Atlas on X-ray and
Angiographic Anatomy
Atlas on X-ray and
Angiographic Anatomy
JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD
New Delhi • London • Philadelphia • PanamaHariqbal Singh MD DMRD
Professor and Head Department of Radiology
Shrimati Kashibai Navale Medical College Pune, Maharashtra, India
Parvez Sheik MBBS DMRE
Consultant Radiology
Shrimati Kashibai Navale Medical College Pune, Maharashtra, India
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Atlas on X-ray and Angiographic Anatomy
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Dedicated to
Our dear consorts Arvind Hariqbal
and Naasiya Musthafa
Anatomy is a nursery
offers framework to enter the infirmary, clasp it firmly
it will help analyze the pathology rightly with foundation in place
all is well
the value of radiology cannot be measured it can only be treasured.
Preface
Human anatomy has not transformed over the years but the advance in imaging has changed the perception of structural details. Thorough understanding of the normal anatomy is an essential prerequisite to precise diagnosis of pathology.
Atlas on X-ray and Angiographic Anatomy is loaded with meticulously labeled illustrations. This book is
steal a look into the anatomy in an easy and understandable manner.
This atlas is meant for undergraduates, residents in orthopedics and radiology, orthopedic surgeons, radiologists, general practitioners and other specialists. It is meant for medical colleges, institutional and departmental libraries and for stand-alone X-ray and orthopedic establishments. They will find the book useful.
Hariqbal Singh
Parvez Sheik
Acknowledgments
We thank Professor MN Navale, Founder President, Sinhgad Technical Educational Society and Dr Arvind V Bhore, Dean, Shrimati Kashibai Navale Medical College, Pune, Maharashtra, India, for their kind acquiescence in this endeavor.
Our special thanks to the consultants Dr Sasane Amol, Roshan Lodha, Santosh Konde, Shishir Zargad, Yasmeen Khan, Shivrudra Shette, Anand Kamat, Varsha Rangankar, Prashant Naik, Abhijit Pawar, Aditi Dongre, Rajlaxmi Sharma, Manisha Hadgaonkar, Subodh Laul, Sumeet Patrikar, Ronaklaxmi, Shrikant Nagare and Vikash Ojha, who have helped in congregation of this imagery and for their indisputable help in assembly of this educational entity.
Our special appreciation to the technicians Mritunjoy Srivastava, Premswarup, Sudhir Mane, Sonawane Adinath, Deepak Shinde, Vinod Shinde, Yogesh Kulkarni, Pravin Adlinge, Parameshwar and Amit Nalawade, for their untiring help in retrieving the data.
Our gratitude to Sachin Babar, Anna Bansode, Sunanda Jangalagi and Shankar Gopale, for their clerical help.
We are grateful to God and mankind who have allowed us to have this wonderful experience.
Last but not least, we would like to thank M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, who took keen interest in publishing the book.
Contents
1. Skull
1
2. Spine
13
3. X- ray Chest
28
4. Abdominal Radiograph
34
5. Upper Limb
37
6. Lower Limb
49
7. Angiograms
67
8. Radiological Procedures
103
9. Ossification Centers
127
10. Production of X-rays
133
11. Digital Subtraction Angiography
135
12. Computed and Digital Radiography
137
13. Picture Archiving and Communications System
140
14. Computed Tomography Contrast Media
142
INTRODUCTION
The term ‘Skull’ includes the mandible, likewise the term ‘Cranium’ is the ‘Skull’ without the mandible (Figs 1.1 and 1.2). The cranial cavity has a roof (cranial vault) and floor (base of the skull).
The frontal bone occupies the upper third of the anterior view of the skull; the rest is formed by the maxillae and mandible. The frontal bone extends downwards to form the upper margins of the orbits. Medially the frontal bone articulates with the frontal process of each maxilla. Laterally the frontal bone projects as the zygomatic process to make the frontozygomatic suture with the zygomatic bone at the lateral margin of orbit (Figs 1.3 to 1.6). The frontal bone articulates with the parietal bones at the coronal sutures (which run transversely).
The temporal bone consists of five parts– Squamous, mastoid, petrous, tympanic and styloid process. The squamous portion forms part of wall of temporal fossa and gives rise to zygomatic process. The mastoid portion contains the mastoid antrum, in adults it elongates into mastoid process. The mastoid antrum communicates with the remainder of mastoid air cells and with the epitympanum via the aditus ad antrum. The petrous portion is wedge-shaped and lies between the sphenoid bone anteriorly and occipital bone posteriorly. The tympanic portion lies below the squamous part and in front of the
mastoid process. The styloid portion forms the styloid process.
The temporal fossa is the area bounded by the superior temporal line, zygomatic arch and the frontal process of the zygomatic bone. The zygomatic arch is formed by the zygomatic process of the temporal bone and the temporal process of the zygomatic bone. The zygomatic process of the maxilla articulates with the zygomatic bone. The zygomatic bone forms the bony prominence of the cheek (Figs 1.7 to 1.10).
The styloid process is a part of the temporal bone, from its tip the stylohyoid ligament passes to the lesser horn of hyoid bone. At the base of the skull medial to the styloid process the petrous bone is deeply hollowed out to form the jugular fossa with an opening called as jugular foramen through which the internal jugular vein passes. Anterior to the jugular foramen the petrous part of the temporal bone is perforated by the carotid canal, allows the internal carotid artery to pass through it (Fig. 1.11). Between the basiocciput and the body of sphenoid bone lies the foramen lacerum, it allows the small emissary vein and meningeal branch of ascending pharyngeal artery to pass through it. The roof of the infratemporal fossa is pierced medially by the foramen ovale, through which passes the mandibular nerve, lesser petrosal nerve, accessory meningeal artery and emissary veins. The base of the spine of sphenoid is perforated by the foramen spinosum
Skull
C H A P T E R
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2
Figs 1.1A to D: CT scan multiplanar reconstruction images of skull: (A) Frontal view; (B) View from back;
(C) Lateral view; (D) View from below
which allows the middle meningeal vessels to pass through it. The stylomastoid foramen lies behind the base of styloid process. Medial to the third molar tooth on either side is the greater palatine, foramen between the horizontal plate
of palatine bone and the palatine process of the maxilla, the greater palatine vessels and nerves pass through it. Behind the greater palatine, there are numerous small openings called the lesser palatine foramina in the pyramidal process of
A B
Figs 1.2A and B: X-ray skull—AP view
A
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4
Figs 1.3A and B: X-ray skull—Lateral view
A
Fig. 1.4: X-ray skull—Mastoid view (Schuller’s view)
Fig. 1.5: X-ray skull—Lateral view (close-up view to show the pituitary fossa)
palatine bone through which the lesser palatine vessels and nerves pass.
