Anatomy exam 2: Spinal cords and spinal nerves

What is the "fat" line called in the anterior aspect of our spinal cord?

anterior median fissure

Where does our spinal cord end?

around L1-L2

What does the common fibular nerve branch into?

deep fibular nerve and superficial fibular nerve

What are thickenings of pia mater that fuse with the dura mater and arachnoid mater?

denticulate ligament

What are the two ganglions that contain soma found on the spinal cord called?

dorsal-root ganglion & ventral-root ganglion

what do the spinal nerves branch into?

dorsal/posterior ramus and ventral/anterior ramus

What are meninges?

dura mater, arachnoid mater, pia mater

What space is located about the dura mater where fat and connective tissue can be found?

epidural space

What anchors our spinal cord inferiorly?

filum terminale

anococcygeal nerve

innervates the skin over the coccyx

What are our thoracic nerves involved with?

involved with information of our thorax and abdominal area

What are our cervical nerves involved with?

involved with information of our upper limbs

What are our sacral nerves involved with?

involved with our genital area

What are our lumbar nerves involved with?

involved with our lower limbs

What does the superior trunk give rise to in the brachial plexus?

lateral cord

What does the inferior trunk give rise to in the brachial plexus?

medial cord

What neurons do the ventral part of our spinal cord receive?

motor

what type of neuron are motor neurons? (multipolar, unipolar, bipolar)

multipolar

what does the lateral cord give rise to in the brachial plexus?

musculocutaneous nerve

Why is the phrenic nerve so important?

only motor supply for the diaphragm

What does the middle trunk give rise to in the brachial plexus?

posterior cord

What is the "skinny" line called in the posterior aspect of our spinal cord?

posterior median sulcus

what does the posterior cord give rise to in the brachial plexus?

radial and axillary nerves

What is the largest nerve in the sacral plexus?

sciatic nerve

What neurons do the dorsal part of our spinal cord receive?

sensory

What are cutaneous fields?

specific areas in our body that are innervated (supply with nerves) by nerves that come from plexuses

what space is found in between the arachnoid mater and dura mater and where CSF is found?

subarachnoid space

what space is located below the dura mater and has interstitial fluid?

subdural space

What does the cervical plexus innervate?

the neck region and superior part of shoulder and chest

What type of neurons are spinal nerves?

they are both sensory and mixed

What are spinal nerves formed by?

they are formed by axons of motor neurons and dendrites of sensory neurons

Clicker question: Pinching someone's arm posteriorly would lead to pain, how would the signal be receive to the CNS?

through the posterior gray horns through the ventral ramus

what does the medial cord give rise to in the brachial plexus?

ulnar nerve

what type of neuron are sensory neurons? (multipolar, unipolar, bipolar)

unipolar

Where are the sacral and coccygeal plexus located?

(L4-S5)

Thoracic nerves characteristics (4)

- DO NOT FORM PLEXUS - intercostal nerves run laterally - responsible for innervating area between the ribs - related to any sensory/motor information related to the lateral/anterior aspect of our chest and abdominal

Ulnar nerve characteristics:

- arises by the medial cord - runs down the ulnar bone - innervates our hand and small section forearm

Musculocutaneous nerve characteristics

- arises from lateral cord - pierces the coracobrachialis and stops in between the brachialis and biceps brachii - innervates the coracobrachialis, brachialis, and biceps brachii

Radial nerve characteristics

- arises from posterior cord - innervates the posterior of our arm and forearm

Axillary nerve characteristics:

- arises from posterior cord - wraps around the axilla - innervates the deltoid and pans minor (shoulder)

Median nerve characteristics

- goes in between the radius, ulna, and humerus - innervates anterior muscles of our forearm and a small amount of our hand

genitofemoral nerve

- goes through genitals and femoral region (thigh)

Femoral nerve

- goes towards the femur - innervates muscle an skin in anterior aspect of thigh

pudendal nerve

-goes towards genital area and innervates skin of the penis, scrotum, and cliteris, etc.

obturator nerve

-passes through obturator foramen to innervate adductor muscles

Sciatic nerve

-runs posteriorly all down our thigh, down our leg and gives rise to the tibial nerve

posterior (dorsal) ramus

-serves the deep muscles and skin of the posterior surface of the trunk -all Sensory and motor information related to the back skin/muscle

Anterior (ventral) ramus

-serves the muscles and structures of the upper and lower limbs and the skin of the lateral and anterior surfaces of the trunk - sensory and motor of the skin/muscle in our lateral & anterior aspect; supplies our limbs

Name each horn of the spinal cord and discuss what they are responsible for:

1. Posterior gray horn: - have neurons that receive sensory information coming from the dorsal root 2. Anterior gray horn: - neurons that relate to motor function. Sends out motor signals to the skeletal muscles 3. Lateral gray horn: - neurons related to autonomic motor neurons - axons will synapse with cardiac, smooth, or glands - *mainly in the thoracic region*

What are the nerves found in the lumbar plexus?

