Lori's A&P blog

The Trigeminal Nerve

2006-05-11T20:59:00.000-07:00

For my LAST blog assignment, I chose to discuss the Trigeminal Nerve, also known as Cranial Nerve V. It is the largest of cranial nerves and is considered to be the “great sensory nerve of the head and neck”. The Trigeminal Nerve has three branches: V1 – the ophthalmic nerve, V2 – the maxillary nerve, V3 – the mandibular nerve. Each branch is responsible for different parts of the face and jaw, but all are responsible for “feeling” in the face.

(V1) Ophthalmic
Sensory – carries information from the skin of the forehead, upper eyelids, and the outer sides of the nose. It is made up of the frontal nerve, masociliary nerve, and the lacrimal nerve. The ophthalmic nerve enters the middle cranial fossa through the superior orbital fissure and stays within the outside wall of the cavernous sinus. Feeling around eyes.

(V2) Maxillary
Sensory – carries information from the lower eyelids, zygomae, and upper lip. This nerve is made up of the zygomatic nerve and the infraorbital nerve. This nerve enters the middle cranial fossa by way of the foramen rotundum, and sometimes, but not always goes through the cavernous sinus. Feeling in the upper lip to below eyes.

(V3) Mandibular
Sensory and Motor – carries sensory information from the scalp, skin in front of ears, lower cheeks, lower lips, and anterior portion of mandible. This branch also carries motor information, such as the pain sensation from the jaw back. This nerve is formed by the buccal nerve, lingual nerve, inferior alveolar nerve, and auriculotemporal nerve. The mandibular nerve enters the middle cranial fossa through the foramen ovale. Feeling in the lower lip to the lower part of the jaw.

All of these branches end up in the same place – the Trigeminal Ganglion. The Trigeminal Nerve then exits the Trigeminal Ganglion and runs backward to go through the mid-lateral aspect of the pons The Trigeminal nerve is primarily a mixed somatic nerve, having both motor and sensory neurons – but it can be visceral. However, visceral motor neurons are not actually a part of the Trigeminal Nerve, but serve as what our text calls “hitchhikers” along its branches. The face is sensory, with the nuclei going from the mid-brain to the cervical cord; and the Mastication, tensor tympani, and the tensor palate are motor, with the nuclei in the pons.

(Image from University of Manitoba)

Upper Limb

2006-04-11T21:28:00.000-07:00

The Upper Limb and How It Moves

The Upper Limb is made up of three mechanisms:

1. Shoulder girdle
2. Elbow
3. Wrist

And Seven joints:
1. Sterno-clavicular joint – where the proximal end articulates from the clavicle onto the sternum
2. Acromio-clavicular joint – where the acromion articulates the scapula onto the distal end of the clavicle
3. Scapulo-thoracic joint – allows the scapula to glide on the thorax
4. Gleno-humeral joint – allows rotation of the head of the humerus in the glenoid fossa of the scapula
5.-6. Ulno-humeral & humero-radial joints – articulates both ulna and radius on the distal end of the humerus
7. Ulno-radial joint – where both distal ends of the ulna and radius join together.

All the joints, except for the scapulo-thoracic joint, are assumed to be ball and socket joints. Meaning that it allows for three degrees of freedom in rotation.

Shoulder Movements:

1. Sterno-clavicular joint – 3 degrees of freedom
a. ventral/dorsal
b. cranial/caudal
c. axial rotations

2. Gleno-humeral joint – 3 degrees of freedom
a. abduction/adduction
b. flexion/extension
c. axial rotation

3. Scapulo-thoracic joint – 5 degrees of freedom
a. elevation/depression
b. protraction/retraction
c. tipping forward/backward
d. medial/lateral rotation

4. Forearm joints – 2 degrees of freedom
a.flexion/extension
b.pronation/supination

Muscular Anatomy:
(University of Minnesota)

To be able to perform these movements, the upper limb has not less the 21 muscles that make it happen. Some muscles even divide into several bundles that attach on different bones.

