Anatomy Exam 1 - Back & Spinal Cord + Thoracic Wall
where does the upper trapezius attach on the head
external occipital protuberance
What are the 3 intercostal muscles?
external, internal, innermost
A large opening at the base of the skull through which the brain connects to the spinal cord.
foramen magnum
functionally related collection of neurons in PNS
ganglion
ganglion + nerve = nucleus + tract =
ganglion + nerve = PNS nucleus + tract = CNS
COSTOVERTEBRAL JOINTS: The ________ of each rib articulates with the body of at least one thoracic vertebra (& often an IV disc; often 2 adjacent vertebral bodies) at a *joint of the head of the rib* The ________ articulates with the transverse process of a single thoracic vertebra at a *costotransverse joint*
head costal tubercle
What is exteroceptive information?
information from the body wall
Rupture of the *transverse ligament of the atlas* may lead to...
injury of the spinal cord by the dens
The innermost intercostal layer has a similar course & similar attachments to the...
internal intercostals
the cauda equine is formed by the roots of what spinal nerves?
lower lumbar sacral coccygeal
The contraction of skeletal muscle is a direct result of stimulus by...
lower motor neurons, located in either the spinal cord or brain stem
Portion of the sternum that articulates with the clavicles & costal cartilage of the FIRST RIB
manubrium
The articular facet for the dens on the Atlas helps form the ______________ with C2
median atlantoaxial joint
the anterior articular facets on the dens of the axis helps to form the...
median atlantoaxial joint
Ribs are considered __________ joints
mobile synovial
bundle of nerve axons in the PNS
nerve
functionally related collection of neurons in CNS
nucleus
The cervical articular facets are oriented how?
oblique to the horizontal by about 30-45 degrees
What surface features does Rib 1 have?
scalene tubercle & grooves for subclavian vessels
Each pair of spinal nerves is formed by the *convergence* of fibers arising from the dorsal & ventral aspects of an individual ____________ of the spinal cord.
segment
the dura mater & arachnoid mater covering the brain are continuous at foramen magnum with the dura & arachnoid covering the cord, as is the ___________________.
subarachnoid space
Reflection of the semispinalis capitis muscles exposes the...
suboccipital muscles
The manubriosternal joint (@ sternal angle) is a ____________ joint. The joint often fuses with age. It marks the articulation of the costal cartilage of the ______________.
symphyseal joint 2nd ribs
Rib 1 goes from T1 to..
the manubrium
What keeps dura mater and arachnoid mater apposed?
the pressure of the CSF in the subarachnoid space
bundle of nerve axons in the CNS
tract
the posterior articular facet on the dens contacts the ______________ of the Atlas
transverse ligament
The small dorsal (posterior) primary rami supplies what? *these contain both afferent & efferent fibers*
- skin of the medial 2/3 of the back - skin of posterior scalp - facet joints - posterior ligaments of the spine - epaxial (intrinsic) back muscles
What are the contents of the Suboccipital triangle?
- vertebral artery - sub-occipital nerve (dorsal ramus C1) - posterior arch of the atlas
The large ventral (anterior) primary ramus supplies what? *these contain both afferent & efferent fibers*
- anterolateral body wall - hypaxial muscles - extremities
known as the "YES" joints
Atlanto-occipital joints
"No" joints - allow the head & atlas to rotate together around the dens as a unit
Atlantoaxial joints
- widest of the cervical vertebrae because of its long transverse processes - arches that feature anterior & posterior tubercles - lateral masses joined by anterior & posterior arches
Atlas (C1)
Known as the STRONGEST cervical vertebra
Axis *this is due to the compact bone of the dens*
CSF is formed by the ___________ within the _____________ of the brain.
Choroid plexus Ventricles
Spasm of the suboccipital muscles causes a rigid & extended head posture, often leading to...
Chronic headaches *Especially your Rectus Capitis Posterior Minor - pulls on the DURA MATER - DURA MATER has sensory receptors - which causes a HELL of a migraine = Tension Migraine*
Rotation around a transverse axis at the costotransverse joints of *ribs 1-6* results in...
