Lecture 10: MSK 1 Flashcards
What is the function of bones?
- Support
- Movement
- Protection
- Storage:
Red blood cell production
Minerals (calcium)
Energy (fat)
Classifications of bones
- Long bones (femur/humerus)
- Short bones
(carpels/metacarpels) - Irregular bones (vertebrae)
- Flat bones (skull)
- Sesamoid bones (knee cap)
Bone composition
Specialized connective tissue
Vascular
Consists of organic extracellular matrix and inorganic materials that make bones hard and rigid (calcium and phosphate)
What are the two types of bone?
Cortical (compact)
Cancellous (trabecular)
Cortical (compact) bone characteristics
Forms outer shell of bone (cortex)
Very dense structure
Always surrounds Cancellous bone, but thickness varies
depending on type of bone, age, diet, and functional requirements
Cancellous (trabecular) bone characteristics
Inside of bone
Thin plates arranged in a loose
mesh structure
Arranged in a concentric layers
with marrow between
Types of joints
Fibrous
Cartilaginous
Synovial
See figure
How are bones held together in fibrous joints? Movement?
Bones are held closely together with fibrous
connective tissue
little or no movement
How are bones connected in cartilaginous joints?
Cartilaginous disc
Synovial joints characteristics
Joints have a space (cavity)
Freely moveable (diarthrodial)
Ends of the long bones lined with hyaline cartilage
Joint has an articular (synovial) capsule
Thickenings in the capsule are called ligaments
How are the surfaces of synovial joints shaped?
Reciprocally
Convex and concave
What is on the articular surfaces of synovial joints?
Hyaline cartilage
Other features of synovial joints
Joint capsule
What are the ligaments of synovial joints?
thickenings of joint capsule which connect bone to bone and provide joint stability
(note not all ligaments are extensions of the capsule)
Role of synovial membrane in synovial joints
secretes synovial fluid which lubricates the joint surfaces and delivers nutrition to articular cartilage
What are the accessory supportive structures of synovial joints?
Intracapsular / extrasynovial ligaments
Extracapsular ligaments [Lateral collateral ligament (LCL)]
Meniscus (fibrocartilage disc of the knee)
Bursa(e) (synovial sacs to prevent friction between muscle / bone, muscle / muscle, and bone / tendon)
How is the movement of synovial joints described?
In terms of the number of possible planes of movement and the shape of the articular surfaces
1) Un-axial (pivot, hinge, plane)
2) Bi-axial (condyloid, saddle)
3) multi-axial (ball and socket)
See figure
What are the functions of the vertebral column?
- Support (upright posture)
- Movement (Flex/extension, Side flex left & right, Rotation left & right)
- Protection (Spinal cord)
How many vertebrae is the vertebral column composed of? What types?
33 total
7 cervical
12 thoracic
5 lumbar
5 sacral
4 coccyx
See figure
What are primary and secondary curvatures?
Primary curvatures refer to the curvatures in the spine that are present at birth (Sacral, thoracic)
Secondary curvatures refer to the curvatures that develop as the individual grows (lumbar, cervical)
See figure
Abnormal curvatures of spine
Kyphotic spine (Thoracic vertebrae are overly curved)
Scoliotic spine (lateral C-shape)
Lordosis (exaggerated lumbar curve)
See figure
What are the general structures of the vertebrae?
Body
Vertebral arch
Spinous processes
transverse processes
Articular proceses
Vertebral foramen
See figure
Where is the body of vertebrae? What does it look like?
Anterior component of the vertebrae
Dense bone square in shape
Function of body of vertebrae
bears body weight
What is the vertebral arch of a vertebrae?
Lamina and pedicle
Posterior portion of vertebrae, form closed circle or arch which surrounds spinal cord
Where do pedicles extend from?
Posterior from both sides of body
What are spinous processes?
Bony processes which extend posteriorly from the junction of the two lamina
What are transverse processes? Function?
Bony processes which extend sideways from the junction between the pedicle and lamina
Act as “handle bars” when muscles attach to them and create movement
What are articular processes of vertebrae?
Paired body projections on the superior and inferior surfaces of the vertebral arch.
Form the facet joints
What is the vertebral foramen?
The opening created by the vertebral arch
With multiple vertebrae it is referred to as the “Vertebral Canal”
How is the intervertebral foramen formed?
There is a vertebral notch between the body and posterior elements
When two vertebrae are stacked one on the other, the notch now becomes the intervertebral foramen
What exits the intervertebral foramen?
The peripheral nerve root exits from the spinal cord through this foramen
Parts of intervertebral disc
Annulus fibrosis (laminated fibrous ring)
Nucleus pulposis (inner core of gel like fluid)
See figure
What is the function of the intervertebral disc?