There are two parietal bones on either side of skull. They are seen better on lateral views of skull and they articulate with the frontal bone anteriorly at the coronal sutures. Posteriorly, the parietal bones articulate with occipital bone and temporal
bone mastoid process at lambdoid suture. The bregma is the area in midline where the coronal sutures and the two parietal bones meet. Behind the bregma, the parietal bones articulate in the midline sagittal suture. This midline sagittal suture ends at the lambda in posteriorly. The lambda is the area posterior where the sagittal suture ends
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Fig. 1.6: X-ray skull—PA view (Caldwell view for paranasal sinuses)
Fig. 1.8: X-ray skull—Reverse Water’s view
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8
Fig. 1.10: X-ray skull—Submentovertical view
in midline and the apex of occipital bone reaches out to join it in midline. The mastoid region of the temporal bone articulates with the parietal and occipital bones posteriorly, the mastoid process projects down at the sides. Inferiorly the parietal bones articulate with the squamous portion of temporal bone on either side.
The occipital bone on its lower surface has a ridge which is pointing towards the base of the mastoid process; this is called the external occipital protuberance. The basiocciput extends forward from the foramen magnum and fuses with the basis phenoid. The foramen magnum is located in the basilar part of the occipital bone (basiocciput). The pharyngeal tubercle is a slight bony prominence in front of the foramen magnum. One-third of the foramen magnum lies in front and two-thirds behind an imaginary line joining the tips of the mastoid processes. This is contrary to the occipital condyles, where two-thirds of the condyles lie in front of this imaginary line.
The internal surface of the base of skull is divided into the anterior, middle and posterior cranial fossa. The orbital part of the frontal bone forms a large part of anterior cranial fossa. The anterior cranial fossa extends up to the posterior edge of the lesser wing of sphenoid. The anterior cranial fossa articulates with the cribriform plate medially. The crista galli is a sharp projection of the cribriform plate.
The sphenoid bone contributes to the middle cranial fossa. The small midline body of sphenoid bone contains the sella turcica (means ‘Turkish saddle’), a small elevation in front of sella turcica is called tuberculum sellae (Fig. 1.5). The tuberculum sellae has three small spikes, the middle spike is called the middle clinoid process, the two lateral spikes are called anterior clinoid process. At the posterior edge of the sella turcica is an elevation called the dorsum sellae, which has two lateral spikes called the posterior clinoid process. A fibrous portion of the dura forms the roof of the sella turcica extending from
the tuberculum sellae to the dorsum sellae and is called the diaphragm sellae. The diaphragm sellae has a central opening to allow the pituitary stalk and vessels to pass through it.
The posterior cranial fossa extends from the petrous temporal bone anteriorly to the internal occipital protuberance in the midline. The floor is formed by the foramen magnum, basiocciput and posterior part of sphenoid bone. The dorsum sellae slopes downwards in front of foramen magnum, this slope is called the clivus.
The mandible or the jaw bone is a U–shaped, a horizontal central part with two lateral ramus on each side. The posterior border of each ramus has a condyle with a neck which articulates with the temporal bone forming the temporomandibular joint, while the anterior border of each ramus is sharp and is called the coronoid process (Figs 1.1 to 1.4).
The temporormandibular joint is a synovial joint between the head (condyle) of the mandible and mandibular fossa on the undersurface of the squamous part of the temporal bone. The joint is separated into the upper and lower cavities by a fibrocartilaginous disc within it. There is no hyaline cartilage within the joint which makes it an atypical synovial joint. The synovial membrane lines the inside of the capsule and the intracapsular posterior aspect of the neck of the mandible. The articular disc is attached around its periphery to the inside of the capsule and to the medial and lateral poles of the head of the mandible. The joint is more stable with the teeth in occlusion than when the jaw is open. The movements at the temporomandibular joint are depression and elevation (opening and closing of the jaws), side to side grinding movements, retraction and protaction movements (retrusion and protrusion).
THE NASAL CAVITY AND NASAL SEPTUM
The nasal cavity is pear-shaped, broader below and narrower at the top. From its lateral walls the
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10
conchae project into the nasal cavity. There are three conchae—Superior, middle and inferior conchae. The superior concha is small and is found high in nasal cavity, its lower edge overlies the superior meatus. The sphenoethmoidal recess lies above and behind the superior concha and receives the ostia of sphenoidal sinus. The middle concha lies between the superior and inferior concha. The area in front of the middle meatus is the atrium of nose. Posteriorly, the middle meatus is related to the splenopalatine foramen. The inferior concha lies below the middle concha articulates anteriorly with the maxilla and posteriorly with the palatine bone. The nasal septum (Fig. 1.12) is normally in the midline, it consists of bone (vomer) and cartilage. It has a lower free margin, superiorly it articulates with the medial ends of frontal bone and also the frontal process of maxilla. The two maxillae on either side meet in the midline and project forwards as the anterior nasal spine at the lower margin of the nasal aperture. The vomer articulates with the sphenoid body and forms the posterior border of the septum. The septal cartilage forms the anterosuperior part of the septum. The floor of the nose is formed by the upper surface of the hard palate. The central part of the roof of nose is the cribriform plate of the ethmoid.
THE PARANASAL SINUSES
The paranasal sinuses all arise as evaginations from the nasal fossa. It comprises of frontal sinuses, maxillary sinuses, sphenoid sinuses and ethmoidal sinuses. The nasal cavity contains the superior meatus, middle meatus and the inferior meatus. The superior meatus drains the posterior ethmoidal air cells and sphenoidal sinuses. The middle meatus drains the frontal sinuses, maxillary sinuses and anterior ethmoidal air cells. The osteomeatal complex comprises of the uncinate process, ethmoid infundibulum, maxillary sinus ostium, middle turbinate, frontal recess and ethmoid bulla. The inferior meatus has opening for the nasolacrimal duct (Figs 1.8 to 1.12).
The maxillary sinus lies in the body of maxilla, the sinus is triangular in shape, the apex in the zygomatic process of maxilla and the base towards the lateral wall of the nose. The roof of the sinus is the floor of the orbit. The floor of the sinus is formed by the alveolar part of maxilla. The infratemporal fossa and pterygopalatine fossa lies behind the posterior wall of maxillary sinus. The ostium of maxillary sinus is on the superomedial aspect of the sinus and opens into the middle meatus on the same side into the nasal cavity (Figs 1.2B and 1.3B).
The ethmoidal sinus lies between the nasal cavity and orbit. The sinus is divided by multiple thin bony septa into the anterior and posterior group of ethmoidal air cells. The lateral wall of the ethmoidal sinus forms a part of the medial wall of orbit; it is paper thin and is called the lamina papyracea. The ostia of anterior ethmoidal air cells drain into the middle meatus. The ostia of posterior ethmoidal air cells drain into the superior meatus.
The sphenoidal sinus occupies the body of sphenoid bone. A vertical septum divides the cavity into two unequal halves. The roof of sphenoid sinus is formed by pituitary fossa and middle cranial fossa. Laterally the sphenoid sinus is related to the cavernous sinus and internal carotid artery. Posteriorly, the sphenoid sinus is related to the posterior cranial fossa and pons. The ostium of sphenoidal sinus is in the anterior wall of the sinus and opens into the superior meatus or into the sphenoethmoidal recess.