DEPTH in the Sagittal Plane
_____________ has a spinal ganglia.
DORSAL root (GSA)
The Axis (C2) has a prominent __________ which projects superiorly through the vertebral foramen of the Atlas to the foramen magnum
Dens or Odontoid process
ligaments that are found *between* emerging nerves that penetrate the arachnoid mater, attach to the dura mater & help to stabilize the spinal cord
Denticulate ligaments
The specific area of skin supplied by the somatic afferents (GSA) in a single pair of spinal nerves is called a...
Dermatome - Cervical dermatome - Thoracic dermatome - Lumbar dermatome - Sacral dermatome
Irritative lesions are caused by acute or chronic mechanical trauma or inflammation; nerve fibers are intact but they are being subject to mechanical trauma or inflammation. What are examples of this?
Impingement, entrapment or stretching
What lies just posteriorly to the dens?
The spinal cord
Under the tectorial membrane, we see the ______________ which forms a collar around the dens; maintaining the median atlantoaxial (atlantodental) joint.
Transverse ligament of the Atlas
Thoracic & abdominal walls share a ____________ structure
Trilaminar
Each intercostal space contains an *intercostal neurovascular bundle* in the plane between the *second* & *third* layers of muscle. Arrangement of elements in this bundle from superior to inferior are...
VAN Vein Artery Nerve
Why is it that at all times, nearly 80% of blood is in the veins and 20% is in the arteries?
Veins have to CONFRONT *GRAVITY*
complete elimination of sensation; possibly experienced secondary to destructive level II peripheral nerve injury
anesthesia
The Atlas has concave, waisted superior articular facets on which the occipital condyles rest at the...
atlanto-occipital joints the "YES" joints
What happens at the Nuchal lines?
attachment of nuchal muscles & the nuchal ligament *nuchal muscles are the same as posterior cervical muscles*
The spinal cord presents ___________ & _________ enlargements. It is therefore NOT a constant shape or thickness along the back.
cervical & lumbosacral enlargements *gives rise to brachial (cervical) & lumbosacral plexuses*
The spinal cord tapers caudally & terminates in the...
conus medullaris at L1-L2 intervertebral level
On XR, dens should take up.... & spinal cord & mininges should take up...
dens = anterior 1/3 spinal cord & meninges = posterior 2/3
These spinal nerves all take the number of the underlying vertebrae
Cervical spinal nerves WITH THE EXCEPTION OF C8
What are the 4 suboccipital muscles?
1) Rectus capitis posterior major 2) Rectus capitis posterior minor 3) Obliquus capitis inferior 4) Obliquus capitis superior
The cervical spine has the greatest ROM of any of the regions of the vertebral column thanks to: 1) the orientation of the ________. 2) the relative thickness of the _______. 3) the small amount of ________.
1) the orientation of the *articular facets* - oriented oblique to the horizon by about 30-45 degrees 2) the relative thickness of the *IV discs* 3) the small amount of *surrounding body mass*
Ribs ___________ of the True Ribs are atypical; shorter & broader with reduced curvature
1-2
True Ribs
1-7 attach directly to the sternum via their *own costal cartilages*
The spinal cord is supplied & drained by blood vessels which course through the subarachnoid space, including:
1. Anterior & Posterior spinal arteries (arise from vertebral arteries) 2. Radicular & Segmental Medullary arteries (enter the vertebral canal through the intervertebral foramina)
There are _____ pairs of both external intercostals and internal intercostals
11
how many cranial nerves do we have?
12
how many pairs of spinal nerves do you have?
31 pairs
Note that while there are 7 cervical vertebrae, there are _____ cervical spinal nerves
8
False Ribs
8-10 ribs - indirectly attach to the sternum through higher true rib costal cartilages
looking at the articulated cervical spine, we note that the intervertebral foramina are *small & round*, with their anterior margins formed primarily by the IV discs. This, along with the relatively *large size & horizontal course of the cervical spine* explain why a cervical disc herniation will impinge upon the spinal nerve exiting where?
AT THAT *SAME* INTERVERTEBRAL LEVEL
A hyper flexion injury producing instability of the head on the ATLAS indicates what type of tear?
