The branch of science concerned with the bodily structure of humans, animals, and other living organisms, especially as revealed by dissection and the separation of parts.

1. Anatomy visual display part 2

10. The Neuromuscular Junction
– The point at which the axon terminal of the motor neuron meets the
sarcolemma of the muscle fibre
– Synaptic cleft (space) – separates the axon terminal from
sarcolemma
– Nerve impulse arrives at axon terminal = Neurotransmitter being
released from the axon terminal into synaptic cleft
– Acetylcholine (ACh) = the neurotransmitter released at the NMJ

11. Neuromuscular Junction
• ACh diffuses across the synaptic cleft & binds to receptors on the sarcolemma
= Ca2+ release from sarcoplasmic reticulum causing muscle contraction
• The sarcolemma at the NMJ is invaginated & has trough-like
depressions
• Acetylcholinesterase enzyme is secreted by cells of the sarcolemma
at the NMJ.
• This breaks down the neurotransmitter ACh so one nerve impulse
produces only 1 contraction in the muscle fibre
11

15. Endoneurium wraps a single axon including the myelin sheath.
Fascicle is a small bundle of nerve fibers/axons.
Perineurium wraps a fascicle. (peri means around)
Epineurium wraps a bunch of fascicles. (epi = upon/top)

19. Connective Tissue Sheaths
• Epimysium
• Surrounds whole muscle
• Dense irregular connective tissue
• Perimysium
• Each skeletal muscle has fibres
separated into groups called
fascicles
• Surrounds groups of muscle fibres
(fascicles)
• Fibrous connective tissue
• Endomysium
• Covers each individual muscle
fibre
• Loose connective tissue

26. 1. Contractility
– Muscle cells shorten and generate pulling force
2. Excitability
– Electrical impulses travel along muscle cells plasma membrane & stimulate muscle cells to contract
– Electrical impulses can come from nerve signals or other factors
3. Extensibility
– Can be stretched by contraction of an opposing muscle
4. Elasticity
– Can recoil passively after being stretched & resume its resting length
– Occurs mainly due to connective tissue in muscle
Functional Characteristics of Muscle Tissue

31. • Contraction initiated by neural stimulation.
• Each muscle fibre is served by a nerve ending that
signals the muscle to contract
• Motor Neurons
– Nerve cells that innervate skeletal muscle fibres
Features of a motor neuron
– Dendrites = receptive regions of neuron
– Axon = long single process that initiates and transmits nerve impulses
– Axon terminals = enlargements at end of axonal processes where neurotransmitter
chemical is released to pass the message on
– Neurotransmitter = chemical released from axon terminal
Neural Control of Skeletal Muscle

34. Muscle Spindles
• Measure changing length of muscle
• Average muscle contains between 50-150 embedded in perimysium
• Contain modified muscle fibres called intrafusal fibres which are surrounded by a connective
tissue capsule
• Intrafusal fibres innervated by
• primary sensory endings wrapped around non-contractile middle which respond to rate
and degree of stretch
• Secondary sensory endings monitor spindle ends for degree of stretch
• Stretching of muscle causes stretching of muscle spindle which sends message to spinal
cord
• When muscle stretches –by antagonists or losing balance etc. intrafusal fibres are
stretched. Stretching activates primary & secondary nerve endings causing them to fire
off impulses to brain and spinal cord. CNS activates alpha motor neurons to contract
muscle to resist further stretching.
• Can be activated by monosynaptic spinal reflex to resist a fall or controlled by cerebellum
for muscle tone
• Gamma efferent neurons also innervate spindle to preset the sensitivity of neurons to
stretch e.g.; gymnast would have very sensitive system
34

35. 35

36. • Located near muscle-tendon junction
• Monitor tension in tendons
• Contracting muscle pulls on tendon and GTO sends signal to brain and spinal cord
– Signal activates reflex that results in relaxation of muscle and contraction of antagonist
muscle

38. • Mechanical Advantage = Small effort to move large load over
a small distance
- occurs when load is close to fulcrum and effort is applied far from fulcrum
• Mechanical disadvantage = large effort exerted to move small load.
– When load is far from fulcrum and effort is applied close to it. But load can be
moved rapidly over large distance.
• Law of Levers
– when the fulcrum-effort distance is larger than the fulcrum-load distance,
lever operates at a mechanical advantage
– when the fulcrum-effort distance is smaller than the fulcrum-load distance,
the lever operates at a mechanical disadvantage
Mechanical Advantage

