 The formation of the spinal nerve from the dorsal and ventral roots  Gray's Fig. 796 - A portion of the spinal cord, showing its right lateral surface. The dura is opened and arranged to show the nerve roots.  Gray's Fig. 797 - Distribution of cutaneous nerves. Ventral aspect. The term spinal nerve generally refers to the mixed spinal nerve, which is formed from the dorsal and ventral roots that come out of the spinal cord. The spinal nerve is the bit that passes out of the vertebrae through the intervertebral foramen. An illustration from the 1918 edition Henry Grays Anatomy of the Human Body, commonly known as Grays Anatomy, is an anatomy textbook widely regarded as a classic work on human anatomy. ...
An illustration from the 1918 edition Henry Grays Anatomy of the Human Body, commonly known as Grays Anatomy, is an anatomy textbook widely regarded as a classic work on human anatomy. ...
Nerves (yellow) Nerves redirects here. ...
Cross-section through cervical spinal cord. ...
A diagram of a thoracic vertebra. ...
There are a total of 31 bilaterally-paired spinal nerves :
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
The first to seventh cervical nerves (C1 to C7) exit from the vertebral canal above the respective cervical vertebra (that is to say, C1 exits above the first cervical vertebra; C2 exits above the second, and so forth). The C8 spinal nerve exits below the seventh cervical vertebra, and all the other spinal nerves leave below their corresponding vertebra.
Formation of the spinal nerves Inside the spinal cord, there is grey matter, surrounded by white matter. From out of the grey matter, two dorsal roots (one on the left side, and one on the right side) and two ventral roots emerge. The dorsal roots contain afferent sensory axons, and the ventral roots contain efferent motor axons. Grey matter[1] is a category of nervous tissue with many nerve cell bodies and few myelinated axons. ...
White matter is one of the two main solid components of the central nervous system. ...
penis ...
In anatomy and neurology, the ventral root is the efferent motor root of a spinal nerve. ...
In the nervous system, afferent neurons, otherwise known as sensory or receptor neurons carry nerve impulses from receptors or sense organs towards the central nervous system. ...
The somatosensory system is the sensory system of somatic sensation. ...
An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ...
In the nervous system, efferent nerves otherwise known as motor or effector neuron carry nerve impulses away from the central nervous systemto effectors - either muscles or glands. ...
In vertebrates, motoneurons (also called motor neurons) are efferent neurons that originate in the spinal cord and synapse with muscle fibers to facilitate muscle contraction and with muscle spindles to modify proprioceptive sensitivity. ...
An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ...
Dorsal means back, ventral means front. As the body is symmetrical, the same thing happens on both the left and right side of the body. This happens in each vertebra of the spine.
The dorsal roots of each side continue outwards, along the way forming a dorsal root ganglion (also called a spinal ganglion). This is a dorsal root ganglion (DRG) from a chicken embryo (around stage of day 7) after incubation overnight in NGF growth medium stained with anti-neurofilament antibody. ...
The ventral roots similarly continue out from the spinal column, and meet and mix with their corresponding dorsal nerve root at a point after the ganglion. At this point they are called a mixed spinal nerve
Fate of the spinal nerve After the dorsal and ventral roots fuse to form a spinal nerve, the nerve bifurcates into dorsal and ventral primary rami. The dorsal primary ramus supplies the muscles and sensory nerves of the back, while the ventral primary ramus supplies the rest of the body wall.
Each primary ramus has two branches: from the dorsal primary ramus emerges a lateral and medial branch; from the ventral primary ramus sprout an anterior and lateral cutaneous branch. In addition, the anterior cutaneous bifurcates, forming a medial and lateral branch, while the lateral cutaneous branch splits into an anterior and posterior branch. These secondary and tertiary branches themselves typically have muscular and sensory branches that innervate the body wall.
The ventral primary rami also give rise to the roots of the various nervous plexuses (e.g. the brachial plexus), which become the sensory and motor nerves of the limbs. PLEXUS (Physics Learning EXperience Using Software) is a name of project that was started by Vibor Cipan, physics student form Croatia and it is based on utilization of usage of computer technology to enhance learning of physics. ...
