jessica's anatomy blog

X. Vagus Nerves

2006-05-12T16:18:00.000-04:00

X. Vagus Nerves
“wanderer” or “vagabond”

What is it?

It is the only cranial nerve to extend beyond the neck and head region.
It is one of the most important nerves in the body because it maintains the normal activities of the visceral organs and their life sustaining processes; if the vagus nerve is destroyed then you die.

What is the route of the nerve?

It emerges from the medulla
Then passes through the skull via the jugular foramen(large hole at the junction of the occipital and petrous temporal bones)
Then descends through the neck region into the thorax and abdomen

Picture of the jugular foramen
http://www.meddean.luc.edu/lumen/meded/grossanatomy/h_n/cn/cn1/cn10.htm

What type of nerve is it?

It is mixed nerve(most nerves are mixed)
It has both sensory and motor fibers which means it transmits impulses to and from the CNS
Carries parasympathetic fibers that serve visceral muscles and glands
Carries afferent fibers from receptors in the muscles that it serves

What organs/structures does it serve?

Pharynx
Larynx
Heart Lung
Abdominal viscera – spleen, liver, gallbladder, stomach, kidney, small intestine, colon(proximal portion)

http://www.city.ac.uk/optometry/cranial_nerves_labs/Vagus%20Nerve%20X.htm

How does it serve such organs?

Supplies the voluntary muscles of the pharynx which is involved in swallowing and most of the larynx
Parasympathetic motor fibers supply the heart which is involved in regulation of heart rate, lungs which are involved with breathing, and abdominal viscera which are involved with digestion
Provides visceral sensory info from the larynx, esophagus, trachea, abdominal and thoracic viscera, carotid sinus which is involved in regulation of blood pressure, and carotid and aortic bodies which are receptors that monitor oxygen, carbon dioxide, and pH levels of the blood
Provides special sensory info of taste sensation from the back posterior tongue and pharynx

Upper Limb

2006-04-10T18:54:00.000-04:00

THE UPPER LIMB

Bones
There are thirty separate bones that make up the upper limb

Humerus – the largest long bone of the upper limb; it is the only bone of the arm
Ulna – one of the bones of the forearm; it is slightly longer than the radius
Radius – the other bone of the forearm; it is thin at its proximal end and wide distally
Carpals – the eight short bones that make up the wrist; they are arranged in two irregular rows of four bones each
Metacarpals – the five small long bones that make up the palm of the hand
Phalanges – the fourteen small long bones that make up the fingers or digits; except for the thumb each finger has three phalanges

picture from www.cmki.org

Bony Tissue
Its rock-hard quality helps to support and protect body structures. It also provides cavities for fat storage and synthesis of blood cells

Osteoblasts – bone forming cells
Osteocytes – mature bone cells
Osteoclasts – large cells that break down or reabsorb bone matrix

Compact bone – external layer of skeletal bone; it is made up of long cylinders called the Haversian system which is riddled with nerves and blood vessels

picture from www.rwc.uc.edu

Spongy bone – internal layer of skeletal bone; it is made up of a honeycomb of small flat pieces called trabeculae with are filled with red or yellow bone marrow

picture from www.exn.ca

Joints
It is the place where two or more bones meet and usually but not always allows for movement. All of the joints of the upper arm are synovial joints in which the articulating bones are separated by fluid containing joint cavities. Hyaline cartilage covers the ends of the bones which absorb compression placed on the joint.