39. First Class Lever
• Fulcrum located between load & point effort is
applied
• Can operate at mechanical
• Advantage for strength or mechanical
disadvantage for speed & distance
• Holding head up operates at a mechanical
advantage
• Lifting hand weight - mechanical disadvantage

40. Second Class Lever
• Load positioned between fulcrum & point of effort
• Operates at a mechanical advantage, enabling great strength
– speed & distance of movement are sacrificed

41. Third Class Lever
• Effort is applied between load & fulcrum
• work speedily & produce large distance movement, not
strength
• always at mechanical disadvantage - effort must be
greater than load
• most m. of body are 3rd class
• permit m. to insert very close to joint across which
movement occurs.
• allows for fast extensive movements as in running or
throwing with relatively little shortening of the muscle

43. Smooth Muscles Characteristics

77. The Parasympathetic Division
The sacral outflow comes from spinal nerves S2 – S4 and innervates:
2nd half of large intestine (smooth muscle)
Urinary bladder and ureters (smooth muscle)
Reproductive organs/erectile tissues of external genitalia (smooth muscle)
This is what points the penis.
The cranial outflow is made up of CN and this is what they innervate:
III (Oculomotor) – constriction of pupils. The pupil is really just a hole; the absence of light. The iris itself has
a smooth muscle inside of it. These muscles are circular. There’s other smooth muscle fibers that run like
spoke wheels that dilate the pupils.
VII (Facial) – lacrimal gland (tears), nasal mucus glands, salivary glands
IX (Glossopharyngeal) – parotid gland (which is a salivary gland)
X (Vagus) – heart (cardiac muscle), lungs (bronchi smooth muscle), liver/gallbladder (glands), stomach
(smooth muscle and secretions), pancreas (gland), small intestine and 1st half of large intestine (smooth
muscle and secretions)

80. The Sympathetic Division (T1 – L2)
it does the opposite of parasympathetic :
Pupil dilation
Inhibit tear, nasal mucus, saliva production
Skin blood vessel constriction (shunt blood away from skin and to vital organs)
Sweat
Increase heartrate and bloodflow to heart muscle
Bronchodilation
Liver/gallbladder – release glucose
Inhibit rest of digestive system
Inhibit defecation and urination
Ejaculation

102. • Body
– anterior- weight bearing
• Vertebral arch
– Posterior
– Formed from pedicles and lamina
• Vertebral foramen
– forms the vertebral canal when articulated with other vertebrae- (where the spinal
cord runs)
• Pedicles X 2
– form sides of the vertebral arch
– project posteriorly from vertebral body
– are short
• Lamina X 2
– like flat roof plates completing the arch posteriorly.

103. • Body
– anterior- weight bearing
• Vertebral arch
– Posterior
– Formed from pedicles and lamina
• Vertebral foramen
– forms the vertebral canal when articulated with other vertebrae- (where the spinal
cord runs)
• Pedicles X 2
– form sides of the vertebral arch
– project posteriorly from vertebral body
– are short
• Lamina X 2
– like flat roof plates completing the arch posteriorly.

104. 7 processes project from the vertebra
• Spinous process X 1 - Projects posteriorly
• Transverse processes X 2 - Project laterally
• Spinous and transverse processes are attachment sites for muscles and ligaments
• Articular Processes - from pedicle and lamina junctions
- 2 X superior articular processes
- 2 X inferior articular processes
- Inferior process of 1 vertebra articulates with the superior process of next
• Facets = smooth joint surfaces of these processes

105. • Intervertebral Foramen
– The pedicles have notches on superior & inferior borders which form lateral
openings between adjacent vertebrae = intervertebral foramina for spinal nerves to
pass through
• Intervertebral
– Located between vertebrae

109. Craniovertebral joints

110. Craniovertebral joint ligaments

111. Craniovertebral joint ligaments

112. Craniovertebral joint ligamentsTable 1.3 Vertebral ligaments
Ligament Location
Vertebral body ligaments
A Anterior longitudinal ligament Along anterior surface of vertebral body
P Posterior longitudinal ligament Along posterior surface of vertebral body
Vertebral arch ligaments
1 Ligamenta flava Between laminae
2 Interspinous ligaments Between spinous process
3 Supraspinous ligaments Along posterior ridge of spinous processes
4 Intertransverse ligaments Between transverse processes
Nuchal ligament*
Between external occipital protuberance and spinous process of
C7
*Corresponds to a supraspinous ligament that is broadened superiorly.