Muscles are divided by:

1. The bone they move
2. The degree of freedom they control

*Most muscles on the scapula insert close to its medial border:

Levator scapulae – thin twisting sheet of fibers covered by the upper fibers of trapezius
Insertion: superior part of medial border of scapula
Function:
Elevation of scapula
Rotation of scapula
Retraction of scapula
Lateral flexion of the neck

Rhomboids – parallel bands forming oblique parallelograms
Insertion: medial border of scapula
Function:
Retraction of the scapula
Rotation of the scapula

Trapezius – large, flat, triangular muscle covering the posterior portion of the neck and the superior portion of the trunk
Insertion: lateral third of clavicle, acromion, spine of scapula
Function:
Superior - elevation of scapula
Middle – retraction of scapula
Inferior – depression of scapula
Mixed – superior rotation of scapula

ROTATOR CUFF: group of muscles that which covers the humeral head and controls some of its rotations.
Subscapularis – thick triangular muscle, lying on the costal surface of scapula
Insertion: the lesser tubercle of humerus
Function:
Medial rotation of the arm
Adduction of the arm
Teres Major – flattened rectangular muscle that lays below the infraspinatus and teres minor muscles
Insertion: medial lip of the intertubercular groove of humerus
Function:
Adduction of the arm
Medial rotation of the arm

AXIAL ROTATIONS:
Infraspinatus – triangular muscle that occupies most of the infraspinous fossa of the scapula
Insertion: middle facet on greater tubercle of humerus
Function:
· Laterally rotate arm
Teres Minor – elongated tapering muscle that lays along the inferior border of the infraspinatus
Insertion: inferior facet on greater tubercle of humerus
Function:
Lateral rotation of humerus
Adduction of the humerus

ABDUCTION:
Supraspinatus – rounded muscle lying in the supraspinous fossa of scapula
Insertion: superior facet on greater tubercle of humerus
Function:
Acts with rotator cuff muscles
Helps deltoid to abduct arm
Deltoideus – thick and powerful triangular muscle covering the shoulder joint
Insertion: deltoid tuberosity of the humerus
Function:
Flexion of the humerus (anterior head)
Abduction of the humerus (lateral head)
Extension of the humerus (posterior head)

ADDUCTION and AXIAL ROTATION:
Latissimus Dorsi – broad, triangular muscle covering the inferior half of the back
Insertion: bottom of the intertubercular groove of the lower four ribs
Function:
Medial rotation of the arm
Extension of the humerus
Adduction of the humerus

Pectoralis Major – large, thick, fan-shaped muscle covering the superior part of the thorax
Insertion: intertubercular groove of the humerus
Function:
· Flexion of the humerus (clavicular head)
· Adduction and medial rotation of the humerus(sternocostal head)

(University of Minnesota)

THE FOREARM:
Two groups of muscles that act as antagonists that control flexion/extension movements of the forearm:

FLEXION:
Brachialis – flattened, fusiform muscle lying posterior to the biceps
Insertion: front of the coronoid process of the ulna
Function:
· Flexion of the forearm

Biceps Brachii – powerful fusiform muscle that lies in the anterior fascial compartment of the arm
Insertion: the tuberosity of the radius
Function:
Flexion of the forearm
Supination of the forearm

Brachioradialis – elongated fusiform muscle along the outer side of the radius
Insertion: lateral port of the radius above the styloid process
Function:
Flexion of the forearm
Supination of the forearm when in extension

EXTENSION:
Anconeus – triangular muscle overlying the back of the head of the radius
Insertion: the outer portion of the olevranon process of ulna
Function:
· Extension of the forearm

Triceps Brachii – large fusiform muscle lying on the posterior fascial of the arm
Insertion: the olecranon process of the ulna
Function:
Extension of the forearm
Adduction of the arm

PRONATION:
Pronator Teres – small, rounded muscle lying on the frontal side of the forearm
Insertion: outerside of the shaft of the radius – middle
Function:
· Pronation of the forearm

2006-03-15T18:35:00.000-08:00

For my Blog entry this week, I will be discussing the Vertebral Column, the Structure of Vertebrae, and the Peripheral Nervous System. There is a lot of information regarding these three topics but to avoid a run-on, I will try to keep it simple.

