3 - Anatomy of Back & Shoulder Flashcards
How many vertebrae are there?
33
How many vertebrae of each region are there?
7 cervical
12 thoracic
5 lumbar
5 sacral
4 coccygeal
What is an abnormal excessive convex (outward) curvature of the spine called?
Kyphosis
What is an abnormal concave (inward) curvature of the spine called?
Lordosis
How many curves do babies have in their spine?
When does this change?
1 primary kyphotic curve
Changes when they start sitting and walking
How many curves do adults have in their spine?
They have 2 kyphosis & 2 lordosis
Kyphosis at thoracic & sacral regions
Lordosis at cervical and lumbar regions
What is a sideways curvature of the spine called?
Scoliosis
In which part of the vertebra does the spinal cord sit?
Vertebral foramen
What is a process on a vertebra?
It is a bony projection on the posterior of the vertebra - is a site of muscle attachment, articular processes form facet joints for movement & spinous processes allow for movement.
What are the three types of process on a vertebra?
Transverse process
Articular process (superior and inferior)
Spinous process
What are facet joints in the spine?
The joints formed by the superior articular process of one vertebrae articulating with the inferior articular process of the vertebrae above it.
What is formed by the articular processes of two vertebrae joining? What passes through this?
Intervertebral foramen
Spinal nerves pass in and out to the spinal cord here.
What pathology can be associated with intervertebral foramen?
Spinal nerve impingement
What is the anatomical name for the facet joint?
Zygopophysial joint
How can you tell if a vertebra is cervical?
It has a bifid (split), short spinous process - only vertebrae to have this
Has triangle shaped vertebral foramen.
What is uniquely formed by the transverse processes of the cervical foramen?
Foramen transversarium
What is contained within the foramen transversarium?
Vertebral vessels (artery, vein & lymph) + sympathetic plexus
Which two vertebrae of the cervical spine are atypical?
Atlas (C1) and Axis (C2)
How do the atlas & axis vertebrae differ from typical cervical vertebrae?
Atlas is ring shaped - has no body (its body has fused to C2).
C2 - has the “odontoid peg” (aka dens) which are the bodies of C1 & C2 which have fused together.
Which vertebrae is this?
Axis - C2 - can tell because it has the odontoid peg.
Which vertebrae is this?
Atlas - C1 - has no vertebral body and is ring shaped.
Is there a vertebral disc between C1 & C2?
No
Which ligament attaches to C1?
Transverse ligament
What does the top of C1 articulate with on the skull?
Occipital condyles
What is a hangman’s fracture?
Fracture that occurs on C2 behind the articular parts - causing the dens to prolapse and kill / paralyse by impinging spinal cord.
How does the body provide stability to the dens?
Ligaments run behind the dens, attaching to the skull - preventing the dens from prolapsing.
How can you identify a thoracic vertebra?
Have demifacets (superior and inferior) on side of body - these articulate with the ribs
The transverse process also has a facet (costal facet).
Has a heart-shaped body
Vertebral foramen is circular.
Which two places on a thoracic vertebrae does a rib articulate with?
The bodies of the vertebrae above and below the rib (at the demifacets) and on the transverse process (costal facet).
What does the superior demifacet of a vertebral body articulate with?
The rib of the same vertebral number.
What does the inferior demifacet of a vertebral body articulate with?
The rib below (I.e. T10 inferior demifacet articulate with T11 rib)
How can you identify typical lumbar vertebra?
They have a large body.
Have a long, thin, transverse process.
Vertebral foramen is triangular.
Articular processes tend to face inwards.
What type of vertebrae is this?
Thoracic vertebrae
= demifacets on side of body
= costal facet on transverse process
= heart-shaped vertebral body
= circular shaped vertebral foramen
What type of vertebrae is this?
Lumbar vertebrae
= large body
= long, thin transverse process
= triangular shaped vertebral foramen
= articular processes face inwards
How many fused bones make up the sacrum?
5
Is the sacrum concave anteriorly or posteriorly?
Anteriorly (convex posteriorly)
Why does the sacrum have a large articular surface? What is its name?
Sacroiliac joint (SIJ)
Articulates with the ilium here - large surface area
How many fused bones make up the coccyx?
3-4
Does the coccyx have a vertebral canal or arches?
No - as there are no coccygeal nerves which need to exit.
Why do intervertebral joints have different orientations at different levels of the spine?
It enables different types of movement at different parts of the spine
What are intervebral discs made of?
3 tough fibrous rings called annulus fibrosus, with a liquid centre (nucleus pulposes)
What type of joint is found between articular processes of vertebrae?
Synovial joints (facet or zygapophysial joints).
What is the nucleus pulposes derived from?
It is a remnant of the notochord
Why do we need strong spinal ligaments?
Most of the body weight is anterior to the spine = so we need strong ligaments to stop collapsing anteriorly
Which are the two ligaments which run anterior and posterior to the vertebral bodies of the spine?
