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shoulder definition
- junction of the upper limb and trunk
- consists of scapular, deltoid and pectoral region, and the axilla
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Scapula
Large, flattened, triangular bone lying on the posterolateral surface of the thorax, overlapping parts of the second to the 7th rbs
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Costal Surface of scapula
- concavity, subscapular fossa
- place for subscapularis muscle placement
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Dorsal surface of scapula
- divided by spine into supraspinous and infraspinous fossa.
- fossae are connectd laterally by the spinoglenoid notch
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scapular notch
- interrupts the superior border at the base of the coracoid process.
- Converted into a foramen by the superior transverse scapular ligament.
- Suprascapular vessels pass over the ligament and the suprascapular nerve passes under it.
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lateral angle
- pearshaped fossa - glenoid fossa
- articulates with the rounded head of the humerus to form shoulder
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Supraglenoid tubercle
- upper border of the glenoid cavity
- attaches the longhead of the biceps
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Infraglenoid tubercle
- lateral border of the scapular immediately below the glenoid cavity is the thickening.
- Attaches the longhead of the triceps
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Neck of scapula
narrow part of the scapula medial to the lateral angle
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Spine of the scap
flat triangular plate projecting POST from upper part of dorsal surface. Posterior border of the spin is subcutaneous.
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Acromion
projects forwards from the lateral end of the spine and forms the point of the shoulder.
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Angle of acromion
Subcuatenous bony prominence posterolaterally marks the sharp forward turn of the acromion
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Acromioclavicular joint
Acromion has a small, flat, oval facet that articulates with the LAT end of the clavicle to form it
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coracoid process
- hooked, located medial to the upper border of the glenoid cavity, projects forward and slightly laterally
- Attachement for the pectoralis minor, coracobrachialis and short head of the biceps
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Scapular articulations
- largely suspended by muscle
- articulates with humurus and clavicle
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Clavicle
- long bone consisting of two expands ends connected by a shaft or body.
- Extends from root of neck laterally towards the point of the shoulder
- subcutaneous throughout
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sternal end of clavicle
- enlarged quadrangular shape with a sellar-shaped articular surface
- convex vertically and slightly concave from front to back
- articulates with articular disc that separates it from the clavicular notch of the manubrium to form SC joint
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shaft of clavicle
- slight S-shaped curve,
- convex forwards in its medial 2/3 and concave forward in its lateral 1/3
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conoid tubercle
- along the back edge of the clavicle
- attachment of the conoid part of the coracoclavicular ligament
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trapezoid line
runs with the conoid tubercle toward acromial end. attachment for the coracoclavicular ligament.
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Acromial end of clavicle
flattened and has a small, flat oval facet that articulates with the medial border of the acromion at the acromioclavicular joint
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Clavicle development
- ossifies before any other bone in the body
- only bone in the limbs that is formed by intramembranous ossification
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clavicle motion
acts as a strut which supports the shoulder and allows the lib to swing clear of the turnk
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Extrinsic muscles features / insertion points
- not confined to the upper limb
- arise from axial skeleton
- insert on bones of either the pectoral girdle (scap and clavicle) or humerus
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Extrinsic muscles and blood supply
- Back muscles, pectoral muscles, and serratus anterior
- supply from subclavian and axillary arteries
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Intrinsic muscles of the shoulder features
- confined entirely to the upper limb
- arise from bones of the pectoral girdle and insert on the humerus
- only act at shoulder joint
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Intrinsic muscles and supplies
- deltoid and muscles of scapular region
- C5, 6 through posterior division branches
- subclavian and axillary
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