113. Craniovertebral joint ligaments
Anterior longitudinal
ligament

114. Craniovertebral joint ligaments
Poterior longitudinal
ligament

121. • Smallest & lightest vertebrae
• All have transverse foramen
• C1 & C2 are unique
– No intervertebral disc between
• C1 = atlas
– No body or spinous process
– Anterior & posterior arches
– Lateral mass with articular facets on superior & inferior surfaces
– Superior articular facet articulates with occipital condyles of skull
• Allows flexion & extension of head & neck (saying ‘yes’)
– Inferior articular facet articulates with C2
Cervical Vertebrae C1-C7

122. • C2= Axis
– Has body & spinous process
– Dens = superior ‘knoblike’projection
• Cradled in anterior arch of atlas, acts
as pivot for rotation of atlas
• Allows rotation of atlas on axis (saying
‘no’)
• C3-C7
– Short bifid spinous processes projecting
directly posterior (except C7 which is not
bifid and is longer)
– Triangular vertebral foramen

128. • Anterior Longitudinal Ligament
– Runs vertically along anterior surface of bodies of vertebrae
– Wide
– Attached to vertebrae & intervertebral discs
– Supports spinal column and prevents hyperextension of back
• Posterior Longitudinal Ligament
– Vertically along posterior surface of vertebral bodies
– Narrow, relatively weak
– Attached only to intervertebral discs
– Helps prevent hyperflexion
• Ligamentum Flavum
– Connects lamina of adjacent vertebrae
• Interspinous Ligament
– Connects spinous processes of adjacent vertebrae
• Supraspinous Ligament
– Runs along tips of spinous processes

132. Thoracic Spine

134. Thoracic Vertebrae T1-T12
• Body has facets for articulating with heads of ribs
– Superior costal facet & inferior costal facet
• Transverse processes have facets for articulating with tubercles of
ribs
– Transverse costal facets
• Heart shaped body
• Small circular vertebral foramen
• Long, inferiorly pointing spinous process

135. Thoracic Spine
Typical Vertebra

136. Thoracic Spine
Typical Vertebra

137. Thoracic Spine
Typical Vertebra

138. Structure of a true rib

139. Structure of a true rib

140. Structure of a true rib

141. Structure of a true rib
Ribs are bowed flat bones
• Shaft
– smooth superior border, sharp inferior border with costal groove on inner
face (for intercostal nerves and vessels)
• Head
– wedge shaped, articulates with vertebral bodies via 2 facets. 1 facet joins
body of vertebra of same number & other joins body of vertebra
immediately superior
• Neck
– short constricted region just lateral to head
• Tubercle
– just lateral to neck on posterior surface. Knoblike, articulates with
transverse process of thoracic vertebra of same number

142. Structure of a true rib
• Angle of rib
– lateral to tubercle shaft angles sharply anteriorly and extends
to costal cartilage
• Costal cartilage
– provides secure but flexible attachments of ribs to sternum
and contribute to elasticity of rib cage.
• 1st Rib- atypical
– Flattened from superior to inferior & quite broad. Groove along superior
surface for subclavian vessels
• Rib 1 & ribs 10-12 articulate with only 1 vertebral body
• Ribs 11-12 do not articulate with a transverse process.

143. • Cone shaped
• Posteriorly = thoracic vertebrae
• Laterally = ribs
• Anteriorly = sternum and costal cartilages
Functions:
• Protective cage around heart, lungs & other organs
• Supports shoulder girdles and upper limbs
• Provides attachment points for muscles of back, neck, chest & shoulders
• Intercostals spaces occupied by intercostal muscles used in breathing
Thoracic Cage

144. Thoracic Cage
• Sternum
• Manubrium
• Clavicular notches x 2 - articulate with clavicles
• Jugular notch= suprasternal notch
• Costal Notches - Articulation with 1st and 2nd ribs
• Body
• Notched laterally where articulates with ribs 2 to 7.
• Xiphoid Process
• only fully ossifies at age 40
• Sternal angle = horizontal ridge across anterior surface of sternum where
manubrium joins body- fibrocartilage joint - acts like a hinge allowing
sternal body to swing anteriorly when inhale. At level of rib 2.
• Xiphisternal joint- sternal body and xiphoid process fuse- at level of T9.
Heart lies on diaphragm deep to this point.