The brachial plexus is an arrangement of nerve fibres (a plexus) running from the spine (vertebrae C5-T1), through the neck, the axilla (armpit region), and into the arm. ...
Before forming the plexuses, the ventral rami have two branches leading to a sympathetic ganglion. These ganglia connect to the one above and below them, forming the sympathetic chain. The Sympathetic Chain is a series of interconnected sympathetic ganglia, belonging to the autonomic nervous system. ...
Importance of the spinal nerves The muscles that one particular spinal root supplies are that nerve´s myotome, and the dermatomes are the areas of sensory innervation on the skin for each spinal nerve. This is of great importance in the diagnosis of neurological disorders, as lesions of one or more nerve roots result in typical patterns of neurologic defects (muscle weakness, loss of sensation) that allow localisation of the causating lesion. In vertebrate embryonic development, a group of tissues formed from somites that develop into the body wall muscle. ...
Dermatome has three meanings: in surgery, a surgical instrument used for slicing skin in order to perform skin grafts. ...
Diagnosis (from the Greek words dia = by and gnosis = knowledge) is the process of identifying a disease by its signs, symptoms and results of various diagnostic procedures. ...
| Major nerves (also see Peripheral nervous system) | | Cranial nerves: I olfactory | II optic | III oculomotor | IV trochlear | V trigeminal | V1 ophthalmic (lacrimal, frontal, supratrochlear, supraorbital, nasociliary, ciliary ganglion) | V2 maxillary (sphenopalatine ganglion) | V3 mandibular (buccal - auriculotemporal - lingual - inferior alveolar - otic ganglion) | VI abducens | VII facial (chorda tympani, nervus intermedius) | VIII vestibulocochlear (cochlear, vestibular) | IX glossopharyngeal | X vagus (recurrent laryngeal, Alderman's nerve) | XI accessory | XII hypoglossal Nerves (yellow) Nerves redirects here. ...
The peripheral nervous system or PNS, is part of the nervous system, and consists of the nerves and neurons that reside or extend outside the central nervous system--to serve the limbs and organs, for example. ...
Cranial nerves are nerves that emerge from the brainstem instead of the spinal cord. ...
The olfactory nerve is the first of twelve cranial nerves. ...
The optic nerve is the nerve that transmits visual information from the retina to the brain. ...
The oculomotor nerve () is the third of twelve paired cranial nerves. ...
The fourth of twelve cranial nerves, the trochlear nerve controls the function of the superior oblique muscle, which rotates the eye towards the nose and also moves the eye downward. ...
The trigeminal nerve is the fifth (V) cranial nerve, and carries sensory information from most of the face, as well as motor supply to the muscles of mastication (the muscles enabling chewing), tensor tympani (in the middle ear) and other muscles in the floor of the mouth, such as the...
The Ophthalmic nerve is one of the three branches of the trigeminal nerve, one of the cranial nerves. ...
The Lacrimal Nerve is the smallest of the three branches of the ophthalmic. ...
The Frontal Nerve is the largest branch of the ophthalmic, and may be regarded, both from its size and direction, as the continuation of the nerve. ...
The supratrochlear nerve, smaller than the Supraorbital nerve, passes above the pulley of the Obliquus superior, and gives off a descending filament, to join the infratrochlear branch of the nasociliary nerve. ...
The supraorbital nerve arises from the orbit by the supraorbital foramen and supplies the upper eyelid and forehead integuments. ...
The Ophthalmic nerve is one of the three branches of the trigeminal nerve, one of the cranial nerves. ...
The ciliary ganglion is small parasympathetic ganglion lying in the orbit between the optic nerve and the lateral rectus muscle that is associated with the nasociliary nerve (a branch of the ophthalmic division of the trigeminal nerve). ...
The Maxillary nerve is one of the three branches of the trigeminal nerve, one of the cranial nerves. ...
The sphenopalatine ganglion is a parasympathetic ganglion found in the spheno-maxillary fossa. ...
The mandibular nerve is the third branch (V3) of the trigeminal nerve. ...
A branch of the mandibular nerve (which is itself a branch of the trigeminal nerve), the buccal nerve transmits sensory information from skin over the buccal membrane (in general, the cheek) and from the second and third molar teeth. ...
