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Vagus nerve Longus colli Scalenus
medius


Fig. 10.20. Ultrasound of the thyroid gland in transverse section. The lobes and
Fig. 10.18(a),(b). Diagrams of thyroid gland: (a) frontal view (b) cross-section.
isthmus of the thyroid gland with their normally homogeneous texture, lie on
either side of the highly echoic tracheal rings. Super¬cial to the gland are the
relatively hypoechoic sternocleidomastoid muscles.



Thyroid and parathyroid glands
The thyroid gland extends on either side of the trachea linked by
Fig. 10.21. Thyroid
an isthmus (Fig. 10.18). The gland is enclosed by the deep cervical
scintigraphy.
fascia and covered anteriorly by the strap muscles. Current imaging
techniques show a relatively homogeneous texture. It is highly
vascular however, and demonstrates intense contrast enhance-
ment on CT and MRI (Fig. 10.19). Its super¬cial location makes
the thyroid gland an ideal organ for ultrasound examination
(Fig. 10.20).
Radionuclide imaging may be performed with [Tc99 m] pertechnetate,
which is trapped by the thyroid in the same way as iodine and gives
morphological information. It will reveal the presence of ectopic
thyroid tissue (Fig. 10.21). Functional data can be obtained with the use
of [23I].
The normal parathyroid glands (four in number) are too small to be
identi¬ed by imaging. Standard now for parathyroid tumour pick-up.

101
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


Fig. 10.23. Continued
(b)
The craniocervical lymphatic system
Occipital artery

Normal cervical lymph nodes (Fig. 10.22) are not readily identi¬ed by Maxillary artery
CT or MRI, but when seen, are of homogeneous soft tissue density or
Facial artery
intensity, respectively, and are less than 1.5 cm diameter in the sub-
Internal carotid
mandibular or jugulodigastric region. Nodes elsewhere in the neck
artery
are considered abnormal if larger than 1 cm.
Lingual artery
Lymph drainage is ultimately via the jugular trunks into the thoracic
duct on the left and either into the right lymphatic duct or directly into External carotid
artery
the junction of the subclavian and internal jugular veins on the right.
Superior thyroid
artery

The cervical vasculature Common carotid
artery
The right common carotid artery arises from the brachiocephalic
artery behind the right sternoclavicular joint. The left common
carotid artery arises directly from the aortic arch. They lie within the
carotid sheath with the internal jugular vein laterally (Fig. 10.18, 10.19)
Fig. 10.24. (a) B-mode
(a)
and the vagus posteriorly. The common carotid artery divides at the
sonogram of the
level of the fourth cervical vertebra (Fig. 10.23). The smaller external common carotid
bifurcation. Doppler
waveforms of the
internal (b) and external
Facial nodes Parotid nodes
(c) carotid arteries.




Submental
Occipital
nodes
nodes

Submandibular
nodes

Mastoid nodes
Internal jugular nodes
(deep cervical chain)



Posterior triangle nodes
Anterior jugular
nodes


(b)
Supraclavicular
nodes


Fig. 10.22. Diagram of the cervical lymph nodes.



(a)
Occipital artery
(c)
Facial artery


External carotid
artery

Fig. 10.23(a),(b).
Internal carotid
Angiogram
artery
demonstrating the
common carotid
Superior thyroid
bifurcation and external
artery
carotid lies initially anteromedial to the internal carotid artery. These
carotid arteries
vessels are well demonstrated by conventional, CT or MR angiography.
(a) anteroposterior
Catheter
The carotid bifurcation is well demonstrated by ultrasound (Fig. 10.24)
(b) lateral. In this subject
which shows both structure (B-mode) and ¬‚ow characteristics
the bifurcation is at the
(Doppler study).
C3/4 level.


102
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


The external carotid artery supplies the upper cervical organs, The vertebral artery is the ¬rst branch of the subclavian artery and
facial structures, scalp, and dura. Traditionally, eight branches traverses the foramina transversaria (entering at the sixth cervical
are described but individual variation is common and many anasto- vertebra) (Fig. 10.25), supplying the cervical musculature and con-
moses exist. The external carotid divides within the parotid gland tributing to the spinal arteries, then passing intracranially through
into the super¬cial temporal and maxillary arteries. the foramen magnum.
The maxillary artery runs forwards from the parotid gland,
through the infra-temporal fossa into the pterygopalatine fossa. (c)
The largest branch is the middle meningeal artery which ascends
passing through the foramen spinosum into the middle cranial
fossa. Its™ terminal branches supply the nasal cavity (sphenopalatine
artery), with other branches supplying the pharynx, maxillary sinus,
palate and orbit.



(a)




Vertebral artery




Subclavian
artery




(d)



Catheter Muscular
branches




Vertebral
artery
(b)

Anterior spinal
artery




(e)



Fig. 10.25(a)“(e). Vertebral
angiography: (a) origin
Anastomosis
with occipital of the left vertebral
artery branches
artery. (b),(c)
anteroposterior and
(d),(e) lateral views of
Muscular
the cervical portion of
branches
the vertebral artery.
Note the muscular
Anterior spinal
branches, branches to
artery
the anterior spinal
artery and the
anastomoses with the
occipital artery.


103
jureerat thammaroj and joti bhattacharya
The extracranial head and neck


The extracranial venous drainage is mainly into the external jugular (a) Fig. 10.27. MRI of the
system, thence to the subclavian veins. brachial plexus.



Brachial plexus C4 Vertebral
artery
The brachial plexus is formed from the anterior rami of the ¬fth cervi- C5
cal to the ¬rst thoracic nerve roots. The fourth cervical and second Branchial
plexus
thoracic roots may also contribute. The alternate division and union of C6
these roots give rise to the complexity of the plexus (Fig. 10.26). MRI
C7
scans in the coronal and oblique planes are the most useful studies
(Fig. 10.27).
T1



Nerve roots
Scalenus
Nerve posterior
trunks
Anterior
division C5
Posterior
C6
division
Musculocutaneous C7
nerve Cords
C8
(b)

T1 Sternocleidomastoid
Circumflex
axillary nerve Subclavian
artery


Pectoralis minor
muscle
Ulnar nerve

Fig. 10.26. Diagram of the
Median nerve
Radial nerve
brachial plexus.