Shoulder – ball & socket joint between the scapula and humerus; allows for flexion, extension, abduction, adduction, circumduction, rotation
Elbow – hinge joint between the humerus and radius/ulna; allows for flexion and extension of forearm
Proximal/Distal Radio-ulnar – pivot joint between the radius and ulna; allows for pronation and subnation
Wrist – condyloid joint between radius and carpals; allows for flexion, extension, abduction, adduction, circumduction of the hand
Metacarpal-Phalangeal – condyloid joint between the metacarpals and phalanges; allows for flexion, extension, abduction, adduction
Interphalangeal – hinge joint between phalanges; allows for flexion and extension
Metacarpal-Carpal – saddle joint located in the thumb; allows freedom of movement

picture from mywebpages.comcast.net

Muscles

Shoulder – trapezius, deltoid, teres major, rhomboid major, latissimus dorsi
Arm – biceps brachii, triceps brachii, brachialis
Forearm(flexors) – pronator teres, brachioradialis, flexor carpi radialis, palmaris longus
Forearm(extensors) – brachioradialis, extensor carpi radialis longus, extensor carpi ulnaris, extensor digitorum

Muscles of the shoulder and arm
Picture from http://www.discovery-services.net/

Muscles of the forearm
Picture from www.dubinchiro.com

Nerves
The five major nerves of the upper limb arise from the brachial plexus

Axillary nerve – runs posterior to the humerus; serves the deltoid, teres minor muscles, skin, and the shoulder joint
Musculocutaneous nerve – runs inferiorly in the anterior arm; serves the biceps brachii and brachialis muscles
Median nerve – runs through the arm to the anterior forearm; supplies most of the flexor muscles and some of the intrinsic muscles of the palm
Ulnar nerve – runs along the medial aspect of the arm and follows the ulna along the medial forearm; supplies the flexor carpi ulnaris, and the intrinsic hand muscles
Radial nerve – runs in the posterior arm around the humerus and extends to the forearm; supplies the posterior skin of the limb and all the extensor muscles of the upper limb

picture from www.cmki.org

Nervous System I

2006-03-18T14:10:00.000-05:00

NERVOUS SYSTEM I

The nervous system can be divided into two parts: the central nervous system(brain and spinal cord) and the peripheral nervous system.

Peripheral Nervous System

What is it?
a. The nerves that carry information to and from the central nervous system to the rest of the body

Spinal nerves – carry impulses to and from the spinal cord
Cranial nerves – carry impulses to and from the brain

b. Links all of the parts of the body to the central nervous system

How is it divided?
a. Sensory/afferent

Nerves that carry impulses to the CNS from the rest of the body
Somatic afferent fibers – the sensory fibers carrying info from the skin, joints, and skeletal muscles
Visceral afferent fibers – the sensory fibers carrying info from the organs in the ventral body cavity

b. Motor/efferent

Nerves that carry impulses from the CNS to the rest of the body
Causes muscles to contract and glands to secrete
Somatic/Voluntary nervous system – carries impulses from the CNS to skeletal muscles; allows for conscious movement

Autonomic/Involuntary nervous system – carries impulses from the CNS to cardiac muscles, smooth muscles, and glands; responsible for the involuntary actions of the digestive tract or heart

Sympathetic – mobilizes body systems during emergency situation
Parasympathetic – promotes non-emergency functions; conserves energy

picture from www.schteched.tec.sc.us

Vertebral Column

What is it?
a. The spine – 28 in. long in the average adult
b. Extends from the skull to the pelvis
c. It is made up of 26 irregular bones

What is its function?
a. It surrounds and protects the spinal cord
b. Forms a strong support for the body
c. Provides attachment points for the ribs and muscles of the back/neck

How is it divided?
a. Cervical region – 7 vertebrae of the neck (C1-C7)
b. Thoracic region – 12 vertebrae (T1-T12)
c. Lumbar region – 5 vertebrae of the lower back (L1-L5)
d. Sacrum region – 5 fused vertebrae
e. Coccyx region – 4 fused vertebrae

picture from www.lrn.org

How is it structured?
a. It has an “S” shape
b. The cervical and lumbar region concave while the thoracic and sacrum region convex
c. The vertebrae become progressively larger from the cervical region downward; this is because the lower vertebrae must support more weight
d. It is resilient flexible and resilient

