Nervous 2Peripheral Nervous System

McKinley and O’Laughlin

Chapter 15&16

XII

XIX

IXVIII

VIIVI

V

IVIII

II

I

C1

Cranial Nerves

What openings in the skull transmit the first cranial nerve? Foramina of the cribriform plate of the ethmoid

bone

What openings in the skull transmit the second cranial nerve? Optic foramen (or optic canal)

Oculomotor (CN III)

What is the function of the third cranial nerve? Somatic motor: 4 extrinsic eye muscles and

levator palpebrae superioris Parasympathetic motor: pupil (iris) and ciliary

muscle

Which cranial nerves innervate eye muscles?

Superior view showing action of superior oblique muscle (down & out)

Trigeminal

What are the functions of the fifth cranial nerve? Sensory:

Ophthalmic: cornea, nose, forehead, anterior scalp Maxillary: nasal mucosa, palate, gums, cheek,

upper teeth Mandibular: anterior 2/3 of tongue, skin of chin,

lower jaw and teeth, part of auricle

Somatic motor: muscles of mastication and others of lower face

Cranial Nerves

What openings in the skull transmit the fifth cranial nerve? Ophthalmic: superior orbital fissure Maxillary: foramen rotundum Mandibular: foramen ovale

Cranial Nerves

What is the function of the seventh cranial nerve? Sensory: anterior 2/3 tongue Somatic motor: muscles of facial expression

and others (e.g. digastric and stapedius) Parasympathetic motor: submandibular and

sublingual glands and lacrimal gland

Cranial Nerves

What openings in the skull transmit the seventh cranial nerve? Internal auditory canal (internal acoustic

meatus). It takes a tortuous course to finally exit the:

Stylomastoid foramen

CN VII (Facial) Passes

through the parotid gland. Does it innervate it??

Tell me about vestibulocochlear nerve

Cranial Nerve IX

What is the name of the ninth cranial nerve? What are its functions?

Sensory: posterior 1/3 of tongue, carotid sinus (blood pressure and chemistry)

Somatic motor: a muscle of the pharynx Parasympathetic motor: parotid gland

What opening in the skull transmits this nerve?

Note the carotid sinus. . . Remember Master Long?

CN X

Let’s talk about the vagabond.

Cranial Nerves

What is the function of the tenth cranial nerve? Sensory: pharynx, larynx, thoracic and

abdominal viscera, external auditory canal, tympanum

Somatic motor: pharyngeal and laryngeal muscles

Parasympathetic motor: myocardium, smooth muscle and glands of viscera

Cranial Nerves

What is the function of the eleventh cranial nerve? Somatic motor:

Cranial root: pharynx (with vagus nerve) Spinal root: trapezius and sternocleidomastoid

muscles

Cranial Nerves

What is the function of the twelfth cranial nerve? Somatic motor: intrinsic and extrinsic tongue

muscles

Spinal Cord and Nerves

What are the 2 functions of the spinal cord? Pathway for motor impulses Reflexes

Spinal Cord Gross Anatomy

What is the general shape of the spinal cord in cross-section? Dorsoventrally compressed cylinder

Spinal Cord Gross Anatomy

What depressions lie on the anterior and posterior surfaces of the spinal cord? Anterior median fissure (wider) Posterior median sulcus

Spinal Cord Gross Anatomy

Where does the spinal cord end in an adult? Extends from foramen magnum to L1 Spine grows more than cord

Gross Anatomy

List the regions of the spinal cord. Cervical Thoracic Lumbar Sacral Coccygeal

Spinal Cord Gross Anatomy

What is the cauda equina? “Horse’s tail” Spinal nerves extending from end of the spinal

cord travel through vertebral canal and exit at each of the lower levels

Spinal Cord Gross Anatomy

How many pairs of spinal nerves are there? 31

List regions and associated spinal nerves. C1-C8 T1-T12 L1-L5 S1-S5 Co1

Spinal Cord Meninges

From superficial to deep list the spaces and structures surrounding the spinal cord.

Spinal Cord Sectional Anatomy

Within the spinal cord, where is the gray matter located and how is it shaped?

Spinal Cord Sectional Anatomy

Within the spinal cord, what are the anterior masses of gray matter that contain the cell bodies of somatic motor neurons?