Scalenus
Trapezius
medius

Levator
Scalenus
scapulae
anterior




Subclavian
artery




Brachial plexus




104
Section 4 The head, neck, and vertebral column

Chapter 11 The vertebral column
and spinal cord

C L AU D I A K I R S C H




to produce sagittal and coronal images. CT utilizes ionizing radiation
General overview
and the dose to the pelvis, in particular to the reproductive organs,
The vertebral column forms the central axis of the skeleton and con- should be borne in mind when requesting imaging of the lumbosacral
sists of 33 vertebrae. region.
There are seven cervical, twelve thoracic and ¬ve lumbar vertebrae CT is displayed using a gray scale based on the degree to which a
(the true, “moveable” vertebrae), and caudally there are ¬ve sacral and tissue attenuates the X-ray beam. The two extremes are bone, which
four coccygeal segments, all of which are fused as the sacrum and appears white and which is radio-opaque and air, which is radiolucent
coccyx, respectively. and appears black. Fat and cerebrospinal ¬‚uid are also radiolucent.
Only in the upper cervical column can the spinal cord be discrimi-
nated from the surrounding CSF. It is possible to inject iodinated con-
Imaging methods
trast agent via a lumbar puncture and perform a CT myelogram. This
Plain radiography reveals structural detail within the dural sac. The contour of the spinal
Plain radiography remains the most commonly performed investiga- cord and nerve roots can thus be demonstrated but not any intrinsic
tion of the vertebral column, especially after trauma. The spatial reso- detail (Fig. 11.2). A myelogram utilizing conventional radiography may
lution of radiographs is high and they are simple to acquire. Vertebral be obtained prior to the patient undergoing CT.
alignment is easy to assess and bone detail is well shown. Soft tissue Bone-targeted CT is valuable in suspected vertebral trauma but, in
detail is poor. other cases, CT of the vertebral column is usually reserved for the
minority in whom MRI is contraindicated.
Computed tomogaphy (CT)
Magnetic resonance imaging (MRI)
CT provides cross-sectional images of bony and soft tissue elements
of the vertebral column. Because CT is a digital technique, the images MRI is the primary imaging method for the vertebral column. It pro-
can be manipulated to optimize either bone or soft tissue detail vides images in multiple planes, does not use ionizing radiation and
(Fig. 11.1). The set of axial scans can also be summated and reformatted displays excellent anatomical and pathological information. A typical


(b)
(a)


Intervertebral
disk


Superior
Ligamentum articular
Inferior
flavum process
articular process
Facet joint




Fig. 11.1. Axial CT at the level of L3/4 intervertebral disk: (a) soft tissue, (b) bone windows.



Applied Radiological Anatomy for Medical Students. Paul Butler, Adam Mitchell, and Harold Ellis (eds.) Published by Cambridge University Press. © P. Butler,
A. Mitchell, and H. Ellis 2007.

105
The vertebral column and spinal cord claudia kirsch

(a) Fig. 11.3. T1W, T2W
(b)
(a)
sagittal MRI, vertebral
Foramen column.
transversarium
Ventral
nerve root

Spinal cord

Dorsal
nerve root




(b)




CSF opacified with
iodinated contrast
medium
Nerve roots of the
cauda equina




Fig. 11.2. Axial CT myelogram (a) cervical spine, (b) lumbar spine.




MRI series will consist of T1W and T2W sagittal and axial images.
Further coronal images and intravenous gadolinium DTPA contrast
administration may be undertaken depending on the clinical picture.
The tissue discrimination of MRI is superior to CT. MRI is the only
method to show an intrinsic abnormality of the spinal cord substance.
On T1W images the CSF is dark and, in general, this sequence shows
the anatomy. On T2W images the CSF appears white and thus there is
a myelographic effect. T2W sequences, in general, demonstrate
pathology.
There are four curves in the sagittal plane: the cervical and lumbar,
which are convex anteriorly (lordotic) and the thoracic and sacrococ-
cygeal curves, which are concave anteriorly (kyphotic) (Fig. 11.3).
The kyphoses are primary curves, present in the fetus; the lordotic
curves develop later in life and are secondary, serving to strengthen
the column.
Despite regional differences, a typical vertebra can be described
with a body anteriorly and a neural arch posteriorly (Fig. 11.4). The
neural arch surrounds the spinal canal and consists, on each side, of
a pedicle laterally and a lamina posteriorly. A transverse process
extends laterally and the laminae fuse posteriorly to form the spinous
process. The intervertebral canals transmit the segmental spinal
nerves between adjacent pedicles.
The vertebral body consists of central cancellous (spongy) bone with
a rim of dense cortical bone.
The vertebral bodies are important sites for hematopoiesis contain-
ing red marrow in the young, converting to yellow (fatty) marrow
with increasing age.
The intervertebral disc is a cartilaginous cushion between adjacent
vertebral bodies, (Fig. 11.3). Each consists of a central nucleus pulposus
surrounded by an annulus ¬brosus.
During childhood the disks are highly vascular but, by the age of 20
years, the normal disk is avascular. With increasing age, the disk
undergoes progressive dehydration with loss of height.

