70 terms

Anat unit 2


Terms in this set (...)

how man processes in a typical vertebra?
The vertebral artery passes through the foramen transversarium of all cervical vertebrae, except which one?
- C1
The interspinales are muscles that belong to which group of true back muscles?
3rd group
How many tarsal bones in the foot?
The ischial spine is a bony feature of which bone?
Gerdy's tubercle is a bony feature of which bone?
Which one forms the inferior boundary of the greater sciatic foramen?
sacrospinous ligament
The innervation of the gluteus maximus muscle is by which nerve?
the inferior gluteal nerve
The main action of the piriformis muscle is?
lateral rotation of the thigh at the hip
What is the name of the deep fascia of the thigh?
the fascia lata
How many muscles in the anterior compartment?
Which muscle can perform flexion, abduction, and lateral rotation of the thigh at the hip?
sartorius muscle
The blood supply to the anterior compartment of the leg is by which artery?
anterior tibial artery
The tibialis anterior muscle inserts on which bone?
medial cuneiform
The extensor hallucis longus is innervated by which nerve?
deep fibular nerve
Which muscles is classified as an intrinsic muscle of the foot?
extensor digitorum brevis
How many intrinsic muscles are in the sole of the foot?
The dorsalis pedis is the continuation of what artery?
anterior tibial artery
Which nerve innervates a small area of skin in the anterior upper thigh, just inferior to the inguinal ligament?
genitofemoral nerve
Which muscle is not innervated by the sciatic muscle?
- semitendinosus muscle
- semimembranosus muscle
- long head of the biceps femoris
- short head of the biceps femoris
short head of the biceps femoris
Which nerve innervates the web space between the first and the second toe?
deep fibular nerve
The superior gluteal artery is a branch of which artery?
The posterior division of the internal iliac artery
The lateral circumflex femoral artery is usually a branch of which artery?
profunda femoris artery
The small saphenous vein drains into which vein?
popliteal vein
The artery that enters the proximal head of the femur passes through which ligament?
round ligament of the head of the femur
The hip flexion in an average human being is about?
125 degrees
The cruciate ligaments are most relaxed in what position of the knee?
30 degrees of flexion
Vertebral Column ad Deep Back Muscles
average adult
- vertebral column: 28 to 30 inches in length
- 33 vertebrae
- 24 true vertebrae 7 cervical, 12 thoracic, 5 lumbar)
- 9 vertebrae (5 sacral and 4 coccycgeal)
- sacrum and coccyx
vertebral column
- houses and provides protection to the spinal cord
- allows the segmental distribution of spinal nerves leaving the cord
- also serves a structural purpose in the body and provides attachments to muscles, articular surfaces for the ribs and other bones
- central supporting of the body and links the skull, the pectoral girdle and the pelvic girdle
vertebral column on its anterior aspect 2 concavities and 2 convexities
2 concavities - present in the thoracic and sacral regions; primary curvatures that are present at the time of birth

