The pectoral girdle and vertebral column Flashcards
Where is the origin of the deltoid?
Scapular origin:
aponeurosis at inferior lip of crest
Acromion origin:
fleshy fibres from lateral edge of acromion
Clavicular origin:
fleshy fibres of anterior surface of lateral third of clavicle
Where is the insertion of the deltoid?
Tendons converge into V-shaped deltoid tuberosity above midshaft of the humerus
What is the function of the lateral fibres of the deltoid?
Abduction at the glenohumeral joint
What is the function of the anterior fibres of the deltoid?
Medial rotation and flexion
What is the function of the posterior fibres of the deltoid?
Lateral rotation and extension
Which nerve supplies the deltoid?
Axillary
How many degrees of internal rotation are due to the scapulothoracic motion?
15
acts after glenohumeral
How many degrees of internal rotation are due to the glenohumeral motion?
120
What is meant by scapulothoracic rhythm?
Coordinated movement of scapulothoracic and glenohumeral joints
Where is the origin of the rhomboids?
Inferior aspect of ligamentum nuchae and spines of upper thoracic vertebrae
Where is the insertion of the rhomboid major?
Medial (vertebral) border of scapula, below spine
Where is the insertion of the rhomboid minor?
Medial (vertebral) border of scapula, above spine
Which nerve supplies the rhomboids?
Dorsal scapular
What is the function of the rhomboids?
Retraction
To a lesser extent, elevation of the scapula
Where is the origin of the levator scapulae?
C1-C4
Where is the insertion of the levator scapulae?
Vertebral border of scapula, from superior angle to root of spine
Which nerve supplies the levator scapulae?
Dorsal scapular
What is the function of the levator scapulae?
Elevation of scapula medially and upwards
simultaneously pulls it forwards
Where is the origin of the serratus anterior?
Outer surfaces of upper 8/9 ribs along anterior axillary line
Where does the serratus anterior insert?
Digitations from ribs 1 and 2:
ventral surface of scapula along a narrow strip immediately adjacent to its vertebral border
Digitations from other ribs:
Ventral surface of interior angle
Which nerve supplies the serratus anterior?
Long thoracic
What is the function of the serratus anterior?
Protracts scapula
Holds scapula close to the thoracic wall
Elevates ribs when scapula is fixed
Where is the origin of the pectoralis minor?
Anterior surfaces of 3rd, 4th and 5th ribs in the vicinity of their costochondral junctions
Where is the insertion of the pectoralis minor
Medial lip of the coracoid process near its tip
What is the function of the pectoralis minor?
Pulls scapula inferomedially
Which nerve supplies the pectoralis minor?
Medial pectoral
Where is the origin of the pectoralis major?
CLAVICULAR HEAD:
medial half of anterior surface of the clavicle
STERNOCOSTAL HEAD:
1. anterior surface of sternum
- upper 6 costal cartilages
- upper part of external oblique aponeurosis
Where is the insertion of the pectoralis major?
CLAVICULAR HEAD:
anterior surface of tendon that inserts into the bicipital groove of the humerus
STERNOCOSTAL HEAD:
fibres converge into tendon which inserts into lateral lip of bicipital groove
What is the function of the pectoralis major?
Adduction and medial rotation at glenohumeral joint
Accessory muscle of respiration
Clavicular head is also a major flexor of the arm
Which nerve supplies the clavicular head of the pectoralis major?
Lateral pectoral
Which nerve supplies the sternocostal head of the pectoralis major?
Medial pectoral
Where is the origin of the latissimus dorsi?
Posterior region of iliac crest via an aponeurosis from the vertebral spines inferior to T6
Where is the insertion of the latissimus dorsi?
Fibres converge to form a tendon which inserts into the floor of the bicipital groove of the humerus, near the crest of the lesser tuberosity
What is the function of the latissimus dorsi?
Adduction
Medial rotation
Extension of arm
Which nerve supplies the latissimus dorsi?
Thoracodorsal
What is the pectoral girdle?
The scapula and clavicle with their interposing joints; 2 anatomical joints (sternoclavicular and acromioclavicular) and a physiological joint (scapulothoracic articulation)
What is the function of the pectoral girdle?
Connects the upper limb to the axial skeleton
What is the classification of the sternoclavicular joint?
Synovial
What does the stenoclavicular joint connect?
Medial end of clavicle to the clavicular notch on the manubrium together with the adjacent superior aspect of the first costal cartilage
What type of disc is contained within the sternoclavicular joint?
What does this give rise to?
A fibrocartilaginous intra-articular disc that divides into 2 separate synovial cavities
What is the classification of the acromioclavicular joint?
Synovial
How much movement is provided by the acromioclavicular joint?
