fibers innervate the suprarenal
gland and synapse in the adrenal medulla. NT released
enter the bloodstream for a systemic effect.
Sympathetic Pathway
…follow 1 of 4 paths:
Presynaptic Neurons
128. 1. Synapse at ganglion at level of entry to the chain
2. Ascend then synapse at a ganglion higher in the chain
3. Descend then synapse at a ganglion lower in the chain
4. Pass through the sympathetic trunk without synapsing.
• Passes through the abdominopelvic splanchnic nerves
• Synapses in prevertebral ganglia before innervating the
abdominopelvic viscera
• Sympathetic presynaptic fibers innervate the suprarenal
gland and synapse in the adrenal medulla. NT released
enter the bloodstream for a systemic effect.
Sympathetic Pathway
…follow 1 of 4 paths:
Presynaptic sympathetic fibers of the head, neck,
body wall, limbs, and thoracic cavity follow one of
these courses.
Presynaptic sympathetic fibers of the
abdominopelvic viscera follows this 4th course
Presynaptic Neurons
129. Sympathetic Pathway
Postsynaptic Neurons
• Postsynaptic sympathetic fibers are great in number
• From the paravertebral ganglia, fibers pass through
gray rami communicans to adjacent anterior rami of
the spinal nerves.
• Enter all branches of all 31 spinal nerves to
stimulate blood vessel constriction, arrector pili
muscle contraction, sweating
• Diffuse actions = widespread affects
130. Parasympathetic (Craniosacral)
Division of the ANS
Presynaptic Neuron cell bodies
Located within:
1. Gray matter of brain stem
• Fibers exit the brainstem via CN III, VII, IX, X
• Innervate Head
• CN X (Vagus Nerve) provides parasympathetic
outflow to thoracic and abdominal visceral (ALL
thoracic and GI from esophagus to left colic
flexure of large intestine.
2. Gray matter of sacral (S2 – S4) spinal cord
• Fibers exit the spinal cord via anterior roots of
spinal nerves S2 – S4
• Supply descending and sigmoid colon and
rectum only.
131. Parasympathetic (Craniosacral)
Division of the ANS
Postsynaptic Neuron Cell Bodies
• 4 Discrete Pairs of parasympathetic ganglia in the
head are associated with 3 cranial nerves
• CN III synapses on ciliary ganglion
• CN VII synapses on pterygopalatine ganglion
and submandibular ganglion
• CN IX synapses on otic ganglion
• CN X synapses on cell bodies directly on wall of
target organ (intrinsic or enteric ganglia)
• Presynaptic fiber is long
• Postsynaptic fiber is short
• Organs include heart, respiratory tract,
liver/gallbladder, stomach, pancreas, kidney,
small and proximal large intestine
133. Medical Imaging Procedures – Conventional Radiography
• Low energy x-rays produce contrast
depending on relative absorption of tissue
• Used to visualize hard, dense structures
such as bone, metal
• Contrast dyes can be used to improve visibility
134. Can study moving structures
Produces images from the echoes of high-frequency sound waves
Choice for obstetrics due to its safety
Medical Imaging Procedures – Ultrasound
135. Medical Imaging Procedures – MRI (Magnetic Resonance Imaging)
• Patient lies in a chamber with a huge magnet
• Computer translates the energy from the magnet into a visual image
• Used to visualize soft tissue
• Cannot be used in patients with pacemakers or other metal implants
MRI is good for viewing plaques caused by
degenerative disorders
136. Functional MRI (fMRI)
Measures brain activity associated with changes in blood flow.
Advantage: not radioactive & no need for injection of tracer dyes
An example of an analyzed fMRI image. The active areas are in
yellow and red.
137. CT (Computerized Tomography)
AKA CaT Scan
X-ray beams are confined to a thin slice of the body
Produces 3D images
R from feet L
Two-dimensional CT images are conventionally rendered from
an inferior view so that the view is as though looking up at it
from the patient's feet
138. Positron Emission Tomography
PET Scan
Patient is injected with radioisotope tracers
Used to view biochemical activity in the body
• Used mostly in patients with cancer, or brain or heart conditions
139. Endoscopy
Involves the insertion of a camera on a tube into the body
Visualizes internal surfaces, but minimally invasive
Can be used to take biopsies or remove foreign objects
140. Radiation in Healthcare
benefits – better view, more detail
risks – slight increase in likelihood of developing cancer later in life.
Imagining that doesn’t use radiation
Ultrasound
MRI
Endoscopy
Imagining that uses radiation
X-rays
PET
CT
141. Cadaver handling issues
• Be ready to cut at start of lab
• Read Lab Objectives and review anatomy before lab
• Change Gloves Often (handling books, doors, etc.)
• Do not throw trash in tissues bags
• No photos of ID tags, face post online – will check prof violation!
• Get instruments
• Not cut the cadaver bag!
• Tissue bags if bigger than dime keep it
• Vent
• Drain bucket, clean valve
• Vent valve end of lab
• Clean tables & tools!