The frontal sinuses are formed within the frontal bone on either side near midline. Its floor forms the roof of orbit medially. Posteriorly the frontal sinus is related to anterior cranial fossa. The ostium of frontal sinus is at its lower medial edge and drains into the middle meatus in nasal cavity or in some cases into the anterior ethmoidal air cells.
THE ORBIT
The bony orbit is a cavity, shaped like a pyramid with its apex posteriorly and the base forming
Fig. 1.12: X-ray skull—Lateral view (for nasal bones)
Fig. 1.13: X-ray skull—AP view in a 2-year-old child
the orbital margins anteriorly. The orbital roof is formed by the frontal bone, which separates the orbit from the anterior cranial fossa. The orbital floor is formed by the orbital plate of the maxilla,
portions of the palatine bone and the zygoma (Figs 1.10, 1.13 and 1.14). The maxillary portion of orbital floor is usually involved in blow out fractures. The medial orbital wall is the thinnest
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Fig. 1.14: X-ray skull—Lateral view in a 2-year-old child
of all the orbital walls and comprises of frontal process of the maxilla, lacrimal bone, lamina papyracea and bony sphenoid. The lateral wall of orbit is formed by the zygoma and greater wing of sphenoid. The superior orbital fissure is a space between the greater and lesser wings of sphenoid. The inferior orbital fissure is formed by the maxilla, the palatine bone and the greater wing of sphenoid. The optic canal lies within the lesser wing of sphenoid, the optic nerve and ophthalmic artery encased in the dural sheath pass through it.
Structures passing through the superior orbital fissure: Superior ophthalmic vein, the rectus muscles (superior, inferior, medial and lateral), lacrimal nerve, frontal nerve, trochlear nerve, oculomotor nerve, abducent nerve, nasociliary nerve.
Structures passing through the inferior orbital fissure: Infraorbital artery, inferior ophthalmic vein, zygomatic nerve, infraorbital nerve.
Structures passing through the optic canal: Optic nerve, ophthalmic artery.
Spine
C H A P T E R
2
Two common radiographic views taken for the spine are the AP view and the lateral view. Most disease process involving the vertebral body or the posterior elements can be noted on these views, however, special views like posterior oblique view may be necessary in some cases.
The spine is made up of five groups of vertebrae. The portion of spine around the neck region is cervical spine. It is formed by first seven vertebrae which are referred as C1 to C7, followed by 12 thoracic vertebrae referred as T1 to T12 and subsequently five lumbar vertebrae L1 to L5 in the low back area. The sacrum is a big triangular bone at the base, its broad upper part joins the L5 vertebra and its narrow lower part joins the coccyx or tail bone.
CERVICAL SPINE
It starts with first cervical vertebra (C1) attached to the bottom of the skull, the basiocciput. Atlas is the name given to C1 vertebra as it supports and balances the weight of the skull. It has practically no body or spinous process, it appears as two thickened bony arches which join anteriorly as anterior tubercle and posteriorly as posterior tubercle. These two thickened bony arches join to form a large hole with two transverse processes. On its upper surface, the atlas has two facets
that unite with the occipital condyles of the skull. Structure of atlas is unique and has a large opening which accommodates spinal cord (Figs 2.1 and 2.2).
The second vertebra is the “axis”, it lies directly beneath the atlas vertebra. It bears large bony tooth-like protrusion on its summit, the odontoid process or the dens. This process projects upward and lies in the ring of the atlas. The joints of the axis give the neck its ability to turn from side to side, i.e. left and right, as the head is turned, the atlas pivots around the odontoid process. The odontoid process arises from anterior part of C2 vertebrae and articulates with the C1 vertebrae above to form the atlanto-occipital joint (Figs 2.2, 2.3 and 2.10). Special views may be taken on plain radiographs to demonstrate the atlantoaxial joint and atlanto-occipital joint.
The transverse processes of the cervical vertebrae have large transverse foramina to allow the vertebral arteries into the cranium. The spinous processes of the second to fifth cervical vertebrae are forked providing attachments for various muscles.
C3-C6 vertebrae have a typical structure. C7 vertebra is called vertebra prominens because of a long prominent thick nearly horizontal not bifurcated spinous process which is palpable from the skin (Figs 2.4 to 2.9).
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Figs 2.1A to D: (A) Cervical spine MRI sagittal section T2WI; (B) Multiplanar reconstructed CT scan images of cervical spine
posterior view; (C) View from above; (D) Lateral view
A B C D
There are eight cervical spinal nerves and the neural foramina of cervical spine allow the cervical spinal nerves to exit out of the spinal canal.
DORSOLUMBAR SPINE
It consists of twelve vertebrae in the chest area, the first thoracic vertebra articulates with the C7 vertebra above and the last thoracic vertebra articulates with the first lumbar vertebra below. The thoracic vertebrae are larger in size than those in the cervical region. They have long, pointed spinous processes that slope downward, and have facets on the sides of their bodies that join with ribs. From the third thoracic vertebra onwards to the last thoracic vertebra, the bodies of these bones increases in size gradually (Figs 2.11 to 2.13). This reflects the stress placed on them by the increasing amounts of body weight they bear. There are five “lumbar vertebrae” in the
lower back. They have larger and stronger bodies to provide support. The transverse processes of these vertebrae project backward at sharp angles, while their short, thick spinous processes are directed nearly horizontally.
LUMBOSACRAL SPINE
The 5 lumbar vertebrae in the lower back are prone to injuries. On AP views the pedicles and transverse process need to be examined to rule out any fracture. On lateral views, the curvature of lumbar spine needs to be examined, note any slipping of one lumbar vertebra over the other. The intervertebral disc spaces should be equal in size (Figs 2.14 to 2.16). Additional views like posterior oblique view may be necessary in some cases. The sacrum is a large triangular bone on AP view at the base of the lower spine. Its broad upper part joins the lowest lumbar vertebrae and its narrow lower part joins the coccyx or “tail
A
B
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Fig. 2.3: X-ray cervical spine—Lateral view for C1-C2 vertebrae
bone” (Fig. 2.17). The sides are connected to the iliac bones (the largest bones forming the pelvis). The sacrum is a strong bone and rarely fractures. The five vertebrae that make up the sacrum are separate in early life, but gradually become fused between the eighteenth and thirtieth years. The spinous processes of these fused bones are represented by a ridge of tubercles. The weight of the body is transmitted to the legs through the pelvic girdle at these joints.
COCCYX
It is the lowest part of the vertebral column and is attached by ligaments to the margins of the sacral hiatus. It is better viewed on lateral views of sacrum with coccyx (Fig. 2.17). Sometimes bowel gases may obscure a clear picture of coccyx. When a person is sitting, pressure is exerted on the coccyx, and it moves forward, acting like a shock absorber. Sitting down with force may cause the coccyx to be fractured or dislocated.