Small degree of motion around all 3 potential axes
What is movement around the mediolateral axis of the acromioclavicular joint described as?
Rotation
What is the classification of the glenohumeral joint?
Synovial ball-and-socket
What is the difference in the surface area of the head of the humerus and the glenoid fossa?
Head of humerus is 3 times bigger
How is the stability of the glenohumeral joint increased?
Margins of the glenoid fossa extended by a fibrocartilaginous labrum
Where does the capsule of the glenohumeral joint attach?
The margins of the anatomical neck of the humerus
Why is the capsule of the glenohumeral joint lax inferiorly?
To allow abduction
What increases the strength of the glenohumeral joint?
coracohumeral ligament and 3 glenohumeral ligaments
What are the 3 planes of movement enabled by the glenohumeral joint?
Flexion/extension, abduction/adduction, medial/lateral rotation
What is circumduction?
A combination of flexion, extension, abduction and adduction to result in circular movement
What are the primary muscles involved in circumduction?
Pectoralis major, deltoid, latissimus dorsi, teres major and coracobrachialis
What are the rotator cuff muscles?
Subscapularis
Infraspinatus
Supraspinatus
Teres minor
What is the purpose of the rotator cuff muscles?
Hold the humeral head within the glenoid, giving strength and dynamic stability
Which muscles are responsible for abduction at the shoulder?
Initiated by supraspinatus and continued by lateral fibres of the deltoid
Which muscles are responsible for adduction of the shoulder?
Coracobrachialis is the only true adductor
Pectoralis major, latissimus dorsi and teres major can adduct the abducted shoulder
Which muscles are responsible for lateral rotation at the shoulder?
Infraspinatus, teres minor and posterior fibres of the deltoid
Which muscles are responsible for medial rotation at the shoulder?
Subscapularis, teres major, latissimus dorsi, pectoralis major and the anterior fibres of the deltoid
How many cervical vertebrae are there?
7
How many thoracic vertebrae at there?
12
How many lumbar vertebrae at there?
5
How many sacral vertebrae at there?
5 fused
How many coccygeal vertebrae at there?
3-4 fused
Where does the vertebral column run?
Back of the head to the natal cleft
How does the vertebral column look when viewed posteriorly?
Linear
How does the vertebral column look when viewed laterally?
Primary and secondary curvatures visible
What causes variation in primary and secondary curvatures of the vertebral column?
Age and pathology
What is the primary curvature of the vertebral column?
Thoracic and sacral regions retain their curvature from birth, this does not vary with movement
What is secondary curvature of the vertebral column?
Lumbar region becomes concave posteriorly when walking
Cervical region becomes concave posteriorly to support the head
How to vertebrae connect together?
Synovial joints between the inferior articular facets on one vertebra and the superior articular facet on the vertebra below
What is the significance of the notches on pedicles?
The notches form 2 contiguous vertebrae from the intervertebral foramen for the spinal nerves to pass
How are intervertebral joints strengthened?
Ligaments connecting the tips and bases of spinous processes (supraspinous and interspinous), the transverse processes (intertransverse) and the laminae (ligamentum flavum)
Where does the spinal cord begin and end?
Starts at the foramen magnum of the skull
Ends at the lower border of L1 where is tapers to a cone shaped ending called the conus medullaris
How does the spinal cord attach to the rest of the vertebral column?
A stalk of pia matter, the filum terminale, attaches it to the end of the dural sac at S2
What is the cauda equina?
A mass of spinal roots from L2 to the lowest coccygeal nerve which pass caudal to the conus to exit at their respective intervertebral foramina
What is the function of the nerves arising from the ventral spinal roots?
Motor
What is the function of the nerves arising from the dorsal spinal roots?
Sensory
Where do spinal nerves arise from
2 roots in the vertebral column join to from a mixed spinal nerve in the intervertebral foramen
What are the 3 meningeal layers?
What is their function?
Pia, arachnoid and dura mater
Protection of the spinal nerves
What happens to the nerve as it emerges from the intervertebral foramen?
For a small distance each nerve takes with it all 3 layers of meningeal covering. The coverings then fuse with the epineurium of the nerve root
How many cervical root are there?
8
Where are nerve roots in relation to their corresponding vertebrae?
What is the exception to this
Below the vertebra
Cervical vertebrae: C1 root starts above its vertebra, hence there are 8 cervical vertebrae
Where is the spinal epidural space?
Between the dura mater and the vertebral periosteum
What is contained in the spinal epidural space?
Loose connective tissue, venous plexuses and lymphatics
What is contained in the subarchnoid space?
Cerebrospinal fluid bathing the brain and spinal cord
Where does the subarchnoid space extend to in adults?
The termination of the lumbar cistern at the level of the second sacral vertebra