Shock Absorbtion
Allows movement (cartilagenous/amphiarthrotic)
Gives height to the vertebral column
Disc problems
Degeneration
Bulging disc
Herniated disc
Thinning disc
Disc degeneration with osteophyte formation (bony projections)
See figure
Special features of cervical region
Small vertebral bodies
Bifid spinous process (EXCEPT C7)
Foramina in transverse process which accommodates vertebral arteries
Large vertebral foramen (canal) that accommodates the large brachial plexus of nerves
Articular processes orientated in horizontal plane which facilitates movement.
See figure
Which cervical vertebrae are considered to be typical
Vertebrae C3 to C6 are considered to be “typical” cervical vertebra.
Vertebrae C1 & C2 are unique or specialized vertebrae.
Which cervical vertebrae has the longest spinous process?
C7 (Vertebra Prominens)
Not bifid
Exception to foramen in transverse process of cervical vertebrae
vertebral artery passes through the transverse foramen while ascending toward the brain.
The vertebral artery passes through the transverse foramen of C1 - C6, BUT NOT C7
Atlas particulars
C1
Supports the skull
Superior articular facets articulate with the occipital condyle of the skull (facilitates nodding your head)
Has anterior and posterior arches – no vertebral body
See figure
Axis particulars
C2
Dens (odontoid) process that projects through the vertebral foramen of the atlas to form pivot rotation
See figure
Which vertebrae form the atlanto/axial joint?
C1 and C2
Special features of thoracic vertebrae
Heart shaped body
Long pointed spinous vertebrae that overlap each other.
Superior and inferior demifacets on the vertebral body (site of rib attachment).
Facets on transverse processes also for rib attachment
Superior and inferior articular facets face in frontal plane, allows little flex/extension movement.
Special features of lumbar vertebrae
Large and Heavy vertebral bodies (for weightbearing)
Large, thick, Square cut spinous process - projects straight back
“Grasping” articular facets face in sagittal plane – allows little rotation.
What happens if you draw a horizontal line from the highest point of the iliac crests…
run through the spinous process of L4
Intervertebral joints: type of joint, location, load
Fibrocartilaginous joints
Anterior column of the spinal cord built for stability
Bear compressive loads
Tremendous ligamentous support (6 in #)
Size of intervertebral joints as you move toward pelvis
Progressively larger
Zygoapophyseal joints: aka, type of joint, location
Facets
Plane type synovial joints
Posterior column of spine is
built for mobility
Determined by region & orientation of superior & inferior articular processes of adjacent vertebral segments.
Atlanto-occipital joint, joint type
C1/C0
Synovial
Condyloid joint
Articular surfaces of atlanto-occipital joint
Occipital condyles of the skull
Facets on superior surface of lateral masses of atlas vertebra
Motions possible thanks to Atlanto-occipital joint
Flexion / extension (nodding head “Yes”)
slight side flexion.
atlanta-axial joint (C1/C2) joint type
Synovial: Pivot (medial) & plane (lateral) joints
Articular surfaces of atlanta-axial joint
Facet on posterior aspect of anterior arch of the atlas
Facet on anterior aspect of dens of the axis.
See figure
Motions possible thanks to atlanta-axial joint (C1/C2)
Rotation (shaking head “No”).
Accounts for 40% of cervical flexion/60% of cervical rotation
Intervertebral disc between C1 and C2?
No
Ligaments that support atlanta-axial joint (C1/C2)
Cruciform ligament
Transverse ligament of the atlas
Alar ligaments
Apical ligament
ROM in C spine
Built for mobility
Flex/Ext, Lat flex, Rotation
ROM in T spine
Built for stability
Little Flex/Ext
Lat flex, Rotation
ROM in L spine
Built to Flex/Ext
Some Lat flex
Little Rotation
Function of back muscles
Protect the spine
Transfers loads from head and trunk to pelvis
Permit motion in all 3 planes
Two main groupings of back muscles
Intrinsic Muscles: Small muscles that stabilize spine & maintain posture, Control / guide precise movements between adjacent segments
Extrinsic Muscles: Large muscles that power global movements of the back
Two groups of back muscles
Superficial (trapezius, latissimus dorsi)
Deep (levitator scapulae, rhomboids, erector spinal and quadrates lumborum)
What is the trapezius?
Large, superficial, triangular muscle of the upper back and neck region
What does the function of trapezius depend on?
Depend on location and direction
Upper fibres of trapezius - function
Scapular elevation/rotation (“shrug“)
Neck Side Flexion (unilateral) or Extension (bilateral)
Middle fibres of trapezius - function
Scapular retraction
Lower fibres of trapezius - function
Pull medial end of scapular spine down (rotates
glenoid fossa upward)
Important to facilitate raising the arm over head
What is the latissimus Dorsi?
Large, superficial, broad muscle of back
Diamond shaped
What anatomical structure does the latissimus dorsi form?
Forms posterior wall of axilla (armpit)
Where does latissimus doors arise from? Where does it insert?