GENERAL FEATURES OF SPINE
The vertebral body is shaped like an hourglass, thinner in the center with thicker ends. Outer cortical bone extends above and below the
superior and inferior ends of the vertebrae to form rims. The superior and inferior endplates are contained within these rims of bone. The bodies of adjacent vertebrae are joined on the front surfaces by “anterior ligaments” and on the back by “posterior ligaments”. A longitudinal row of the bodies supports the weight of the head and trunk.
Intervertebral discs are found between each vertebra. They are better viewed on lateral radio-graphs. Intervertebral discs make up about one-third of the length of the spine and constitute the largest organ in the body without its own blood supply. The discs receive their blood supply through movement. The discs are flat, round structures about a quarter to three quarters of an inch thick with tough outer rings of tissue called the annulus fibrosis that contain a soft, white, jelly-like center called the nucleus pulposus. Flat, circular plates of cartilage connect to the vertebrae above and below each disc. Intervertebral discs separate the vertebrae, and act as shock absorbers for the spine.
Projecting from the back of each body of the vertebra are two short rounded stalks called “pedicles”. They form the sides of the “vertebral foramen”. They can be viewed on both AP and
Figs 2.4A and B: X-ray cervical spine—AP view
A
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Fig. 2.5: X-ray cervicothoracic junction—AP view
Fig. 2.6: X-ray cervical spine swimmer’s view for cervicothoracic junction
lateral radiographs. Pedicles extend posteriorly from the lateral margin of the dorsal surface of the vertebral body.
The laminae are two flattened plates of bone extending medially from the pedicles to form
the posterior wall of the vertebral foramen. These laminae are better seen on lateral views on radiographs. They fuse posteriorly in the midline to become spinous process. The pars interarticularis is a special region of the lamina
Fig. 2.7: X-ray cervical spine right posterior oblique for intervertebral foramina
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Fig. 2.9: X-ray cervical spine—Lateral view in extension
Fig. 2.10: X-ray cervical spine open mouth view for atlantoaxial junction
between the superior and inferior articular processes. A fracture or congenital anomaly of the pars may result in a spondylolisthesis.
The pedicles, laminae, and spinous process together complete a bony vertebral arch around the vertebral opening, through which the spinal cord passes. Between the pedicles and laminae
of a typical vertebra is a “transverse process” that projects laterally and toward the back. Various ligaments and muscles are attached to the transverse process. Projecting upward and downward from each vertebral arch are “superior” and “inferior” arti culating processes. These processes bear cartilage-covered facets by
Figs 2.11A to C: Multiplanar reconstructed CT scan images of dorsolumbar spine: (A) Posterior view;
(B) Anterior view; (C) Lateral view
A B C
which each vertebra is joined to the one above and the one below it. These facet joints facilitate smooth gliding movement of one vertebra on another to produce twisting motions and rotation of the spine. Facet joints are also called as zygapophyseal joints.
On the surfaces of the vertebral pedicles are notches that align to create openings, called “intervertebral foramina”. These openings provide passageways for spinal nerves that exit out of the spinal cord.
SPINAL CANAL AND SPINAL CORD
The spinal canal is bounded anteriorly by the vertebral bodies, the intervertebral discs,
posterior longitudinal ligament. Posteriorly it is related to the lamina and ligamentum flavum. Laterally on either side, it is related to the pedicles. The intervertebral foramina contain the spinal nerves, posterior root ganglia, spinal arteries and veins. The vertebral canal contains the spinal cord. The spinal canal encases the spinal cord. The bones and ligaments of the spinal column are aligned in such a manner to create a column that provides protection and support for the spinal cord. The outermost layer that surrounds the spinal cord is the dura mater, which is a tough membrane that encloses the spinal cord and prevents cerebrospinal fluid from leaking out. The space between the dura and the spinal canal is called the epidural space. This
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Figs 2.12A and B: X-ray dorsolumbar spine—Lateral view
A
Figs 2.13A and B: X-ray dorsolumbar spine—AP view
A
B
space is filled with tissue, vessels and large veins. Up to the third month of fetal life, the spinal cord is about the same length as the canal. The growth of the canal outpaces that of the cord from the 3rd month onwards. In an adult the lower end of the spinal cord usually ends at approximately the first lumbar vertebra, where it divides into many
individual nerve roots that travel to the lower body and legs. This collection of group of nerve roots is called the “cauda equina”. MRI spine is the modality of choice to examine the spinal canal and spinal cord. CT spine is preferred in cases of acute trauma and those who cannot undergo MRI studies.
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Figs 2.14A to D: Multiplanar reconstruction CT scan images of lumbosacral spine: (A) Posterior view; (B) Lateral view; (C)
Lateral view showing the intervertebral neural foramina; (D) Oblique view
A B
C
D
SOME DIFFERENTIATING FEATURES BETWEEN CERVICAL, THORACIC AND LUMBAR VERTEBRAE
C3-C6 vertebrae have atypical features. The body of these four vertebrae is small and broader from side-to-side than from front-to-back. The pedicles are directed laterally and backward. The laminae are narrow, and thinner above than below. The vertebral foramen is large and has triangular shape. The spinous process is short and bifid. Superior articular facets face backward, upward, and slightly medially and inferior face forward, downward, and slightly laterally.
The foramen transversarium is an opening in the transverse processes of the seven cervical verte brae. It gives passage to the vertebral artery, vein and plexus of sympathetic nerves in each of the vertebrae except the seventh, which lacks the artery. C7 has enlarged spinous process called the vertebral prominence.
The thoracic vertebrae have costal facets for ribs on either sides of the vertebral body. They increase in size gradually from T3 vertebra downwards.
The lumbar vertebrae have neither a foramen in transverse process nor costal facets; they are larger than the dorsal and cervical vertebrae in size.
RADIOLOGICAL IMPORTANCE OF
VERTEBRAL COLUMN IN SPINAL INJURIES
The vertebral column can be sub divided as anterior column, middle column and the posterior column. Injuries involving the middle and posterior columns result in unstable injuries. • Anterior column is formed by anterior longi tudinal ligament, anterior annulus fibrosus and anterior part of vertebral body.
• Middle column is formed by posterior longi tudinal ligament, posterior annulus fibrosus and posterior part of vertebral body.
Figs 2.15A and B: Lumbosacral spine X-ray—AP view
A
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Figs 2.16A and B: Lumbosacral spine X-ray—Lateral view
A
Fig. 2.17: Sacrum and coccyx X-ray—Lateral view
• Posterior column includes posterior elements and ligaments.
RADIOLOGICAL IMPORTANCE OF CRANIOVERTEBRAL JUNC TION
Chamberlain line is the line between posterior part of hard palate and posterior margin of
foramen magnum. Normally the tip of odontoid process lies at or below this line. Basilar line is the line along the clivus and it usually falls tangent to the posterior aspect of the tip of odontoid.
Craniovertebral angle (Clivus-canal angle) is angle between basilar line and a line along posterior aspect of odontoid process. If this angle is < 150º, cord compression can occur on the ventral aspect.
