Scapula
The scapula (plural: scapulae) is a roughly triangular shaped bone of the pectoral girdle with several articulations connecting to the humerus and clavicle.
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Gross anatomy
Osteology
The main part of the scapula, the body, consists of a somewhat triangular-shaped flat blade, with an inferiorly pointing apex, referred to as the inferior angle as well as lateral and superior angles. The scapula is described as having superior, medial, and lateral borders.
Posteriorly, the scapula is divided into a supraspinous fossa and infraspinous fossa by the scapular spine. Anteriorly, on the costal surface, is the shallow subscapular fossa.
Laterally is the glenoid fossa, anteriorly is the coracoid process and superiorly is the acromion that is continuous with the scapular spine and arcs anteriorly over the humeral head. The suprascapular notch lies immediately medial to the base of the coracoid process. The spinoglenoid notch lies posteriorly behind the neck.
Articulations
- acromion: clavicle (forming the acromioclavicular joint)
- glenoid cavity: humeral head (forming the glenohumeral joint)
Attachments
Musculotendinous
- supraspinous fossa: supraspinatus muscle
- infraspinous fossa: infraspinatus muscle, teres minor muscle
- subscapular fossa: subscapularis muscle, serratus anterior
- transverse scapular ligament and adjacent superior border of blade: inferior belly of omohyoid
- acromion: acromial part of deltoid muscle, trapezius
- scapular spine: spinous part of deltoid muscle, trapezius
- coracoid process: coracobrachialis, pectoralis minor, short head of biceps muscle
- lateral border (margo lateralis): teres minor muscle, teres major muscle
- vertebral border (posterior): levator scapulae, rhomboid minor muscle, rhomboid major muscle
- inferior angle: teres major muscle, a small slip of latissimus dorsi
- supraglenoid tubercle: long head of biceps muscle
- infraglenoid tubercle: long head of triceps muscle
Ligamentous
- transverse scapular ligament: crosses suprascapular notch, with the suprascapular nerve below (within the resulting foramen) and the suprascapular vessels above
- coracoacromial ligament
- coracoclavicular ligament
- coracohumeral ligament
- glenohumeral ligaments: upper, middle, and lower bands
- acromioclavicular ligament (weak)
Blood supply
The scapula is surrounded by an arterial anastomosis, the scapular anastomosis which aims to ensure an adequate supply of blood to the upper limb, but has added benefit of adequate supply to the bone itself. It consists of the:
- suprascapular artery
- dorsal scapular artery
- branches of subscapular artery (i.e. circumflex scapular artery)
Variant anatomy
- Sprengel deformity
- os acromiale
- tubercle of Luschka
- unfused coracoid process 5
- os omovertebrale
Development
See "ossification centers of the pectoral girdle" for information on the scapular ossification centers.
Related pathology
- scapular fracture
- coracoid process fracture
- Bankart lesion
- acromioclavicular joint injury
- osteochondroma
- giant cell tumor
- aneurysmal bone cyst
- chondrosarcoma
- osteosarcoma
- Ewing's sarcoma
- multiple myeloma
- metastasis
- paget disease
Fun fact
17 muscles attach to the scapula (in alphabetic order):
Related Radiopaedia articles
Anatomy: Upper limb
-
skeleton of the upper limb
- clavicle
- scapula
- humerus
- radius
- ulna
- carpal bones (mnemonic)
- metacarpals
- phalanges
- accessory ossicles of the upper limb
- accessory ossicles of the shoulder
- accessory ossicles of the elbow
-
accessory ossicles of the wrist (mnemonic)
- os centrale carpi
- os epilunate
- os epitriquetrum
- os styloideum
- os hamuli proprium
- lunula
- os triangulare
- trapezium secondarium
- os paratrapezium
- os radiostyloideum (persistent radial styloid)
- joints of the upper limb
-
pectoral girdle
-
shoulder joint
- articulations
- associated structures
- joint capsule
- bursae
- ligaments
-
movements
- scapulothoracic joint
- glenohumeral joint
- arm flexion
- arm extension
- arm abduction
- arm adduction
- arm internal rotation (medial rotation)
- arm external rotation (lateral rotation)
- circumduction
- blood supply - scapular anastomosis
- ossification centers
-
shoulder joint
-
elbow joint
- proximal radioulnar joint
- ligaments
- associated structures
- movements
- alignment
- blood supply - elbow anastomosis
- development
-
wrist joint
- articulations
-
ligaments
- intrinsic ligaments
- extrinsic ligaments
- radioscaphoid ligament
- dorsal intercarpal ligament
- dorsal radiotriquetral ligament
- dorsal radioulnar ligament
- volar radioulnar ligament
- radioscaphocapitate ligament
- long radiolunate ligament
- Vickers ligament
- short radiolunate ligament
- ulnolunate ligament
- ulnotriquetral ligament
- ulnocapitate ligament
- ulnar collateral ligament
- associated structures
- extensor retinaculum
- flexor retinaculum
- joint capsule
- movements
- alignment
- ossification centers
-
hand joints
- articulations
- carpometacarpal joint
-
metacarpophalangeal joints
- palmar ligament (plate)
- collateral ligament
-
interphalangeal joints
- palmar ligament (plate)
- collateral ligament
- movements
- ossification centers
- articulations
-
pectoral girdle
- spaces of the upper limb
- muscles of the upper limb
- shoulder girdle
- anterior compartment of the arm
- posterior compartment of the arm
- anterior compartment of the forearm
-
posterior compartment of the forearm (extensors)
- superficial
- deep
- hand (mnemonic)
- accessory muscles
- blood supply to the upper limb
-
arteries
- subclavian artery (mnemonic)
- axillary artery
- brachial artery (proximal portion)
- ulnar artery
- radial artery
- veins
-
arteries
- innervation of the upper limb
- intercostobrachial nerve
-
brachial plexus (mnemonic)
- branches from the roots
- branches from the trunks
- branches from the cords
- lateral cord
- posterior cord
- medial cord
- terminal branches
- lymphatic drainage of the upper limb