Anterior and posterior longitudinal ligaments
Which is stronger - the anterior or posterior longitudinal ligament?
Posterior is strongest - resists flexion of the spine.
Anterior is slightly less strong - it resists extension of the spine.
Which ligament lies behind the spinous process?
The supraspinous ligament
Which ligaments run in between the spinous processes of the vertebra?
The interspinous ligaments
Which ligament attaches from the lamina of one vertebral arch to the lamina of the arch above (between the transverse process and the spinous process)?
Ligamentum flavum
What is the thickening of the supraspinous ligament between C7 & the skull called?
Ligamentum nuchae
What is the difference in function between extrinsic and intrinsic muscles of the back?
Extrinsic muscles - move upper limbs & ribs (breathing)
Intrinsic muscles - move vertebral column, maintain posture
Which muscles are the extrinsic muscles of the back?
The superficial and intermediate muscles
- Trapezius
- Latissimus dorsi
- Levator scapulae
- Rhomboid major & minor
- Serratus posterior (superior & inferior)
Which rami are the extrinsic and intrinsic muscles supplied by?
Extrinsic muscles - are supplied by the anterior rami
Intrinsic muscles - are supplied by the posterior rami
Which are the superficial muscles of the back?
Trapezius
Latissimus dorsi
Rhomboids (major & minor)
Levator scapulae
What are the intermediate muscles of the back?
Serratus Posterior Superior & Serratus Posterior Inferior
What is the function of the trapezius muscle? Which nerve innervates it?
Rotate and elevate scapula
Spinal Accessory Nerve (CN XI)
What is the function of levator scapulae?
Elevates scapula
What is the function of latissimus dorsi? Which nerve innervates it?
Extends, adducts, medially rotates the humerus
Innervated by thoracodorsal nerve (C6-C8)
What is the function of the rhomboid muscles? Which nerve innervates them?
Retract and elevate the scapula.
C4 & C5 innervate (dorsal scapular nerve)
Which two groups of muscles make up the intrinsic muscles of the back?
Spinotransversales muscles
Erector spinae muscles
Which muscles are found in the spinotransversales group?
Splenius capitis
Splenius cervicis
What is the function of the spinotransversales muscles? What innervation are they supplied by?
To draw head backwards, extend neck, rotate head.
Found only in the cervical spine (outside of this area they are erector spinae muscles).
Supplied by posterior rami
What is the function of erector spinae muscles? What are the innervated by?
How many muscles are in this group?
Extend the spine, flex vertebral column laterally
Found outside of the cervical spine.
Supplied by posterior rami
10
What does the lateral end of the clavicle articulate with?
The acromion
What does the medial end of the clavicle articulate with?
The sternum and first costal cartilage
To which parts of the clavicle do the coracoclavicular ligament attach?
To the conoid tubercle and to the trapezoid line
What does the pectoral girdle comprise of?
The clavicle and scapula together
Why is the clavicle important clinically?
It is the only bone which connects the upper limb to the body by attaching to the sternum and the scapula.
The scapula doesn’t attach to the the body at any other point.
What are the two joints found by the clavicle?
Sternoclavicular joint and acromioclavicular joint
What type of joint is the sternoclavicular joint?
What movement does it allow?
Synovial
Allows the clavicle to move anteriorly / posteriorly and vertically in small amounts.
The clavicular joints are very wobbly - what do they have to stop this excessive movement?
Strong ligaments in front, behind and in between.
Which ligaments support the acromioclavicular joint?
The acromioclavicular ligament and and the coracoclavicular ligament
A tear to which ligament supporting the acromioclavicular joint will often result in surgery?
The coracoclavicular ligament tear means the clavicle will move a lot (often comes through the skin) and will often need surgery.
A tear to the acromioclavicular ligament doesnt result in as much movement of the clavicle.
At which end of the clavicle is the acromioclavicular joint found?
Lateral end of the clavicle.
What does the coracoclavicular ligament comprise of?
Conoid ligament
Trapezoid ligament
What does the conoid ligament attach to?
The conoid tubercle on the clavicle and the coracoid process on the scapula.
What does the trapezoid ligament attach to?
The trapezoid line on the clavicle and the coracoid process on the scapula.
What does the scapula articulate with?
The clavicle (acromioclavicular joint) and
the humerus (glenohumeral joint)
Which fossa are found on the anterior and posterior surfaces of the clavicle?
Anterior surface = subscapular fossa
Posterior surface = supraspinous & infraspinous fossa
What are the three borders of the scapula?
Superior, lateral and medial
What are the three processes of the scapula?
Acromion, coracoid & spine
What are the names of the two tubercles found near the glenoid cavity?
Supraglenoid tubercle
Infraglenoid tubercle
Which muscle attaches to the supraglenoid tubercle?