Alar ligament tear often accompanied by a fracture of the dens *high school football players get these injuries often because they don't know how to tackle - hyper flexion injuries
ligaments that extend from the dens to the occipital condyles
Alar ligaments
Transversus Thoracic is limited to the ____________ chest wall. It is an accessory muscle for EXPIRATION
Anterior
Lumbar puncture "spinal tap" or Spinal Anesthesia will be placed into what space...
Below L2, Above S2 (between L2-S2)
Where (between which intercostal muscles) is the neurovascular plane of the trunk found (VAN = Vein, Artery, Nerve); where nerves & blood vessels supplying the chest wall are found
Between the 2nd & 3rd layers 2nd = Internal intercostals 3rd = Innermost intercostals
most common fracture site of a rib is where?
Between the costal groove & the costal angle of the rib
Portion of the sternum that is formed by the fusion of multiple sternebrae; articulates with the costal cartilages of Ribs 2-7
Body
The spinal cord presents cervical & lumbosacral enlargements, which give rise to the spinal nerves contributing to the...
Brachial plexus (cervical enlargements) + Lumbosacral plexus (lumbosacral enlargements) = innervating the upper & lower limbs respectively
When the angles of the *lower ribs* are elevated, they move laterally, increasing the transverse dimension - increasing WIDTH in the coronal plane. This is called the...
Bucket-handle effect
A blow to the top of the head may cause a burst fracture of the ____________, known as a... *This often times happens when unrestrained drivers go through a windshield*
Burst fracture of the Atlas known as Jefferson Fracture
The _____ spinal nerves pass between the *base of the skull* and the *atlas*
C1
The _____ spinal nerves exit *intervertebral foramina* between the *atlas & axis*
C2
Cervical vertebrae that is long & without a bifurcated spinous process
C7 = Verebral prominens
The ______ spinal nerves exit the intervertebral foramina between *C7 & T1*
C8
Cranial nerve responsible for innervating the skin & face of the anterior scalp
CN V (5)
a fluid that bathes the entire CNS; considered to have its own closed circulatory system in the body
CSF
a clear & colorless liquid that is *low in protein* & cellular content; which functions as a liquid cushion for the CNS within the bony confines of the skull & spine.
CSF *blood in LP with subarachnoid space = trauma*
What is found in the subarachnoid space?
CSF & vasculature (arteries & veins) *remember, the spinal cord is supplied & drained by blood vessels in the subarachnoid space including the anterior & posterior spinal arteries AND the radicular & segmental medullary arteries*
Inferior to the conus medullaris is the ________________; which is formed by the roots of the *lower lumbar, sacral* and *coccygeal spinal nerves*
Cauda equina
___________ bridges the gap between the sternum & our 12 pairs of ribs
Costal cartilage
The ___________ contains & protects an intercostal neurovascular bundle (nerve + vein + artery)
Costal groove
These movements combine with the increase in the vertical dimension of the thorax resulting from the contraction of the diaphragm to facilitate...
DEEP or FORCED RESPIRATION
Because the spinal cord & vertebral column are unequal in length, there is...
Disparity in the location of most cord segments & the IV foramina through which their spinal nerves emerge + Variation in the LENGTH & ORIENTATION of the nerve roots *As we DESCEND caudally along the length of the spinal cord, there is an increase in discrepancy in the relative position of the spinal cord segments and the intervertebral foramina through which their spinal nerves emerge*
SPINAL GRAY _____________ horn is comprised of somatic AFFERENT roots, carrying information *from the periphery* to the CNS.
Dorsal (posterior) horn
collections of pseudo unipolar *sensory* neuron cell bodies; located on the dorsal root in the IV foramen just proximal to the Mixed Spinal Nerve
Dorsal Root (Spinal) Ganglia
Exteroceptive information, along with information from *proprioceptors* located in muscles, tendons & joints, ENTERS the spinal cord via central processes of the neurons in the...
Dorsal Root Ganglia
meningeal layer that projects laterally at each intervertebral level to encompass the roots of the spinal nerves; NOT forming a cylindrical sheath, rather pouching outward to the left & right to encompass spinal roots that leave the vertebral column.