I. Vertebral Column
A. Characteristics
1. consists of 26 bones
· 7 cervical
· 12 Thoracic
· 5 Lumbar
· 1 sacrum
· 1 coccyx (tailbone)
2. intervertebral discs - gel like cushions located in between the vertebrae.
3. curvatures of the vertebral column
· thoracic curve - primary
· sacral curve - primary
· cervical curve - secondary
· lumbar curve - secondary

B. Functions
1. Protection
· Spinal cord & Nerve roots
· Internal organs
2. Base for Attachment
· Ligaments
· Tendons
· Muscle
3. Support
· Head, shoulders, chest
· Connects upper & lower body
· Balances & weight distribution
4. Flexibility
· Flexion
· Extension
· Side Bending
· Rotation
5. Produces red blood cells & mineral storage
C. What the Vertebral Column consists of:
1. Vertebrae:
· Cervical region - 7 vertebrae = C1-C7
· Thoracic region - 12 vertebrae = T1-T12
· Lumbar region - 5 vertebrae = L1-L5
· Sacral region - 5 fused vertebrae = S!-S5
· Coccygeal region - 3-5 vertebrae = Co1-Co5
2. Ligaments
· Anterior longitudinal ligament - limits extension
· Posterior longitudinal ligament - limits flexion
· Ligamenta flava - maintains normal posture &
spinal curves
· Supraspinous & Interspinous ligaments - span the distance between adjacent spinous processes

3. Intervertebral Discs
A. These discs are like shock absorbers - cushions that are between the vertebrae in the spine to move and flex. They play a big part in weight bearing. Discs have 2 portions:
1. Annulus fibrosis - an outside fibrous or rubbery covering
2. Nucleus pulposis - an inside, more gel-like portion
B. Water makes up 90% of the gelatinous core and discs account for about ¼ of the total length of the spinal column.
C. Structure of Vertebrae
i. Body - thick, cylinder shaped part that lies in between the vertebral discs
ii. Vertebral Arch - an arch of bone that encloses the vertebral foramen; made of pedicles and luminae
iii. Pedicles - the base of the arch; attaches to the body
iv. Laminae - top part of arch; joins its mate on the other side
v. Vertebral Foramen - space formed by the neural arch; foramen of other vertebrae stacked on top of each other forms the spinal cavity
D. Peripheral Nervous System (PNS)
It is composed of nerves (bundles of neurons) and connects the Central Nervous System (CNS) to other parts of the body.
1. 2 Main Divisions
· Sensory/afferent system - provides input from the body to the CNS
· Motor/efferent system - carries signal to muscles and glands
E. Subdivided into the sensory-somatic system and the autonomic nervous system
1. Components of each:
Sensory-somatic system
· 12 pairs of cranial nerves
· 31 pairs of spinal nerves - mixed, contain both sensory & motor neurons
· Includes all nerves that control the muscular system and external sensory receptors

Autonomic Nervous System
· Consists of motor neurons that control internal organs running between the CNS
· Monitors the internal environment and causes appropriate changes in them.
· Controls the contraction of the cardiac muscle, the heart and the smooth muscle of internal organs e.g. the intestine, bladder, and uterus.
· Actions are involuntary
· Uses two groups of motor neurons to stimulate effectors, preganglionic and postganglionic
· Sympathetic Nervous System - fight or flight response
· Parasympathetic Nervous System - relaxation
F. Schwann cells
· Cells that wrap around the axons of peripheral nerves and form the insulating myelin sheath.
· Serve as supportive, nutritive, and service facilities for neurons
G. Satellite Cells - type of glial cell that provides physical support to the neurons.
4. Neurons
· Functional unit of the nervous system
· Dendrites; receive information from another cell and transmits the message to the cell body
· Cell body contains the nucleus, mitochondria and other organells or eukaryotic cells
· Axon; conducts messages away from the cell body
· Large
· Cannot be replaced or divided
· High metabolic rate
· Axonal terminus
5. Classes of Neurons
Structural - they can be multi-polar (3 or more processes, bipolar (2 processes or unipolar (one short process)
· Mulitpolar neurons are the most common motor neurons and are found mostly in the CNS
· Bipolar neurons are rare, they have 1 axon and 1 dendrite opposite each other and are found only in special sense organs
· Unipolar neurons are sensory neurons that are found mostly in the PNS
Functional
· Sensory - unipolar structure; has a long dendrite and short axon; mostly found in the PNS, carry messages from sensory receptors to the CNS
· Motor - multipolar structure; found mostly in the CNS; have a long axon and short dendrites; transmits messages from the CNS to the muscles and glands
· Interneurons - multipolar structure; found only in CNS connecting neuron to neuron