Arises from lower back
inserts prox. humerus
Functions of latissimus dorsi
Shoulder extension
Shoulder adduction
Shoulder medial rotation
Composite action: swimming, paddling
Levator scapulae location
Deep to trapezius
Runs from cervical spine to scapula
Function of levator scapulae
Elevate scapula
Location of rhomboid muscles
Deep to trapezius (middle fibres)
Extends from vertebral column to medial border of scapula
Runs obliquely down and laterally
Function of rhomboid muscles
Retract scapula
Sections of erector spinae muscle group
Spinalis
Longissiumus
Iliocostalis
See figure
Function of erector spinae muscle group
Extension
What is the quadrates lumborum?
Square muscles on either side of the lumbar spine.
Runs between the 12th rib and iliac crest
Function of quadratus lumborum?
Side flexion of the lumbar spine
See figure
How is upright posture maintained?
Back muscles contract isometrically (without changing muscle length or joint angle)
Abdominal muscles remain quite or contract isometrically.
Functional movements essential for posture
Eccentric (lengthening) muscle contractions to control the body against gravity.
Shoulder rules of 3
3 bones: Clavicle, Scapula & Humerus
3 joints: SC, AC & GH
3 groups of muscles: thorax to humerus, thorax to scapula/clavicle, scapula/clavicle to humerus
Importance of shoulder joint
Only attachment of appendicular skeleton (arm) to axial skeleton (trunk)
Shape of clavicle
S shaped
Medial one third is convex anteriorly (rounded outward)
Lateral one third is concave anteriorly (curved inward)
Functions of clavicle
keeps shoulders back and arms at side
Force absorption & dissipation (Foosh - fall onto outstretched hand)
Rotation of the scapula in abduction
Shape of scapula
Spade
Triangular
Thin , flat
Attachment of scapula to chest wall?
No
Held against ribs by muscles
What does humorous articulate with in shoulder?
Head of humerus (proximal end) articulates with the Glenoid fossa of scapula
Shape of humorous
Typical long bone (shaft and 2 enlarged ends)
See figure
What is sternoclavicular (SC) joint formed by?
Formed by medial clavicle and clavicular notch of the Sternum
See figure
SC joint type
Saddle type
Movements of SC joint
Subtle movements occur about a multi axial plane.
What is acromioclavicular (AC) joint formed by?
Lateral clavicle articulates with acromion process of scapula
See figure
AC joint type
Plane
Support of AC joint
Supported by thick ligaments
Movements of AC joint
Allows for rotational movements of clavicle on acromion
Injury of joint referred to as “shoulder separation”
What is Glenohumeral (GH) joint formed by?
Shoulder joint
Articulation between head of humerus
and glenoid of the scapula
See figure
GH joint type
Synovial
Multi-axial, ball and socket type
Movement of GH joint
Freely movable, but structurally unstable because very little of humeral head (1/3rd) is in contact with fossa at any one time.
Flexion / Extension
Abduction / Adduction
Medial / Lateral Rotation
Glenoid characteristics
Glenoid is deepened by a cartilaginous ring (labrum), and stabilized by strong ligaments
Scapulo-thoracic motion
Movement of the scapula on the thorax to facilitate movement of the humerus to bring hands overhead
Not an actual bony articulation
1° of scapular movement (on the thorax) for every 2° of GH movement at shoulder.
What happens during 180 degrees of shoulder abduction?
120° from GH joint
60° from ST articulation
Other paired movements of shoulder
Require movement in all three joints
Elevation / Depression
Protraction / Retraction
Cross flexion / Extension
3 main groups of shoulder muscles
1) Thorax to humerus
2) Thorax to scapula/clavicle
3) Scapula/Clavicle to humorous
Thorax to humerous
Posterior: latissimus dorsi (superficial back muscle)
Anterior: pectoralis major
Pectoralis major
Large, superficial muscle of chest that forms the anterior wall of axilla
Functions of pectoralis major
Shoulder flexion
Shoulder adduction
Shoulder medial rotation • ie. ‘bear hug
See figure
Thorax to scapula/clavicle
Posterior: trapezius (superficial back muscle), Rhomboids (deep)
Anterior: Pectoralis minor
Location of pectoralis minor
Positioned deep to pectoralis major muscle
See figure
Function of pectoralis minor
Protraction of scapula
powers reach beyond reach
See figure
Scapula/Clavicle to humorous
Posterior: rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis)
Anterior: deltoid
See figure
What is the rotator cuff?
Intrinsic muscles of shoulder
Comprised of four separate muscles
Location of rotator cuff
Originate from scapula to attach to head of the humerus
Function of rotator cuff
SITS
1) Supraspinatus – Abduction of shoulder
2) Infraspinatus - Lateral rotation of shoulder
3) Teres minor - Lateral rotation of shoulder
4) Subscapularis - Medial rotation of shoulder
Which is the round muscle on top of shoulder?
Deltoid
Provides bulk of shoulder, forms “U” - 3 distinct heads
Functions of deltoid
Anterior: Shoulder flexion
Middle: Shoulder abduction
Posterior: Shoulder extension
See figure