Dura mater
The dermatomes of the limbs are understood in terms of the ________________. It is extremely important to familiarize yourself with the dermatomes as a first step to localizing spinal & peripheral nerve lesions
Embryological development
these muscles fill the intercostal spaces incompletely; helping to keep the intercostal spaces rigid during respiration without bulging
External & internal intercostals
Run anterioinferiorly from the rib above to the rib below
External intercostals
Which is most active during expiration and which is most active during inspiration? External Intercostals VS Internal Intercostals
External intercostals are most active during INSPIRATION as they ELEVATE the ribs in forced inspiration Internal intercostals are most active during EXPIRATION as they DEPRESS the ribs
a projection of Pia mater that descends from the tip of the conus medullaris through the sacral hiatus to the coccyx; the ONE meningeal extension; a silvery feature. *this projecting feature reflects that at one point, the spinal cord & spinal column WERE the same length*
Filum Terminale
Heads of these specific ribs articulate with ONE *vertebral body ONLY*; short, less curvature; have NO articulation with the transverse processes
Floating Ribs 11-12
Each pair of spinal nerves is formed by the *convergence* of fibers arising from the dorsal & ventral aspects of an individual *segment* of the spinal cord. Within each *segment*, the are _______ & ______ fibers arising.
GSA & GSE
Each pair of spinal nerves is formed by the *convergence* of fibers arising from the dorsal & ventral aspects of an individual *segment* of the spinal cord. Within each *segment*, the are *GSA & GSE* fibers arising. The GSA supplies a specific area of the body wall called the _____________. The GSE supplies a specific muscle mass, called the _____________.
GSA = Dermatome GSE = Myotome
Fracture of the axis through the pedicles between the superior & inferior articular facets - separates the neural arch, disrupting arteries & nerves
Hangman's Fracture (axis)
Run inferoposteriorly from the floor of the costal groove to the ribs below
Internal intercostals
So if there is a herniation of the nucleus pulposus of the L4/L5 disc, what will be affected?
L5 spinal nerve L5 often causes sciatica
a bilaminar fibroelastic septum which runs from the external occipital protuberance of the skull to the spinous process of the vertebra prominens; provides surface area for the attachment of posterior cervical musculature, which maintains head position & resists gravity in erect posture
Ligamentum Nuchae
In order to ease the access of the needle, the patient is put into flexion; separating the gap between the spinous processes of vertebrae. When you appreciate a "popping sound" you are going through what ligament?
Ligamentum flavum you are technically going through the supraspinous ligament & interspinous ligament & then the ligamentum flavum
Discrepancy: Lower cervical & upper thoracic segments = Middle thoracic segments = All Lumbar, Sacral & Coccyx segments =
Lower cervical & upper thoracic segments = ONE level higher Middle thoracic segments = TWO levels higher All Lumbar, Sacral & Coccyx segments = lie adjacent to the T11-L1 Vertebrae
Ventral root (Efferent from Ventral Horn) + Dorsal root (Afferent from Dorsal horn) Mixed Spinal Nerve - through the IV foramen Ventral Ramus & smaller Dorsal Ramus = ___________ signals
MIXED with AFFERENT & EFFERENT
this joint is formed by the articulation of the *manubrium* & *body* of the sternum
Manubriosternal joint (sternal angle)
There are 3 Atlantoaxial articulations... Median Atlantoaxial joint (dens) Right Lateral Atlantoaxial joint Left Lateral Atlantoaxial joint which are synovial PIVOT joints & which are PLANE synovial (gliding) joints?
Median Atlantoaxial joint = Synovial PIVOT joint (around dens) Lateral Atlantoaxial joints = PLANE Synovial (gliding) joints
surrounded by the bony thoracic cage, the thorax contains *2 pulmonary cavities* separated by a midline soft tissue partition called the...
Mediastinum
The spinal cord descends from the caudal portion of the brain stem called the _______________; through the ______________ at the base of the skull.