Epithelial & Connective Tissues

2006-02-12T15:32:00.000-08:00

In this blog entry, I will discuss the different types of tissues, along with their general features and functions.

There are 4 types of Tissues:
1. Epithelium
2. Connective
3. Muscle
4. Nervous

The standard definition of tissue, taken from our notes is a group of cells closely associated that have a similar structure and perform a related function.
Each tissue has a purpose -

· Epithelium = Covering
· Connective = Support
· Muscle = Movement
· Nervous = Control

I. Epithelial

First, I will start with the Epithelial Tissues and its sub-classes. I will do my best to explain each one and give examples of where it can be found.

1. Simple Squamous - single layer of cells that look rounded and flattened. Mesothelial and endothelial cells have flattened nuclei. This tissue type can be found in the:
· Lungs (alveoli)
· Capillary endothelium
· Lining of the pleural cavity, pericardium and peritoneum
· Kidney

2. Stratified Squamous, non-keratinized - has many layers, the surface layer is flattened and the inner layer is polygonal. Stratified Squamous, keratinized also has many layers with a flattened surface layer, but the basal layer is columnar with polygonal cells in between. Both of these can be found:

lips
pharynx
esophagus
anal canal
uterine cervix & vagina
sking (keratinized)

3. Simple Cuboidal - single layer, the cells are cubic shaped, sometimes has
Microvilli & cilia. This type of tissue is common in glandular epithelium. It can be found:
· Follicle of the thyroid gland
· Collecting ducts of the kidney
· Salivary glands
· Pancreas

4. Stratified Cuboidal - usually has 2 layers with cubic cells in both the surface
And basal layers. This tissue type is rare. It is found in the sweat gland ducts.

5. Simple Columnar - single layer, the cells are tall (column-like) with polygonal cross sections. It has cilia & microvilli. It’s also called
" high cuboidal". It can be found:
· Gall bladder
· Surface epithelium of stomach
· Uterine glands (all phase)
· Small intestine

6. Stratified Columnar - usually has 2 layers, the surface layer cells are tall, with
The basal layer cells being cuboidal or polygonal. This tissue type is also rare. It can be found:
· Large excretory duct of salivary glands
· Parotid
· Submandibular
· Sublingual
· Rectal-anal & gastroesophageal junctions.

7. Pseudostratified columnar - single layer with columnar shaped cells dominate
With short basal layer. It has cilia & microville. In this tissue type, all cells touch the basal lamina, only some cells reach the surface. It can be found:
· Male urethra
· Trachea, bronchi (pseudostratified ciliated columnar)

8. Transitional - many layers, the cells are dome shaped when organ’s are empty
And flattened when they are distended. Found only in the urinary tract:
· Pelvis of the kidney
· Ureter
· Urinary bladder

II. Connective Tissues

Connective tissues are the most abundant of the primary tissues. They are very different from the other tissues. The cells of muscle, nervous, and epithelial are together, the cells of connective tissues are far apart. They are separated by the extracellular matrix.
Connective tissues can be found everywhere in the body. Its functions are:
a. Binding, support and packaging - of other tissue types. They also form tendons & ligaments which bind bones to each other or muscles.
b. Protection, defense and repair - scar tissue is made up of connective tissue and its cellular and molecular components defend against invading bacteria or chemical substances.
c. Insulation - fat cells and adipose tissue used to cushion the body organd, insulate them and reserve energy fuel.
d. Transportation - blood is a connective tissue that carries and delivers oxygen and nutrients to the tissues.

