A peripheral nerve contains two types of tissue:(1) nerve fibers, and (2) connective tissue. Dendrites and axons with schwann cells and myelin sheath are surrounded by connective tissue

Connective tissue

"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...

. A nerve fiber

Nerve fiber

A nerve fiber is a threadlike extension of a nerve cell and consists of an axon and myelin sheath in the nervous system. There are nerve fibers in the central nervous system and peripheral nervous system. A nerve fiber may be myelinated and/or unmyelinated. In the central nervous system , myelin...

 in the peripheral nervous system

Peripheral nervous system

The peripheral nervous system consists of the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system to the limbs and organs. Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood–brain...

 consists of an axon or long dendrite, myelin sheath (if existence) and their schwann cells. Peripheral sensory fibers contain long dendrites, but peripheral motor fibers have long axons. Long dendrites of sensory fibers have structural properties as motor axons.

Layers of connective tissue in the peripheral nerve

Three layers of connective tissue surround each peripheral nerve that include:

• Epineurium
• Perineurium
• Endoneurium

Epineurium

The epineurium

Epineurium

The epineurium is the outermost layer of connective tissue surrounding a peripheral nerve. It is made of dense irregular connective tissue and usually contains multiple nerve fascicles as well as blood vessels which supply the nerve...

 surrounds the peripheral nerve trunk (i.e. Superficial epineurium). This is considered the outermost layer. The epineurium separates the nerve fascicles, but lies outside the perineurium (i.e. Interfascicular epineurium).

Perineurium

Each nerve fascicle

Nerve fascicle

A small bundle of nerve fibers, enclosed by the perineurium, is called a funiculus; if the nerve is of small size, it may consist only of a single funiculus; but if large, the funiculi are collected together into larger bundles or nerve fascicles, which are bound together in a common membranous...

 is surrounded by the perineurium

Perineurium

In the peripheral nervous system, nerve fibers are each wrapped in a protective sheath known as the endoneurium. These are bundled together into groups known as fascicles, each surrounded by a protective sheath known as the perineurium. Several fascicles may be in turn bundled together with a blood...

 that includes a group of nerve fibers. The perineurium has very important role in the protection and support from nerve fibers. This section of connective tissue is an important factor in preventing the passing of large molecules from the epineurium into a fascicle.

Endoneurium

Each nerve fiber is surrounded by the endoneurium

Endoneurium

The endoneurium, also referred to as an endoneurial channel, sheath or tube, is a layer of delicate connective tissue made up of endoneurial cells that encloses the myelin sheath of a spinal cord nerve fiber. These are bundled up into groups called nerve fascicles, which have a protective sheath...

. This section is a thin layer of connective tissue. The endoneurium is the tube that places the components of a nerve fiber such as axon, the myelin sheath and Schwann cells into itself. Thus, the endoneurium separates nerve fibers of a fascicle.

See also

• Peripheral nerve
• Epineurium
  Epineurium
  The epineurium is the outermost layer of connective tissue surrounding a peripheral nerve. It is made of dense irregular connective tissue and usually contains multiple nerve fascicles as well as blood vessels which supply the nerve...
  
  
• Perineurium
  Perineurium
  In the peripheral nervous system, nerve fibers are each wrapped in a protective sheath known as the endoneurium. These are bundled together into groups known as fascicles, each surrounded by a protective sheath known as the perineurium. Several fascicles may be in turn bundled together with a blood...
  
  
• Endoneurium
  Endoneurium
  The endoneurium, also referred to as an endoneurial channel, sheath or tube, is a layer of delicate connective tissue made up of endoneurial cells that encloses the myelin sheath of a spinal cord nerve fiber. These are bundled up into groups called nerve fascicles, which have a protective sheath...
  
  
• Connective tissue in skeletal muscle
  Connective tissue in skeletal muscle
  Each skeletal muscle consists of two kinds of tissue: connective tissue, and muscle tissue. Connective tissue of skeletal muscle contains:*Layers of connective tissue*Tendon, and sometimes aponeurosis...
  
  
• Nerve fascicle
  Nerve fascicle
  A small bundle of nerve fibers, enclosed by the perineurium, is called a funiculus; if the nerve is of small size, it may consist only of a single funiculus; but if large, the funiculi are collected together into larger bundles or nerve fascicles, which are bound together in a common membranous...
  
  
• Nerve tissue
• Nerve fiber
  Nerve fiber
  A nerve fiber is a threadlike extension of a nerve cell and consists of an axon and myelin sheath in the nervous system. There are nerve fibers in the central nervous system and peripheral nervous system. A nerve fiber may be myelinated and/or unmyelinated. In the central nervous system , myelin...
  
  
• Connective tissue
  Connective tissue
  "Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...
  
  

Reference

• fa:بافت همبند در دستگاه عصبی محیطی
• Williams & Warwick. Gray's Anatomy .THIRTY-SEVENTH EDITION.ISBN:0 443 04177 6