Nerve and Blood Supply of the Back Flashcards
Connective tissue membranes
Meninges
Types of meninges
- Dura
- Arachnoid
- Pia
Meningeal spaces
- Subarachnoid space
- Subdural space
- Epidural space
Meningeal space filled with CSF and arteries
Subarachnoid space
Meningeal space where veins are located
Subdural space
Meningeal space where fat is located
Epidural space
Where does the spinal cord begin?
Medulla
Where does the spinal cord end?
Conus medullaris
Conical distal end of the spinal cord
Conus medullaris
Where is the conus medullaris?
L1-L2 vertebral level
Nerve roots extending beyond conus medullaris
Cauda equina
Cell bodies of alpha and gamma motor neurons (LMN)
Ventral horn
T1-L2= Preganglionic sympathetic neurons
S2-S4= Preganglionic parasympathetic neurons
Intermediolateral gray
Sensory cell bodies
Dorsal horn
Where is spinal nerve C1 found?
Between occipital and atlas
Where is C2 found
Between atlas and axis
Where is C3 found
Between C2 and C3
Where is C8 found
Between C7 and T1
Where is T1 found
Between T1 and T2
Sensory (afferent) root
Dorsal root
Ganglion on dorsal root commanding cell bodies of sensory neurons in the dorsal route (pseudounipolar)
Dorsal root ganglion
Motor (efferent) root
Ventral root
What are ventral roots formed by
Union of smaller ventral rootlets from ventral side of spinal cords
Each represents a fusion of two roots
Spinal nerve
Where are spinal nerves formed?
Intervertebral foramen
What do spinal nerves divide into?
Dorsal and ventral rami
Difference between rami and roots
Roots: Inside vertebral canal and join to form spinal nerve
Rami: Outside intervertebral foramen and represent bifurcation of spinal nerve
What do dorsal rami divide into?
Medial and lateral branches
Provides motor innervation to intrinsic muscles of the back
Dorsal rami
Branches of the dorsal rami in which all levels supply muscles, only levels T6 and UP are also cutaneous to upper back
Medial branches
Branches of the dorsal rami in which all levels supply muscles, only levels T6 and BELOW are also cutaneous to lower back and medial gluteus region
Lateral branches
These dorsal rami do not split into medial and lateral branches
- C1
- S4/S5
- Cx1
What do both branches of cervical nerves supply?
Intrinsic back muscles
Medial branches of C2, C3, C4, and usually C5 become what?
Cutaneous
What is the dorsal ramus of C1 called?
Suboccipital nerve
Does the suboccipital nerve divide into medial and lateral branches?
No
Largest of all dorsal rami
C2
What is the medial branch of dorsal ramus of C2 called?
Greater occipital nerve
What is the medial branch of the dorsal ramus of C2 cutaneous to?
Large are of the back and scalp
What is the medial branch of dorsal ramus of C3 called?
Third occipital nerve
All thoracic dorsal rami are divided into:
Medial and lateral branches
Thoracic dorsal rami that have medial branches becoming cutaneous after innervating intrinsic muscles
T1-T6
Medial branches of T1-T6 supply and pass between which muscles, supplying them?
- Semispinalis
- Multifidis
Medial branches of T1-T6 pierce which muscles to become cutaneous?
- Rhomboids
- Trapezius
From T1-T6, the lateral branch remains purely:
Muscular
Lateral branches of T1-T6 pass between which muscles, supplying the remaining intrinsic muscles?
- Longissimus
- Iliocostalis
Thoracic dorsal rami that have lateral branches becoming cutaneous after innervating intrinsic muscles
T7-T12
What do the medial branches of the lumbar dorsal rami supply?
Multifidi
What do the lateral branches of the lumbar dorsal rami supply?
- Erector spinae
- Lateral branches of L1-L3 become cutaneous
Ventral rami motor innervation
Hypaxial muscles including limbs
Ventral rami cutaneous innervation
Most of the body except head and back
Ventral rami plexuses
- Cervical plexus
- Brachial plexus
- Lumbosacral plexus
What does the cervical plexus innervate?