Medulla oblongata Foramen magnum
Destructive peripheral nerve injuries (level II) may result from trauma such as cutting, crushing or stretching or neuropathy. - Motor symptoms: - Sensory symptoms:
Motor symptoms: - paralysis (complete destruction) - paresis (weakness) Sensory symptoms: - anesthesia (complete elimination of sensation) - hypesthesia (diminished sensation) - pain (neuralgia) - dysesthesia (phantom pain for example following the loss of a limb or breast)
*Posterior* herniation of a *lumbar* IV disc would cause the posterior longitudinal ligament to buckle & may affect...
Multiple spinal nerve roots in the caudal equina
*Posterolateral* herniation of a *lumbar* IV disc (for example; herniation of the disc between L2-L3) will usually compress the roots of the spinal nerve emerging through the...
NEXT IV foramen down (L3)
Is there an intervertebral disc between Atlas & Axis?
NO
Are dermatomes discrete?
NO! they overlap with each other!
Are there any synapses between these Dorsal Root Ganglia?
NO!!!!!
Again, how many neurons are there between the CNS & the skeletal muscle?
ONE
In the Somatic Nervous System, how many neurons are there between the CNS & either the skeletal muscles (GSE) or sensory receptors (GSA)?
ONE neuron *ONLY one neuron between the CNS & the peripheral target in the Somatic Nervous System!*
___________ rest upon & articulate with the ATLAS
Occipital condyles
The costovertebral joints are ___________ joints that permit movements of the ribs necessary for deep breathing
PLANE synovial
meningeal layer that is intimately covering the spinal cord; not possible to pick away because it is adherent to the spinal cord
Pia mater
Posterior & anterior spinal arteries - where do these go?
Posterior & anterior spinal arteries run the ENTIRE LENGTH of the spinal cord
The *vertebral arteries* course through the ______________ membrane & enter the *foramen magnum*. Ossification of portions of this membrane are NOT uncommon in the elderly; creating bony tunnels which may reduce flow through the vertebral arteries.
Posterior Atlanto-occipital Membrane
When the upper ribs are *elevated*, the anteroposterior dimension of the thorax is increased; depth increased. This is known as the...
Pump Handle Effect *pulling the sternum anteriorly, increasing the depth of the thoracic cavity*
*Rotation around* a transverse axis at the *costotransverse joints* of ribs ______ results in *elevation & depression* of their *sternal ends* in the SAGITTAL PLANE - having an effect on DEPTH
Ribs 1-6
Floating Ribs
Ribs 11-12; NO sternal attachment
Gliding at the Costotransverse Joints of Ribs _______ results in *elevation & depression* of the *angles* of the ribs in the CORONAL PLANE - having an effect on WIDTH
Ribs 7-10
While the spinal cord ends at L1-L2, the dural sac extends caudally to the...
S2 level
muscles that run ANTERIORLY (front of body) between the cervical spine & the upper ribs; serve as accessory muscles of inspiration
Scalene muscles
Irritative lesions may initiate impulses in sensory *or* motor fibers. - If sensory fibers are stimulated, what do you experience? - If motor fibers are stimulated, what do you experience?
Sensory fiber stimulation = pain or paresthesia Motor fiber stimulation = spasm (uncontrolled contraction) or twitching of the skeletal muscles
Why do dermatomes overlap?
So that the loss of a single spinal nerve or dorsal root does NOT produce anaesthesia
The PNS is broken into:
Somatic Nervous System + Autonomic Nervous System (AKA Visceral Nervous System)
______________ transmit information TO the CNS concerning sensory information including: - touch, pain, pressure, temperature - modalities of joints (think about pain & proprioception in regard to the Z-joints)
Somatic afferent (AKA GSA; Somatosensory fibers) GSA = General Somatic Afferent
_______________ transmit commands *from the CNS* that stimulate voluntary & reflex contraction of skeletal muscles.
Somatic efferent (AKA GSE; Somatomotor fibers) GSE = General Somatic Efferent
The spinal cord, meningeal sac & spinal column are ALL of different length. The spinal cord ends at ___________. The dural sac ends at ____________; as does the subarachnoid space.
Spinal cord = L1-L2 Dural sac = S2
There is an extensive amount of anastomosis of these vessels within the __________________; anastomosis is free and open communication. Given the absence of valves in the arterial system, blood can move in different directions in response to physiological demands. Anastomosis ensures that every tissue in the body can receive a nourishing blood supply from at least 2 blood vessels.