When viewing the chest X-ray, check first for the technical factors: • Projection AP or PA view, etc. • Orientation (right or left) • Rotation • Penetration • Degree of inspiration.
On posteroanterior (PA) view, the X-ray beam first enters the patient from the back and then passes through the patient to the film that is placed anterior to the patient’s chest. It uses 80-120 kV and focus film distance of 6 feet. On a PA film, lung is divided radiologically into three zones:
1. Upper zone extends from apices to lower border of 2nd rib anteriorly.
2. Middle zone extends from the lower border of 2nd rib anteriorly to lower border of 4th rib anteriorly.
3. Lower zone extends from the lower border of 4th rib anteriorly to lung bases. Please note that radiological division of lung in upper, middle and lower zone does not depict anatomical lobes of the lung. ANATOMICAL SEGMENTAL DIVISION OF LUNGS Right lung has three lobes: 1. Upper lobe which has an apical, anterior and a posterior segment. 2. Middle lobe has a lateral and a medial segment. 3. Lower lobe has superior segment, medial
basal segment, anterior basal segment, lateral basal segment and a posterior basal segment. Left lung has two lobes:
1. Upper lobe which has an apicoposterior, anterior, superior lingular and an inferior lingular segment.
2. Lower lobe has superior segment, anterior basal segment, lateral basal segment and a posterior basal segment. Left lung has no middle lobe. When viewing the chest X-ray PA view look for (Figs 3.1 to 3.4):
• Check patient’s name and date • Lung fields
• Hilum – Normally left hilum is higher than right hilum
• Cardiac shape and borders • Mediastinum
• Diaphragm—right diaphragm is higher than left diaphragm
• Costophrenic angles should be well-defined and acute
• Trachea should be slightly deviated to the right around the aortic knuckle
• Look at bones for any lesions and fractures • Look for soft tissue abnormalities
• Look at the area under the diaphragm. When viewing the chest X-ray lateral view (Figs 3.5 and 3.6):
X-ray—Chest
C H A P T E R
Figs 3.1A to E: CT scan multiplanar reconstructed (MPR) images of thorax: (A) View from front; (B) Lateral view;
(C) View from back; (D) CT scan coronal section of thorax; (E) CT scan axial section of thorax
Fig. 3.2: X-ray chest—PA view
A B C
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Fig. 3.3: X-ray chest—PA view mediastinal borders
Fig. 3.4: X-ray chest PA view—Cardiothoracic ratio (Cardiothoracic ratio = a+b c ; Cardiothoracic ratio is estimated from the PA view
of chest to calculate the size of heart. It is the ratio between the maximum transverse diameter of heart and the maximum width of thorax above the costophrenic angles. a = Right heart border to midline; b = Left heart border to midline and c = Maximum thoracic diameter above costophrenic angles from inner borders of ribs
• Check patient name and date
• Identify the diaphragms (gastric air bubble lies under the left hemidiaphragm
• Compare the lung fields in retrosternal space, retrocardiac space and supracardiac space, they should all have the same density on the X-ray film
• Look carefully at the retrosternal space, a mass in this space will obliterate this space turning it white on the X-ray film
• Check the position of horizontal fissure and oblique fissures
• Check the density of the hila
• Do not forget to carefully examine the vertebral bodies on the chest X-ray lateral view.
Lung Fissures
They are thickening of the septae in the lung parenchyma. For a fissure to be seen on a radiograph, the X-ray beam has to be tangential to it. The right lung has horizontal and oblique
fissures while the left lung has only the oblique fissure.
The location of these fissures are:
• On chest X-ray, PA view the horizontal fissure appears as a faint white line that runs from the midpoint of the right hilum to the anterior chest wall.
• On chest X-ray, lateral view the oblique fissure runs obliquely downwards from the D4/D5 vertebral level, crossing the hilum in front and continuing downward direction to end near the anterior 1/3rd of diaphragm.
Locating Lesions of the Lungs
We need to have both PA and lateral views to locate a lesion on chest X-ray. On PA view locate the lung zone where the lesion lies, also look at the borders of the lesion well-defined/ill-defined/silhouette sign. On lateral view identify the horizontal fissure and oblique fissure. After this is done try to localize the lesion carefully:
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Fig. 3.6: X-ray chest—Apicogram
• Lesion in right lung field
– If the lesion lies posterior to the oblique fissure it must lie within the lower lobe, does not matter how high it appears on the PA view.
– If the lesion lies anterior to the oblique fissure it may be in the upper or middle lobe.
– If the lesion is below the horizontal fissure it is in the middle lobe
– If the lesion lies above the horizontal fissure it is in the upper lobe.
• Lesion in left lung field
– If the lesion is behind the oblique fissure it must be in the lower lobe.
– If the lesion is anterior to the oblique fissure then it must be in upper lobe (there is no middle lobe in left lung).
IMPORTANT POINTS TO OBSERVE ON CHEST X-RAYS
• In a well-centered chest X-ray, medial ends of clavicles are equidistant from vertebral spinous process. Both lung fields are of equal radiolucency.
• Both hila are concave outwards. The pulmonary arteries, upper lobe veins and bronchi contribute to the making of hilar shadows (Fig. 3.7).
• The normal length of trachea is 10 cm, it is central in position and bifurcates at T4-T5 vertebral level. Left atrial enlargement increases the tracheal bifurcation angle (normal is 60° to 75°). An inhaled foreign body is likely to lodge in the right lung due to the fact that the right main bronchus is shorter, straighter and wider than left.
• Mediastinum is the space between the lungs. It is divided into a superior and an inferior com-partment. Superior compartment consists of the thoracic inlet. Inferior compartment
has anterior, middle and posterior subcompartments. Retrosternal region is included in the anterior compartment, heart lies in the middle com partment and descending aorta with esophagus and paraspinal region is located in the posterior mediastinal compartment. Thymus is located in the anterior part of superior as well as inferior compartment of mediastinum. • Normal heart shadow is uniformly white
with maximum transverse diameter less than half of the maximum transthoracic diameter. Cardio thoracic ratio is estimated from the PA view of chest (Fig. 3.4). It is the ratio between the maximum transverse diameter of the heart and the maximum width of thorax above the costophrenic angles: a = right heart border to midline, b = left heart border to midline, c = maximum thoracic diameter above costophrenic angles from inner borders of ribs. Cardiothoracic ratio = a + b/ c. Thus on chest X-ray PA view the cardiothoracic ratio is less than 1/2 the maximum thoracic diameter, in children this cardiothoracic ratio may be increased. In adults the normal cardiothoracic ratio is 2:1.
