Exam 2 Lecture Material

Why does the stifle joint require menisci & several ligaments for stability?

It is inherently incongruent due to structures of femur and tibia articular surfaces

What are the components that help stabilize the stifle joint?

2 fibrocartilaginous menisci & 10 ligaments

3 axes of femoral and tibial movement at stifle joint without stabilization

• Mediolateral axis

• Craniocaudal axis

• Longitudinal axis

Menisci shape

C-shaped with thin concave axial borders and thick convex abaxial borders; flattened on distal surface

What material makes up the menisci?

Fibrlocartilage

Functions of menisci

• Make the joint congruent

• Shock absorption

Meniscal ligaments

4 meniscotibial ligaments, transverse lig., miscofemoral lig.

Meniscotibial ligaments functions

Tack down the cranial and caudal corners of the medial and lateral menisci

The 2 meniscotibial ligg. that attach to the medial meniscus incline in a ______ direction

cranial

The 2 meniscotibial ligg. that attach to the lateral meniscus incline in a ______ direction

caudal

Transverse lig.

Transversely oriented lig. that connects the cranial corners of the menisci to each other

Meniscofemoral lig.

Large lig. that connects caudal corner of lateral meniscus to intercondylar area of femur

Femorotibial ligaments

Collateral ligg. & cruciate ligg.

Function of femorotibial ligg.

Stabilize femur and tibia

Extracapsular femorotibial ligg.

Medial and lateral collateral ligg.

Function of stifle joint collateral ligg.

Prevent movement in mediolateral axis & help limit rotary movement

How do the collateral ligg. sit in relation to the menisci?

Medial collateral lig. is fused to the medial meniscus

Tendon of origin of popliteus m. sits between lateral collateral lig. and lateral meniscus

Intracapsular femorotibial ligg.

Cranial and caudal cruciate ligg.

Function of cruciate ligg.

Prevent craniocaudal movement & help limit rotary movement

How are the cruciate ligg. oriented in the stifle joint?

Located within joint along central axis and cross each other at pivot point of joint

Why do the cruciate ligg. cross at the joint’s pivot point?

Prevent interference with normal flexion & extension

How are the cruciate ligg. named?

Designated cranial and caudal based on where they attach on the tibia

Drawer sign

Abnormal movement of the crus cranially or caudally relative to the thigh due to a torn cruciate lig. - useful for diagnosing cruciate lig. tears

Crus movement cranially relative to the thigh is a positive…

cranial drawer sign

Crus movement caudally relative to the thigh is a positive…

caudal drawer sign

Hand placement for testing drawer sign

Upper hand:

Index finger - Patella

Thumb - Lateral femoral condyle

Lower hand:

Index finger - Tibial tuberosity

Thumb - Head of fibula

Which hand performs the movement in a drawer sign?

Lower hand

What movements are performed to test the cranial vs caudal drawer sign?

Push with thumb to test cranial

Push with index finger to test caudal

2 joints that make up the stifle joint

Femorotibial and femoropatellar joints

Femoropatellar joint is between…

trochlea of femur and patella

Relationship between femorotibial and femoropatellar joints in small animals

Synovially continuous

The patella is a sesamoid bone within the tendon of…

quadriceps femoris m.

The portion of the tendon of the quadriceps femoris m. between the patella and tibial tuberosity is commonly referred to as the…

patellar ligament

Regions of the vertebral column

• Cervical (neck)

• Thoracic (thorax)

• Lumbar (abdomen)

• Sacrum (pelvis)

• Caudal (tail)

How many cervical vertebrae are there in small animals?

7

How many thoracic vertebrae are there in small animals?

13

How many lumbar vertebrae are there in small animals?

7

How many sacral vertebrae are there in small animals?

3

How many caudal vertebrae are there in small animals?

Variable; 20 ±

Mobility in the cervical vertebrae

Very mobile

Thoracic vertebrae articulate with…

ribs

Mobility of lumbar vertebrae

Relatively little mobility

Function of lumbar vertebrae

Stabilize caudal trunk and support weight of abdomen/contents

Mobility of the sacral vertebrae

No mobility - fused together

Mobility of caudal vertebrae

Greatest mobility

Dog & cat vertebral formula

C7 T13 L7 S3 Cd±20

Functions of the vertebrae

• Support head, neck, trunk, & tail

• Protection of spinal cord and spinal nerve roots

• Sites for m. attachment of mm. that move head, neck, tail,& trunk

The short, hollow tube formed by the arch and body of each vertebra is called the…

vertebral foramen

The space formed by the stacked foramina of the vertebrae when articulated together is callled the…

vertebral canal

The vertebral canal houses the…

spinal cord and initial portions of nerves that come off of it (nerve roots)