The auriculotemporal nerve is a branch of the mandibular nerve (Viii) and supplies motor fibres to the temporomandibular joint and parasympathetic fibres to the parotid glands. ...
The Lingual Nerve supplies the mucous membrane of the anterior two-thirds of the tongue. ...
The inferior alveolar nerve is a branch of the mandibular nerve, which is itself the third branch (V3) of the fifth cranial nerve, the trigeminal nerve (cranial nerve V). ...
The Otic Ganglion is a parasympathetic ganglion located immediately below the foramen ovale. ...
The sixth out of twelve cranial nerves, the abducens nerve controls the lateral rectus muscle - this means that the action of this nerve controls each eyes ability to look laterally (away from the midline). ...
The facial nerve is seventh of twelve paired cranial nerves. ...
The chorda tympani are nerves of special sensation given off the facial nerve (VII) inside the skull. ...
The nervus intermedius, or intermediate nerve, is the part of the facial nerve (cranial nerve VII) located between the motor component of the facial nerve and the vestibulocochlear nerve (cranial nerve VIII). ...
The vestibulocochlear nerve is the eighth of twelve cranial nerves and also known as the auditory nerve. ...
The Cochlear nerve (n. ...
The Vestibular nerve is one of the two branches of the Vestibulocochlear nerve (the cochlear nerve is the other. ...
The glossopharyngeal nerve is the ninth of twelve cranial nerves. ...
The vagus nerve is tenth of twelve paired cranial nerves and is the only nerve that starts in the brainstem (somewhere in the medulla oblongata) and extends all the way down past the head, right down to the abdomen. ...
The recurrent laryngeal nerve is a branch of the vagus nerve (the tenth cranial nerve) which supplies motor function and sensation to the larynx (voice box). ...
The Auricular branch of the tenth cranial or vagus nerve is often termed the Aldermans nerve. ...
The accessory nerve is the eleventh of twelve cranial nerves. ...
The hypoglossal nerve is the twelfth cranial nerve. ...
Posterior spinal nerves: greater occipital The greater occipital nerve is a spinal nerve arising between the first and second cervical vertebrae, along with the lesser occipital nerve. ...
C1-C4 - Cervical plexus: lesser occipital | greater auricular | lesser auricular | phrenic | ansa cervicalis The cervical plexus is a plexus of the ventral roots of the first four cervical spinal nerves which are located from C1 to C4 cervical segment near the neck. ...
The lesser occipital nerve is a spinal nerve arising between the first and second cervical vertebrae, along with the greater occipital nerve. ...
The greater auricular nerve originates from the cervical plexus, composed of branches of spinal nerves C2 and C3. ...
The lesser auricular nerve originates from the cervical plexus, composed of branches of spinal nerves C2 and C3. ...
The phrenic nerve arises from the third, fourth, and fifth cervical spinal nerves (C3-C5). ...
The ansa cervicalis (or ansa hypoglossi in older literature) is a loop of nerves that are part of the cervical plexus. ...
C5-C8, T1 - Brachial plexus: supraclavicular branches (dorsal scapular, suprascapular, long thoracic) | lateral cord (musculocutaneous, lateral antibrachial cutaneous, lateral head of median nerve) | medial cord (ulnar, medial head of median nerve, medial antibrachial cutaneous, medial brachial cutaneous) | posterior cord (axillary, radial) The brachial plexus is an arrangement of nerve fibres (a plexus) running from the spine (vertebrae C5-T1), through the neck, the axilla (armpit region), and into the arm. ...
The dorsal scapular nerve arises from the brachial plexus, specifically from spinal nerves C4 and C5. ...
The Nervus suprascapularis (Suprascapular nerve) is a nerve of the plexus brachialis. ...
The long thoracic nerve supplies motor innervation to the serratus anterior muscle. ...
The Lateral cord is a division of the brachial plexus. ...
The major end branch of the lateral cord, courses inferiorly within the anterior arm, supplying motor fibers to the arm muscles that flex the forearm (the biceps brachii and brachialis). ...
The lateral antibrachial cutaneous nerve (branch of musculocutaneous nerve, also sometimes spelled antebrachial) passes behind the cephalic vein, and divides, opposite the elbow-joint, into a volar and a dorsal branch. ...