Subarachnoid space
_________________ help to resist the pull of gravity on the head, resisting flexion at the atlanto-occipital joints & maintaining normal head & eye position when standing or sitting upright
Suboccipital muscles
All 4 of the suboccipital muscles are innervated by the...
Suboccipital nerve from the C1 Dorsal Ramus
The plane of the sternal angle marks the plane of the bifurcation of the trachea, as well as the boundary between the...
Superior & inferior mediastinum
The _________________ is an opening that is continuous with the deep neck & upper limb; transmits A LOT of viscera & neurovasculature between the thorax & the deep neck - each lung actually protrudes through this a little!
Superior Thoracic Aperture
______________ : opening that is continuous with the deep neck & upper limb ______________ : opening that is largely filled by the diaphragm
Superior thoracic aperture Inferior thoracic aperture
A transverse plane through the sternal angle intersects the spine at the __________ intervertebral level
T4-T5
The integrity of the craniovertebral joints are maintained by a number of strong ligaments; each of which limits rotation & lateral bending of the head to the opposite side. The ______________ is a continuation of the PLL connecting the Atlas to the Occipital bone along the anterior margin of the foramen magnum
Tectorial membrane
After being formed by the Choroid plexus in the ventricles of the brain, CSF circulates along the length of the subarachnoid space before being absorbed into the network of ____________ in the skull.
Venous dural sinuses
like lymphatic fluid in the body, CSF will ultimately be absorbed into the...
Venous system good fluids, pathogens, metabolic products, cancer cells, all dumped into the venous system *specifically into the venous dural sinuses*
SPINAL GRAY ___________ horn is comprised of somatic EFFERENT roots, carrying information *from the CNS* to the periphery; specifically, skeletal muscle.
Ventral (anterior) horn
In the *spinal cord*, the cell *bodies* of the *lower motor neurons* (which contract skeletal muscle if stimulated) are located in the...
Ventral horns of the spinal gray
The spinal arteries arise from the vertebral arteries, which ascend through the ________________ & are therefore subject to compression, particularly with changes in the vertebrae; potentially reducing blood flow to the brain stem & cerebellum.
Vertebral arteries ascend through the *TRANSVERSE FORAMINA*
Gliding at the Costotransverse Joints of Ribs 7-10 results in __________?
WIDTH in the Coronal Plane
Elevation of the rib cage increases the *WIDTH* in the _____________ plane & the *DEPTH* in the __________ plane; both of which are crucial for maximum airflow into & out of the lungs.
Width in the coronal plane (increase in transverse diameter) Depth in the sagittal plane (increase in sagittal diameter) PICTURE PLANES, then draw expanding line along that line
Upon exiting the intervertebral foramen, each MIXED SPINAL NERVE divides into...
a large ventral (anterior) primary ramus & a smaller dorsal (posterior) primary ramus
The spinal cord descends through the vertebral canal within a closed meningeal sac; composed of the outer most layer of the meninges called the...
dural sac AKA thecal sac
phantom pain
dysesthesia
Spinal nerve roots arise from & enter the...
horns
diminished sensation; possibly experienced secondary to destructive level II peripheral nerve injury
hypesthesia
The ATLAS is the *lonliest vertebrae,* why?
it has no BODY
The round, flat inferior articular facets of the ATLAS form the ____________ with C2 (Axis)
lateral atlantoaxial joints
the superior articular facets of the Axis are horizontal and help to form the...
lateral atlantoaxial joints
irritative lesions are considered...
level I peripheral nerve injury
destructive lesions are considered...
level II peripheral nerve injury
With the exception of C8, cervical spinal nerves are numbered according to the number of the ___________ vertebrae. In contrast, thoracic & lumbar & sacral spinal nerves are numbered according to the number of the ____________ vertebrae
underlying vertebrae (Cervical) overlying vertebrae (Thoracic & Lumbar & Sacral)
The posterior arch of the Atlas is grooved superiorly for the...
vertebral arteries
The spinal arteries (posterior & anterior) arise from...
vertebral arteries