What is the first bone to begin ossification during fetal development? Also last bone to complete ossification at 21 yrs.
What is the only bone to be ossified intramembranously?
Spine of scapula
Triangluar shaped process that continues laterally as the acromion.
What does the spine of the scapula divide into?
Supraspinous and infraspinous fossae.
What muscles are associated with the spine of the scapula?
Origin for deltoid and insertion for trapezious
Lateral end of scapular spine and articulates with clavicle. Origin for deltoid and insertion for trapezius.
Origin for coracobrachialis and biceps brachii
Insertion for pectoralis minor
Attachment site for coracoclavicular, coracohumeral, and coracoacromial ligaments and costocoracoid membrane
Bridged by superior transverse scapular ligament and converted into foramen for suprascapular nerve.
How is the clavicle typically fractured?
1) Fall on shoulder or outstretched hand
2) Infant presses against maternal pubic symphysis during passage through birth canal
What part of the clavicle is most commonly fractured?
What happens when the middle third of the clavicle is fractured?
1) Upward displacement of proximal fragment by sternocleidomastoid muscle
2) Downward displacement of distal fragment by deltoid muscle and gravity.
What other structures can be damaged by fx of clavicle?
1) Brachial plexus causing parasthesia (numbness, tingling, burning) in skin supplied by medial brachial and antebrachial cutaneous nerves
2) Fatal hemmorhage from subclavian vein
3) Thrombosis of subclavian vein leading to PE
Deepened by glenoid labrum from head of humerus
Supraglenoid and infraglenoid tubercles
Origin for tendons of long heads of biceps brachii and triceps brachii
Articulates with scapula at glenohumeral joint
Humeral Anatomic Neck
Indentation distal to head; provides attachement for fibrous joint capsule
Greater Tubercle of Humerus
Lateral to anatomic neck, attachment for supraspinatus, infraspinatus, and teres minor muscles
What happens with calcification of the superior transverse scapular ligament?
May trap or compress the suprascapular nerve as it passes through scapular notch under superior transvers scapular ligament.
Affects functions of supraspinatus and infraspinatus muscles
Lesser Tubercle of Humerus
Lies on anterior medial side of humerus, just distal to anatomic neck. Provides insertion for subscapularis muscle.
Intertubercular (Biceptal) Groove
B/w greater and elsser tubercles, lodges tendon of long head of biceps brachii muscle. Bridged by transverse humeral ligament. Insertions for pecoralis major on later lip and teres major on medial lip and latissimus dorsi on floor.
Surgical Neck of Humerus
Narrow area distal to tubercles that is a common site of fracture and is in contact with axillary nerve and posterior humeral circumflex artery
Rough triangular elevation on lateral aspect of midshaft that marks insertion of deltoid muscle
Contains radial nerve, separating origin of lateral head of triceps above origin of medial head below
What could the fracture of the surgical neck of humerus also injure?
1) Axillary nerve
2) Posterior humeral circumflex artery
What could the fracture of the humeral shaft also damage?
1) Radial nerve
2) Deep brachial artery in spiral groove
What is a supracondylar fx?
Fracture of distal end of humerus. Common in children when child falls on outstretched hand with elbow partially flexed. May injure median nerve.
What nerve could be injured by fx of medial epicondyle?
Ulnar nerve. May be compressed in groove behind medial epicondyle "funny bone" causing numbness.
Spool shaped, medial articular surface. Articulates with trochlear notch of ulna.
Lateral articular surface, globular shape, articulates with head of radius.
Posterior depression above trcholea of humerus that houses the olecranon of ulna on full extension of forearm.
Anterior depression above trochlea of humerus that accomodates coronoid process of ulna on flexion of elbow.
Anterior depression above the capitulum that is occupied by the head of radius during full flexion of the elbow joint.
Projects from capitulum and provides origin of supinator and extensor muscles of forearm
Projects from trochlea and has groove on back for ulnar nerve and superior ulnar collateral artery.
Attachment sites for ulnar collateral ligament, pronator teres, and common tendon of forearm flexor muscles.
Shorter than ulna, lateral to ulna.
Fx of distal end of radius. Displacement of hand dorsally and radially. Distal fragment displaced posteriorly creating dinner fork deformity
Smith's Fracture (reverse Colle's fx)
Fx of distal end of radius with distal fragment displcaced anteriorly. May show styloid processes of radius and ulna line up on x-ray.
Head of Radius (Proximal End)
Articulates with capitulum of humerus and radial notch of ulna. Surrounded by annular ligament
Distal End of Radius
Articulates with proximal row of carpal bones including scaphoid, lunate, and triquetral bones, exluding pisiform.
Oblong prominence just distal to neck of radius and provides attachment to biceps brachii tendon.
Styloid Process of radius
Distal end of radius, approx 1 cm distal to styloid process of ulna. Insertion of brachiordialis muscle. Palpable in proximal part of anatomic snuffbox between extensor pllicis longs and brevis tendons.
Curved projection on back of elbow that provides an attachment site for triceps tendon.
Located below trochlear notch and provides attachment site for brachialis.
Recieves trochlea of humerus
Roughened prominence distal to coronoid process that provides attachment site for brachialis
Accommodates head of radius at proximal radioulnar joint.
Head of Ulna (Distal End)
Articulates with articular disk of distal radioulnar joint and has styloid process.
Two rows. Lateral to medial: Scaphoid, Lunate Triquetrium, Pisiform, Trapezium, Trapezoid, Capitate, and Hamate.
Proximal Row of Carpal Bones
Lateral (thumb) to medial (pinky): Scaphoid, Lunate, Triquetrium, Pisiform
Articulates with radius only and articular disk
Sesamoid bone contained in flexor carpi ulnaris tendon.
Distal Row of Carpal Bones
L to M (thumb to pinky): Trapezium, Trapezoid, Capitate, Hamate
Fracture of the scaphoid
Fall on outstretched hand. Deep anatomical snuffbox tenderness and damages radial artery and causes avascular necrosis of bone and degenerative joint disease of wrist.
Fracture of Hamate
May injure ulnar nerve and artery because they are near hook of hamate.
Fracture of base of metacarpal of thumb proximal to trapezium
In pros: Fx neck of 2nd and 3rd metacarpals
In non-pros: Fx neck of 5th metacarpal
Guyon's canal (Ulnar tunnel)
Formed by pisiform, hook of hamate, and pisohamate ligament deep to palmaris brevis and palmar carpal ligament. Transmits ulnar nerve and artery.
Guyon's canal syndrome
Entrapment of ulnar nerve in Guyon's canal causing pain, numbness, and tingling in ring and pinky fingers followed by loss of sensation and motor weakness. Treated surgically.
Miniature long bones consisting of bases (proximal ends), shafts (bodies), and heads (distal ends). Heads form knuckles of fist.
Mini long bones consisting of bases, shafts, and heads. Heads of proximal and middle phalanges form knuckles. 3 in fingers, 2 in thumb.