106
The vertebral column and spinal cord claudia kirsch

(a)
joins adjacent laminae and the interspinous ligaments run between
the spinous processes.
Body
In the axial plane the ligamentum ¬‚avum appears V shaped and is
thickest in the lumbar region. It is the only spinal ligament having
Superior
costal facet
elastic properties, increasing in length in ¬‚exion.
The vertebral column can be considered as a three-column struc-
ture. The anterior column is formed by the anterior longitudinal liga-
Transverse process
Transverse
costal facet
ment, the anterior annulus ¬brosus, and the anterior part of the
Lamina
vertebral body. The middle column comprises the posterior longitudi-
nal ligament, the posterior annulus ¬brosus, and the posterior part of
Spinous process
the vertebral body. The posterior column consists of the neural arch
and posterior ligamentous complex. This concept has implications for
(b)
spinal stability following trauma.
Superior
articular facet

Superior Transverse
costal facet costal facet

Pedicle
Inferior
articular process
Inferior
costal facet




Fig. 11.4. A typical vertebra (T6): (a) superior, (b) lateral views.
Exiting nerve root




There are regional variations in disc morphology. In the cervical and
lumbar regions the disks are thicker anteriorly and contribute to the
lordoses. The disks are thinnest in the upper thoracic region and
thickest in the lumbar region. Overall, the disks account for 20% of
the total height of the vertebral column.
The facet joints are synovial articulations in the neural arches,
which unite the posterior elements of the vertebral column (Fig. 11.1).
The articular processes project superiorly and inferiorly at the junc-
tion between the lamina and pedicle. The articular process of the Fig. 11.5. T1W MRI, parasagittal plane, the lumbar neural foramina.
vertbra above (i.e., its inferior facet) is posterior to that of the vertebra
below (i.e., its superior facet).


The vertebral canal
The vertebral canal transmits the spinal cord and, in the lumbar
region, the cauda equina. It is formed by the posterior margins of the
vertebral bodies and discs anteriorly, and the pedicles and laminae
(the neural arch) posteriorly.


The intervertebral canal (the neural foramen)
The spinal nerves arise from the spinal cord and leave the spinal canal
through the intervertebral canals, each of which is situated between
adjacent pedicles (Fig. 11.5). The nerves are accompanied by blood
vessels and are supported by extradural fat within each canal.


The ligaments of the vertebral column
A number of ligaments strengthen the vertebral column (Fig. 11.6).
The anterior longitudinal ligament runs superoinferiorly between the
anterior surfaces of the vertebral bodies from the occiput to the
sacrum. The posterior longitudinal ligament is applied to the posterior
surfaces and narrows as it passes downward. The ligamentum ¬‚avum



107
The vertebral column and spinal cord claudia kirsch


(a)
Ligamentum flavum
Posterior
longitudinal ligament
Interspinous ligament
Intervertebral canal
Supraspinous ligament
Anterior
Occipital
longitudinal ligament
condyle

Atlas, C1

Axis, C2

(b)

Fig. 11.8. Coronal CT reformat, the craniovertebral junction.
Pedicle

bone with no vertebral body (Fig. 11.9). It articulates superiorly with
the occipital condyles of the skull as the atlanto-occipital joints.
Posterior
longitudinal
Think of the Greek myth of Atlas who carried the world on his
ligament
shoulders and you realize the responsibility of the ¬rst vertebra as it
carries your “world” or head on your shoulders!
The axis vertebra (C2) has a superior extension, the odontoid
Intervertebral disk
process (or dens) which represents the body of C1 (Fig. 11.10). The ante-
rior arch of C1 is maintained in a ¬xed position relative to the dens by
the transverse ligament, which attaches to the lateral masses of C1.
Four joints are formed between C1 and C2, namely the anterior arch
of C1 and the dens, the dens and the transverse ligament, and the
right and left articular facets. Damage to the ligament, either by
trauma or due to an erosive arthropathy, like rheumatoid arthritis,
Fig. 11.6. The ligaments of the vertebral column, (a) lateral view, (b) vertebral
can result in atlanto-axial subluxation and cervical cord compression.
bodies viewed from behind.
C3 to C6 may be regarded as typical (Fig. 11.11). The small, oval
vertebral bodies increase in size to C7. The superior projection of
each vertebra, the “uncinate process,” forms a rim or ¬‚ange, which
indents the posterior“lateral disk and vertebrae above, creating the
“uncovertebral joint.” The short pedicles extend laterally from the
anterior body forming a bridge to the articular pillars, which bear the
inferior and superior articular facets. The spinous processes may be
Anterior arch of atlas (C1)
Odontoid peg (dens)
bi¬d and the transverse processes terminate with anterior and
Spinal cord posterior tubercles. Each transverse process encloses the foramen
transversarium, which transmits the vertebral arteries and veins on
each side. C7, the vertebra prominens, has a long, non-bi¬d spine,
Spinous process
and no anterior tubercle on its transverse process. Its foramen trans-
versarium is often small; it only transmits small tributaries of the
vertebral vein “ the artery enters at C6. The vertebral arteries arise
from the subclavian arteries, enter the foramen transversarium of C6,
traverse the successive foramina transversaria above this level and
enter the skull through the foramen magnum. The cervical canal is
funnel-shaped in the sagittal plane, widest superiorly. It is triangular
Fig. 11.7. T2W sagittal MRI, cervical spine.
in cross-section.
In addition to making sure that the lateral masses of C1 are aligned
The craniocervical junction and cervical vertebral column
appropriately on C-2, ¬ve important contour lines are evaluated on
lateral cervical spine plain ¬lms, (Fig. 11.9(c)). The ¬rst is the anterior
The craniocervical junction (CVJ) is composed of the occiput, atlas,
soft tissue or prevertebral space. At C-3, the prevertebral soft tissues
and axis, and supporting ligaments, enclosing the soft tissues of the
should be no more than 4“5 mm, with a maximum about 7 mm. At
medulla, spinal cord, and lower cranial nerves. MRI is the most appro-
C6, this increases to approximately 10“20 mm. In children, this space
priate means of showing the relationship of bone and soft tissue in
may measure 14 mm and up to 22 mm in adults, with the soft tissues
this important region (Fig. 11.7). CT demonstrates the bony anatomy,
usually measuring 15 mm on average. The next lines evaluated include
(Fig. 11.8).A variety of congenital anomalies of the bony skull base can
the anterior and posterior spinal lines extending along the anterior
lead to basilar invagination, when the vertebral column extends into
and posterior vertebral bodies, respectively. Lastly, the spinolaminal
skull base. A similar result, better described as cranial “settling,” can
line and spinous process line should be evaluated for appropriate
occur in the erosive arthropathies due to ligamentous damage.
alignment.
There are seven cervical vertebrae. The atlas vertebra (C1) is a ring of

108
The vertebral column and spinal cord claudia kirsch


(a) Fig. 11.10. The
Tectorial membrane (cranial
craniovertebral
extension of PLL)
ligaments viewed in
Vertebral artery
Apical sagittal section.
ligament
Uncovertebral joint of dens
Transverse process


Anterior
Transverse
arch of C1
ligament
Spinous process
of dens

Posterior
Transverse process of T1 longitudinal
ligament (PLL)

Anterior
longitudinal
(b) ligament (ALL)



Fig. 11.11. Cervical
Foramen
Body
vertebra.
transversarium
Odontoid peg
Lateral mass
(dens)
of atlas, C1
of axis, C2

Pedicle
Superior
articular
facet
Articular pillar
Lamina
Mandibular
dentition Spinous process



(c)
(a)



Pedicle


Atlas, C1 Spinous process


Axis, C2

Rib
Prevertebral
soft tissue




(b)




Vertebral body

Fig. 11.9. Cervical spine radiographs: (a) anteroposterior, (b) per oral, (c) lateral
Superior articular facet
views.



