Anatomy Exam 1

Oogenesis

Results in one viable oocyte; finite resource

Spermatogenesis

Results in 4 viable sperm; easily replenished

Nondisjunction

Failure of homologous chromosomes to separate, resulting in some gametes with extra chromosomes and others with not enough

Day 1

Fertilization of oocyte

Week 1

Zygote cleaves into morula, then becomes blastocyst; implantation into superior-posterior wall of uterus

Ectopic pregnancy

When implanation occurs anywhere other than the superior-posterior uterus, most commonly in uterine tubes

Blastocyst

Embryonic structure formed during the first week following fertilization; consists of embryoblast as inner cell mass and trophoblast (embryonic contribution to placenta) which divides into cytotrophoblast and syncytiotrophoblast, hypoblast, and blastocystic cavity

Syncytiotrophoblast

Derived from trophoblast; invades the endometrium seeking blood vessels and nutrients

Morula

Formed when the zygote divides into a ball consisting of 16-32 cells

Week 2

Embryoblast differentiates into bilaminar disc; amniotic cavity forms within epiblast; hypoblast grows all around the blastocystic cavity, making it the exocoelomic cavity, which will become the primary umbilical vesicle; chorionic cavity houses embryo, amniotic sac, and secondary umbilical vesicle; primordial uteroplacental circulation begins

Bilaminar disc

Consists of epiblast and hypoblast

Embryonic blood supply

Earliest, directly from endometrium; then, provided by yolk sac (umbilical vesicles) until week 12, which are connected to the gut tube via the vitelline duct

Ileal (Meckel’s) Diverticulum

Failure of vitelline duct to resorb around 12 weeks gestation, resulting in a blind pouch in the distal ileum

Umbilical artery

Takes deoxygenated blood and waste away from the embryo; occurs when the placenta matures between weeks 4-12

Umbilical vein

Brings oxygenated blood and nutrients to the embryo; occurs when the placenta matures between weeks 4-12

Early week 2

Lacunar network forms between mother and embryo

Late week 2

Placenta forms with decidual cells and uterine vessels of the endometrium as the maternal contribution and the chorionic villa of the cytotrophoblast as the embryonic contribution

Anatomical position

Head, eyes, and toes anteriorly; upper limbs by sides with palms facing anteriorly; lower limbs together with feet directed anteriorly

Median (midsagittal) plane

Plane dividing the body into left and right sides

Sagittal plane

Plane parallel to the median plane

Coronal (frontal) plane

Plane dividing the body into front and back (anterior and posterior)

Transverse plane

Plane dividing the body into top and bottom

Superficial

Nearer to the surface

Intermediate

Between a superficial and a deep structure

Deep

Farther from surface

Medial

Nearer to the median plane

Lateral

Farther from the median plane

Superior (cranial)

Nearer to head

Inferior (caudal)

Nearer to feet

Posterior (dorsal)

Nearer to the back

Anterior (ventral)

Nearer to the front

Proximal

Nearer to trunk or point of origin

Distal

Farther from trunk or point of origin

Contralateral

Opposite sides

Ipsilateral

Same side

Radiolucent

Structures that permit the passage of the x-ray; tissues that are less dense, causing the representative areas to appear black on the exposed film (ex. air)

Radiopaque/radiodense

Structures that do not permit the passage of x-rays; tissues that are very dense, causing the representative areas to appear light or white on exposed film (ex. bone)

PA (Posterior-Anterior chest

Most common x-ray

Radiographic image rule

To reduce the undesirable effect of magnification, have the part of greatest interest closest to the film

Ultrasound

Allows healthcare professionals to visualize structures, superifcial to deep, by recording ultrasonic sound waves reflecting off the tissues

Cervical vertebrae

7 total; have transverse foramina; 6th has a carotid tubercle to allow the artery to pass through

C1

Atlas; no definitive vertebral body

C2

Axis; no definitive vertebral body

Thoracic vertebrae

12 total; have superior, inferior, and transverse costal facets for articulation with the ribs; elongated spinous processes

Lumbar vertebrae

5 total; have accessory and mammilary processes which are attachment points for critical muscles; large vertebral bodies

Lumbosacral angle

Change of shape in L5 results in natural anterior curvature of the spine

Sacral vertebrae

5 total; all fused together; have sacral foramina where spinal nerves exit

Coccygeal vertebrae

4 total; remnant of vestigial tail

Spinal curvatures present at birth

Thoracic and Sacral

Cervical curvature

Develops as a child learns to hold its head up

Lumbar curvature

Develops as a child learns to walk upright

Scoliosis

An abnormal lateral curvature of the spine

Kyphosis (hunchback)

An abnormal thoracic curvature of the spine

Lordosis (swayback or saddleback)

An abnormal lumbar curvature of the spine

Nucleus pulposus

Middle section of intervertebral disc that is a remnant of the notochord; surrounded by a cartilaginous ring called annulus fibrosus

