Muscle, Bone And Nerve Flashcards
The 3 types of cartilage
Elastic cartilage
- lots of large Chondrocytes
- mostly elastic fibres
- found in ears and epiglottis
Fibrocartilage
- mostly collagen fibres
- Chondrocytes found in rows between fibres
- found in intervertebral discs, symphysis pubis and articulate discs
Hyaline cartilage
- most abundant
- chondrocytes houses in lacunae
- found in joints etc
Growth of cartilage (2)
Appositional growth:
- new surface matrix added to pre-existing matrix by new chondroblasts (young and active cartilage cell) derived from the perichondrium
Interstitial growth:
- grow and divide and lay down more matrix inside the pre-existing cartilage, form clusters (lacunae)
Impaired calcification
Leads to higher levels of Osteoid tissue than normal, bone bends more than it should.
Calcification only occurs in presence of collagen fibres
Leads to rickets in children and osteomalacia in adults
If removed minerals in bone it bends
Structure of bone
Proximal epiphysis - - Diaphysis - - Distal epiphysis
Section through an epiphysis:
Compact bone on outside, spongy bone on inside
Also has nutrient artery
Section through shaft/diaphysis:
Spongy bone replaced by yellow marrow (fat and mesenchyml stem cells)
Outside is layer of connective tissue called Periosteum (a source of new bone cells)
Nutrient artery pierces the periosteum to reach bone tissue since the bone is highly vascular
Compact bone structure
Made of osteons (tightly packed units) which are formed around blood vessels in central canal, lamella bone around them
Spongy bone results from osteons being partly removed, leaving gaps for remaining struts of bone
Types of bone cell
Osteocytes:
Maintains bone tissue
Mature bone cells
Located within bone
Osteoblasts:
Forms bone matrix (deposition of osteoid)
Located at surfaces of the bone
When become trapped in their own osteoid matrix, stop dividing, and then are terms osteocytes
Osteogenic cell:
Stem cell
Produce the next generation of osteoblasts
Located in close proximity of blood vessels in spongy bone, found by periosteum in compact bone
Produce the next generation of osteoblasts
Osteoclast:
Derived from different lineage
Resorbs bone
Located in cavities on the surface of bone
Axial skeleton
Skull
Vertebral column
Ribs
Sternum
Appendicular skeleton
Limb bones
Limb girdles
Bones than connect the limb bones to the trunk bones
Shoulder girdle:
Clavicle and scapula
Pelvic girdle:
Hip bones
Classification of bone (by shape):
Long bone (humerus) Short bone (carpal bone) Flat bone (sternum) Irregular bone (vertebra) Sesamoid bone (patella/knee cap, where a tendon turns a corner)
Ossification / bone development (2)
Intramembranous ossification:
Bones originate from soft connective tissue
(Hyaline cartilage missing from this ossification which is necessary in load bearing joints)
Endochondral ossification:
Bones are guided in their formation by a development from a cartilaginous model
Endochondral ossification
Bone collar formed by osteoblasts
Hypertrophy of chondrocytes
Blood vessels invade shaft
Secondary centre of ossification forms in the epiphysis’
Epiphyseal/growth plate formed from the growth of bone restricting the cartilage growth
Bumps on a bone
Process: Projecting out of bone (If hooked - Hamulus) (If sharp - spine) (If round - tubercle, large tubercles are tuberosity’s)
Ramus:
Particularly large
Lumps & bumps due to the pull of tendons or ligaments
Grooves and holes in bones
Groove in bone:
Sulcus
Deeper than a groove:
Notches
Pit in bone:
Fossa
Hole in a bone:
Foramen
Articular surfaces
Small and round joint:
Facet
Rounded articular surfaces:
Condyle (means knuckle)
Joints
Bone-bone
Bone-cartilage
Cartilage-cartilage
Function of joints
Allow movement
OR
To allow growth (or both)
Joint classification (3)