• Borders of the mediastinum are sharp and distinct (Fig. 3.3). The right heart border is formed by superior vena cava superiorly and right atrium inferiorly, the left heart border is formed by the aortic knuckle superiorly, left atrial appendage and left ventricle inferiorly. • The right ventricle lies anteriorly, posterior to
the sternum and the right atrium lies on the right lateral side. The left ventricle lies on the entire left side, the outlet of the left ventricle and the ascending aorta lie in the center of the heart. The left atrium is the most posterior chamber of the heart. The inferior vena cava is seen further caudally just at the section the diaphragm appears together with the upper part of liver.
The standard projections requested for abdominal radiographs are (Figs 4.1 and 4.2):
• Supine • Erect
• Lateral decubitus
The radiation exposure of an abdominal radiograph is equivalent to 28 chest radiographs.
Key to densities in abdominal radiographs: • Black—Gas • White—Calcified structures • Grey—Soft tissues • Darker gray—Fat • Intense white—Metallic objects. Always view the radiograph using a view box. The contrast of outlines of structures depends on the differences between their densities. These differences are less apparent on the abdominal radiograph as most structures are of similar density—Mainly soft tissue.
On a routine supine, abdominal radiograph look for the following:
• Dark margins outlining the spleen, liver, kidneys, bladder and psoas muscles—This indicates intra-abdominal fat.
• Gas in—Body of stomach, descending colon, small intestines.
• Fecal matter in cecum gives it a mottled appearance, seen as a mixture of gray densities representing a gas-liquid-solid mixture. • Pelvic phleboliths are small round/oval
calcific densities in pelvic cavity
• A dark skinfold across the upper abdomen is normal finding
• Check the bony pelvis, spine and visualized ribs
• The heart shadow should be on the left side above the diaphragm
• Check whether the right ‘R’ marker is placed on the right side of the abdominal radiograph • Make sure that the abdominal radiograph
covers both the hemidiaphragms to the inguinal canal regions
• Check the lung bases.
On an erect abdominal radiograph the following changes occurs:
• The air rises
• Fluid goes down due to gravity
• The transverse colon, small bowel loops and kidneys drop down a bit lower due to gravity • A slight increase in radiographic density in
lower abdomen
• The lung bases appear clearer as the diaphragms move down a little
• The liver and spleen become more visible. The abdominal radiograph is most helpful in cases of acute abdomen. A normal initial abdominal radiograph does not exclude intra-abdominal trauma, follow up radiographs, ultrasound, CT scan and MRI (Figs 4.1A to E) may be necessary. Abnormal air-fluid levels become easier to visualize on erect abdominal radiographs. Gas under diaphragm is seen in
Abdominal Radiograph
C H A P T E R
cases of perforated viscus. Also remember not to waste any time if the patient’s condition is critical, stabilize the patient and shift the patient to operating theater if needed.
Radiation exposure in early pregnancy can be disastrous. It is always safer in female patients of reproductive age group to check the date of their last menstrual period. Written consent form is needed confirming that the patient is not pregnant/ unlikely to be pregnant at the time of examination. Additional points to note while examining abdominal radiographs: • Maximum diameter of small bowel should not exceed 3 cm and that of large bowel by more than 5 cm in diameter. • Cecum is said to be dilated if it measures more than 8 cm. • The haustra of the large bowel extends only a third of the way across the bowel from each side, whereas the valvulae conniventes of the small bowel traverse from wall to wall.
• Presence of small amounts of intraluminal gas throughout the gut is normal, but if found in excess may be abnormal. Also absence of bowel gas in one area may indicate bowel pathology. • Presence of extraluminal gas is abnormal
(look for it under the diaphragm, in the bowel wall, in biliary system).
• Metallic objects may appear as bright densities, so ask for appropriate history of
Figs 4.1A to E: CT scan (A to C) multiplanar reconstructed images of abdomen: (A) Coronal view; (B) Sagittal view; (C) Axial view; (D) MRI-T2WI coronal section of abdomen; (E) MRI-T2WI axial section of abdomen
A B C
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Fig. 4.2: X-ray abdomen—Supine view
operations, trauma, ingestion of foreign body, therapeutic/diagnostic procedures.
• Look for nasogastric tube placements, catheters, etc. to mention them in the report. • Look for normal calcified structures which
can cause diagnostic difficulty—excessive costal cartilage calcification, calcified aortic/ splenic arteries, pelvic phleboliths, calcified mesenteric lymph nodes, etc.
• Normal liver has a fairly pointed tip, if this tip appears more rounded with displacement of adjacent intra-abdominal structures it is suggestive of hepatomegaly.
• The spleen is not normally seen on abdominal radiographs, when spleen is enlarged more than 15 cm, it displaces the adjacent intra-abdominal organs and becomes more obvious on abdominal radiographs.
• Normal kidneys extend from the lower margin of 12th dorsal vertebra to the upper margin of
3rd lumbar vertebra, the left kidney is usually slightly larger in size and slightly higher placed as compared to the right kidney. The outline of kidney visible on abdominal radiograph is due to perinephric fat.
• An abdominal mass can arise anywhere in abdomen and would produce a dense area with displacement of bowel loops around it, calcification may also occur within it, CT scan maybe required to investigate such masses. • A full bladder appears in the pelvic cavity as a
smooth rounded mass of uniform density, the outline is due to perivesical fat tissue.
• Retroperitoneal masses usually obscure or displace the psoas muscle outline on abdominal radiographs.
• An erect chest radiograph and not abdominal radiograph is the best projection to diagnose a small pneumoperitoneum (gas in the peritoneal cavity).
SHOULDER JOINT
It is a ball and socket joint and can produce a range of movement such as adduction, abduction, extension and flexion. The head of humerus articulates with the shallow glenoid cavity of scapula thus connecting the upper limb to the chest (Figs 5.1A and B). The joint is made more stable by the articular capsule, ligaments, glenoid labrum and the rotator cuff. The labrum is a fibrocartilaginous rim attached
around the margin of the glenoid cavity. It deepens the articular cavity, cushions and stabilizes the humeral head. The articular capsule completely encircles the joint; it is attached to the circumference of the glenoid cavity beyond the labrum. The ligaments of the glenohumeral joint are coracohumeral ligament and glenohumeral ligament. The rotator cuff surrounds the shoulder joint; it is formed by tendons of four muscles— Supraspinatus, infraspinatus, teres minor, subscapularis and inserts into anatomical neck
Figs 5.1A and B: (A) Multiplanar reconstructed CT scan image of shoulder joint;
(B) MRI-T1WI coronal section of shoulder joint
A B
Upper Limb
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and tuberosities of humerus. The rotator interval is the portion of the joint capsule which lies between the supraspinatus and subscapularis tendons. On AP view of shoulder joint (Figs 5.2 and 5.3) the normal acromioclavicular distance is <8 mm, coraco-clavicular distance is <13 mm, and the inferior margin of clavicle is in line with the inferior acromion.