Biceps brachii long head
Which muscle attaches to the infraglenoid tubercle?
Triceps brachii long head
What are the three joints of the shoulder?
Acromioclavicular joint
Sternoclavicular joint
Glenohumeral joint
Why is the shoulder the most unstable complex in the body?
Because it has to allow for such a wider range of movement,. Glenhumeral joint = shallow cavity with a big head - means its easier for dislocation than other joints.
What do the acromioclavicular joint (ACJ) and the sternoclavicular joint (SCJ) link together?
The pectoral girdle to the trunk.
What type of joint is the glenohumeral joint?
Synovial ball & socket joint
What is the most commonly dislocated joint in the body and which is the most common presentation of this dislocation?
Glenohumeral joint is the most frequently dislocated joint in the body,
Anterior dislocation is the most common presentation.
What provides stability to the glenohumeral joint?
Extracapsular ligaments
Long head of biceps brachii tendon
Rotator cuff muscles
Glenoid labrum
Bony processes
Negative intra-articular pressure
What is the glenhumeral ligament divided into?
3 bits - superior, middle and inferior
Which muscles make up the rotator cuff?
Supraspinatus
Infraspinatus
Teres Minor
Subscapularis
SITS
What is the collagen attached to the edge of the glenoid cavity called? How does this increase stability of the joint?
Glenoid labrum
Labrum increases the surface area and helps hold the humeral head in place.
What stops the humerus going too far superiorly?
Coracoid & acromion process
What is the function of the deltoid muscle? How is innervated?
Abducts, flexes & extends arm.
Innervation = C5 & C6 - axillary nerve
Which muscles are involved in movement of the shoulder?
Trapezius
Deltoid
Levator scapulae
Rhomboid major & minor
Pectoralis major & minor
Subclavius
Serratus anterior
Rotator cuff muscles (SITS - supraspinatus, infraspinatus, teres minor & subscapularis)
Terres major
What does pectorals major do in terms of the shoulder? What is it innervated by?
Flexes, adducts & medially rotates the arm
Innervated by C5-T1 (medial and lateral pectoral nerves)
What does pectoralis minor do in terms of the shoulder? What is it innervated by?
Protracts scapula
Innervated by medial pectoral nerve (C5-T1)
What does the subclavius muscle do?
Depresses the clavicle
What does the serrates anterior muscle do? What is it innervated by?
Protracts and rotates the scapula.
Innervated by long thoracic nerve (C5-C7)
What are the first three SIT muscles of the rotator cuff innervated by?
C5 & C6 - via suprascapular nerve (SI) and axillary nerve (T).
What is the role of the supraspinatus muscle? What is it innervated by?
Initiates abduction of the arm
C5, C6 (suprascapular nerve)
What is the role of infraspinatus?
What is it innervated by?
Lateral rotation of the arm
C5 & C6 (suprascapular nerve)
What is the role of Teres Major?
What is it innervated by?
Medial rotation and extension of the arm
C5 - C7 (inferior suprascapular nerve)
What is the role of Teres Minor?
What is it innervated by?
Lateral rotation of the arm
Innervated by axillary nerve (C5 & C6)
What is the function of subscapularis?
What is it innervated by?
Medial rotation of the arm.
C5-C7 (upper and lower subscapscapular nerves)
What does the subclavian artery change to at the level of the 1st rib?
Axillary artery
Shoulders have a rich anastomosis of blood supply to them - why?
So that the arm gets blood supply no matter what position it is in, even if certain vessels are compressed at that time.
What does the subclavian artery arise from on the RHS and the LHS of the body?
RHS - arises from brachiocephalic trunk
LHS - arises directly from aortic arch
What does the suprascapular artery arise from?
The thyrocervical trunk
What doe the circumflex humeral, subscapular and circumflex scapular arteries all arise from?
The axillary artery
What does the suprascapular artery anastomose with?
The subscapular artery (3rd part of axillary artery)
How many parts if the axillary artery divided into and by what?
Divided into 3 parts by pectorals minor
What does the axillary artery become when it crosses the lower border of teres major?
Brachial artery
What is the path of the venous drainage of the shoulder?
Basilic vein –> Axillary –> Subclavian
External jugular vein empties into subclavian
Internal jugular vein also joins subclavian = brachiocephalic vein
Which are the two main nerves which supply the shoulder?
Suprascapular nerve
Axillary nerve
What does the suprascapular nerve arise from?
Upper trunk of brachial plexus
What does the suprascapular nerve innverate?
Supraspinatus & infraspinatus - motor control
What does the axillary nerve arise from?
Posterior cord of brachial plexus
What does the axillary nerve innervate?
Deltoid & Teres Major - motor control
Cutaneous sensation to upper outer arm
In which space of the shoulder is the axillary nerve found?
Quadrangular space
Which area of skin is tested for sensation in shoulder dislocation?
Axillary nerve area (soldier’s badge)
