A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system.
The axillary nerve or the circumflex nerve is a nerve of the human body, that originates from the brachial plexus at the level of the axilla (armpit) and carries nerve fibers from C5 and C6. The axillary nerve travels through the quadrangular space with the posterior circumflex humeral artery and vein.
The external oblique muscle is the largest and the outermost of the three flat muscles of the lateral anterior abdomen.
The intercostal nerves are part of the somatic nervous system, and arise from the anterior rami of the thoracic spinal nerves from T1 to T11. The intercostal nerves are distributed chiefly to the thoracic pleura and abdominal peritoneum and differ from the anterior rami of the other spinal nerves in that each pursues an independent course without plexus formation.
The posterior cutaneous nerve of the thigh provides innervation to the skin of the posterior surface of the thigh and leg, as well as to the skin of the perineum.
The lumbar plexus is a web of nerves in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve. Additionally, the ventral rami of the fourth lumbar nerve pass communicating branches, the lumbosacral trunk, to the sacral plexus. The nerves of the lumbar plexus pass in front of the hip joint and mainly support the anterior part of the thigh.
The iliohypogastric nerve is a nerve that originates from the lumbar plexus that supplies sensation to skin over the lateral gluteal region and motor to the internal and transverse abdominal muscles.
The ilioinguinal nerve is a branch of the first lumbar nerve (L1). It separates from the first lumbar nerve along with the larger iliohypogastric nerve. It emerges from the lateral border of the psoas major just inferior to the iliohypogastric, and passes obliquely across the quadratus lumborum and iliacus. The ilioinguinal nerve then perforates the transversus abdominis near the anterior part of the iliac crest, and communicates with the iliohypogastric nerve between the transversus and the internal oblique muscle.
The lateral cutaneous nerve of the thigh is a cutaneous nerve that innervates the skin on the lateral part of the thigh.
The erector spinae or spinal erectors is a set of muscles that straighten and rotate the back.
The medial antebrachial cutaneous nerve arises from the medial cord of the brachial plexus.
The medial brachial cutaneous nerve is distributed to the skin on the medial brachial side of the arm.
The intercostobrachial nerves are cutaneous branches of the intercostal nerves.
The wing of ilium is the large expanded portion which bounds the greater pelvis laterally. It presents for examination two surfaces—an external and an internal—a crest, and two borders—an anterior and a posterior.
The anterior division of the twelfth thoracic nerve is larger than the others; it runs along the lower border of the twelfth rib, often gives a communicating branch to the first lumbar nerve, and passes under the lateral lumbocostal arch.
The anterior divisions of the seventh, eighth, ninth, tenth, and eleventh thoracic intercostal nerves are continued anteriorly from the intercostal spaces into the abdominal wall; hence they are named thoraco-abdominal nerves.
The superior cluneal nerves innervate the skin of the upper part of the buttocks. They are the terminal ends of lateral rami of the posterior rami of lumbar spinal nerves.
The anterior cutaneous branches of the femoral nerve consist of the following nerves: intermediate cutaneous nerve and medial cutaneous nerve.
The posterior branches of the lumbar nerves branch from the dorsal rami of the lumbar nerves.
The posterior branches of cervical nerves branch from the dorsal rami of the cervical nerves.
