Lab Pratical 8 - PNS and special senses

What are the three Sensory Cranial Nerves?

• Olfactory (I)

• Optic (II)

• Vestibulocochlear (VIII)

What are the five Motor Cranial Nerves?

• Oculomotor (III)

• Trochlear (IV)

• Abducens (VI)

• Accessory (XI)

• Hypoglossal (XII)

What are the four mixed cranial nerves

• Trigeminal (V)

• Facial (VII)

• Glossopharyngeal (IX)

• Vagus (X)

Olfactory (I)

Sensory cranial nerve; nerve for olfaction or the sense of smell

Optic (II)

Sensory Cranial Nerve; nerve for vision

Vestibulocochlear (VIII)

Sensory Cranial Nerve; balance and equilibrium

Oculomotor (III)

moves the eyeball; opening the eye; constricts the pupil; changes the lens shape

Trochlear (IV)

innervate superior oblique muscle which moves the eye medially and inferiorly (outward and downward)

Abducens (VI)

innervate lateral rectus muscle; abducts the gaze when it turns the eye laterally (horizontally outward)

Accessory (XI)

innervates certain muscles of speech; spinal component innervates muscles that move the head and shoulder

Hypoglossal (XII)

innervates the muscles of the tongue (no role in taste sensation)

Trigeminal (V)

Sensory detects facial sensation, including stimuli from the oral and nasal cavities; motor supply to the masseter and temporalis muscles, which elevate the mandible (close the jaw) during mastication (chewing) and swallowing

Facial (VII)

taste sensation from chemoreceptors ⅔ of tongue, somatic sensation from the external ear; motor root supplies the muscles of facial expression and other facial muscles; salivary glands, lacrimal (tear) glands, nasal mucous glands

Glossopharyngeal (IX)

Detects sensation on ⅓ of tongue, innervate external ear; responsible for swallowing, trigger salivation from parotid gland (salivation in cheeks from salty or acidic foods such as pickles or lemons

Vagus (X)

sensory around skin of ear, taste sensation from pharnyx; muscles surrounding the pharynx and larynx voice box during speaking and swallowing

Name all the nerve plexus

• Cervical plexuses

• Brachial plexuses

• Lumbar plexuses

• Sacral plexuses

What muscles does the Cervical Plexus (C₁-C₅) supply

skin and muscles of neck and shoulder

• Phrenic- diaphragm

What muscles does the Brachial Plexus (C₅-T₁) supply

skin and muscles of upper limb

• Axillary- deltoid, teres minor

• Musculocutaneous- biceps brachii, brachialis

• Radial- triceps brachii, brachioradialis

• Median- palmaris longus

• Ulnar- flexor carpi ulnaris

What muscles does the Lumbar Plexus (L₁-L₄) supply

skin and muscles of abdomen and anterior thigh

• Genitofemoral

• Femoral- rectus femoris, vastus medialis, vastus lateralis, vastus intermedius, sartorius

• Obturator- gracilis, adductor longus

What muscles does the Sacral Plexus (L₄-S₄) supply

skin and muscles of posterior thigh, leg, and buttocks

• Sciatic- made up of 2 nerves

  • Tibial- biceps femoris (long head), gastrocnemius, soleus

  • Common fibular- tibialis anterior, biceps femoris (short head) Pudendal

Tactile corpuscle

light pressure, discriminative touch

Lamellated corpuscle

deep pressure, vibration

Axons of sensory neurons

Ruffini ending

deep pressure, stretch

Merkel discs (cell fibers)

light touch

Free nerve endings

temperature and pain

Papillae

Taste buds on the tongue are located within the surface projections

Four types of papillae

• vallate

• foliate

• fungiform

• filiform

Vallate

largest, arranged in an inverted V shape on the posterior surface of the tongue

Foliate

located on the lateral surfaces of he tongue, are present mostly in children

Fungiform

Scattered across the anterior two thirds of the tongue’s surface Muschroom shaped

Filiform

• Scattered across the anterior two thirds of the tongue’s surface; most abundant; contain tactile receptors instead of  taste buds, provide a rigid, abrasive surface for food manipulation

Gustatory cells

receptors for gustation; located primarily on the superior surface of the tongue

Basal cells

stem cells that divide to produce new gustatory cells

Supporting cells

support and nourish gustatory cells

taste bud

Microvilli

taste pore

Cranial Nerves involved in olfaction

Olfactory nerve (I)

Cranial Nerves involved in Gustation

• Facial (VII)

• Glossopharyngeal (IX)

• Vagus (X)

Cranial Nerves involved in vision

Optic Nerve

Cranial Nerves involved in hearing

Cochlear nerve

Cranial nerve involved in equilibrium

Vestibular nerve

Three layers of the eye

• Outer fibrous layer

• Middle vascular layer

• Inner neural layer

Cornea

bends light as it enters the eye

Sclera

protects the eye and serves as an attachment site for the extrinsic eye muscles

Choroid

• supplies oxygen and nutrients to the cells of the eye

  • Contains melanocytes, which produce the pigment melanin, and absorbs excess light

Ciliary body

regulates the shape of the lens to enable light to be focused on the retina; secretes aqueous humor (clear watery fluid)

Iris

contains pigmented cells that are responsible for eye color and smooth muscle fibers that regulate the size of the pupil & the amount of light that enters the eye

Retina

• The retina is composed of two layers

  • Outer pigmented epithelium - absorbs light and prevents it from scattering

  • Inner neural layer - contains the photoreceptors (rods and cones)

Ora Serrata

serrated boundary between the retina and the ciliary body

Optic disk

the point at which the optic nerve leaves the eyeball

Macula lutea

yellow spot in retina; concentration of cones is high wich are responsible for color vision and sharp detail

 Fovea centralis

small pit within the macula lutea concentration of cones is greatest, vision is the sharpest

Optic Nerve (II) eye diagram

Central artery and vein of the retina

Suspensory ligament

Outer ear

Middle ear

Inner ear

Semicircular canals

vestibule

Vestibulocochlear nerve (VIII) ear diagram

Cochlea

Round window

Tensor tympani muscle

Pharyngotympanic tube (to pharynx)

Tympanic Membrane

Auditory ossicles: Malleus

Auditory ossicles: Incus

Auditory ossicles: Stapes

Lobule

External auditory canal

Auricle (pinna)

Semicircular ducts: Anterior

Semicircular ducts: Posterior

Semicircular ducts: Lateral

Vestibule: Utricle

Vestibule: Saccule

Ampulla

Perilymph

Cochlear duct filled with endolymph

temporal bone