Diagram from Grays anatomy, depicting the peripheral nerves of the upper extremity, amongst others the median nerve The median nerve is a nerve that runs down the arm and forearm. ...
The Medial cord is a division of the brachial plexus. ...
Grays Fig. ...
Diagram from Grays anatomy, depicting the peripheral nerves of the upper extremity, amongst others the median nerve The median nerve is a nerve that runs down the arm and forearm. ...
The Medial Antibrachial Cutaneous Nerve (internal cutaneous nerve, also sometimes spelled antebrachial) arises from the medial cord of the brachial plexus. ...
The Medial Brachial Cutaneous Nerve (lesser internal cutaneous nerve; nerve of Wrisberg) is distributed to the skin on the ulnar side of the arm. ...
The Posterior cord is a division of the brachial plexus. ...
The axillary nerve is a nerve of the human body, that comes off the posterior cord of the brachial plexus at the level of the axilla (armpit) and carriers nerve fibers from C5 and C6. ...
The radial nerve is a nerve in the human body, that supplies the arm, the forearm and the hand. ...
T2-T11: intercostal The thoracic spinal nerves T3 through T12. ...
T12, L1-L5 - Lumbar plexus: iliohypogastric | ilioinguinal | genitofemoral | lateral femoral cutaneous | femoral | obturator Grays Fig. ...
The Iliohypogastric Nerve arises from the first lumbar nerve. ...
The Ilioinguinal Nerve, smaller than the Iliohypogastric nerve, arises with it from the first lumbar nerve. ...
In human anatomy, the genitofemoral nerve originates from the upper part of the lumbar plexus of spinal nerves. ...
The Lateral Femoral Cutaneous Nerve (external cutaneous nerve) arises from the dorsal divisions of the second and third lumbar nerves. ...
The Femoral Nerve supplies innervation the anterior portion of the leg. ...
The Obturator Nerve arises from the ventral divisions of the second, third, and fourth lumbar nerves; the branch from the third is the largest, while that from the second is often very small. ...
S1-S4 - Sacral plexus: gluteal | posterior femoral cutaneous | tibial | sciatic | sural | common peroneal In human anatomy, the Sacral plexus refers to the nerve plexus emerging from the sacral vertebrae (S1-S4), and which provides nerves for the pelvis and lower limbs. ...
The Superior Gluteal Nerve () arises from the dorsal divisions of the fourth and fifth lumbar and first sacral nerves: it leaves the pelvis through the greater sciatic foramen above the Piriformis, accompanied by the superior gluteal vessels, and divides into a superior and an inferior branch. ...
The Posterior Femoral Cutaneous Nerve (small sciatic nerve) is distributed to the skin of the perineum and posterior surface of the thigh and leg. ...
The Tibial Nerve The tibial nerve passes through the popliteal fossa to pass below the arch of soleus. ...
The sciatic nerve is a large nerve that runs down the lower limb. ...
The sural nerve (short saphenous nerve), formed by the junction of the medial sural cutaneous with the peroneal anastomotic branch, passes downward near the lateral margin of the tendo calcaneus, lying close to the small saphenous vein, to the interval between the lateral malleolus and the calcaneus. ...
The Common peroneal nerve is a branch of the Sciatic nerve. ...
S2-S5 - Pudendal plexus: perforating cutaneous | pudendal | visceral | muscular | anococcygeal The pudendal plexus is not sharply marked off from the sacral plexus, and as a consequence some of the branches which spring from it may arise in conjunction with those of the sacral plexus. ...
The Perforating Cutaneous Nerve usually arises from the posterior surface of the second and third sacral nerves. ...
The pudendal nerve is responsible for orgasm, urination, and defecation in both sexes. ...
The Visceral Branches arise from the third and fourth, and sometimes from the second, sacral nerves, and are distributed to the bladder and rectum and, in the female, to the vagina; they communicate with the pelvic plexuses of the sympathetic. ...
The Muscular Branches are derived from the fourth sacral, and supply the Levator ani, Coccygeus, and Sphincter ani externus. ...
Anococcygeal Nerves: The fifth sacral nerve receives a communicating filament from the fourth, and unites with the coccygeal nerve to form the coccygeal plexus. ...
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