Elbow joint.

It is the hinge variety of synovial joint. It is situation between the lower end of humerus and upper end of radius and ulna bone. 

Bones involved - 

1. Humerus

2. Radius

3. Ulna

Articular surface - 

a. Upper articular surface 

1. Trochlea and capitulum of humerus.

b. Lower articular surface

1. Upper surface of head of radius with capitulum.

2. Trochlear notch of ulna with trochlea of humerus. 

Ligaments of elbow joint

1. Capsular ligament.

2. Ulnar collateral ligament.

3. Radial collateral ligament.

Relations 

1. Anterior 

Brachialis, median nerve, brachial artery and tendon of biceps brachii.

2. Posterior

Triceps brachii and anconeus.

3. Medially 

Ulnar nerve, flexor carpi ulnaris and common flexors.

4. Laterally 

Supinator, extensor carpi radialis brevis and other extensor muscles.

Blood supply 

Anastomoses around elbow joint.

Nerve supply 

1. Ulnar nerve

2. Median nerve 

3. Radial nerve

4. Musculocutaneous nerve

Movements

1. Flexion 

2. Extension

Muscles producing movements

1. Flexion 

a. Brachialis

b. Biceps brachii

c. Brachioradialis

2. Extension 

a. Triceps brachii

b. Anconeus

Note - Carrying angle 

When the forearm is in extension position then the transverse axis of the elbow joint is directed medially and downwards. Because forearm is not in the straight line with the arm. So it makes an angle of 13 degrees which is known as carrying angle. This carrying angle becomes null when the elbow is in full flexion condition.

Clinical anatomy 

1. Dislocation of the elbow 

(Usually posteriorly because of the weak capsule).

2. Pulled elbow or subluxation of the head of the radius which happens when forearm is suddenly pulled in pronated state.

3. Tennis elbow 

It happens in tennis players and there is abrupt pronation with the fully extended elbow. It leads to pain and tenderness over lateral epicondyl.

4. Student's elbow

Bursae on olecranon process gets inflammed.

5. Golfer's elbow 

Pain in common flexor origin 

Erythropoiesis

Erythropoiesis is the process of formation of RBC in various stages. 

There are 6 steps under which a matured RBC is formed. These steps are discussed below - 

1. Proerythroblast (megaloblast)

It is the first cell which is derived from colony forming unit erythroid (CFU -E). Proerythroblast multiplies several times and finally forms the cell of next stage called early normoblast.

Synthesis of hemoglobin starts in this stage. However, appearance of hemoglobin occurs only in intermediate normoblast. 

Characteristics - 

a. Large in size. 

b. Diameter is about 20 micron. 

c. Nucleus is large and occupies the cell completely. 

d. Nucleus has two or more nucleoli and a reticular network. 

e. Cytoplasm present inside the cell is basophilic in nature. 

f. Proerythroblast cells does not contain hemoglobin. 

2. Early Normoblast 

Characteristics -

a. The early normoblast cell is little smaller than proerythroblast. 

b. Diameter of this cell is around 15 µ.

c. In the nucleus, the nucleoli disappear. 

d. There is condensation of chromatin network and it becomes dense.

e. The cytoplasm is still basophilic in nature, so this cell is also called basophilic erythroblast. 

This cell develops into next stage called intermediate normoblast. 

3. Intermediate Normoblast 

Characteristics - 

a. Cell is smaller than the early normoblast with a diameter of 10 to 12 µ. 

b. The nucleus is still intact.

c. Chromatin network is continuously condensed. 

d. The hemoglobin starts appearing. 

e. Cytoplasm is still basophilic. 

Note - Because of the presence of hemoglobin, it stains with both acidic as well as basic stains. So this cell is called polychromophilic or polychromatic erythroblast. This cell develops into next stage called late normoblast. 

4. Late Normoblast 

Characteristics

a. Diameter of the cell decreases further to about 8 to 10 µ. 

b. Nucleus becomes very small with highly condensed chromatin network so it is known as ink-spot nucleus. 

c. Quantity of hemoglobin increases. 

d. Nature of cytoplasm becomes almost acidophilic. So, the cell is now called orthochromic erythroblast. 