How is it structured?
a. Ligaments

Helps us to stand up straight
Continuous bands that run down the front and back surfaces of the spine
Anterior longitudinal ligament – attached to the bony vertebrae and discs; prevents hyperextension of the spine
Posterior longitudinal ligament – attached only to the discs; prevents hyperflexion of the spine

picture from http://www.backrelief.ca/

b. Intervertebral discs

Act as shock absorbers during walking, jumping, running
Allow the spine bend, flex, and extendAccounts for 25% of the height of the vertebral column
The lumbar and cervical regions contain the thickest discs

picture from newton.ex.ac.uk

Each is made up of two parts

Nucleus pulposus – jelly-like; gives the disc elasticity and compressibility
Annulus fibrosus – made up of collagen fibers and fibrocartilage; resists tension in the spine

picture from www.spineuniverse.com

Individual Vertebrae

What are the general characteristics?
a. Body/Centrum – weight bearing region; located anterior
b. Vertebral arch – located posterior

2 pedicles – short pillars that form the sides of the arch
2 laminae – flattened plates that fuse together

c. Spinous process – a medial, posterior projection from between the 2 laminae
d. Transverse process – extends laterally from each side of the vertebral arch
e. Spinous and transverse processes are where the muscles and ligaments are attached
f. Superior and inferior articular processes – protrude from junction of the pedicle and lamina
g. Vertebral foramen – an opening enclosed by the body and vertebral arch
h. Vertebral canal – where the spinal cord passes through

picture from webschoolsolutions.com

What type of movements do vertebrae allow?
a. Depending on which of the 5 regions the vertebrae is located in determines their function and structure
b. Flexion and extension – anterior bending and straightening of the spine
c. Lateral flexion – bending the upper body to the right or left d. Rotation – rotating the vertebrae on one another

TISSUES

2006-02-12T14:12:00.000-05:00

(not that kind!!!)

TISSUES
a group of similar cells that perform the same or related function

EPITHELIAL TISSUE

What is it?
a. covers the whole surface of the body - SKIN
b. forms the lining of cavities in the body
c. cells are closely packed together with only a small amount of extracellular material in between d. structured as one or more layers of cells

What are its functions?
a. protection
b. absorbtion
c. filtration
d. excretion
e. secretion
f. sensory reception

How is it classified?
a. By the number of cell levels

simple epithelia - made up of a single cell layer
stratified epithelia - made up of two or more cell layers stacked on top of each other

b. By the shape of the cells

squamous - thin, flat, scalelike cells; nucleus is an elliptical flattened disc
cuboidal - roughly square shape, boxlike cells; nucleus is spherical in shape
columnar - elongated, column shaped cells; nucleus is tall and located close to the cell base

Simple squamous – allows passage of nutrients, wastes and gases by diffusion and filtration; lines the heart, blood vessels, and air sacs of lungs (picture from www.uoguelph.ca)

Simple cuboidal – secretes and reabsorbs water and small molecules; lines kidney tubules and glands (picture from www.uoguelph.ca)

Simple columnar – absorbs nutrients and secretes mucus; lines most of the digestive tract (picture from www.uoguelph.ca)

Stratified squamous – protects tissue from abrasion, infection, and drying out; is the outer layer of skin and lines the mouth and vagina (picture from www.visualsunlimited.com)

Stratified cuboidal – secretes water and ions; lines ducts of sweat and mammary glands (picture from www.mhhe.com)

Stratified columnar – secretes mucus; lines larynx and epididymus (picture from www.mhhe.com)

What is glandular epithelia?
a. a gland is one or more cells that make and secrete a particular product
b. 2 types of glands

endocrine glands – produces hormones
exocrine glands – secretes onto body surfaces or into body cavities

CONNECTIVE TISSUE

What is it?
a. provides support for your body
b. connects all the parts of your body
c. found everywhere in the body
d. has nonliving extracellular matrix in between cells
e. develops from the mesenchyme

What are its functions?
a. binding and support
b. protection
c. insulation
d. transportation

How is it structured?
a. ground substance – fills the space between the cells; contains the fiber
b. fibers
collagen fibers – very strong and found in matrix of connective tissue
elastic fibers – long, thin fibers that can stretch and recoil
reticular fibers – form delicate networks that surround blood vessels and support organs
c. cells