Inferior articular facet
The thoracic vertebral column
Intervertebral canal
There are 12 thoracic vertebrae distinguished by articulations for the
ribs (Fig. 11.12). The vertebral bodies have a slight wedge-shape anteri-
orly. They also bear demifacets for the ribs on the superior and infe- Rib
rior vertebral bodies. Otherwise, the anatomy conforms to that of the
“typical vertebra” given above. The annulus ¬brosus, ALL, and PLL are
the thickest in this region.
The ribs attach at two places: the head of the rib attaches to the
vertebrae at the disk and additionally the tubercle of the rib attaches Fig. 11.12. Thoracic spine radiographs: (a) anteroposterior, (b) lateral views.


109
The vertebral column and spinal cord claudia kirsch


to the transverse process costotransverse joint (Fig. 11.13). Typically,
therefore the ribs arise posteriorly between vertebrae. The ¬rst rib
Vertebral body articulates only with T1 and similarly the tenth, eleventh, and twelfth
Costovertebral
articulation
ribs articulate only with T10, T11, and T12 vertebrae. At remaining
levels, demifacets superior and inferior to the disk communicate with
Spinal cord
the head of the rib creating a costovertebral synovial joint. Therefore,
Costotransverse the ribs arise posteriorly between vertebrae. In the thoracic region the
articulation
canal is constant in size and circular in cross-section.


Fig. 11.13. Axial CT myelogram, thoracic spine. The lumbar vertebral column
There are ¬ve lumbar vertebrae, the third (L3) being the largest
(Fig. 11.14). Lumbar vertebrae have square-shaped anterior vertebral
bodies covered by fenestrated cartilage attached to the adjacent
(a)
disks. Projecting posteriorly are bilateral pedicles composed of thick
cortical bone connecting to lamina forming the spinal canal. The artic-
ular facets face each other in the sagittal plane (Fig. 11.15), and the
transverse distance between the pedicles increases (the interpedicular
distance) from L1 to L5. L5 is somewhat atypical with a wedge-shaped
body, articulating inferiorly with the sacrum. Not infrequently, it may
Superior articular process
be fused, wholly or partly, with the body of the sacrum (“sacralization
of L5”). Extending from the pedicles is a bony plate called the pars
Inferior articular process articularis from which extend the superior and inferior articular
facets. The posterior superior articular facet of an inferiorly located
Spinous process
vertebra connects to the posterior inferior facet of the superior verte-
bra above creating a diarthrodial synovial lined joint, surrounded by a
Pedicle
¬brous capsule posterolaterally with absence of the joint capsule ante-
riorly, where the ligamentum ¬‚avum and synovial membrane are
present, (Fig. 11.16).

Sacroiliac joint
The spinal cord
The spinal cord extends from the foramen magnum to the level of the
¬rst or second lumbar vertebrae. It is oval and elliptical in the cervical
spine (Fig. 11.17), more rounded in the thoracic region (Fig. 11.18)
always being wider in the transverse plane. A cleft anteriorly is
(b)
referred to as the ventral median ¬ssure and a small shallow sulcus is




Intervertebral canal

Vertebral body Transverse process



Superior articular facet
Pedicle

Superior articular
process of L4

Inferior articular facet




Pedicle




Fig. 11.14. Lumbar spine radiographs: (a) anteroposterior, (b) lateral views. Fig. 11.15. Lumbar spine radiograph, oblique projection.


110
The vertebral column and spinal cord claudia kirsch




Superior
articular
process


Inferior Facet joint
articular
Exiting nerve root,
Ligamentum
process part of the cauda
flavum
equina




Fig. 11.16. T1W axial MRI, lumbar vertebra.




Fig. 11.19. T2W sagittal MRI, lumbar spine showing the cauda equina.



Spinal cord




Dorsal root ganglion


Fig. 11.17. GRE axial MRI, cervical spine. Note that this sequence (gradient
recalled echo) demonstrates gray matter within the spinal cord.




Fig. 11.20. T1W axial image, lumbar vertebra.


the nerve roots in the lumbar region pass almost vertically down to
Spinal cord
form the cauda equina (horse™s tail) (Fig. 11.19).
There are 31 pairs of spinal nerves: 8 cervical, 12 thoracic and 5
lumbar. Each spinal nerve is formed from a dorsal (posterior) sensory
root and a ventral (anterior) motor root emerging from the spinal
cord. The ventral roots contain axons of the neurons in the spinal gray
matter. The neurons of the dorsal roots are found in the ganglion
borne by each dorsal root. The ganglion is usually situated in the
Fig. 11.18. T2W axial MRI, thoracic spine.
intervertebral canal (Fig. 11.20) and distal to this ventral and dorsal
roots merge to form the spinal nerve (Fig. 11.2a). C1 root exits between
the occiput and C1 vertebra. Each cervical nerve root therefore exits
noted posteriorly. In cross-section the cord has central gray matter
above the correspondingly numbered vertebra. C8 root exits between
shaped like a butter¬‚y H-shaped pattern surrounded by white matter.
C7 and T1 vertebrae. Because of this, thoracic nerve roots exit below
The lower end of the spinal cord tapers to form the conus medullaris
the correspondingly numbered thoracic vertebra.
and from the conus the thin ¬lum terminale extends to the coccyx.
In the lumbar spine each root leaves the spinal canal laterally below
The caliber of the spinal cord increases in two regions as the cervi-
the pedicle of the corresponding vertebra and above the disk.
cal (C5“T1 segments) and lumbar (L2“S3 segments) expansions con-
cerned with the arms and legs, respectively.

