Suboccipital triangle-Shoulder region Posterior. Flashcards
Suboccipital triangle
Mention:
- Location
- Boundaries
- Roof
- Floor
- Contents
Location - Inferior to occipital region
Boundaries -
- Rectus capitis posterior major
- Obliquus capitis superior
- Obliquus capitis inferior;
Roof –
- Semispinalis capitis
- Trapezius
Floor -
- Posterior atlanto-occipital membrane
- Posterior arch of the atlas
Contents -
- Vertebral artery
- Suboccipital nerve (dorsal ramus of C1)
Suboccipital group of back muscles:
- Rectus capitis posterior major
- Rectus capitis posterior minor
- Obliquus capitis superior
- Obliquus capitis inferior
Rectus capitis posterior major
Mention:
- Origen
- Insertion
- Innervation
- Function
Origen:
Spinous process of axis (C2)
Insertion:
Lateral portion of occipital bone below inferior nuchal line
Innervation:
Posterior ramus of C1 (motor)
Function:
- Extension of head
- Rotation of face to same side as muscle
Rectus capitis posterior minor:
Mention:
- Origen
- Insertion
- Innervation
- Function
Origen:
Posterior tubercle of atlas (C1)
Insertion:
Medial portion of occipital bone below inferior nuchal line
Innervation:
Posterior ramus of C1
Function:
Extension of head
Obliquus capitis superior
Mention:
- Origen
- Insertion
- Innervation
- Function
Origen:
Transverse process of atlas (C1)
Insertion:
Occipital bone between superior and inferior nuchal lines
Innervation:
Posterior ramus of C1
Function:
Extension of head and bends it to same side
Obliquus capitis inferior
Mention:
- Origen
- Insertion
- Innervation
- Function
Origen:
Spinous process of axis (C2)
Insertion:
Transverse process of atlas (C1)
Innervation:
Posterior ramus of C1
Function:
Rotation of face to same side
Suboccipital group of back muscles
Are innervated by what? and where does these muscle act?
Innervated by the posterior ramus of C1 (suboccipital nerve)
These muscles are mainly postural- act on the head directly or indirectly
Flexion and extension of head (atlanto-occipital joints)
Flexion
- Rectus capitis anterior
2. Longus capitis
Flexion and extension of head (atlanto-occipital joints)
Extension
- Rectus capitis posterior major
- Rectus capitis posterior minor
- Superior oblique of head
Scapulohumeral Muscles (intrinsic shoulder muscles)
- Deltoid
- Supraspinatus
- Infraspinatus
- Teres minor
- Teres major
- Subscapularis
Deltoid
Clavicle, acromion and spine of scapula
Deltoid tuberosity of humerus
Anterior: flexes, medially rotates
Middle: abducts (to 90%)
Posterior: extends, laterally rotates
–> Axillary nerve
–> Posterior circumflex humeral artery
Infraspinatus
- -> Infraspinous fossa
- -> Greater tuberosity
- -> Lateral rotation
–> Suprascapular nerve
–> Suprascapular artery
To test the infraspinatus, the person flexes the elbow and adducts the arm. The arm is then laterally rotated against resistance.
Supraspinatus
Origin
Insertion
Innervation
Function
Origin
Medial two-thirds of the supraspinous fossa of the scapula and the deep fascia that covers the muscle
Insertion
Most superior facet on the greater tubercle of the humerus
Innervation
Suprascapular nerve (C5, C6)
Function
Rotator cuff muscle; participates in:
Abduction (ABB) of the glenohumeral joint
Stabilization of glenohumeral joint
Infraspinatus
Origin
Medial two-thirds of the infraspinous fossa of the scapula and the deep fascia that covers the muscle
Insertion
Middle facet on posterior surface of the greater tubercle of the humerus
Innervation
Suprascapular nerve (C5, C6)
Function
Rotator cuff muscle; lateral rotation of arm at the glenohumeral joint
Stabilization of glenohumeral joint
Teres minor
Origin
Upper two-thirds of a flattened strip of bone on the posterior surface of the scapula immediately adjacent to the lateral border of the scapula
Insertion
Inferior facet on the posterior surface of the greater tubercle of the humerus
Innervation
Axillary nerve (C5, C6)
Function
Rotator cuff muscle; lateral rotation of arm at the glenohumeral joint
Stabilization of glenohumeral joint
Teres Major
Origin
Elongate oval area on the posterior surface of the inferior angle of scapula
Insertion
Medial lip of the inter tubercular sulcus of the anterior surface of the humerus
Innervation
Inferior subscapular nerve (C5, C6, C7)
Function
Medial rotation and extension of the arm at the glenohumeral joint;
stabilization of glenohumeral joint
Subscapularis
Origin
Insertion
Innervation
Function
Origin
Medial two-thirds of sub scapular fossa
Insertion
Lesser tubercle of humerus
Innervation
Upper and lower sub scapular nerves (C5, C6, C7)
Function
Rotator cuff muscle;
Medial rotation of the arm at the glenohumeral joint
Shoulder (Pectoral) Girdle :
is comprised of the bones that connect the upper extremity to the axial skeleton. Two bones comprise the shoulder: the clavicle and scapula.
