Structure of a Nerve
• Bundle of axons • Nerve fibers in
PNS have myelin sheath • Layers of connective tissue
– Epineurium 外膜 – Perineurium 束膜 – Endoneurium 内膜
– Thoracic region – forms intercostal nerve
• Meningeal branch – reenters vertebral canal, innervates meninges, vertebrae, & spinal ligaments
• Communicating rami
• Innervates upper limb & Pectoral girdle & shoulder muscles， skin
锁骨上分支 胸长神经、肩胛背神经、肩胛上神经 锁骨下分支 肩胛下神经、胸内侧神经、胸外侧神经、胸背神经 腋神经
T1
肌皮神经 正中神经 尺神经 桡神经 臂内侧皮神经 前臂内侧皮神经
Distal Branches
Spinal Nerve Plexuses
Spinal Nerve Plexuses
• Ventral rami of spinal nerves fuse and form networks with ventral rami of other spinal nerves.
– Crossing of fibers
• A peripheral nerve may contain axons from several spinal segments.