Meninges
The spinal nerves
The spinal and cranial meningeal sheaths are continuous. The spinal
dural sac extends from the posterior cranial fossa to the second sacral
Since the spinal cord is shorter than the vertebral column, the spinal
segment. It surrounds the spinal cord, nerve roots and cerebrospinal
nerves take a progressively oblique course caudally to emerge through
the intervertebral canals. Below the termination of the spinal cord, ¬‚uid (CSF).

111
The vertebral column and spinal cord claudia kirsch




Right vertebral artery




Radicular feeding artery
The artery of
Adamkiewicz

Anterior spinal artery



Intercostal artery




Fig. 11.21. Vertebral angiogram showing the anterior spinal artery and radicular
arteries.




Within the dura is the avascular arachnoid and the pia mater, the
Fig. 11.22. The artery of Adamkiewicz arising from the left intercostal artery
second component of the leptomeninges, forms a layer over the spinal
at T9 level.
cord. Between the two is the subarachnoid space, which contains
cerebrospinal ¬‚uid.

segmental thoracic intercostal and lumbar arteries. These feeding
The blood supply to the spinal cord
vessels extend through the intervertebral canals and bifurcate into
The cervical spinal cord blood supply is from the anterior spinal artery anterior and posterior vessels extending along the dorsal and ventral
and paired posterior spinal arteries. The anterior spinal artery is nerve roots. One very important major contribution comes from the
formed superiorly from branches that extend inferiorly from both of Artery of Adamkiewicz, which usually arises from the left side and/or
the vertebral arteries (Fig. 11.21). It supplies the anterior two-thirds of the intercostals arteries at the T-9 to T-12 vertebral levels. This vessel
the cord. This critical area includes the corticospinal and spinothala- comes into the spinal canal with nerve roots and has a classic
mic tracts as well as the central gray matter anterior column. “hairpin loop” (Fig. 11.22). This vessel supplies the anterior spinal
The posterior spinal arteries, which also arise from the vertebral cord in the thoracolumbar region via a large descending vessel
arteries, supply the posterior one-third of the cord, including the which anastamoses with the posterior spinal arteries at the conus.
posterior columns and central gray matter posterior horn. Draining veins leave the spinal cord through the intervertebral
The spinal arteries, running the length of the cord, also receive canals to join an extensive interconnecting plexus of veins in the
numerous contributions from various cervical arteries and from the epidural space.




112
Section 5 The limbs

Chapter 12 The upper limb


A L E X M . BA R NAC L E
and A DA M W. M . M I T C H E L L




The skeletal anatomy of the upper limb is well demonstrated on con-
The shoulder and upper arm
ventional plain radiographs, which are quick and simple to acquire
The shoulder girdle
and have better spatial resolution than computed tomography (CT) or
The shoulder girdle connects the upper limb to the axial skeleton,
magnetic resonance imaging (MRI). Radiographs are usually acquired
allowing movement at both the shoulder joint and the scapulotho-
in two planes, at 90 degrees to one another, to overcome issues such
racic joint (Fig. 12.1). The weight of the arm is transmitted to the trunk
as foreshortening and overlying bony structures. When imaging
primarily via the clavicle.
complex joints such as the shoulder, supplementary views may also be
required.
The scapula
In complex orthopedic or trauma cases, 3-D image reconstructions
The scapula overlies the posterolateral aspect of the chest wall, its
of CT examinations provide excellent visualization of regions of
inner surface closely applied to the posterior aspects of the second to
abnormal skeletal development or complex fractures. MRI is more
often applied in the assessment of soft tissues, including the joints,
the neurovascular structures, especially the brachial plexus, and the
bone marrow. Ultrasound (US) is used increasingly commonly in
the evaluation of the super¬cial soft tissue structures, such as the
tendons of the rotator cuff within the shoulder and the tendons of
the wrist.
Arthrography involves the injection of a contrast agent such as air
or iodinated contrast medium into a joint space to allow visualiza-
tion of the joint, its capsule and articular surfaces under
¬‚uoroscopy. This technique has been largely superseded by other
imaging modalities such as MRI, although arthrography combined
with MR or CT, where gadolinium or iodinated contrast medium is
instilled into the joint prior to imaging, gives exquisite detail of the
joint spaces and any disruption of the joint capsule or supporting
structures.
Angiography and venography are used to assess arterial and venous
anatomy for reasons such as the placement of central venous
catheters, planning the formation and maintenance of arteriovenous
¬stulas and the management of arterial trauma. This can be per-
formed via traditional catheter angiography techniques or by digitally
reconstructing the vascular detail from a contrast medium enhanced
CT or magnetic resonance (MR) examination
In most musculoskeletal cases, more than one imaging modality is
required to acquire the breadth of radiological information necessary
Fig. 12.1. Anteroposterior radiograph of the left shoulder.
to make a full and accurate diagnosis.



Applied Radiological Anatomy for Medical Students. Paul Butler, Adam Mitchell, and Harold Ellis (eds.) Published by Cambridge University Press. © P. Butler,
A. Mitchell, and H. Ellis 2007.

