Exam 4, Chapter 13a - Somatic Motor (Part 1) Flashcards
All neural structures outside the brain and spinal cord
Peripheral Nervous System
Includes sensory receptors, peripheral nerves, associated ganglia, and motor endings
Peripheral Nervous System
Provides links to and from the external environment
Peripheral Nervous System
- cordlike organ of the PNS consisting of peripheral axons enclosed by connective tissue
- Connective tissue coverings include???
Structure of a Nerve
-loose connective tissue that surrounds each individual axons
Structure of a Nerve
Endoneurium
-coarse connective tissue that bundles fibers into fascicles (a bunch of axons)
Structure of a Nerve
Perineurium
-tough fibrous sheath around an entire nerve (bunch of bunches of axons)
Structure of a Nerve
Epineurium
Classification of Nerves
-carry impulse to the CNS
Classification of Nerves
sensory (afferent)
Classification of Nerves
-carry impulses from CNS
Classification of Nerves
Motor (efferent)
Classification of Nerves
-sensory & motor fibers carry impulses to & from CNS; most common type of nerve
Classification of Nerves
Mixed
Classification of Nerves
- are mixed nerves
- carry somatic and autonomic (visceral) impulses
Classification of Nerves
Peripheral Nerves
Classification of Nerves
- Somatic afferent
- Somatic efferent
- Visceral afferent
- Visceral efferent
Classification of Nerves
Peripheral Nerves
Four types of mixed nerves
-nerves originate from the brain (cranial nerves) or spinal column (spinal nerves)
Peripheral nerves
-Collections of neuron cell bodies with similar function associated with nerves in the PNS
Ganglion
plural=ganglia
-Ganglia associated with afferent nerve fibers contain cell bodies of sensory neurons
Ganglion
plural=ganglia
- lead into the spinal cord
Ganglion
(plural=ganglia)
Dorsal root ganglia
- are associated with efferent nerve fiber;
- these are cell bodies of autonomic motor neurons involved with visceral innervation (names & details later in unit)
Ganglion
(plural=ganglia)
Autonomic ganglia
- Damage to the neuron cell body is serious because mature neurons are amitotic.
- However, if the __ of a damaged nerve remains intact, damage can be repaired.
Regeneration of Nerve Fibers
soma
-(occurs where an axon is damaged)
Regeneration of Nerve Fibers
Wallerian Degeneration
- Axon becomes fragmented at injury site
- Macrophages – remove debris
Regeneration of Nerve Fibers
Wallerian Degeneration
-follows degeneration and involves coordinated activity among:
Regeneration of Nerve Fibers
Regeneration
- form regeneration tube;
- secrete growth factors
Regeneration of Nerve Fibers
Schwann cells
-regenerate via filaments at a rate of 1.5 mm per day
Regeneration of Nerve Fibers
Axons
- New myelin sheath forms
Regeneration of Nerve Fibers
Scwann cells
-Twelve pairs of c____ arise from the brain
Cranial Nerves
Arises from the olfactory epithelium (pseudostratified ciliated columnar)
Cranial Nerves
I. Olfactory (S)
Passes through the cribriform plate of the ethmoid bone
Cranial Nerves
I. Olfactory (S)
Fibers run through the olfactory bulb and terminate in the primary olfactory cortex (located in the deep temporal lobe, in the uncus);
Cranial Nerves
I. Olfactory (S)
ipsilateral; do NOT synapse in the thalamus
Cranial Nerves
I. Olfactory (S)
In order to correlate a smell with a memory, however, axons will pass through the thalamus
Cranial Nerves
I. Olfactory (S)
Sensory: Functions solely by carrying afferent impulses for the sense of smell
Cranial Nerves
I. Olfactory (S)
- Arises from the retina of the eye
Cranial Nerves
II. Optic (S)
-Optic nerves pass through the optic canals (sphenoid bone) and converge at the optic chiasma (“X” cross-over) which sits just anterior to the pituitary gland
Cranial Nerves
II. Optic (S)
-They continue to the thalamus where they synapse
Cranial Nerves
II. Optic (S)
-From there, the optic radiation fibers run to the primary visual cortex (calcarine sulcus)
Cranial Nerves
II. Optic (S)
-Sensory: Functions solely by carrying afferent impulses for vision
Cranial Nerves
II. Optic (S)
-Somatic Motor: Fibers extend from the ventral midbrain (base of the cerebral peduncle), pass
through the superior orbital fissure (sphenoid), and go to the extrinsic eye muscles
Cranial Nerves
III. Oculomotor (M)
Functions in raising the eyelid, directing the eyeball (4 of 6 muscles controlling eye movement:
-superior, inferior & medial rectus plus inferior oblique)
Cranial Nerves
III. Oculomotor (M)
Autonomic Motor (Parasympathetic): cell bodies are in the ciliary ganglia - Functions in constricting the iris, and controlling lens shape for focusing
Cranial Nerves
III. Oculomotor (M)
-Fibers emerge from the dorsal midbrain (corpora quadrigemina) and enter the orbits via the superior orbital fissures;
Cranial Nerves
IV. Trochlear (M)
-innervate the superior oblique muscle (1 of 6 muscles controlling eye
movement)
Cranial Nerves
IV. Trochlear (M)
-Somatic Motor: Functions primarily as a motor nerve that directs the eyeball
Cranial Nerves
IV. Trochlear (M)
Largest cranial nerve; mixed nerve
Cranial Nerves
V. Trigeminal (B)
Three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3)
Cranial Nerves
V. Trigeminal (B)
Sensory: Afferent fibers run from the face, lips, gums, teeth & tongue [not taste buds] to the
pons via the superior orbital fissure (V1), the foramen rotundum (V2), and the foramen ovale (V3) [all in sphenoid]
Cranial Nerves
V. Trigeminal (B)
Cell bodies converge at the large trigeminal ganglion
Cranial Nerves
V. Trigeminal (B)
Somatic motor: Mandibular division (V3) supplies motor fibers for mastication (chewing)
Cranial Nerves
V. Trigeminal (B)
-Fibers leave the inferior pons and enter the orbit via the superior orbital fissure
Cranial Nerves
VI. Abducens (M)
- innervate the lateral rectus muscle (1 of 6 muscles controlling eye movement)
Cranial Nerves
VI. Abducens (M)
- Somatic Motor: Functions primarily as a motor nerve that directs the eyeball
Cranial Nerves
VI. Abducens (M)
Fibers leave the pons, travel through the internal acoustic meatus, and emerge through the stylomastoid foramen (in temporal bone) to the lateral aspect of the face
Cranial Nerves
VII. Facial (B)
Mixed nerve with five major branches: temporal, zygomatic, buccal, mandibular, cervical)
Cranial Nerves
VII. Facial (B)