Within the spinal cord, from T1-T12, what structures contain the cell bodies of of autonomic motor neurons?

Within the spinal cord, what are the posterior masses of gray matter that contain the axons of sensory neurons and the cell bodies of interneurons?

Spinal Cord Sectional Anatomy

What horizontal bar of gray matter surrounds the central canal within the spinal cord? Gray commissure “commissure” just means a place where two

parts join (the corners of your mouth are commissures)

What fills the central canal of the spinal cord? CSF

Spinal Cord Sectional Anatomy

Within the regions of the spinal cord’s gray matter what are the various functional groups of neuron cell bodies? Nuclei

Sensory Somatic motor Autonomic motor

Spinal Cord Sectional Anatomy

Where does the white matter of the spinal cord lie in relation to the gray matter?

The white matter of the spinal cord is organized/partitioned into three regions. What is each called? Funiculus (means a “slender rope” or “cord”

and is referring to a bundle of nerve fibers) Posterior, lateral, and anterior Ascending and descending

Spinal Nerves

Anteriorly and posteriorly what are the small attachments of a spinal nerve to the spinal cord?

The numerous small attachments of a spinal nerve to the spinal cord converge to form what structures?

Spinal Nerves

The cell bodies of sensory neurons associated with the spinal cord are in what structures?

The cell bodies of motor neurons within the spinal cord are found in what structures?

Spinal Nerves

What are the 2 main branches of a spinal nerve? Anterior and posterior rami Which is larger?

What branches of a spinal nerve are associated with the autonomic nervous system? Communicating rami (rami communicantes)

Spinal Nerves

What is a specific segment of skin supplied by a single spinal nerve? Dermatome

Note face Which areas

are innervated by cauda equina nerves?

Intercostal Nerves

The anterior rami of T1-T11 travel in intercostal spaces. What are these nerves called? Intercostal nerves

What term is used to refer to T12 because it lies below the ribs (T12) rather than between them? Subcostal nerve

Intercostal Nerves

In general, what do intercostal nerves innervate? Intercostal muscles Abdominal muscles Associated skin area

A “plexus” is a combined set of spinal nerves that are going to the same area

What is a network of interweaving anterior rami of spinal nerves? Nerve plexus

The cervical plexus arises from what spinal nerves? C1-C4

Where is the cervical plexus located? Deep on each side of the neck

Cervical Plexus

What regions of the body does the cervical plexus innervate? Anterior neck muscles Skin of neck, parts of face and head

What branch of the cervical plexus innervates the diaphragm? Phrenic

C3-C5 (primarily C4) Don’t damage your spinal cord above this

Brachial Plexus

What regions of the body does the brachial plexus innervate? Pectoral girdle Upper limbs

Brachial Plexus

The brachial plexus arises from what spinal nerves? C5-T1

Where is the brachial plexus located? Superior to 1st rib (subclavicular) Axilla

Brachial Plexus

List the 5 (major) nerves that innervate the upper extremity. Axillary nerve Median nerve Musculocutaneous nerve Radial nerve Ulnar nerve I’m asking that you know the general

innervation but be able to list at least 1 specific muscle for each nerve

Brachial Plexus: Axillary Nerve

What is the motor innervation of the axillary nerve? Deltoid Teres minor

What is the cutaneous innervation of the axillary nerve? Superolateral arm (deltoid region)

Brachial Plexus: Median Nerve

What is the motor innervation of the median nerve? Most anterior antebrachial muscles

(flexors/pronators) Thenar muscles Lateral 2 lumbricals

What is the cutaneous innervation of the median nerve? Palmar aspects & dorsal tips of lateral 3.5

digits

Median nerve & carpal tunnel

Brachial Plexus: Musculocutaneous

What is the motor innervation of the musculocutaneous nerve? Anterior brachial muscles (coracobrachialis,

biceps brachii, brachialis) What is the cutaneous innervation of the

musculocutaneous nerve? Lateral antebrachium

Brachial Plexus: Radial Nerve

What is the motor innervation of the radial nerve? Posterior brachial muscles (triceps brachii,

anconeus) Posterior antebrachial muscles (supinator,

extensors, brachioradialis)

Brachial Plexus: Radial Nerve

What is the cutaneous innervation of the radial nerve? Posterior brachium Posterior antebrachium Dorsal portion of lateral 3.5 digits