Fibrous joints:
- don’t allow significant movt (synarthrosis)
- connective tissue connects bones
- no joint cavity
Cartilaginous joints:
- provide limited mobility (amphiarthrosis)
- cartilage to bone
- no joint cavity
Synovial joints:
- freely moveable joint (diarthrosis)
- support articulating bones
- contains joint cavity (synovial fluid)
Fibrous joints
Sutures (eg. all found in skull):
- serrated (bones interlock)
- squamous (bones bevelled on eachother/angle)
- plane (bones meet edge to edge)
Syndesmoses (eg. inferior fibular tibular joint)
- bones bound by ligaments/membranes
Gomphoses (eg. Tooth and jaw)
- peg and socket
Types of cartilaginous joints (2)
Primary:
- little movt
- Bone segments separated by hyaline cartilage
- seen in growth plates in the growing skeleton AND first sternal costal joint (joint between first rib and sternum)
Secondary:
- bones separated by a pad of fibral cartilage
- limited movt
- seen in intervertebral discs
- all in the mid line of the body
Synovial joints
Slide over eachother with ease due to hyaline cartilage on their surfaces (also lubricated by synovial fluid)
Articular shape and movement
Uniaxial joint:
Moves in one plane only
(Gliding joints, hinge joints, pivot joints)
Biaxial joint:
Moves in 2 planes
(Ellipsoid joint, saddle joint)
Multiaxial joint:
Moves in 3 planes
(Ball and socket)
Stability of a joint is dependent upon:
Most stable - close packed position
Least stable - loose packed position (most likely to dislocate)
Mobility is inversely related to stability (all factors limit mobility)
Articular shape
(Deep pocket more stable than shallow)
Strength of the capsule
(Capsule that tightens upon movt is more stable against that movt)
Ligaments
(Inside or outside the capsule will give added support)
Muscle
Tendons
(Physical barrier to unwanted movt to joint)
Types of muscle tissue (3)
Striated skeletal muscle:
- multinucleated cells
- un-branched
- controlled by somatic nervous system
Striated cardiac muscle:
- single branched cells joined by intercalated disc
- controlled by autonomic
Non-striated smooth muscle:
- spindle shaped single cells
- controlled by autonomic
Types of isotonic muscle contraction (2)
(Think of dumbbell)
Concentric = muscle shortens during force production
Eccentric = muscle produces force but length increases (lowering db)
isometric muscle contraction (2)
(Pull on immovable object)
- muscle exerts force without changing length
- or postural muscles keeping body upright
Example of antagonistic muscle groups
Flexors:
- Brachialis
- Biceps brachii
Extensors:
- triceps brachii
- anconeus
Formation of skeletal muscle
- myoblasts fuse into myotubules (immature muscle fibres)
- satellite cells (resident muscle stem cells) on surface of muscle cells can be activated to enter cell cycle and become myoblasts which proliferate and differentiate to provide new myonuclei for existing muscle fibres, or fuse together to generate new myofibrils
- satellite cells can also self-renew to maintain stem cell pop
Myofibril structure
Contain 2 protein filaments:
Thick = myosin
Thin = actin
Myofibrils are divided into sarcomeres
Muscle contraction in relation to bands
Sacromere shortens (Z lines move closer)
H & I bands shorten
A band remains the same
Sub-division of muscle fibres depending on speed of contraction
Speed depends on myosin heavy chain isoform present
(Spotted histochemically)
Type I slow division
(Slow oxidative)
Type II fast fibres: - IIa (fast oxidative) - IIb (fast glycolytic) - IIx (super-fast glycolytic) (Spotted by immunostaining)
Fast myosin isoform found in white muscle fibres, bc small amount of myoglobin (o2 binding molecule)
Slow myosin isoform found in red muscle fibres, bc lots of myoglobin
What structures are all embryonic trunk and limb muscles derived from?