113
alex m. barnacle and adam w. m. mitchell
The upper limb


and the spine of the scapula give attachment to larger muscles of the
seventh ribs. The anterior and posterior surfaces of the scapula give
shoulder girdle, trapezius, and deltoid.
attachment to many of the muscles of the rotator cuff. The rotator
cuff is the term used to describe the tendons of the four smaller
The clavicle
muscles surrounding the shoulder joint; the tendons are intimately
related to the capsule of the shoulder joint (Fig. 12.2). Subscapularis The clavicle is an S-shaped bone that develops from a mesenchymal or
attaches to the convex costal surface of the scapula and inserts onto membranous origin and is the ¬rst bone in the body to ossify. It is
the lesser tubercle of the humerus. Supraspinatus arises from the unusual in that it does not contain a medullary cavity. The clavicle
supraspinous fossa of the posterior aspect of the scapula and inserts articulates with the manubrium of the sternum and the ¬rst costal
onto the greater tubercle of the humerus. Adjacent to this, infraspina- cartilage medially, forming the sternoclavicular joint. The costoclavic-
tus arises from the infraspinous fossa and also attaches to the greater ular ligament arises from the inferior surface of the medial clavicle
tubercle. The supraspinous and infraspinous fossae communicate and inserts onto the upper surface of the ¬rst costal cartilage and the
laterally around the base of the spine of the scapula. Teres minor ¬rst rib. Laterally, the clavicle articulates with the acromion of the
arises from the lateral margin of the scapula and inserts inferiorly scapula, the coracoclavicular ligament arising from the inferior
onto the greater tubercle of the humerus. surface of the clavicle just medial to this joint. The large muscles of
Laterally, the angle of the scapula forms the articular surface of the the shoulder girdle gain some of their attachments from the clavicle:
bone, known as the glenoid fossa; this articulates with the humeral pectoralis major, deltoid, sternocleidomastoid and trapezius.
head. The bony tubercles above and below the glenoid fossa give The clavicle transmits part of the weight of the upper limb to the
attachment to the long heads of biceps and triceps respectively. The trunk and, with the scapula, allows the arm to swing clear of the
projection known as the acromion is formed by the ¬‚attened lateral trunk.
extension of the spine of the scapula. It articulates with the lateral
The sternoclavicular joint
end of the clavicle and overlies the shoulder joint, providing some
protection for both the joint and the overlying supraspinatus tendon The ¬brocartilaginous sternoclavicular joint is formed by the artic-
of the rotator cuff. Medial to the acromion, the coracoid process of the ulation of the manubrium sternum and the ¬rst costal cartilage with
scapula projects anteriorly, giving attachment to the short head of the medial aspect of the clavicle. The strong ¬brous costoclavicular
biceps, pectoralis minor, and coracobrachialis, and to the coracoclavic- ligament arises from the inferior surface of the clavicle just lateral
ular ligament. Latissimus dorsi, teres major, and serratus anterior to the sternoclavicular joint, attaching to the superior aspect of the
attach to the inferior angle of the body of the scapula. The acromion ¬rst rib and stabilizing the joint. Further stability is afforded by the




(b)
(a)




Fig. 12.2. T2 weighted MR images acquired in the sagittal plane (lateral view): (a) image through the body of the scapula, the coracoid process and acromion. The
muscles of the rotator cuff surround the body of the scapula; (b) More lateral image through the humeral head showing the tendons of the rotator cuff before their
insertion onto the humerus.


114
alex m. barnacle and adam w. m. mitchell
The upper limb


The humerus
interclavicular ligament, which lies within the suprasternal notch,
and focal thickening of the joint capsule known as the anterior and The hemispherical head of the humerus articulates with the glenoid
posterior sternoclavicular ligaments. Each joint contains a ¬brocarti- fossa of the scapula. The anatomical neck of the humerus is formed by
lagenous disk dividing the joint into medial and lateral synovial the boundary of the joint capsule. The surgical neck is the term used
compartments. for the slightly narrowed junction between the head of the humerus
The joint is capable of small movements, which are associated with and its shaft, because of the tendency of the humerus to fracture at
movement at the acromioclavicular joint and which act to increase this point. The lateral aspect of the humeral head forms two promi-
the range of movement of the whole upper limb. Movements at the nent tubercles, known as the greater and lesser tuberosities or tuber-
sternoclavicular joint include elevation and depression, horizontal cles, which are separated by the intertubercular or bicipital groove.
forward and backward movement, circumduction, and axial rotation. The greater tuberosity lies posterior to the lesser tuberosity. Many of
the tendons of the rotator cuff insert onto the humeral tubercles:
The acromioclavicular joint supraspinatus, infraspinatus, and teres minor attach to the greater
tuberosity and subscapularis to the lesser tuberosity. The long head of
The acromioclavicular joint is a complex synovial joint between the
biceps lies within a vertical channel known as the bicipital groove.
lateral border of the clavicle and the medial aspect of the acromion of
A spiral groove along the posterior aspect of the shaft of the
the scapula. The joint contains an incomplete ¬brocartilaginous disk
humerus accommodates the radial nerve. Deltoid inserts onto a small
and is surrounded by a weak synovial joint capsule. Accessory liga-
protrusion on the lateral aspect of the shaft known as the deltoid
ments comprise the aromioclavicular ligament, a ¬brous band that
tuberosity, triceps attaches posteriorly and brachialis anteriorly. The
overlies the superior surface of the joint, and the coracoclavicular liga-
neurovascular bundle of the median nerve, brachial artery, and basilic
ment that extends from the inferior surface of the clavicle to the supe-
vein lies more super¬cially, medial to the humerus.
rior surface of the coracoid process, providing a strong attachment of
At the elbow, the humerus expands and ¬‚attens to form the medial
the clavicle to the scapula and lending stability to the joint.
and lateral supracondylar ridges and the medial and lateral epi-
Disruption of the ligaments or the joint capsule itself will result in
condyles, from which the common ¬‚exor and extensor origins, respec-
widening of the joint space, and the clavicle will override the
tively, arise. The lateral rounded capitellum and the medial trochlea
acromion.
form the articular surfaces of the humerus at the elbow. The fat-¬lled
The supraspinatus tendon runs immediately below the acromioclav-
olecranon fossa posteriorly accommodates the olecranon process of
icular joint. Any degenerative disease in the joint may cause irregular-
the ulna during elbow ¬‚exion, and a similar fossa anteriorly accom-
ity of the under surface of the joint, which in turn causes wear and
modates the head of the radius.
tear of the tendon, and loss of the normal tendon thickness. When
assessing plain radiographs of the shoulder, observe the soft tissues
inferior to the acromioclavicular joint for narrowing of the distance The glenohumeral joint
between it and the humeral head and for calci¬cation within the The glenohumeral or shoulder joint is a synovial ball and socket joint.
supraspinatus tendon. Ultrasound examination of the shoulder pro- The shallow glenoid fossa is deepened by the glenoid labrum, a cir-
vides useful “real-time” imaging of the rotator cuff (Fig. 12.3). Changes cumferential outer ¬brocartilaginous ring (Fig. 12.4). Even with the
in the re¬‚ectivity of the tendons and the surface of the bony contours labrum present, the articular surface of the glenoid remains less than
are suggestive of in¬‚ammatory or degenerative change. Dynamic one-third of the surface area of the humeral head. The joint capsule
information can also be gained by imaging the shoulder in different attaches to the glenoid labrum and inserts into the articular margin of
positions and during movement. the humeral head, except inferiorly where it extends on to the medial
aspect of the humeral neck. The anterior portion of the joint capsule
is strengthened by the three glenohumeral ligaments surrounding the
Lateral Medial shoulder joint. The capsule is lax inferiorly, as demonstrated by
arthrography (Fig. 12.5). The tendon of the long head of biceps runs
through the joint capsule, enclosed by the synovial membrane of the
capsule, and can therefore be involved in diseases of the joint. The
Deltoid
transverse humeral ligament is an accessory ligament of the shoulder
joint; it bridges the intertubercular groove between the greater and
Echo
lesser tuberosities, holding the long tendon of biceps in place.
reflective
border of The movements of the shoulder joint are:
supraspinatus
tendon
• Flexion: clavicular head of pectoralis major, anterior ¬bers of deltoid,
coracobrachialis
• Extension: posterior ¬bers of deltoid, reinforced in the ¬‚exed posi-
tion by latissimus dorsi, pectoralis major, teres major
• Abduction: initiated by supraspinatus, continued by deltoid
Bony margin of the Tendon
• Adduction: pectoralis major, latissimus dorsi, subscapularis, teres
head of the humerus
major
• Medial rotation: pectoralis major, anterior ¬bres of deltoid, latissimus
dorsi, teres major, subscapularis
Fig. 12.3. Ultrasound image of the shoulder, showing the hyperechoic superior
• Lateral rotation: posterior ¬bres of deltoid, teres minor, infra-
border of the supraspinatus tendon. The contour of the bony surface of the
spinatus.
humeral head remains smooth.



