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Where is the brain located?
In the cranial cavity
What are the functions of the brain?
- Sensory perceptions
- Issues moto commands
- Coordinates muscular movements
- Regulates visceral (organ) activities
What are the 4 major parts of the brain?
- Cerebrum (last portion to develop)
- Diencephalon (inner part)
- Brain stem (midbrain, pons and medulla oblongata)
What makes up the Cerebrum?
- 2 hemispheres connected by a bridge of nerve fibers called the corpus callosum (L & R)
- The two hemispheres are separately the falx cerebri (midsagittal plane)
- Gyri: ridges
- Sulci: shallow grooves
- Fissures: deep grooves
Frontal lobe of cerebrum
Primary MOTOR area
Parietal lobe of cerebrum
- Posterior to frontal lobe
- Primary SENSORY area
Temporal lobe of cerebrum
Inferior to frontal and prietal lobes
Occipital lobe of the cerebrum
Posterior portion of cerebrum
What is the insula?
- we still don't know much about it
- Covered by parts of frontal, parietal and temporal lobes
What is gray matter?
- Unmyelinated cell bodies (no sheath)
- Cerebral cortex (surface/magic shell): superficial portion of the hemispheres consit of thin layer (2-5 mm thick)
- Consistd mostly of the *nerve cell bodie of nuclei (which appear gray in color)
What is white matter?
- Beneatht he cortex
- Consists of mostly *myleinated nerve anons (has white sheath, appears white in color)
What is the Basale Ganglia?
- Masses of gray matter that are located deep within the cortex of the cerebrum
- Caudate nucleus, putamen,a nd globus padillus
- *Relay states for MOTOR impulses originating in the cerebral cortex and can inhibit motor functions by searching dopamine (=movement)(NT) (Parkinsons)
Where is the diencephalon located?
Bwtween the cerebral hemispheres and above the brain stem. (Deep)
What does the diecephalon consist of?
Mostly gray matter
What are the regions of the diecephalon?
- Limbic system
- Optic tracts
- Optic chiasma
- Infundibulum (stalk)
- Posterior pituitary gland (right behind bridge of nose)
- Pineal gland
*What does the thalamus do?
Receives sensory impulses and channels them to appropriate regions of the cortex for interpretation.
What does the hypothalamus do?
Regulates heart rate, arterial BP, body temperature, water and electrolyte balance, controls hunger and body weight.
*What does the Limbic System do?
Controls emtions (also memory and smell)
What is the function of the brain stem?
Connects the brain and spinal cord
What makes up the brain stem?
- Pons (connects it with cerebellum)
- Medulla oblongata
Where is the midbrain located?
Lies between the diencephalon and the pons
Where is the pons located?
Separates the midbrain from the medulla oblongata
Where and what is the medulla oblongata?
- Enlarged superior continuation of the spinal cord (lower end)
- -Olives (bundles of nerve fibers)
- -Nucleus gracilis and cuneatus (receive sensory impulses from the spinal cord)
- -"Centers" formed by nuclei
What are the functions of the "Centers" formed by nuclei (of the medulla)?
- Cardiac center: controls heart rate
- Vasomotor center: alters blood pressure by controlling dilation and constriciton of bl. vessels
- Respiratory center: regulates rate, rhythm and depth of breathing
What is reticular formation?
- Located throughout the brainstem and is a network of nerve fibers connected by small nucli (spread out)
- Deals with psychological disorders - filtering issues
- Receives sensory impulses from the spinal cord & responds by activating the cerebral cortex into a state of wakefulness (high energy)
- "Fliters" incoming sensory impulses (passes them along or disregards them)
- Regulates and coordinates motor activities
What is the Cerebellum?
- Old or Little Brain
- Is an error detection & correction center
- Has 2 hemisoheres
- Consists of an outer cortex (gray matter) and inner cortex(white matter) which are connected by a structure called the vermis (worm)
- Communicates with other parts of the CNS via cerebellar peduncles
*What is the function of the cerebellum?
*Functions: to coordinate skeletal muscle activity and maintain posture (affect behavior, what makes you you)
How many spinal nerves are there?
- Numbered superior to inferior in each spinal region (C1-C8, T1-T12, L1-L5, S1-S5 and Co1)
Where does the spinal cord end?