- Sternoclavicular (SC) joint :
is the only bony link between the upper limb and the axial skeleton (sternum). Allows for movements of the scapula; double synovial plane gliding joint
- Acromioclavicular (AC) joint
Allows the upper limb to be away from the thorax permitting a greater range of upper limb motion.
- Glenohumeral (shoulder) joint:
Is formed by the articulation of the head of the humerus with the glenoid cavity of the scapula. Greatest range of motion of any joint in the body.
- Scapulothoracic joint
A “functional” joint between the subscapularis and serratus anterior muscle
Coracoclavicular ligament has 2 parts -
vertical conoid ligament and nearly horizontal trapezoid ligament
Coracoclavicular ligament rupture – cross over adduction test is positive and seen as step-off deformity
Boundaries and contents of Quadrangular and Triangular spaces:
- Quadrangular space
2. Triangular space
Quadrangular space
- -> axillary nerve
- -> posterior circumflex humeral artery
Boundaries:
- Teres minor
- Teres major
- Long head of triceps
- Surgical neck of humerus *
Triangular space
Contains? –> Circumflex scapular artery
- Teres Minor
- Teres Major
- Long head of triceps
Triangular interval:
Boundaries:
- Triceps long head
- Teres major
- Shaft of humerus
- Radial nerve
- Deep brachial artery
Blood and nerve supply to
posterior shoulder:
Suprascapular artery
Note:
–> Artery goes over
–> Nerve goes under superior transverse ligament of the scapula
How do you test the deltoid?
Remember:
You can test the deltoid or the function of the axillary nerve that supples it…
The arm is ABDUCTED, starting from approximately 15°, against resistance
**Surgical neck of humerus
Clinical problems
Fractures of the surgical neck of the humerus:
Fractures of the surgical neck of the humerus can damage the axillary nerve compromising the function of the deltoid especially abduction of the arm
The suprascapular n.and artery can become entraped by the inferior transverse ligament and cause atrophy of the infraspinatus muscle
Rotator Cuff
The glenoid cavity is relatively shallow and by itself cannot hold the head of the humerus in place
The muscles of the rotator cuff hold the head of the humerus in position
Rotator cuff muscles:
Supraspinatus- superiorly to greater tubercle (lateral rotator)
Infraspinatus- posteriorly to greater tubercle (lateral rotator)
Teres minor- posteriorly to greater tubercle (lateral rotator)
Subscapularis- anteriorly to lesser tubercle (medial rotator)
There is no support to prevent displacement of the head of the humerus inferiorly
Supraspinatus: is the most commonly injured muscle of the rotator cuff
Injury or disease may damage the musculotendinous rotator cuff, producing?
Producing instability of the glenohumeral joint.
Trauma may tear or rupture one or more of the tendons of the ?
Of the SITS muscles
What disease of the rotator cuff affects older people?
Degenerative tendonitis
Adhesive capsulitis (“frozen shoulder”) is caused by?
Adhesive fibrosis and scarring between the inflamed joint capsule of the glenohumeral joint, rotator cuff, subacromial bursa, and deltoid.
This is a condition seen in individuals 40- 60 years of age
The supraspinatus, besides being part of the rotator cuff, initiates the?
Initiates the first 15° of abduction of the arm.
Inflammation and calcification of the subacromial bursa result in ?
Pain, tenderness, and limitation of movement of the glenohumeral joint.
This condition is also known as calcific scapulohumeral bursitis.
Clinical: Shoulder Dislocation
Anteroinferior dislocation (most common)
Shoulder pain, often with visible deformity.
Weakness in shoulder abduction (deltoid) and numbness over the deltoid suggest axillary nerve injury (common)
May damage posterior humeral circumflex artery
Inferior glenohumeral ligaments (IGHL) lesion and lack of support by rotator cuff tendons
90% of injuries
Clinical: Fracture of the clavicle
The clavicle is the most commonly fractured bone
in the body
Typical site of fracture middle third
After fracture medial portion is pulled superiorly by sternocleidomastoid muscle
The lateral portion is pulled inferiorly by the weight of the shoulder
The shoulder is pulled medially by the pectoralis major
Scapular Anastomoses
Anastomoses:
Anastomoses is communications between arteries
Suprascapular artery is a branch of?
Thyrocervical trunk
Dorsal scapular artery comes from?
Subclavian artery
Circumflex scapular artery:
Subscapular artery, from axillary artery
Possibly intercostal arteries from?
Thoracic aorta
Jobe (or empty can) test:
Patient hold their arm in 90 degrees of abduction,
30 degrees of forward flexion,
resist a downward force while in the thumbs down position
Weakness in this position (positive test) indicates supraspinatus injury
