Download (cranial) nerves

Brain and spinal nerve
By: shirin Kashfi
Nervous system:
central nervous system (CNS)
peripheral nervous system (PNS)
Brain (cranial) nerves
Spinal nerves
Ganglions (dorsal root ganglions, sympathetic & parasympathetic ganglions)
The difference between brain and spinal nerves
• Cranial nerves supply the sensory and motor functions of the face and head
and autonomic function of the body
• Unlike the spinal nerves which supply all sensory and motor functions for a
specific body segment, each cranial nerve is associated with a specific
function or set of functions and may take in a larger territory
Brain (cranial) nerves
• There are 12 pairs
• All of them originate from ventral surface of brain except for IV nerve
Cranial nerve I: Olfactory nerve
• Type: sensory
• Function: carries sense of smell
– The olfactory nerve is composed of axons from the olfactory receptors in the nasal
sensory epithelium. It carries olfactory information (sense of smell) to the olfactory bulb
of the brain
Cranial nerve II: optic nerve
• Type: sensory
• Function: carries visual information
– The optic nerve is composed of axons of the ganglion cells in the eye
Cranial nerve III: oculomotor nerve
• Type: motor
• Function: It provides somatic motor innervation to four of the extrinsic eye
muscles: the superior rectus, inferior rectus, medial rectus, and the inferior
oblique muscles. Oculomotor nerve innervates the muscles of the upper
eyelid. It also provides the parasympathetic innervation responsible for
pupillary constriction in response to light and accomodation of the lens for
near vision
Cranial nerve IV: trochlear nerve
• Type: motor
• Function: The trochlear nerve provides somatic motor innervation to the
superior oblique eye muscle
Cranial nerve V: trigeminal nerve
• Type: sensory & motor
• Function: It provides sensory information from the face, forehead, nasal
cavity, tongue, gums and teeth (touch, and temperature) and provides
somatic motor innervation to the muscles of mastication or “chewing”,
inner ear (tensor tympani) and upper neck
– The trigeminal is the largest cranial nerve
– This cranial nerve has 3 branches: the ophthalmic, maxillary and mandibular
branches
Cranial nerve VI: abducens nerve
• Type: motor
• Function: It carries somatic motor innervation to one of the extrinsic eye
muscles, the lateral rectus muscle
Cranial nerve VII: facial nerve
• Type: sensory &motor
• Function: It carries somatic motor innervation to the many muscles for
facial expression. It carries sensory information form the face (deep
pressure sensation) and taste information from the anterior two thirds of the
tongue
Cranial nerve VIII: vestibulocochlear nerve
• Type: sensory
• Function: sense of balance and sense of hearing
– This cranial nerve branches into the Vestibular branch (balance) and the cochlear branch
(hearing)
Cranial nerve IX: glossopharyngeal nerve
• Type: sensory & motor
• Function: It carries sensory information (touch, temperature, and pressure)
from the pharynx and soft palate. It carries taste sensation from the taste
buds on the posterior one third of the tongue. It provides somatic motor
innervation to the throat muscles involved in swallowing. It provides
visceral motor innervation to the salivary glands. This cranial nerve also
supplies the carotid sinus and reflex control to the heart
Cranial nerve X: vagus nerve
• Type: sensory and motor
• Function: It provides sensory information (touch, temperature and pressure)
from the external auditory meatus (ear canal) and a portion of the external
ear. It carries taste sensation from taste buds in the pharynx. It also
provides sensory information from the esophagus, respiratory tract, and
abdominal viscera (stomach, intestines, liver, etc.). It provides visceral
motor innervation to the heart, stomach, intestines, and gallbladder
Cranial nerve XI: spinal accessory nerve
• Type: motor
• Function: The spinal accessory nerve has two branches. The cranial branch
provides somatic motor innervation to some of the muscles in the throat
involved in swallowing. The spinal branch provides somatic motor
innervation to the trapezius muscles, providing muscle movement for the
upper shoulders head and neck
Cranial nerve XII: hypoglossal nerve
• Type: motor
• Function: It provides somatic motor innervation to the muscles of the
tongue
Spinal nerves
• Mammals have 31 pairs spinal nerves
– 8 pairs cervical, 12 pairs thoracic, 5 pairs lumbar, 5 pairs sacral and 1 pairs coccygeal
Conus Medullaris
Caudal end of spinal cord
Cauda Equina
(L1-L5, S1-S5, Co1)
Filum Terminale
a thickening of the pia
and glial cell (anchors
the spinal cord to the
coccyx)
Spinal nerves
• Each of them have sensory
and motor function
• Each spinal nerves innervates
certain area of body which is
called dermatome