3 essential parts of all vertebrae

• Body

• Arch

• Processes

Vertebral body

Short rod of bone that forms the ventral portion of the vertebra

Vertebral body structure

Centrally constricted with a convex cranial surface and concave caudal surface

Components of vertebral arch

2 pedicles & 2 lamina

Vertebral arch forms the _____ aspect of the vertebra

Dorsal

The pedicles of the vertebral arch attach to the _____

body

The laminae form the _____ of the vertebral arch

roof (dorsal most aspect)

Intervertebral foramina

Foramina formed by articulation of cranial and caudal vertebral notches of adjacent vertebrae where spinal nerves exit

3 main processes on vertebrae

1. Spinous

2. Transverse

3. Articular

Spinous process

Single process projected dorsally from the junction of the left and right laminae

Spinous processes are particularly well-developed in what region?

Thoracic

Transverse processes

Paired processes projecting laterally in a transverse plane from the junction of the pedicle and body on the right and left sides

Transverse processes are particularly well developed in what region?

Lumbar

Articular processes

Processes jutting from junction of pedicle and lamina at the cranial and caudal aspects on the right and left sides of each vertebrae (2 pairs in each vertebra)

Function of articular processes

Covered with articular cartilage, forming synovial joints between vertebrae where caudal articular process of one vertebra articulates with cranial articular process of adjacent vertebra (mobility)

What processes are responsible for location where mobility occurs in the vertebral column?

Articular processes

How does mobility change as you course caudally down the vertebral column?

Progressively decreases

Intervertebral discs

Fibrocartilaginous discs between the bodies of adjacent vertebrae forming fibrocartilaginous joints

Intervertebral disc structure

Tough outer fibrous portion and gelatinous central portion

Outer fibrous portion of IV disc

Annulus fibrosus

Gelatinous center of IV discs

Nucleus pulposus

Annulus fibrosus structure

Thin dorsally and thicker ventrally

How is annulus fibrosus structure clinically relevant?

Disc herniations are most likely to occur in the thinner dorsal aspect of the annulus fibrosus

2 primary functions of IV discs

1. Join adjacent vertebral bodies (via symphysis)

2. Inner nucleus allows for shock absorption

What are the effects of IV disc herniations?

The nucleus pulposus protrudes through the dorsal aspect of annulus fibrosus and will place pressure on spinal cord and nerve roots

Trunk muscles

Attach to and cause movement of axial skeleton

2 basic groups of trunk muscles

Hypaxial & epaxial

Hypaxial muscles

Located below/ventral to the transverse processes of vertebrae

Epaxial muscles

Located above/dorsal to transverse processes of vertebrae

3 functional systems of epaxial muscles

1. Transversospinalis system

2. Longissimus system

3. Iliocostalis system

Transversospinalis system location relative to other epaxial muscles

Most medial and dorsal

Transversospinalis system runs from ______ to _______

Sacrum/ilium to skull

Transversospinalis system muscles are enclosed in a tube of…

thoracolumbar fascia

Longissimus system location relative to other epaxial muscles

Lateral and ventral to transversospinalis system; Medial & dorsal to iliocostalis system

Longissimus system runs from _____ to ______

Ilium to skull

Ililocostalis system location relative to other epaxial muscles

Most lateral and ventral

Iliocostalis system runs from _____ to ______

Ilium to level of the first rib

Functions of epaxial muscles

• Extension of vertebral column

• Lateral flexion if only one side contracts

• All subtle movements of vertebral column

Regional groups of hypaxial muscles

1. Muscles of the ventral neck

2. Muscles of the abdominal wall

3. Muscles of the thorax

Important muscles of the ventral neck

1. Sternocephalicus m.

2. Sternohyoideus m.

3. Sternothyroideus m.

4. Longus colli m.

Important muscles of the abdominal wall

1. Rectus abdominis m.

2. Transversus abdominis m.

3. Internal abdominal oblique m.

4. External abdominal oblique m.

Important muscles of the thorax

1. Diaphragm m.

2. Scalenus m.

3. Serratus dorsalis cranialis m.

4. External intercostal mm.

5. Internal intercostal mm.

Longus colli m. is intimately associated with…

ventral aspects of cervical and thoracic vertebrae

Cranial attachment of longus colli m.

Ventral aspect of atlas

Longus colli function

Flex cervical vertebral column

Clinical significance of longus colli m.

Surgical approaches to cervical vertebrae

Importance of abdominal wall muscles

Form the lateral and ventral walls of the abdomen

Rectus abdominis attachments

Sternum to pecten of the pubis

Rectus abdominis forms the _____ of the abdominal wall

ventral floor

Is the rectus abdominis paired or single?

Paired