115
alex m. barnacle and adam w. m. mitchell
The upper limb


surface of the clavicle, and the aponeurosis of external oblique. It
inserts on to the lateral lip of the humeral intertubercular groove.
Pectoralis minor lies deep to pectoralis major, arising medially from
the anterior surfaces of the third, fourth, and ¬fth ribs and inserting
onto the coracoid process of the scapula.
Serratus anterior arises from the lateral aspects of the upper eight
ribs, forming the medial wall of the axilla. It attaches to the costal
surface of medial border of the scapula.
Trapezius is a broad, ¬‚at, super¬cial muscle arising from the nuchal
line of the occiput, the ligamentum nuchae, the thoracic vertebral
spines, and the supraspinous ligaments. It inserts onto the lateral
aspect of the clavicle, the acromion, and the scapula spine. Latissimus
dorsi has an extensive origin, including the spines and supraspinous
ligaments of the lower six thoracic vertebrae, the thoracolumbar
fascia of the back, the posterior part of the iliac crest, and the lower
four ribs. It forms a strap-like tendon that inserts on to the ¬‚oor of the
intertubercular groove of the humerus.
Levator scapulae and the major and minor rhomboids lie deep to
trapezius, running from the thoracic vertebrae to the medial border
of the scapula.
Deltoid arises from the lateral third of the clavicle, the acromion,
and the scapular spine, inserting on to the deltoid tuberosity of the
body of the humerus.
Teres major forms part of the posterior axillary wall, arising from
the lateral border and angle of the scapula and inserting onto the
Fig. 12.4. T2 weighted axial MR image at the level of the head of the humerus,
medial lip of the intertubercular groove of the humerus.
showing the low signal labrum projecting from the margins of the glenoid and
The muscles of the rotator cuff have been covered in the scapula
a sliver of high signal synovial ¬‚uid within the joint.
section.

Bursae of the shoulder
A bursa is a sac lined with a synovial membrane, which secretes lubri-
cating synovial ¬‚uid. Bursas usually occur around joints and serve to
reduce friction at sites where tendons or ligaments rub across bony
structures.
The glenohumeral joint is surrounded by several bursae. The most
clinically signi¬cant of these is the large subacromial“subdeltoid
bursa, which lies between the supraspinatus and the inferior surface
of the coracoacromial arch. This bursa does not communicate with
the joint capsule unless the supraspinatus tendon is ruptured. Spill of
contrast medium into the bursa during joint arthrography therefore
implies disruption of the supraspinatus muscle or tendon.

Imaging of the shoulder
The standard plain radiographic views of the shoulder are the antero-
Fig. 12.5. Conventional arthrogram of the shoulder. Iodinated contrast medium
posterior (Fig. 12.1) and axial projections (Fig. 12.6). The axial view
has been instilled into the joint through a butter¬‚y cannula, which is seen
allows assessment of the congruity of the glenohumeral joint. In sus-
overlying the image (arrow). Contrast ¬lls the joint capsule and outlines the
pected shoulder dislocation, the trans-scapular view provides informa-
tendon of the long head of biceps.
tion on the relationship of the humeral head to the glenoid fossa,
which is projected behind the humeral head (Fig. 12.7). The Striker™s
view is acquired with the beam angled through the axilla to provide
As mentioned above, movement of the shoulder girdle increases the anatomical detail of the posterior aspect of the humeral head, which
range of movement of the shoulder. Note that ¬‚exion/extension at the is obscured on the axial view and may be damaged in cases of recur-
shoulder joint does not occur in a true anteroposterior plane; in rent dislocation (Fig. 12.8).
¬‚exion, the upper arm moves anteriorly and medially, so that anatom- The ¬brocartilaginous components of the shoulder joint and its sur-
ical ¬‚exion of the shoulder involves a degree of abduction. rounding tendons are well demonstrated on MR. Information regard-
ing the joint capsule, the bony con¬guration of the humeral head, and
Musculature of the shoulder the integrity of the labrum can be acquired by instilling arthrographic
Pectoralis major arises from the anterior chest wall structures, which contrast medium into the joint capsule. Arthrography can be per-
comprise the sternum, the upper six costal cartilages, the anterior formed using air or iodinated contrast medium, and then acquiring