UPPER ARM
Humerus is the long bone of upper arm. The head of humerus articulates with scapula superiorly at shoulder joint (Figs 5.4 and 5.5); inferiorly the humerus articulates with radius and ulna at elbow joint. The humerus at its upper end has a head and neck. The head of humerus is rounded almost like a sphere and is about four times the size of the glenoid cavity of scapula with which it articulates. The head of humerus
has two bony projections called the greater and lesser tuberosities which serve as attachments for muscles around the shoulder joint (Figs 5.6 and 5.7). The surgical neck of humerus lies at the junction with the shaft of humerus. The axillary nerve runs behind this neck and is likely to be injured in fractures of neck of humerus. The deltoid tuberosity is a bony prominence at the middle of the lateral side of shaft; and provides attachment to the fibers of deltoid muscle. The lower end of the humerus has articular surfaces for the elbow joint, capitulum and trochlea. The capitulum articulates with the head of radius while the trochlea partly articulates with the ulna. The olecranon fossa found on the posterior aspect of humerus at the distal end. Provides articulation for olecranon process of ulna. The medial and lateral epicondyles are projections of humerus, which provide attachment for muscles around the elbow joint.
Fig. 5.3: X-ray shoulder joint—Axial view
Fig. 5.4: X-ray shoulder joint—Transthoracic view
The soft tissues comprise mainly of muscles, arteries, veins and nerves and are divided by a medial intermuscular septum into anterior and posterior compartments. The biceps brachii,
brachialis and coracobrachialis muscles lie in the anterior compart ment. The triceps brachii and anconeus muscles lie in posterior compartment. The main action of biceps brachii is to supinate
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Fig. 5.6: X-ray upper arm—AP view
Figs 5.5A and B: (A) Multiplanar reconstructed CT scan image of upper arm; (B) MRI-T1WI sagittal section of upper arm
the forearm. The main action of brachialis muscle is to flex the forearm. Both the biceps brachii and brachialis muscle are innervated by the musculocutaneous nerve (C5 and C6). The main action of coracobrachialis muscle is to flex and abduct the arm. It is innervated also by musculocutaneous nerve (C5, C6, and C7). The main action of triceps brachii muscle is extension of forearm. It is innervated by the radial nerve (C6, C7 and C8). The main action of anconeus is to stabilize the elbow and assist triceps brachii in extension.
ELBOW JOINT
Elbow joint is a hinge-type of synovial joint formed by the distal humerus, proximal ulna, and radius (Fig. 5.8). The distal aspect of the humerus is flat and the medial third of its articular surface, the trochlea, articulates with the ulna while the
lateral capitulum articulates with the radius. On the posterior surface of the humerus is a hollow area, the olecranon fossa (Figs 5.9 and 5.10). The posterior capsular attachment of the humerus is located above the olecranon fossa.
The anterior aspect of the distal humerus contains two fossae, the coronoid fossa, located medially, and the radial fossa, located laterally. The anterior capsular attachment to the humerus is located above these fossae. The proximal end of the ulna has the olecranon and the coronoid process (Fig. 5.11). The radial head has a round shallow articular surface which articulates with the capitulum of the humerus.
A fibrous capsule envelops the elbow joint; and a synovial membrane outlines the deep surface of this fibrous capsule. A number of fat pads are located between the fibrous capsule and the synovium. The muscles around the elbow
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Fig. 5.9: X-ray elbow joint—AP view
Figs 5.8A and B: (A) Multiplanar reconstructed CT scan image of elbow joint; (B) MRI-T1WI coronal section of elbow joint
Fig. 5.10: X-ray elbow joint—Lateral view (in flexion)
Fig. 5.11: X-ray elbow joint—Oblique view (in extension)
joint comprise of posterior, anterior, lateral, and medial groups. The muscles of the posterior group are the triceps and the anconeus. The muscles of the anterior group are the biceps and
brachialis. The lateral group of muscles includes the supinator and brachioradialis muscles and the extensor muscles of the wrist and hand. The medial group of muscles includes the pronator
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Figs 5.12A and B: (A) Multiplanar reconstructed CT scan
image of forearm; (B) MRI-T1WI coronal section of forearm
teres, the palmaris longus, and the flexors of the hand and wrist.
FOREARM
The radius is a long bone on the lateral side of forearm. It has a cylindrical head and articulates with the capitulum at elbow joint (Figs 5.12 and 5.13). It has a narrow neck below which is the long shaft of radius. The radius has a bony prominence on its medial side called the radial tuberosity (Fig. 5.14). Distally, the radius articulates with the proximal row of carpal bones, known as the radiocarpal joint. The styloid process of radius is bony projection on its lateral side at the radiocarpal joint. On its medial aspect at the radiocarpal joint it has a small facet to articulate with the ulna.
The ulna is the long bone on the medial side of forearm. It has an olecranon process at the elbow joint which articulates with the olecranon fossa of humerus on posterior aspect of elbow joint. The coronoid process of ulna is a bony prominence on the anterior aspect of ulna at the elbow joint. The lower part of coronoid process is called the ulnar tuberosity, which serves as attachment to the brachialis muscle. Between the coronoid process and the olecranon process of ulna there is a saddle-like depression which articulates with the trochlea of humerus. The shaft of ulna provides attachment to the muscles of forearm and wrist. At the wrist joint the ulna narrows down, it has a bony projection on its medial side called the styloid process. The lateral side of ulna at the wrist has a surface that articulates with the radius, this is called as distal radioulnar joint. The ulna articulates with the proximal row of carpal bones on medial side, called as carpoulnar joint.
The anterior muscle group comprises of: pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus and pro nator quadratus.
The posterior muscle group comprises of: brachioradialis, extensor carpi radialis longus,
A B
exten sor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus and extensor indicis.
WRIST JOINT AND HAND
The small bones of the hand can be classified into carpal bones, metacarpal bones and phalanges. The carpal bones are made up of two rows of eight carpal bones forming a semicircle (Figs 5.15A and B). The proximal row lies where the wrist creases on bending the wrist. From lateral to medial, the
Fig. 5.13: X-ray forearm—AP view
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Figs 5.15A and B: (A) Multiplanar reconstructed CT scan image of hand and wrist joint,
(B) MRI-T1WI coronal section of wrist joint
proximal row of carpal bones is made up of the scaphoid, lunate, triquetrum and pisiform. The distal row is made up of the trapezium, trapezoid, capitate and hamate bones (Figs 5.16 to 5.18). The distal row of carpal bones articulates with the bases of metacarpals in hand. All the carpal bones are surrounded and supported by the joint capsule containing synovial fluid. The scaphoid is boat-shaped bone. Its convex surface articulates with radius, its medial surface articulates with lunate, laterally it articulates with trapezium and trapezoid. The waist of scaphoid is narrower and more likely to fracture in trauma. The lunate has a semilunar shape and it articulates with radius at the wrist. It also articulates with the scaphoid and triquetral bones in proximal row of carpal bones.