There are 4 classes of Connective Tissue that can be placed in two categories:
· Blood
· Bone
· Cartilage
· Connective tissue proper

1. The first category is the cells of the connective tissue which secrete the matrix, or maintain it. The primary blast cells for each category are:
· Hemocytoblasts = blood
· Osteoblast = bone
· Chondroblasts = cartilage
· Fibroblast = connective tissue proper

2. The second category is the accessory cells which are supported by the connective tissue. Home to fat storing cells, white blood cells, mast cells, macrophages and antibody producing plasma cell.

Loose Connective Tissue

· Areolar Tissue - contains fibroblasts, collagenous fibers, elastic fibers, macrophage, and mast cell that has granular cytoplasm.
· Adipose Tissue - contains adipose cells, an adipose nuclei compressed along the edge, fibroblast cells between adipose cells, and mesotheliem at the edge, if it is there.
· Reticular Tissue - contain reticular fibers.

Dense Regular Connective Tissue

· White Fibrous Tissue (tendon) - contains fibroblasts flattened in rows and collagenous fibers in parallel bundles.
· Yellow Elastic - contains fibroblast nuclei distributed through tissue, collagenous fibers, and elastic fibers ( open spaces)

Dense Irregular Connective Tissue - contains fibroblasts, collagen bundles and venule.

III. Extracellular Matrix - made up of fibers and ground substance.
The ground substance fills the space between the cells and contains fibers.
It is composed of interstitial fluid, cell adhesion proteins and proteoglycans.
Fibers of the matrix provide strength. There are 3 types - Collagen, Elastic and
Reticular.

1. Collagen ( white fibers) - extremely tough
2. Elastic Fibers (yellow fibers) - can be stretched to 1 ½ x’s their length but return to their original size when released found in areas where elasticity is necessary such as the lungs and blood vessel walls.
3. Reticular Fibers - fine collagenous fibers. They support soft organs such as the liver and spleen.