Between the level of L1 and L2 (conus medullaris)
How do lumbar, sacral and coccygeal spinal nerves travel?
As a bundle (cauda equina) through the spinal canal
*How are spinal nerves formed?
By the merging of the dorsal root (sensory) and ventral root (motor)
What are the branches of the spinal nerve after it exits the IVF?
- Meningeal (sinuvertebral) branch
- Posterior branch (dorsal ramus)
- Anterior branch (ventral branch)
*Posterior branch of the spinal nerve
- (dorsal ramus) sensory branch
- Innervates (supplies) muscles (motor) and skin of the back
Describe the Plexuses (cervical and lumbarsacral)
- Network of cervical, lumbar and sacral ventral rami
- Spinal nerve fibers are sorted and combined into named individual nerves
Ventral rami (motor) of the thoracic spinal nerve
- Do NOT form Plexuses, but instead travel between ribs (intercostal spaces) where they are called intercostal nerves
- They innervate (supply) intercostal and upper abdominal muscles and the skin of the throax and abdomen
*What is the location and function of the Cervical Plexus?
- Lies deep in gthe neck and is formed by the ventral rami of C1-C4 (not the upper extremity)
- Nerves formed by the cervical plexus innervate muscles and skin of the NECK (not the face)
- *Nerve fibers fromt he ventral rami C3, 4 & 5 form the phrenic nerve which innervates the diaphragm ("C3, 4&5 keep the diaphragm alive")
What is the location and function of the Brachial Plexus?
- Located between the neck and axilla (arms and upper extremities)
- Formed by the ventral rami of C5-8 and T1 (nerve roots)
- It innervates the skin, joints and muscles of the shoulder, chest and upper limbs.
- Travels with the subclavian artery and its contination, the axillary artery b/t the anterior and middle scalene muscles and b/t the pectoralis minor and the upper ribs
What are the major branches of the Brachial Plexus?
- Musculocutaneous nerve
- Ulnar nerve
- Median nerve
- Radial nerve
- Axillary nerve
- Lateral and medial pectoral nerves
- Dorsal scapular nerve
- Thoracodorsal nerve
- Suprascapular nerve
Innervates the coracobrachialis, biceps brachii and brachialis muscles. It ends by forming the lateral antebrachial cutaneous nerve which innervates the skin of the lateral forearm
- innervates the flexor carpi ulnaris and the medial half of the flexor digitorum profundous muscles and skin of the hand (deep muscles and fingers)
innervates all of the muscles of the anterior forearm except the flexor carpi unlaris and it innervates some of the muscles and skin fo the hand (thumb action)
innervates the triceps, brachioradialis and the extensor muscles of the forearm as well as the skin of the posterior forearm and hands (back of arm)
Innervates the teres minor and deltoid and skin of the superior, lateral and posterior regions of the arm
What is the location and function of the Lumbosacral Plexus?
- Formed by the ventral rami from T12, L1-5 S1-5 and the coccygeal nerves
- Everything from the waist down (iliac crest)
- The nerves formed by this plexus innervate the skin, joints and muscles of the lower abdominal wall, external gentalia, buttocks, thighs, legs and feet
Major branches of the Lumbrosacral Plexus are:
- Obtuator nerve
- Femoral nerve
- Siatic nerve
- Pudendal nerve - innervates muscles of the perineum (floor of the pelvis) and sensory from the external genitalia
- Interior gluteal nerve
- Superior gluteal nerve
Innervates the adductors muscles (except pectineus) and skin fo the medial thigh
Innervates iliacus, sartorius, pectineus and quadricepts femoris and skin of the thigh and legs
- Consists of two divisions in the posterior thigh (tibial and fibular) that innervate the hamstring muscles
- Proximal to the knee it splits into the tibial and common fibular (peroneal) nerves
- Tibial nerve innervates the posterior leg muscles and the foot
- Common fibular nerve innervates muscles of the anterior and lateral leg
- They both innervate the skin and joints of the gluteal region and lower limbs
*What/where are the Dermatomes?
- Regions (areas) on the skin innervated from nerve fibers that originate from a specific spinal cord level (sensory not motor)
- Sensory fibers from each spinal cord level will innervate skin of the body in a characteristic pattern that varies in size and shape from person to person