2 convexities - observed at the level of the cervical and lumbar regions; secondary curvatures that not present at birth and are acquired after birth
each vertebra is formed of an anterior body and a posterior vertebral arch, closing the vertebral foramen
posterior arch: 2 pedicles and 2 laminae
each typical vertebra has 7 processes: 1 spinous process, 2 transverse process, 4 articular processes (2 superior and 2 inferior)
note how the body and the posterior arch together form the vertebral foramen, which contains and protects the spinal cord
Intervertebral disc
- found between the (true) vertebrae
- functions as a shock absorber but also allows movements to take place between adjacent vertebrae (flexion, extension, rotations, and side-bending)
- consists of a center of watery and gelatinous substance, the nucleus pulposis and a peripheral more fibrous layer of fibrocartilage named anulus fibrosis
note that the anulus fibrosis is thicker anteriorly than posteriorly.
with age, this intervertebral disc undergoes changes, such as decreased water content and increased stiffness, and can become partially or totally ruptured
each typical vertebra has several articular surfaces covered with hyaline cartilage.
-these articular surfaces are found on the superior and inferior aspects of the vertebral body for articulation with the intervertebral disc.
- these surfaces are also found at the tip of the 4 articular processes
- the superior articular processes articulate with the inferior articular process of the vertebra above with the opposite being true for the inferior articular processes
Using the Netter plate, the typical cervical vertebra (C4) differs from the typical vertebra by:
- presence of a foramen in the transverse process, the foramen transversium, allowing the passage of the vertebral vein through all 7 cervical vertebrae with the artery passing usually through the upper 6 cervical vertebrae. note that the vertebral artery does not pass through C7
- groove for the spinal nerve
- uncinate process
- except for C1 and C7, the spinous processes are bifid
- vertebral foramen is large and somewhat triangular
The first and the second cervical vertebrae present interesting additional features. The first cervical vertebra:
- does not have a vertebral body nor a spinous process
- possesses an anterior and a posterior arch
- presents articular surfaces on upper aspect for the occipital condyles
- note that the upward and downward movement of the skull over C1 (like saying "yes") takes place between the occipital condyles and the superior articular surfaces (facets) of C1
the second cervical vertebra possesses the odontoid process or dens, projecting superiorly from the superior aspect of its body.
- as a consequence, there is no intervertebral disc between C1 and C2.
- note also that the movement of rotation of C1 over C2 (like saying "no") takes place between the inferior articular facets of C1 and the superior articular facets of C2
On this Netter plate, the dens of the axis articulates with the articular facet found on the posterior aspect of the anterior arch of the atlas.
note the cruciate ligament made of 3 separate parts: the transverse ligaments of the atlas, and the superior and inferior longitudinal bands
the thoracic vertebra has a few additional features
- the body is medium size and has a heart shape
- vertebral foramen is small and circular
- spinous process is long and inclined downward
in addition, the costal facets on the side of the vertebral body for articulation with the head of the matching rib and on the transverse processes for articulation with the tubercle of the matching rib
note that T11 and T12 do not have facets for the tubercle of the ribs on their transverse processes
The typical lumbar vertebrae present the following features:
- the vertebral body is large and kidney shaped
- the vertebral foramen is triangular
- the laminae are thick, the pedicles strong but the transverse processes are long and slender, with the L3 transverse processes being the widest
- the mammillary and accessory processes
The sacrum is the result of the fusion of the 5 sacral vertebrae.
- it is wedge shaped bone, presenting an anterior concavity
- has an articular surface superiorly for articulation with the inferior aspect of the intervertebral disc L5-S1(5th lumbar vertebra.
- inferiorly, it articulates with the coccyx.
note that laterally, the sacrum articulates with the auricular surfaces of the iliac portion of the pelvic bone
the following features are also important:
- the sacral promontory
- the vertebral foramina (sacral canal)
- the anterior and posterior sacral foramina for dorsal and ventral primary rami of sacral nerves
The articular facets on the superior articular processes in the cervical region are directed upward and backward, with the inferior being the opposite, downward and forwards.
in the thoracic region, the articular facets on the superior articular process are facing backward and laterally, with the inferior being the opposite, forward and medially