C2-C4, innervates neck, parts of the head and shoulders
What does the brachial plexus innervate?
C5-T1, innervates the pectoral girdle and upper limbs
What does the lumbosacral plexus innervate?
L1-S4, innervates the pelvic girdle and lower limbs
Areas of skin innervated by cutaneous branches of a single spinal nerve
Dermatomes
Dermatome C5-T1
Upper extremity
Dermatome C5
Thumb
Dermatome C7
Middle finger
Dermatome C8
Pinky
Dermatome T4
Nipple
Dermatome T10
Umbilicus
Dermatome L1-S2
Lower extremity
Dermatome L1
Groin
Dermatome L4
Shin and medial foot
Dermatome L5
Lateral leg and top of foot
Dermatome S1
Pinky toe and bottom of foot
In the thoracic region, arteries are the dorsal branches of
The posterior intercostal arteries
In the lumbar region, arteries are dorsal branches of
The four paired lumbar arteries
Branches of the descending aorta
- Posterior intercostal arteries (except the first two)
- All lumbar arteries
Circulatory system is composed of? Is this seriously a question?
- Arteries
- Veins
- Lymph vessels/nodes
- Heart
Central to circulatory system
Heart (duh)
Receives de-oxygenated blood. Sends deoxygenated blood to the lungs for oxygenation
Right side of the heart
Receives oxygenated blood from the lungs and returns it to the body
Left side of the heart
Created by the union of blood channels.
Anastomoses
Arteries branch to smaller…
Arterioles
Arterioles give rise to…
Capillaries
How thick are capillaries
So thick that yo mama…..I mean a single cell layer thick
An alternative route of circulation to a body part created by anastomoses of arterial channels. Similarly, there may be collateral venous return created by anastomoses of venous channels
Collateral circulation
Where is collateral circulation frequent?
Around joints of the limbs
Anastomostic vessels proceeding from superior to inferior are termed
Collateral vessels
Anastomostic vessels proceeding from inferior to superior are termed
Recurrent vessels
From the right ventricle to the lungs to the left atrium
Pulmonary circulation
From the left ventricle to the body to the right atrium
Systemic circulation
Descending aorta above the diaphragm
Thoracic aorta
Descending aorta below the diaphragm
Lumbar aorta
Ascending aorta branches
- Right coronary artery
- Left coronary artery
Direct branches of the arch of the aorta
- Brachiocephalic trunk (right)
- Left common carotid artery
- Left subclavian artery
Direct branches of the brachiocephalic trunk
- Right common carotid artery
- Right subclavian artery
Direct branches of the right and left subclavian arteries
- Vertebral artery
- Thyrocervical trunk
- Costocervical trunk
Direct branches of the right and left common carotid arteries
Occipital artery
Direct branches of the right thyrocervical trunk
- Transverse cervical artery
- Internal thoracic artery
Direct branches of the right and left costocervical trunks
- Highest intercostal
- Deep cervical
Direct branches of the left thyrocervical trunk
Transverse cervical artery
Direct branches of the transverse cervical artery
Superficial and deep branches
Direct branches of the internal thoracic artery (branch of the subclavian artery)
Anterior intercostal arteries
Direct branches of the descending thoracic aorta
Posterior intercostal arteries
Direct branches of the descending abdominal aorta
Lumbar arteries
Venous return is via
Vena cava
Venous return from the head and neck and upper limbs
Superior vena cava
Venous return from abdomen and lower limbs
Inferior vena cava
Functions of the lymphatic system
- Drains interstitial fluid from tissue spaces
- Cleans and returns cellular waste to blood
- Produces agranular leukocytes to develop immunity
95% of the lymph content is drained from where?
GI tract
Drains lymph to nodes
Afferent vessels
Drains lymph from nodes to larger lymph channels
Efferent vessels
Major lymph channel of the body
Thoracic duct