Somites
(Contain the progenitors of many tissues)
Head muscles come from unsegmented cranial mesoderm NOT somites
Types of progenitors for embryonic tissues that somites contain (3) & examples
Dermomyotome:
- skeletal muscle
- satellite cells
- dermis
Sclerotome:
- cartilage
- VSMC
- endothelial
- meninges
- joints
- tendons
Myotome:
- differentiated myocytes
Formation of limb muscles
Precursors of muscle originates from somites
They migrate into the limb bud
Receive instructions about which muscle to form from extrinsic signals in limb periphery (muscle connective tissue fibroblasts)
Grey and white matter
Grey matter - made up of cell bodies of the neurons
White matter - made up of the axons of the neurons surrounded in myelin
Ganglia
Collections of nerve cell bodies outside of the CNS
Structure of the meninges
Dura mater = fibrous connective tissue - - Arachnoid mater = impermeable membrane - - Pia mater = vascular layer
Glial cells in the CNS
Oligodendrocyte:
- form myelin sheaths around axons in CNS
- a single cell (unlike Schwann cells in PNS) can myelinate many axons
Astrocytes:
- most plentiful
- form blood brain barrier, wrap capillaries
Microglia:
- immune defence cells of the brain
Ependymal cells:
- form epithelial layer
- involved with cerebral spinal fluid
Types of nerve fibres
Somatic sensory
Visceral sensory
Somatic motor
Autonomic motor
Efferent VS Afferent nerve
Efferent:
Out from spinal cord to periphery
Afferent:
In from periphery to spinal cord
Neuron processes
Motor neuron:
- upper motor neurones
- carry motor info down to:
- lower motor neurones
Sensory neurons
- 1st order neurons
(Conduct sensory info from receptor to CNS)
- 2nd order neurons
(Conduct info from brain and spinal cord into thalamus)
- 3rd order neurons
(Conduct info from thalamus to sensory cortex of brain)
Nerve fibre classification
A fibres: myelinated
(Decreasing in size: alpha, beta, gamma, delta)
B fibres: smaller myelinated
C fibres: unmyelinated
Sensory nerve ending receptors
Meissner’s corpuscle:
In places with high sensitivity (fingers/lips)
Pacinian corpuscle:
Give sense of vibration
Ruffini end organs:
Sensations of continuous touch and pressure
Merkel’s discs:
Sensation of continuous pressure
Free nerve endings:
Movt of hairs, thermal sensations
Cranial nerves
I : olfactory (nose) II : optic (eye) III : oculomotor (eye muscle) IV : trochlear (eye muscle) V : trigeminal (facial sensors) VI : abducens (eye muscle) VII : facial (face muscle) VIII : vestibulocochlear (inner ear) IX : glossipharyngeal (pharynx) X : vagus (lots of organs) !!! XI : accessory (2 neck muscles) XII : hypoglossal (tongue muscles)
Structure of spinal nerves
Spinal nerve connected to spinal cord
Have posterior sensory root & anterior motor root
When emerging from intervetebral foramen, each spinal nerve divides into anterior ramus and posterior ramus (mixed)
Spinal nerves (going down the spinal cord)
Cervical nerves (C1-C8) (cervical plexus & brachial plexus)
Thoracic nerves (T1-T12)
Lumbar nerves (L1-L5)
Sacral nerves (S1-S5)
Coccygeal nerve (CO)
Number of nerves
Cranial = 12 pairs Spinal = 31 pairs (all mixed)
Define dermatome & myotome
The skin supplied by a single nerve
The group of similar muscles that are supplied by a single nerve
Define nerve plexus
Network of peripheral nerve fibres from intersecting differing spinal nerves
Sympathetic neuron
Preganglionic nerve:
Short, myelinated
Synapses in the sympathetic ganglion
Uses acetylcholine as its neurotransmitter
Postganglionic nerve:
Long, unmyelinated
Synapses in target organ
Uses noradrenaline as its neurotransmitter
Sympathetic augmentation
Chromaffin cells are stimulated by the preganglionic neurons
Adrenal medulla release adrenaline (acts like noradrenaline) and some noradrenaline
In bloodstream to target
Parasympathetic neuron
Pre-ganglionic nerve:
Long, unmyelinated
Post-ganglionic nerve:
Short, myelinated
Neurotransmitter:
Acetylcholine
(for both pre&post ganglionic neurons)
Pre-ganglionic sympathetically (3)
Pre-ganglionic sympathetic neuron can synapse with a post-ganglionic neuron at the same level of origin
(Provided it arises from T1-L2)
Neuron can travel up or down the sympathetic chain to another ganglion at a different level
Neuron can travel through ganglion without synapsing and run to a pre-vertebral (visceral) ganglion
Basic neurotransmission
Sensory neuron bring sensory info into spinal nerve via the dorsal root
Will synapse with another neuron in the spinal cord
To the brain
Out via motor neurons via ventral root
Number of cranial nerves
12
2 - from cerebrum
10 - from brain stem
Aponeurosis
Type of deep fascia in the form of a sheet that attaches muscles needing a wide area of attachment
(Eg. Abdominal)