1. genitofemoral nerve 2. femoral nerve 3. obturator nerve

What are the general components of a reflex arc?

1. sensory receptor 2. sensory neuron 3. integrating center 4. motor neuron 5. effector

How many trunks are there in the brachial plexus?

3 (superior, middle, inferior)

How many spinal nerves are there?

31 pairs

*Quiz question* The sciatic nerve eventually branches into which nerves? A. Common fibular and tibial nerves B. Tibial and fibular nerves C. Deep and superficial fibular nerves D. Obturator and femoral nerves

A. Common fibular and tibial nerves

*Quiz question* The phrenic nerve _____________________. A. Reaches diaphragm and innervates it B. Is an integral part of the reflex arc C. Branches off at the clavicle into the sternothyroid nerve D. Is part of the brachial plexus

A. Reaches diaphragm and innervates it

*Quiz Questions* Below L1-L2, the vertebral canal is occupied by a bundle of spinal nerve roots called the: A. cauda equina B. sacral plexus C. descending tracts D. filum terminale E. conus medullaris

A. cauda equina

*Quiz question* Which of the following branch patterns of nerves is part of the brachial plexus? A. middle trunk, posterior cord, medial nerve B. superior trunk, lateral cord, musculocutaneous nerve C. superior trunk, lateral cord, axillary nerve D. inferior trunk, posterior cord, ulnar nerve

B. superior trunk, lateral cord, musculocutaneous nerve

*Quiz Questions* In the spinal cord, the somas of the lower motor neurons are found in the: A. Cauda equina B. posterior horns C. anterior horns D. central canal E. dorsal root ganglia

C. anterior horns

Where are the cervical plexuses located?

C1-C4; C5 is split into the cervical and brachial plexus

What cervical plexuses make up the phrenic nerve?

C3, C4, C5

What is the brachial plexus formed by?

C5-T1

*Iclicker question * Pinching someone's arm posteriorly would lead to the pain that reaches the person's central nervous system in what way? A. The sensory information reaches the posterior gray horn of the spinal cord via the dorsal ramus B. The sensory information reaches the posterior gray horn via the dorsal root C. The sensory information reaches the anterior gray horn via the ventral root D. The sensory information reaches the posterior gray horn via the ventral ramus

D. The sensory information reaches the posterior gray horn via the ventral ramus

*Quiz questions* The dorsal root ganglion has which types of neurons relaying what type of information? A. Multipoar neurons, motor information B. Unipolar neurons, motor information C. Multipolar, sensory information D. Unipolar neuron, sensory information

D. Unipolar neuron, sensory information

*Quiz question* The _______ is the outermost meninx and forms a supportive and protective partition between some portions of the brain. A. denticulate mater B. pia mater C. arachnoid mater D. dura mater

D. dura mater

*Quiz question* The posterior cord gives rise to which nerves? A. musculocutaneous and median B. radial and ulnar C. axillary and median D. radial and axillary E. median and ulnar

D. radial and axillary

*Quiz question* The longest nerve that innervates the digestive system is the: A. hypoglossal B. trigeminal C. glossopharyngeal D. vagus

D. vagus

Which meninges is the most durable/toughest and is closest to the vertebra?

Dura mater

What is the lumbar plexus composed of?

L1-L4

What nerves arise from cervical plexuses?

Phrenic nerve

Which meninges is the most pliable/flexible and hugs the spinal cord?

Pia mater

What nerve do S2, S3, and S4 make?

Pudendal nerve

Brachial plexus branching/flow:

Remember To Drink Cold Beer Roots, trunks, divisions, cords, branches

What nerve is located in the coccygeal plexus?

anococcygeal nerve

What is the proper definition of commissure?

a bundle of nerve fibers that connect the hemispheres of the brain

What is the proper name for the "hair-like" nerves at the end of our spine?

caudo equina

How many nerves are cervical, thoracic, lumbar, sacral, and coccyx?

cervical (8), thoracic (12), lumbar (5), sacral (5), coccyx (1)

Name all the Plexuses

cervical, brachial, lumbar, sacral

What are the two branches of the sciatic nerve?

common fibular nerve and tibial nerve

What is the proper name for the "end" of our spinal cord?

conus medullaris