Anatomy of nerve plexuses Flashcards
What does the peripheral nervous system consist of
12 pairs of cranial nerves, 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral plus coccygeal nerve)
What is the somatic nervous system
Voluntary nervous system which provides general sensory and motor innervations to body except viscera in body cavities, smooth muscle and glands
What does the dorsal (posterior) ramus supply
Dorsal 1/3 of the body wall (not limb)
-supplies deep muscles of back (extensor muscles of the vertebral column) and overlying skin and synovial joints of vertebral column
What does the ventral (anterior) ramus supply
Ventral 2/3 of the body wall, including limbs
What is a primary ramus
Branch of a spinal nerve
Are ventral or dorsal rami larger
Ventral rami and are more clinically important
What is a feature of all spinal nerves in relation to their rami
Their ANTERIOR rami branch and rejoin forming nerve plexuses
Where do the plexuses formed from anterior rami occur in
Cervical, brachial, lumbar and sacral regions
How can nerve fibres regroup within a plexus
- Branches can contain fibres from more than one spinal level (convergence)
- Given spinal level may contribute to more than one branch (divergence)
Why does damage to one spinal segment not usually lead to complete loss of function or sensation
Because of regrouping
What are the five groups of ventral rami and their spinal root value
Cervical plexus (C1-C5) Brachial plexus (C5-T1) Nerves of the trunk (T1-L1) Lumbosacral plexus (L1-S3) Sacrococcygeal plexus (S3-S5)
What does the cervical plexus supply
Head and neck
What does the brachial plexus supply
Upper limb
What do the nerves of the trunk supply
Trunk
What does the lumbosacral plexus supply
Trunk and lower limb
What does the sacrococcygeal plexus supply
Pelvis and lower trunk
List cutaneous cervical spinal segments which contribute to the cervical plexus and their spinal root value
Lesser occipital- C2/(C3)
Greater auricular- C2/C3
Transverse cervical cutaneous- C2/C3
Supraclavicular- C3/C4
List motor (deep) cervical spinal segments which contribute to the cervical plexus and their spinal root value
Ansa cervicalis - C1-C3
Phrenic - C3-C5
Other muscular branches - C1-C5
What does the lesser occipital nerve supply
Skin of neck and scalp posteriosuperior to auricle
What does the greater auricular nerve supply
Skin over parotid gland, part of the auricle, skin from angle of mandible to mastoid process
What does the transverse cervical nerve supply
Skin of anterior cervical region
What do the supraclavicular nerves supply
Branches to skin of neck and over clavicle to skin of shoulder
What is the brachial plexus divided into
Roots Trunks Divisions Cords Branches
what are the roots of the brachial plexus
C5, C6, C7, C8, T1
Which roots converge together to form the upper trunk
C5 and C6
Which roots converge to form the middle trunk
None, it is just C7
Which root converge to form the lower trunk
C8 and T1
What are the divisions of the trunks
Anterior and posterior divisions
What is the posterior division
All three trunks converge to make the posterior divisions
What are the anterior divisions
Upper and middle divisions converge and lower division is by itself
What are the different cords the brachial plexus
Lateral
Posterior
Medial
What branches does the posterior cord have
Axillary and radial
What branch does the lateral cord have
Musculocutaneous
What branch does the medial cord have
Ulnar
Where does the median branch come from
Lateral and medial cord (looks like an M)
What is the spinal root value of the musculocutaneous nerve
C5-C7
What is the spinal root value of the median nerve
C5-C7
C8-T1
What is the spinal root value of the ulnar nerve
C8-T1
What is the spinal root value of the radial nerve
C5-T1
What is the spinal root value of the axillary nerve
C5,C6
What is the spinal root value of the dorsal scapular
C5
What is the spinal root value of the subscapular: upper and lower
C5,C6
Spinal root value of suprascapular nerve
C5,C6
Spinal root value value of long thoracic nerve
C5-C7
Spinal root value of pectoral: medial and lateral nerve
C5-T1
Spinal root value of thoracodorsal nerve
C7,C8
What is the autonomic plexuses formed by
Sympathetic and parasympathetic nerves
What do sympathetic and parasympathetic nerves to viscera form
Series of plexuses anterior to vertebral bodies (in or on the viscera or associated vessels)
What preverterbal autonomic plexuses are especially large
Cardiac plexus
Pulmonary plexus
Coeliac plexus
Hypogastric plexus
What does the cardiac plexus innervate
The heart
What do the sympathetic nerves arise from
cervical and upper thoracic parts of sympathetic trunk
What does the parasympathetic supply derive from
Vagus nerve
What do the sympathetic nerves and parasympathetic nerves contribute to
Oesophageal plexus
What do sympathetic fibres do
-What are the afferent fibres associated with
Speed up heart and dilate coronary arteries
-Pain
Want do parasympathetic fibres do
-What are the afferent fibres associated with
Reduce heart rate and constrict arteries
-Afferent fibres take part in cardiovascular reflexes
What does the pulmonary plexus surround
Lung root and has branches from the upper thoracic sympathetic trunk and vagus nerve