Preembryonic Development of the Basic Body Plan

2006-02-02T20:19:00.000-08:00

Preembryonic development begins with fertilization, commonly known as conception. Fertilization, or conception, is achieved after the sperm reaches the ovulated secondary oocyte. Fertilization occurs when a sperm fuses with an egg to form a zygote, the first cell of a new individual. Almost as soon as the maternal and paternal pronuclei come together their chromosomes replicate. Preembryonic development continues as the preembryo travels through the uterine tube to implant itself in the uterine wall. The offspring is referred to as the conceptus and this is when the first stage mitotic division begins.
Cleavage, rapid mitotic divisions of zygote happen after fertilization. Cleavage produces cells with a high surface-to-volume ration, which enhance their uptake of nutrients and oxygen, and disposes of wastes. This also produces a large number of cells that serve as building blocks for making the embryo. By day 4 or 5, the preembryo consists of about 100 cells and floats free in the uterus. The zona pellucida breaks down and the blastocyst escapes. The blastocyst is a fluid-filled sphere composed of a single layer of large flattened cells called trophoblast cells, which take part in placenta formation, and small cluster of round cells called the inner cell mass. The inner cell mass becomes the embryonic disc, which forms the embryonic proper.
Implantation is next to occur. It takes about one week and is usually done by the 14th day after ovulation. The proliferating trophoblast initiates the chorion, which is a layer of extraembryonic mesoderm on its inner surface. The chorion develops finger like villi and the deciduas basalis. During implantation, the blastocyst is being converted to a gastrula, in which the three primary germ layers form - the endoderm, mesoderm, and the ectoderm. Also, the embryonic membranes develop – the yolk sac, allantois, and chorion. The three primary germ layers serve as the primitive tissues from which all body organs will derive. Ectoderm (“outer skin”) is responsible for structures of the nervous system and the skin epidermis. Endoderm (“inner skin”) forms epithelial linings of the digestive, respiratory, and urogenital systems and associated glands. The mesoderm (“middle skin) forms everything else. Gastrulation begins when the primitive streak appears on the dorsal surface of the embryonic disc and establishes longitudinal axis of the embryo. The mesodermal cells just below the primitive streak aggregate, forming a rod of mesodermal cells called the notochord, the first axial support of the embryo.
Next comes the formation of body organs and organ systems, called organogenesis. When the embryo is 22mm long, less than 1-inch from head to buttocks – all the adult organ systems are recognizable. The differentiation of the ectoderm, neurulation – produces the brain and spinal cord. By the end of the first month of development the three primary brain vesicles are formed (fore, mid, and hindbrain). By the end of the second month all brain flexures are evident, the cerebral hemispheres cover the top of brain stem and brain waves can be recorded.
The embryo starts off as a flat plate that grows into a cylinder body shape. The folding occurs from both ends, progressing to the central part of the embryonic body where the yolk sac and umbilical vessels protrude. The tube formed is called the primitive gut which forms the epithelial lining of the GI tract. The organs of the GI tract (pharynx, esophagus, etc.) become apparent and the oral and anal openings perforate. The mucosal lining of the respiratory tract forms and glands such as the thyroid, parathyroids, and the thymus form, also the liver and the pancreas.
In the mesoderm we see the first sign of mesodermal differentiation with the appearance of the notochord in the embryonic disc. Somites are the largest paired mesodermal blocks on either side of the notochord. On either side of the somites are the intermediate mesoderm and lateral mesoderm. The somites have 3 functional parts – the sclerotome, dermatome, and the myotome. Collectively, they produce vertebra, rib, the dermis of the skin in the dorsal part of the body, the skeletal muscles of the neck, body trunk, and through their limb buds, the muscles of the limbs. The intermediate mesoderm forms the gonads, and kidneys. The lateral mesoderm, with it’s two plates form the dermis of the skin in the ventral body region, the parietal serosa migrate into the limbs and form bones, ligaments, and the dermis of the limbs. It also produces the mesenchymal cell that form the heart and blood vessels and most connective tissues and serosae coverings of the digestive and respiratory organs. These two plates also cooperate to form the coelom or ventral body cavity.
Bones begin to ossify and skeletal muscles are almost fully developed and are contracting spontaneously by the end of the embryonic period. The adult circulatory pattern is derived at birth from the conversion of the fetal circulatory pattern. Blood cells arise in the yolk sac. Tiny spaces appear in the lateral mesoderm that are lined with endothelial cells, covered with mesenchyme and linked together to rapidly spread vascular networks, like the heart, blood vessels and the lymphatics. During the fetal period the developing fetus grows, from head to buttocks, to about 30mm and weighs approximately 2g. – to about 360mm and 2.7-4.1 kg. or more.
The human body is made up of many levels of structural organization that starts with the chemical level. In the chemical level, atoms combine to form molecules which in turn form organelles, basic components of microscopic cells. Because cells are the smallest units of living things we are then brought to the cellular level where cells are studied, some have the same function but their size and shape vary dramatically reflecting their unique functions in the body. The hierarchy continues to the tissue level, the human body contains four basic tissue types, epithelium, muscle, connective, and nervous tissue. Each tissue type serves its own purpose in the body. The organ level is where the extremely complex functions become possible, like the stomach for example. Each organ is responsible for its own function that no other organ could perform. The organ system level is where organs work together to accomplish a common purpose. Such as the heart and blood vessels of the cardiovascular system that make sure that blood is constantly circulating and carrying oxygen and nutrients to all body cells. Other body systems include the integumentary, skeletal, muscular, nervous, endocrine, respiratory, digestive, lymphatic, urinary, and reproductive systems. The highest level of organization is the organism, the living human being. The organismal level represents the sum total of all structural levels working together to promote life.

Intro Information

2006-01-23T07:30:00.000-08:00

Lori A. Perry
New Bedford - 9/16/74
Thomas Kinkade
I am here because it is a requirement for the Nursing program.
I have a 7yr. old son and a family I wouldn't trade for the world.

Digital Native Score: 8