116
alex m. barnacle and adam w. m. mitchell
The upper limb



Coracoid process


Lesser tubercle

Greater tubercle
Intertubercular
groove




Coracoid
process


Humeral
head

Acromion



Clavicle
Glenoid
cavity
Spine of
Glenoid cavity
scapula


Acromio-
clavicular
joint


Fig. 12.6. Axial radiograph of the shoulder.
Clavicle


Rib



Fig. 12.8. Striker™s view of the shoulder. This view clearly demonstrates the
posterior aspect of the humeral head.




radiographs to demonstrate the extent of the joint capsule (see
Fig. 12.5). Alternatively, MR contrast agents such as gadolinium can
be instilled prior to MR examination of the shoulder, allowing very
detailed imaging of the labrum and the articular surface (Fig. 12.9).

The axilla
The axilla lies between the lateral chest wall and the upper arm. The
fat-¬lled pyramidal space contains the axillary artery and vein, cords
and terminal branches of the brachial plexus, the coracobracialis and
biceps muscles, and the axillary lymph nodes. The apex of the space is
formed by the ¬rst rib and the middle third of the clavicle. The medial
wall of the axilla is made up of the lateral aspects of the upper four
ribs and their accompanying intercostal muscles and fascia, and serra-
tus anterior. The anterior wall is bounded by pectoralis major and
minor, the posterior wall by subscapularis, latissimus dorsi and teres
major, and the lateral wall by the intertubercular groove of the
humerus onto which the muscles of the anterior and posterior walls
insert. The base of the axilla is formed by skin and super¬cial fascia.
This allows an excellent window for ultrasound examination of the
axilla, which is useful in the assessment of soft tissue pathology such
as lymphadenopathy. The structures of the axilla are also well demon-
strated on MRI.

The musculature of the arm
The musculature of the upper arm is divided into two compartments
by the medial and lateral intermuscular septa, which extend from the
Fig. 12.7. Trans-scapular radiograph of the shoulder. The body of the scapula is
humerus to fuse with the deep fascia of the arm. The anterior compo-
projected behind the shaft of the humerus and the glenoid fossa is seen en
nent contains the ¬‚exor muscles: the biceps, coracobrachialis and
face.


117
alex m. barnacle and adam w. m. mitchell
The upper limb


ulnar at the elbow joint (Fig. 12.10). The radial tuberosity, onto which
biceps inserts, projects from the anteromedial surface of the radius,
just beyond the radial head. Supinator and pronator quadratus have
broad insertions onto the proximal and distal radius, respectively. The
distal radius is expanded to accommodate the insertions of the ¬‚exor
and extensor muscle groups of the wrist and hand. The distal radius is
angled medially. The lateral margin of the radius forms the styloid
process and the medial surface is grooved to accommodate the ulna at
the distal radioulnar joint.

The ulna
The expanded proximal ulnar has a deep-cupped anterior surface,
known as the trochlear notch, which articulates with the trochlea of
the humerus. The olecranon is formed by the most proximal aspect of
the ulna and ¬lls the olecranon fossa of the humerus on elbow exten-
sion. It gives insertion to the triceps. Anteriorly, the coronoid process
of the ulna projects from the border of the trochlear notch and gives
attachment to brachialis. The annular ligament, which holds the
radial head in articulation with the ulna at the proximal radioulnar

(a)




Radial head
Fig. 12.9. T1 weighted fat-suppressed (“fat-sat”) coronal MR arthrogram of the
shoulder joint. Gadolinium within the joint space is of high signal intensity,
highlighting the joint capsule and outlining the superior aspect of the glenoid
Radial
labrum. The articular cartilage is of intermediate signal intensity. No contrast tuberosity
spills into the subacromial-subdeltoid bursa, con¬rming that the supraspinatus
tendon is intact.



brachialis. The posterior compartment contains the extensor muscle
group: the medial, lateral, and long heads of the triceps.
The biceps has short and long heads, which unite in the distal third
of the arm; the short head arises from the coracoid process and the
Shaft of radius
long head from the supraglenoid tubercle. The tendon crosses the
elbow joint, inserting onto the radial tuberosity and fusing via the ¬‚at
tendon of biceps, known as the bicipital aponeurosis, with the deep
fascia of the medial aspect of the forearm.
Shaft of ulna
The coracobrachialis arises from the tip of the coracoid process and
inserts onto the medial aspect of the shaft of the humerus.
The brachialis arises from the anterior surface of the humerus and
inserts on to the anterior surface of the coronoid process of the ulna.
The triceps has three heads; the long head arises from the infragle-
noid tubercle of the scapula, and the medial and lateral heads arise
from the posterior aspect of the shaft of the humerus. The heads of
triceps combine to form a single strong tendon that inserts onto the
olecranon of the ulna.
Head of ulna


The forearm Radial and
ulna styloid
Fig. 12.10. Radiographs of
processes
The radius the radius and ulna:
The narrow proximal radius has a small, cupped head, which articu- Carpus (a) anteroposterior view,
lates with the capitellum of the humerus and the radial notch of the (b) lateral view.


118
alex m. barnacle and adam w. m. mitchell
The upper limb


(b) Fig. 12.10. Continued The ossi¬cation centers of the elbow should be considered as one
unit. The pattern of ossi¬cation follows the mnemonic CRITOL; the
secondary ossi¬cation centre for the Capitulum appears at 1 year of
age, the Radial head and Internal (medial) epicondyle at 5 years of age,
the Trochlea at 11 years, the Olecranon at 12 years and the lateral
Epicondyle at 13 years (Fig. 12.11). Fusion of the epiphyses with the
humerus should be complete by 17 years of age.
Radial head
(a)i
Oblique view
Radial
tuberosity




Humerus

Radius

Ulna
Capitulum




Ulna Radius

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