2. The brain
I lies in the cavity inside the skull called cranial cavity
it divided into the following region :
1. Cerebrum , which is divided into 4 functional lobes .
2. Cerebellum
3. Brain stem which contain mid brain ,pons and medulla oblongata
it controls the whole body
it contains many centers . They are :
a. Motor center : It controls the skeletal muscles of the body .
b. sensory center : It controls the sensation of the body .
c. Visual center : It controls the vision.
d. auditory center : it controls the hearing .
e. speech center : It controls the speech.
3. The brain
It gives 12 pairs of nerves called nerves
Cerebral function
1. Frontal lobe : motor and intellectual in function.
2. Parietal lobe : sensory in function
3. Occipital lobe : visual in function
4. Temporal lobe : taste , smell and hearing .
Also it has :
- Thalamus : sensory functions, general and special.
- Typothalamus : body temperature regulation ,autonomic , sleep regulation and
endocrine function
4. The brain
Cerebellar function
1. Equilibrium .
2. Muscle coordination
3. Muscle tone
Spinal cord
It is characterized by :
1) It is the continuation of the oblongata. It begins at the foramen magnum
2) It present in the cavity of the vertebral column
3) Covered by meninges
4) It ends at the second lumber vertebra
5) It gives 31 pairs of nerves called spinal nerves .
5.
6.
7. Peripheral nervous system
This system contains
1. 31 pair of spinal nerves
2. 12 pair of cranial nerves
Spinal nerves
1) The are 31 pairs
2) They arise from the spinal cord
3) They are divided into :
a. 7 cervical nerves : For supplying the neck and upper limb
b. 12 thoracic nerves: For supplying thorax and the abdomen
c. 5 lumber nerves: For supplying the abdomen and lower limb
d. 5 sacral nerves: For supplying the pelvis and lower limb
e. One coccygeal nerve : For supply small part of pelvis
8. Peripheral nervous system
The Cranial Nerves
I. Olfactory nerve : for sensory ( smell ) , olfactory area of the nasal mucosa
II. Optic nerve : for sensory ( vision ) , the retina of the eyeball
III. oculomotor nerve , motor and parasympathetic . All extrinsic muscles of the
eyeball except two ( superior oblique and lateral rectus ) . Intrinsic muscles of
the eyeball except the dilator papillae muscle .
IV. Trochlear nerve , motor , superior oblique muscle of the eye .
V. Trigeminal nerve :
1. Ophthalmic , sensory , skin of forehead , upper eyelid conjunctive , cornea
and tip of the nose .
2. Maxillary , sensory , , skin over the zygoma , lower eyelid , upper lip, side
of nose mucosa of the nose , palate and upper of teeth .
3. Mandibular , mixed , sensory to the auricle , cheeks , over the mandible ,
lower lip , anterior 2/3 of the tongue and lower set of teeth .
Motor for the muscle of mastication to the masseter, temporalis , lateral
pterygoid ,medial pterygoid , mylohyoid and anterior belly of digastric
VI. Abducent nerve , motor ,lateral rectus of the eye.
9. VII. Facial nerve :
Motor , muscle of facial expression – ( branch -temporal zygomatic , buccal ,mandibular , cervical and
posterior auricular – para, chorda tympani)
Sensory , taste sensation from the anterior 2/3 of the tongue . To stylohyoid and posterior belly of digastric
Parasympathetic : sensory motor to the submandibular and sublingual salivary gland and nose
VIII. Stato acoustic:
1. Vestibular , sensory ( equilibrium ) ,to vestibular of internal ear , semicircular canal .
2. Cochlear sensory (hearing ) to the cochlea of internal ear .
IX. Glossopharyngeal
motor , sensory and parasympathetic: Motor to stylopharyngeus muscle. Sensory and taste of
posterior 1/3 of tongue . Parasympathetic to the parotid gland
Branches : pharyngeal and lingual branches , lesser superficial petrosal nerves to the parotid gland ,
nerve supply to stylopharyngeus muscle.
X. Vagus nerve :
Motor and sensory and parasympathetic to the heart , respiratory system ,gastrointestinal system
except part of colon , rectum and anal canal.
Branches : superior laryngeal branches , cardiac branches , recurrent laryngeal nerve ,pulmonary
branches , branches to : coleac plexus , superior mesenteric plexus and inferior mesenteric plexus
10. XI. Accessory nerve :
motor ( cranial ) – to the muscle of the pharynx and larynx.
motor ( spinal ) - To sternocleidomastoid muscle and trapezius muscle
Branches : sharing in the formation of the pharyngeal plexus .- motor branch
to sternocleidomastoid muscle and trapezius muscle .
XII. Hypoglossal nerve :
Motor to the muscles of the tongue
Branches : motor to the intrinsic and extrinsic muscles of the
tongue muscles of the tongue
