Anatomy Quiz 3

connective tissue functions

• Connecting & binding

• Support \n • Protection \n • Transport

ECM

_________ plays extensive role in all connective tissues

fibroblasts

loose connective tissue is formed by _______

elastin, collagen

Gel-like ground substance and 2 types of proteins: _______ and _________

collagen

densely packed ______ fibers

• **fibroblasts and ground substance less abundant**

• **Tendons & Ligaments**

• **Cartilage and Bone**

cartilage

present in the ears nose and between bones

from mesenchyme

chondroblast, chondrocyte

2 cell types in cartilage

chondroblast

immature cells

chondrocyte

mature cells that inhabit **lacunae**

perichondrium

Blood supply limited to **________**

bone

Composed of **organic and inorganic** compounds • Collagen fibers

• Ground substance (osteoid) \n • Calcium phosphate crystals (**hydroxyapatite crystals**)

osteoblasts, osteocytes, osteoclasts

3 bone cell types

osteoblast

deposition; associate with **periosteum**

osteocyte

maintenance

osteoclast

resorption

Intramembranous ossification

Built upon model of embryonic connective tissue

• **mesenchymal membrane**

• **Dermal bone**

• Ground substance calcifies in rods called **trabeculae**

* clavicles and bones of the skull

Endochondral ossification

• Built upon model of **hyaline cartilage**

• Primary and secondary ossification centers

* all bones besides the clavicles and bones of the skull

longitudinal growth

lengthening of bone

• Division of **chondrocytes** in **epiphyseal plate**

appositional growth

Bones also grow in width

• Osteoblasts between periosteum and bone surface deposit new bone; Osteoclasts break down old bone

• **Thickens compact bone of diaphysis**

compact bone

dense outer bone

cancellous bone

inner lattice of trabeculae

• houses red bone marrow and stem cells

chondrocranium

• Surrounds brain ventrally, posteriorly, laterally

• Derived from neural crest; posterior elements from sclerotome

• Endochondral ossification

splanchnocranium

• Derived from gill arches

• Neural crest

• Cartilage or bone (endochondral ossification)

dermatocranium

• Covers other two cranial components

• Neural crest and dermatome

• Dermal bone (intramembranous ossification)

agnathans

• Lack jaws

• Splanchnocranium supports the pharyngeal basket • jaws arose from one of the anterior pair of gill arches

Elasobranchs

• Gill arches and jaws develop in series \n • Jaw musculature modified from branchial arch musculature

**Paleostyly**

(agnathans) no attachment

**Euautostyly**

(early gnathostomes)

• Mandibular arch attached directly to the skull

**Amphistyly**

(basal chondrichthyans)

* double attachment
* Ligament attaching PQ to skull
* Posterior attachment to hyomandibula
* Most modern sharks a variant of this

hyostyly

(derived sharks and actinopterygians)

• Attachment via the hyomandibula only

craniostyly

(mammals)

* Upper jaw incorporated into braincase
* Lower jaw is suspended from the dermal squamosal bone
* Low jaw consists entirely of dentary
* PQ and Meckel’s cartilage only ossify

at the posterior end
* Incus and malleusnd

splanchnocranium

In mammals, the ___________________ does not contribute to the adult jaws or to their suspension

hyoid apparatus, styloid, three middle ear bones

(In mammals) Instead splanchnocranium forms

First amniotes

small lizard-like animals (anapsid)

• Roof of skull had openings for eyes, pineal organ, nostrils

anapsid

no temporal fenestra

diapsid

two temporal fenestra

synapsid

one temporal fenestra

fenestra

1. cranial kinesis
2. jaw closing muscle origins expand
to roof of skull
* mammals: differentiation of jaw
muscles

cranial kinesis

ability to move parts of skull relative to other parts

“flexible” skull

fragile but highly mobile

Palatoquadrate

epipterygoid and quadrate bones

primitive amniotes

• Stapes present but relatively robust \n • Strong jaw-closing muscles

basal synapsid skull

2 jaw closing muscles:

1. pterygoid: palate to medial lower jaw

2. adductor mandibulae

derived skull

3 jaw closing muscles:

1. pterygoid: palate to medial lower jaw

2. temporalis: pulls posterior

3. masseter: side to side

function of occipital

basioccipital, exoccipitals, supraoccipital

function of sphenoid

orbitosphenoid, presphenoid, basisphenoid, alisphenoid

function of temporal

components of all three parts of skull

axial skeleton

* Two structures combine to form long axis of vertebrates
* Notochord
* Vertebral column
* from scerotome
* condense around notochord and DHNC
* intersegmental position but myomeric muscles
develop w/in segment
* allows flexion between vertebrae

vertebrae, ribs, sternum

3 parts of axial seleton

notochord, vertebral column

Two structures combine to form long axis of vertebrates

functions of axial skeleton

• Provides sites for muscle attachment

• Prevents anteroposterior telescoping

• Major role in supporting body weight

Ribs

* Struts that articulate or fuse with vertebrae

• Provide sites for secure muscle attachment
* Help suspend the body
* Form a protective case around

the viscera (rib cage)
* Sometimes serve as accessory breathing devices

myosepta

Embryonically, ribs arise from cartilage within the _________

tetrapod ribs

• Tetrapods retain the dorsal set of these from fishes

• Two articulations in primitive tetrapods = bicipital

• capitulum (ventral)àparapophysis

• ventral process on intracentrum,

• pleurocentrum (diapsids)

• centra (mammals)

• tuberculum (dorsal)àdiapophysis (process on neural arch)

true

attach to sternum • via sternal rib (cartilage)

vertebrosternel

false

attach to rib

vertebrocostal

free

attach to nothing

vertebral

floating

centra structure

Variation in structure of pleurocentrum & intercentrum

6

**number of 2-Toed Sloth cervical bones**

9

**number of 3-Toed Sloth cervical bones**

6

**number of Manatee cervical bones**

angled zygapophysis

narrow centrum

horizontal zygapophysis

flat/shallow centrum

origin of paired fins

• We know that paired fins arose in the gnathostomes

• but WHERE did they come from?

• Early fishes would have been unsteady swimmers • Fins initially function as stabilizers

stabilizers

Fins initially function as ________

• Leads to the evolution of paired fins (and associated girdles)

basal

Gnathostomes have two types of fins \n • both are derived from a chain of _______ elements

fin-fold theory

• Proposed independently by Balfour and Thacher

• Paired fins arise within a paired, but continuous set of ventrolateral folds

pterygiophores

Paired fins arise within a paired, but continuous set of ventrolateral folds (supported by _______________)

girdles

fusion of basals →_________

• strengthen by dermal bone

*Haikouichthys*

Early vertebrates had skin folds

Acanthodians

had paired rows of spines

iliac portion

dorsal girdle

pubic portion

**Anteroventral girdle**

ischiac portion

**Posterioventral girdle**

cleithrum

usually lost in early amniotes

crossopterygian fin

In lineage leading to tetrapods: fin develops along axis along posterior lengeth of fin and radial pterygiophores only emerge on anterior side of the axis

sarcopterygians

shift from tribasic fin to monobasic fin (one basal pterygiophore) (fin attachment is more flexible/maneuverable)

distal elements (digits)

newly evolved in tetrapods

numbering schemes

1. digits assigned number from what was ancestrally anterior to posterior

* thumb and hallux are digit 1


* pinky and little toe are digit 5


2. Phalangeal formula: lists number of phalanges in each digit in order from #1-#5

* ancestrally was 2-3-4-5-3

glenoid

articular facet for humerus

ilium, ischium, pubis

three distinct bones that fuse together during development to form the acetabulum

acetabulum

hip socket

astragalus

formed from consolidation of several tarsals = talus

olecranon

posterior ulna

longer olecranon

increased mechanical advantage (recall F in x L in = F out x L out)

pectoral

* Derived tetrapods
* Reduction in dermal elements
* ALL loss of cleithrum
* SOME lose clavicle and interclavicle
* Sacapula and coracoid condence seperately

pelvic

* Foramen developes between pubic and
ischium - increases muscle attachment area
* Several lineages show modifications for specific modes of locomotion

frogs

huge anterior projection from ilium
\- muscle attachment for jumping

polydactyly

increase number of digits

polyphalangy

increase number of phalanges per digit

birds

lose two digits and fuse carpals and metacarpals into carpometacarpus

bats

elongate digits

pterosaurs

elongate digit 4
and shorted proximal bones

furcula

wing downstroke pulls _______ apart, but it acts like a spring and recoils, helping to pull wings up for upstroke

more upright posture

keeled sternum

attachment for flight muscles power wings

synsacrum

highly fused to stabilize standing

7

most mammals have __ vertebrae

atlas

first cervical vertebrae

white

develops only from first intercentrum and neural arch (i.e. it has no pleurocentra)

axis

second cervical vertebrae

grey