145. Rib
12 pairs
• All attach to thoracic vertebrae posteriorly & run anteroinferiorly to reach front of
chest.
• True Ribs (1-7) - attach directly to sternum via costal cartilages = vertebrosternal ribs
• False Ribs (8 -12) - attach to sternum indirectly or not at all
– 8-10 attach to sternum indirectly, each joins costal cartilage above it =
vertebrochondral ribs
– 11-12 are floating ribs or vertebral ribs - no anterior attachments. Costal cartilages
are embedded in muscles of lateral body wall.
• Ribs increase in length 1-7 and decrease in length 8-12
• Costal margin
– inferior margin formed by cartilages 7-10
• Infrasternal angle
– where right & left costal margins diverge from xiphisternal joint

146. Thoracic Spine
Typical Vertebra

147. Thoracic Spine
Typical Vertebra
Sternoclavicular joint

148. • Largest & thickest body
• Short flat spinous processes, project
straight posteriorly

149. Thoracic Spine
Typical Vertebra
Ligaments of the vertebral column: Thoracolumbar junction

150. Lumbar spine

151. Lumbar spine
Typical Vertebra

153. Sacrum

154. Sacrum
Anterior Surface
• Sacral Promontory = anterosuperior margin of 1st sacral
vertebra. Bulges anteriorly into pelvis cavity. Human body
centre of gravity lies about 1 cm posterior to this point.
• Transverse ridges X 4- cross anterior surface of sacrum
marking fusion of sacral vertebrae
• Anterior sacral foramina - openings for ventral divisions of
sacral spinal nerves
• Lateral part = large region lateral to foramina
• Ala= superior to lateral region
– wings articulate with the 2 hip bones to form sacroiliac joints of pelvis

155. Sacrum
Posterior Surface
• Median sacral crest = in midline - fused spinous processes of
vertebrae
• Posterior sacral foramina - transmit dorsal rami of sacral
spinal nerves
• Lateral sacral crest- lateral to foramina - represents tips of
transverse processes
• Sacral Canal = continuation of vertebral canal
• Sacral hiatus = enlarged external opening at inferior end of
sacral canal where laminae of 5th sacral vertebrae fail to fuse
medially.

156. Sacrum and Coccyx

157. Sacrum and Coccyx

158. Sacrum and Coccyx

159. Sacrum and Coccyx

161. Intervertebral disk in the vertebral column

162. Structure intervertebral disk

163. Relation of intervertebral disk to vertebral canal

164. • Nucleus pulposus
– Inner sphere
– Gelatinous like a rubber ball
– Allows spine to absorb compressive stress
• Annulus fibrosus
– outer collar approx. 12 concentric rings - inner = fibrocartilage
- outer = ligament.
– Main function is to contain the nucleus pulposus, limiting its expansion when spine is compressed.
– They also function like a woven strap binding successive vertebrae together
– They resist tension in the spine and absorb compressive forces
– Collagen fibres in adjacent rings cross like an X allowing spine to withstand twisting(similar to bone
lamellae in osteons)
• Vertebral end-plates
– Connective tissue (cartilaginous caps) covering top & bottom surfaces of the vertebral bodies. Tightly
bound to the disc by the collagen fibres of the annulus but loosely bound to vertebral bodies.
Intervertebral Discs

165. Outer zone of the annulus fibrosus

166. Table 1.2 Joints of the vertebral column
Craniovertebral joints
1 Atlanto-occipital joints Occiput–C1
2 Atlantoaxial joints C1–C2
Joints of the vertebral bodies
3 Uncovertebral joints C3–C7
4 Intervertebral joints C1–S1
Joints of the vertebral arch
5 Zygapophyseal joints C1–S1

167. Zygapophyseal (intervertebral facet) joints

168. Uncovertebral joints

169. Spinal nerve