in the lumbar region (including T12), the articular facets on the superior articular processes are facing medially, with the inferior facing the opposite direction, laterally.
Facet joint orientation is also important in radiology, where it is necessary to take the x-ray at the correct angle if proper visualization of the articular surfaces is required to make the diagnosis
the cervical region presents unique features
- the intervertebral joints differ from the intervertebral joints of the thoracic and lumbar region due to the presence of the uncinate process
- note also how the spinal nerve rests in its groove upon exit through its intervertebral foramen
In the lumbar region, the intervertebral foramina are created by the juxtaposition of the pedicles of the lumbar vertebra above and below (separated by the intervertebral disc) and how the spinal nerves exit downward manner through these openings
ligaments of the vertebral column:
- the anterior longitudinal ligament, a wide and strong ligament, is running longitudinally over the anterior and lateral surfaces of the vertebral bodies
- posterior longitudinal ligament, is contained within the vertebral canal, and running longitudinally over the posterior surface of the vertebral bodies
Ligamentum flavum
ligament found running segmentally between the vertebral laminae
interspinous ligament
runs between adjacent spinous processes
supraspinous ligament
runs between and over the spinous processes
- recall that in the cervical region, this ligament is thick and called ligamentum nuchae
associated with the vertebral bodies
- anterior longitudinal ligament
- posterior longitudinal ligament
associated with the posterior (neural) arch
- interspinous ligament
- supraspinous ligament
- ligamentum flavum
spinal cord
-18 inches in length (avg male)
- presents two enlargements, called the cervical and lumbosacral enlargementsthat are related to the innervation of the upper and lower limbs.
31 pairs of spinal nerves are attached to the spinal cord by their spinal roots:
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
- note that the spinal nerves C1 - C7 leave the vertebral column above the matching vertebra with C8 spinal nerve exiting below the C7 vertebra. below this level, the spinal nerves exit below their matching vertebra, with the S1 to S4 spinal nerve exiting the matching sacral foramina and S5 and Coc1 through the sacral hiatus.
- recall also how the cervical spinal nerves exits in the horizontal plane whereas the lower spinal nerves exit in a downward manner
spinal cord presents several additional features
- due the differential growth between the bony structures of the vertebral column and the soft itssue of the spinal cord, the spinal cord in the adult stops the lower border o the L1 vertebra
- the tapered caudal end of the spinal cord is called the conus medullaris
- the dorsal and ventral roots of the lumbar and sacral nerves forming a leash of nerves belowe the L1 level are collectively called the cauda equina
Each spinal nerve is attached to the spinal cord by an anterior root(motor) and a posterior root(sensory)
-each root is formed by a series of rootlets
- due to the difference in length of the vertebral column and the spinal cord, the root increases progressively from the cervical region to the lumbar region
-recall the conus medullaris and the caudis equina
like the brain, the spinal cord is covered by 3 meninges:
- dura mater
- arachnoid
- pia mater
dura mater
- tough, protective, impermeable outer layer that encloses the spinal cord and the cauda equina.
- it is continuous superiorly with the dura mater covering the brain
- inferiorly, it ends at the level of the 2nd sacral vertebra
- at the level of the intervertebral foramen, it becomes continuous with the connective tissue surrounding the spinal nerve (epineurium)
- the arachnoid mater lines the inside of the dura mater
- a delicate impermeable membrane
- found deep to the dura mater
- it is also continuous with the arachnoid layer covering the brain and ends inferiorly at the 2nd sacral vertebra.
- separated from the most internal layer, the pia mater, by the subarachnoid space, which is filled with cerebrospinal fluid
pia mater
- vascular membrane covering the spinal cord itself
- superiorly, it is continuous with the pia mater covering the brain
- inferiorly, it ends at the level of L1 with the filum terminale, descending to attach distally on the coccyx
- laterally, the pia mater is thickened to form the denticulate ligament, which attaches to the dura mater at mid-distance between the nerve roots
blood supply to the spinal cord is from 3 main longitudinal arteries
-two posterior spinal arteries
- and anterior spinal artery
note how the anterior and posterior radicular arteries, branching from the segmental spinal artery, enter through the intervertebral foramina to anastomose with the network created by the 3 main arteries
True back muscles, innervated by the posterior primary rami of spinal nerces, can be divided into 3 separate groups:
- the erector spinae muscles(1st group)
- transversospinalis muscles(2nd group)
- deepest group(3rd group)
3 subgroups for the erector spinae (1st group):
- spinalis medially
- and longissimus and iliocostalis laterally
also present is the serratus posterior superior and inferior
3 subgroups of transversospinalis (2nd group):
- semispinalis
- multifidus
3rd group
- intertransversarii
these muscles are classified as postural muscles, meaning that they are essential and primary role is to maintain posture during daily activities. because the center of gravity of the human body is anterior to the vertebral column, these muscles function as extensors of the trunk. they also can act to rotate the trunk
posterior longitudinal ligament is attaching to the inferior and posterior aspect of each intervertebral disc
this ligament is fairly narrow and weak when compared to the anterior longitudinal ligament
Lumbar puncture
-invasive procedure aiming at sampling cerebrospinal fluid (CSF) for diagnostic purpose by placing the tip of a needle into the subarachnoid space.
- with the patient either side- lying or sitting in a forward position with the lumbar region on the edge of the table, the clinician visualizes a line connecting the two iliac crests
- knowing the fact that this line usually passes at the level of the L4 vertebra, the clinician identifies the L4-L5 (or the L5-L1) intervertebral space
-after cleaning the area with a disinfecting solution and anesthetizing, the region, the clinician passes a spinal needle between the spinous processes of the L4-L5 or the L5-S1 intervertebral space.
-the needle passes successively through the ligaments, the dura mater(lined internally by the arachnoid), and it finally enters the subarahnoid space.
- the lumbar puncture(commonly called spinal tap) must be performed in the low lumbar region to avoid injury to the spinal cord (recall that the spinal cord stops at the level of the L1 lumbar vertebra)