The lunate is the most commonly dislocated carpal bone. The triquetral bone articulates with the pisiform, hamate and lunate bones. The pisiform articulates with the triquetral bone. The trapezium articulates with the trapezoid, scaphoid and also with the bases of the first and second metacarpals. The trapezoid is a small bone, it articulates with the scaphoid, trapezium, capitate and partly with base of second metacarpal. The capitate lies between the hamate medially and trapezoid laterally. It articulates with the base of third metacarpal and partly with base of fourth metacarpal. The hamate is wedge-shaped carpal bone. Proximally it articulates with lunate and distally it articulates with bases of fourth and fifth metacarpals. The metacarpal bones are
Fig. 5.17: X-ray hand and wrist joint—AP view Fig. 5.16: X-ray hand and wrist joint oblique view
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Fig. 5.18: X-ray both wrist joints, AP view in an 18-month-old child
5 in number, they articulate with the carpal bones proximally, while distally they articulate with their respective phalanges. The phalanges articulate with heads of metacarpals proximally at metacarpophalangeal joint. The first digit has two phalanges while the rest of digits have three phalanges.
The wrist joint comprises of bones and joints, ligaments and tendons. The distal end of ulna articulates with lunate and triquetrum. The distal end of radius articulates with scaphoid and lunate, this is also called as radiocarpal joint. The distal radioulnar joint is a pivot joint that allows pronation and supination of wrist joint. It is formed by the head of ulna and the ulnar notch of radius; this joint is separated from the radiocarpal joint by an articular disk lying between the radius
and the styloid process of ulna. The tendons that cross the wrist begin as muscles that start in the forearm. The radial and ulnar collateral ligaments stabilize the wrist joint. Those that cross the palmar side of the wrist are the flexor tendons. Those tendons that travel at the back of wrist are the extensor tendons.
HAND
The metacarpal bones are five in number, its bases articulate with the distal row of carpal bones. This articulation is known as carpometacarpal joints. The head of the metacarpal bones arti culate with the base of phalanx, it is called as metacarpophalangeal joint. Between the phalanges are the proximal and distal interphalangeal joints.
HIP JOINT
On plain X-rays, the hip joint is appreciated on AP, lateral and postero-oblique views (Figs 6.1 to 6.5).
The hip joint is a multiaxial synovial joint (ball and socket joint). It comprises of the head of femur articulating with the acetabular cavity of the hip bone. The hip joint is supported by muscle and ligaments which not only provide stability, but also produce a range of movements at the joint. The three parts of the hip bone are ilium, ischium and pubis, they join together at the acetabulum to form the triradiate synchondrosis. The acetabular labrum is attached to the acetabular rim and the transverse acetabular ligament. It forms a complete ring encircling the head of femur which fits into the acetabular cavity (Figs 6.2 and 6.3). Movements at the hip joint include flexion (normal range 120o), extension (normal range
20o), adduction (normal range 30o), abduction
(normal range 60o), medial and lateral rotation
(normal range along a vertical axis 40o). The fibers
of the capsule become stiffer during movements like extension and medial rotation of the femur. The ligament of head of femur connects the head of femur to the acetabular cavity. The ligament of the head of femur becomes stiffer during adduction movement of the hip joint, when the legs are crossed in front.
Major anastomosis occurs around the femoral neck involving branches from the femoral
arteries (medial and lateral circumflex branches) and obtu rator artery branches. As the medial circumflex artery supplies a major portion of blood to the head and neck of femur, in fracture of femoral neck this blood supply is disrupted and the head of femur may undergo avascular necrosis. The obturator artery divides into anterior and posterior branches. The acetabular artery is a branch of the posterior branch of obturator artery. The acetabular branches pass through the acetabular foramen and enter the aceta bular fossa where they diverge in the fatty tissue. The nutrient branches radiate to the margins of the acetabular fossa to enter the nutrient foramina. Radiological interventions like aspiration or injec tions into the hip joint can be done anteriorly or from the side, laterally. In case of lateral approach to hip joint the needle passes in front of the greater trochanter and parallel to the femoral neck to enter the joint capsule. In the anterior approach, the needle is inserted just below the anterior inferior iliac spine and directed upwards and medially into the joint capsule.
Important Radiologic Lines of Hip Joint Position
Hilgenreiner’s line: It is a line connecting the
superolateral margins of triradiate cartilage.
Perkin’s line: It is a vertical line to the Hilgenreiner’s
line through the lateral rim of acetabulum.
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Figs 6.1A to D: CT scan multiplanar reconstructed (MPR) images of pelvis with hip joints: (A) Anterior view; (B) As seen from
below; (C) Oblique view; (D) MRI-T1WI hip joint coronal section
Acetabular angle: It is the angle that lies between
Hilgenreiner’s line and a line drawn from supero-lateral ossified edge of triradiate cartilage. Acetabular angle > 30o suggest hip joint dysplasia. Shenton’s curved line: It is an arc formed by inferior
surface of superior pubic ramus and medial surface of proximal femur to the level of lesser trochanter.
Center-edge angle: It is the angle formed by a
line drawn from the acetabular edge to the center of femoral head, a second line is drawn perpendicular to the first line thereby connecting
the centers of femoral heads. Radiologically, if this angle is less than 25o it suggests femoral head
instability.
THIGH
On plain X-rays, the thigh is appreciated on both AP, lateral and posterior oblique views (Figs 6.6 to 6.9). The thigh comprises of the femur along with soft tissues (mainly muscle groups).
The femur has a long shaft, the proximal end of femur has a rounded head and a slender neck, the distal end of femur at the knee has
A B
Fig. 6.2: X-ray pelvis with both hip joints—AP view
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Fig. 6.4: X-ray hip joint—Posterior oblique view
Figs 6.6A to E: (A) CT scan topogram of thigh with both hip joints; (B to D) CT scan multiplanar reconstructed (MPR) images of
femur with hip joint; (B) Anterior view; (C) Lateral view; (D) Posterior view; (E) MRI-T1WI coronal section of femur with hip joint
two condyles that articulate with the upper end of tibia. The head of femur has the fovea on its medial surface where the ligament of head attaches to it. The neck of femur has an angle of around 125°with the shaft of femur and slightly tilted forwards. The greater trochanter projects upwards and backwards from the junction of the neck and shaft of femur, it is slightly pyramidal in shape with its apex pointed outwards. The lesser trochanter arises from the lowermost part of the neck of femur on the posterior aspect of femur. Between the greater trochanter and lesser trochanter anteriorly lies the intertrochanteric line, posteriorly lies the intertrochanteric crest. The shaft of femur is long and gives attachment
to muscles. At the lower end of femur are two condyles, lateral condyle and medial condyle. Between these condyles lies the intercondylar fossa.
The muscle groups of the thigh provide support to the hip and knee joints and help in movement. The main muscle groups are—The anterior, medial, gluteal region, posterior thigh muscles and iliotibial tract on lateral aspect. The muscles of the anterior thigh are the iliopsoas and quadriceps femoris. The iliopsoas muscle group consists of the psoas major, iliacus, tensor fascia lata and sartorius.
The main action of this group of muscles at the hip is flexion and medial rotation.
A
B C
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Fig. 6.7: X-ray thigh (femur)—AP view