Wrist Drop

The radial nerve can be damaged if the humerus (the bone of the arm) is broken, because it runs through the radial groove on the lateral border of this bone

Can also be caused by lead poisoning

Brachial Plexus: Ulnar Nerve

What is the motor innervation of the ulnar nerve? Anterior antebrachial muscles (1/2 flexor

digitorum profundus, flexor carpi ulnaris) Hypothenar muscles Most intrinsic muscles of the hand (interossei,

adductor pollicis, medial 2 lumbricals)

Brachial Plexus: Ulnar Nerve

What is the cutaneous innervation of the ulnar nerve? All of medial 1.5 digits and associate hand

(dorsal and palmar)

Remember your “funny bone?”

Lumbar Plexus

The lumbar plexus arises from the anterior rami of what spinal nerves? L1-L4

We will learn two of the nerves that branch off the lumbar plexus (there are others we won’t learn)

Lumbar Plexus: Femoral Nerve

What is the main nerve of the posterior division of the lumbar plexus? Femoral nerve

What is the motor innervation of the femoral nerve? Anterior thigh muscles (quads, iliopsoas,

sartorius) Pectineus

Lumbar Plexus: Femoral Nerve

What is the cutaneous innervation of the femoral nerve? Anterior thigh Inferomedial thigh Medial leg Medial foot Basically the pathway of the great saphenous

vein

Femoral nerve innervations

Lumbar Plexus: Obturator nerve

What is the main nerve of the anterior division of the lumbar plexus? Obturator nerve

Lumbar Plexus: Obturator Nerve

What is the motor innervation of the obturator nerve? Medial thigh muscles (adductors, gracilis,

pectineus*) *femoral, obturator, or both

Obturator externus What is the cutaneous innervation of the

obturator nerve? Superomedial thigh

Lumbar Plexus: Other Branches

What other regions of the body do small branches of the lumbar plexus innervate? Abdominal wall Scrotum/Labia Inferior portions of abdominal muscles (also

innervated by intercostal nerves)

Sacral Plexus

The anterior rami of what spinal nerves form the sacral plexus? L4-S4

Nerves emerging from the sacral plexus innervate what portions of the body? Gluteal region Pelvis Perineum Posterior thigh Leg and Foot

Sacral Plexus

What are the 2 main divisions of the sacral plexus? Anterior and posterior divisions

Nerves of the sacral plexus arising from the anterior division tend to innervate what muscles? Muscles that flex and plantar flex

Hamstrings and hamstring portion of adductor magnus Posterior crural muscles Plantar foot muscles

Sacral Plexus

Nerves of the sacral plexus arising from the posterior division tend to innervate what muscles? Muscles that extend and dorsiflex

We’ll discuss these for each branch of the posterior division

Sacral Plexus: Sciatic Nerve-anterior

What is the largest and longest nerve in the body? Sciatic nerve

What nerve is formed from the anterior divisions of the sciatic nerve? Tibial nerve

Sacral Plexus: Sciatic Nerve: Tibial

What division of what nerve innervates the hamstrings? Tibial division of the sciatic nerve

Within the leg what nerve innervates the plantar flexors of the foot and the flexors of the toes? Tibial nerve

Sacral Plexus: Sciatic Nerve: Fibular

What nerve is formed from the posterior division of the sciatic nerve? Common fibular nerve

What division of what nerve innervates the short head of the biceps femoris? Common fibular division of the sciatic nerve

Sacral Plexus

What are the 2 main divisions of the common fibular nerve? Deep fibular nerve Superficial fibular nerve

Sacral Plexus: Sciatic: Deep Fibular

What is the motor innervation of the deep fibular nerve? Anterior leg muscles (tibialis anterior, extensors) Dorsal muscles of foot (extensor brevia muscles)

What is the cutaneous innervation of the deep fibular nerve? Dorsally between digits I and II

Sacral Plexus: Sciatic: Superficial Fibular

What is the motor innervation of the superficial fibular nerve? Lateral leg muscles (Fibularis brevis and longus)

What is the cutaneous innervation of the superficial fibular nerve? Anteroinferior leg Dorsum of foot

Wow! That’s the End!

Now on to Autonomic Nervous System!