How is it classified?
a. connective tissue proper

loose connective tissue

areolar connective tissue – wraps and cushions organs (picture from virtual.yosemite.cc.ca.us)

adipose connective tissue – insulates and provides food fuel; located under the skin and in mesentaries (picture from www.city.ac.uk)

reticular connective tissue – supports other cell types in marrow, spleen, and lymph nodes (picture from www.mhhe.com)

dense connective tissue

dense regular – attaches muscles to bones or muscles and bones to bones; located in tendons and most ligaments (picture from a-s.clayton.edu)

dense irregular – provides structural support; located in the dermis of the skin (picture from biology.clc.uc.edu)

b. cartilage

dense and tough yet flexible

c. bone

supports and protects body structure

d. blood

transports nutrients, wastes, and gases for the cardiovascular system

NERVOUS TISSUE

What is it?
a. main component of the nervous system
b. carries messages back and forth between the brain, spinal cord, and every other part of the body
c. made up of neurons and supporting cells
(photo from www.cytoritx.com)

MUSCLE TISSUE

What is it?
a. responsible for body movement
b. has the ability to contract or shorten

How is it classified?
a. skeletal muscle – responsible for body movement
b. cardiac muscle – propels blood into the circulation system by contrating; found only in the heart
c. smooth – propels substances along internal passageways

*All information came from the textbook, supplemental powerpoint presentations, and my class notes*

2006-02-02T18:52:00.000-05:00

Levels of Organization in the Human Body

Cells – the building block of living things
a. Absorbing cells
b. Assembly cells
c. Movement cells
Tissues – a group of similar cells that perform the same function
a. Muscle – the only kind of tissue with the ability to contract or shorten
b. Connective – provides support for the body and connects all its parts
c. Nerve – carries messages back and forth between the brain and spinal cord and every other part of the body
d. Epithelial – forms a protective surface on the outside of the body and lines the cavities of the mouth, throat, ears, stomach, and other body parts
Organs – a group of different tissues with a specific job (3 examples below)
a. Heart
b. Stomach
c. Brain
Organ Systems – a group of organs that work together to perform a specific job
a. Skeletal – protects, supports, allows movement, produces blood cells, and stores minerals
b. Muscular – allows body movement and maintains posture
c. Digestive – breaks down food and absorbs nutrients
d. Circulatory – transports nutrients, wastes, and other materials and plays a role in the immune response
e. Respiratory – exchanges oxygen and carbon dioxide between blood and air
f. Excretory – removes solid and liquid wastes
g. Nervous – detects sensation and controls most functions
h. Endocrine – plays a part in the regulation of metabolism, reproduction, and many other functions
j. Reproductive – performs reproduction and controls male and female functions and behaviors
k. Immune – controls the immune response and fights disease
l. Integumentary(skin) – protects, regulates temperature, prevents water loss

"It is not birth, marriage, or death, but gastrulation, which is truly the most important time in your life." Lewis Wolpert (1986)

Gastrulation - a very important time in the development of multicellular animals. During gastrulation, several important things occur:
a. The three primary germ layers of an embryo are formed: endoderm, ectoderm,mesoderm
b. The basic body plan of the mature organism is established
c. Major reshuffling of cells which leads to new interactions
Endoderm
a. The most internal germ layer
b. Forms the inner lining of the digestive and respiratory tract
c. Forms glands such as the liver and pancreas
Ectoderm
a. The most exterior germ layer
b. Forms epidermis and associated structures such as skin, hair, nails
c. Forms nervous system
d. Neural tube – forms brain and spinal cord
Mesoderm
a. The middle germ layer
b. Forms muscle, excretory system, circulatory system and outer covering of internal organs
c. Forms dermis – inner skin layer
d. Forms bones and cartilage

About me

2006-01-24T18:39:00.000-05:00

Jessica Logan

05/31/83 Attleboro, MA

Lauryn Hill

I'm taking this class to fill a lab requirement for my communications major.