Uncovertebral joint

Vertebral joint that forms a U shape and prevents extra movement

Zygapophyseal joint

Vertebral joint that prevents friction

Posterior longitudinal ligament

Lines the back of the spine, preventing herniation

Anterior longitudinal ligament

Lines the front of the spine, all the way from the sacral processes to the skull, preventing herniation

Intertransverse ligament

Accessory vertebral ligament between transverse processes

Ligamentum flavum

Accessory vertebral ligament that connects the laminae

Supraspinous ligament

Accessory vertebral ligament that lies superior to the spinous processes of vertebrae

Interspinous ligament

Accessory vertebral ligament that lies between the spinous processes of vertebrae

Ligamentum nuchae

Accessory vertebral ligament that is a thick band stretching from the skull to the last cervical vertebra

Atlanto-occipital joint

Craniovertebral joint connecting the skull and the atlas

Atlanto-axial joint

Craniovertebral joint connecting C1 and C2

Cruciate ligament

Craniovertebral ligament formed by the intersection of the superior and inferior longitudinal bands with the transverse ligament of the atlas; forms a cross shape

Spina bifida

Failure of the caudal neuropore to close properly during the first month of pregnancy

Week 3-4

Bilaminar disc develops into trilaminar disc; notochord forms and signals ectoderm to begin neurulation; lateral mesoderm divides via coelomic vesicles; paraxial mesoderm organizes into somites

Trilaminar disc

Develops from bilaminar disc during gastrulation; begins with primitive streak that delineates axis that becomes the body; primitive node delineates the head vs body

Ectoderm and neuroectoderm

Becomes epidermis, nervous system, and retina

Mesoderm

Becomes muscles, connective tissue, bones, and dermis; paraxial, intermediate, and lateral variants; includes the notochord

Endoderm

Becomes the epithelial linings of the respiratory and GI systems

Notochord

Rod of mesoderm extending from the primitive node towards the cranial end of the embryo; defines the midline (axis); signals ectoderm to start neurulation by sending out genes and transcription factors; remains as nucleus pulposus in the intervertebral disc

Neural tube

Becomes the central nervous system following neurulation

Neural crest cells

Break away from the neural groove during neurulation and become the peripheral nervous system, facial bones, and more

Spina bifida occulta

Failure of laminae to fuse during neurulation, leading to a deficient spinous process

Spina bifida cystica

Types that include the meningocele, meningomyelocele, and myeloschisis

Anencephaly

Failure of the rostral neuropore to close properly during neurulation, leading to an underdeveloped brain

Gastrulation

The process of the bilaminar disc becoming the trilaminar disc

Lateral mesoderm

Becomes the body walls; somatopleure becomes the body walls and dermis; splanchnopleure becomes the gut wall; intra-embryonic coelom becomes body cavities`

Paraxial mesoderm

Also known as somites that each form three segments; sclerotomes become the vertebrae and ribs and surround the notochord; myotomes become the muscle mass with spinal nerves that migrate into the lateral mesoderm and limbs; dermatomes become dermis layers of the skin with spinal nerves

Intermediate mesoderm

Becomes the urogenital tract

Chorion

Consists of extra-embryonic mesoderm and cyto- and syncytiotrophoblasts; develops from the extra-embryonic coelom

Extrinsic back muscles

More superficial; originate on back, but insert/move other regions

Intrinsic back muscles

Deeper muscles; originate and insert on back to move the vertebral column; innervated by dorsal rami; bilateral actions are extension of vertebral column or head/neck; unilateral actions vary from flexion to rotation

Acromioclavicular joint

Relatively weak plane joint with limited mobility; some rotation of the acromion process occurs accompanying scapular movements

Sternoclavicular joint

Mobile saddle joint surrounded by strong ligaments; all scapular motion is accompanied by movement of this joint

Glenohumeral joint

Extremely mobile and relatively weak ball and socket; motion at this joint is often accompanied by motion at the sternoclavicular and acromioclavicular joints

Superficial fascia

Subcutaneous tissue that is primarily adipose and varies in thickness

Deep fascia

Dense connective tissue that lies deep to superficial fascia

Investing fascia

Extensions of deep fascia surrounding muscles and neurovascular bundles

Superficial extrinsic back muscles

Move the upper limb; trapezius, latissimus dorsi, levator scapulae, rhomboids

Deep extrinsic back muscles

Accessory muscles of respiration; serratus posterior superior/inferior

Trapezius origins

Occipital bone, nuchal ligament, all cervical and thoracic spinous processes

Trapezius insertions

Scapular spine, acromion process, and 1/3 of clavicle

Trapezius actions

Elevates/depresses, retracts, and superiorly rotates scapula; extends and laterally flexes neck

Trapezius innervation

Accessory nerve that runs with the transverse cervical artery

Latissimus dorsi origins

Spinous processes of lower thoracic vertebrae (T7-T12) and thoracolumbar fascia

Latissimus dorsi insertions

Anterior humerus in the intertubercular sulcus, also wraps medially and around to the front of the arm