Note - In the final stage of late normoblast just before it passes to next stage, the nucleus disintegrates and disappears and the process by which nucleus disappears is called pyknosis. Late normoblast develops into the next stage called reticulocyte. 

5. Reticulocyte 

Reticulocyte is also known as immature RBC. 

Characteristics - 

a. Size is slightly larger than matured RBC. 

b. The cytoplasm contains the reticular network or reticulum so the cells are also known as reticulocyte.

c. Reticulocyte is basophilic due to the presence of remnants of disintegrated Golgi apparatus, mitochondria and other organelles of cytoplasm. 

Note - During this stage, the cells enter the blood capillaries through capillary membrane from site of production by the process of diapedesis. 

6. Matured Erythrocyte 

Characteristics - 

a. Reticular network disappears. 

b. The cell becomes the matured RBC and attains the biconcave shape. 

c. The cell decreases in size to 7.2 µ diameter. 

d. The matured RBC is with hemoglobin but without nucleus. 

Note - It requires 7 days for the development and maturation of RBC from proerythroblast. It requires 5 days up to the stage of reticulocyte. Reticulocyte takes 2 more days to become the matured RBC.

Temporomandibular joint

It is a condylar variety of synovial joint, present in the buccal region. Temporo-mandibular joint helps in chewing.

Bones involved - 

1. Temporal

2. Mandibular

Articular surface - 

A. Upper articular surface is formed by the temporal bone.

1. Articular tubercle of temporal bone.

2. Anterior part of mandibular fossa of temporal bone.

3. Posterior non articular part formed by head of mandible of temporal bone.

B. Lower articular surface is formed by mandible bone.

Note - The articular surfaces are covered with fibrocartilage and the joint cavity is divided into upper and lower parts by an inter articular disc.

Ligaments of TMJ -

1. Fibrous capsule

2. Lateral TM ligament

3. Sphenomandibular ligament

4. Stylomandibular ligament

Relations - 

A. Lateral - 

1. Skin and fasciae

2. Parotid gland

3. Facial nerve (only temporal branch)

B. Medial 

1. Tympanic plate

2. Spine of sphenoid bone

3. Auriculo temporal and chorda tympani nerves

4. Middle meningeal artery

C. Anterior 

1. Lateral pterygoid

2. Masseteric nerves and artery

D. Posterior

1. Parotid gland

2. Superficial temporal vessels

3. Auriculotemporal nerves

E. Superior

1. Middle cranial fossa

2. Middle meningeal vessels

F. Inferior

1. Maxillary artery

2. Maxillary vein

Blood supply of TMJ - 

1. Superficial temporal artery and vein.

2. Maxillary artery and vein.

Nerve supply of TMJ - 

1. Auriculotemporal nerve.

2. Masseteric nerve.

Movements of TMJ - 

1. Depression 

2. Elevation

3. Protrusion

4. Retrusion

5. Lateral or side to side movements (during chewing)

Main muscles producing movements of TMJ - 

1. Depression - 

a. Lateral pterygoid

2. Elevation -

a. Masseter

b. Temporalis

c. Medial pterygoid 

3. Protrusion -

a. Lateral and medial pterygoid

b. Superficial oblique fibres of masseter

4. Retraction - 

a. Posterior horizontal fibres of temporalis

b. Deep vertical fibres of masseter

5. Lateral movements - 

A. Right side movement - 

 

a. Left lateral and medial pterygoid

b. Right temporalis 

c. Right masseter

B. Left side movement -

a. Right lateral and medial pterygoid.

b. Left temporalis

c. Left masseter

Clinical anatomy - 

1. Dislocation of mandible during excessive opening of mouth.

2. During operations of TMJ, facial and  auriculotemporal and mandibular division of trigeminal nerves should be taken care.

Shoulder joint

It is a ball and socket variety of synovial joint. 

Bones involved in shoulder joint

1. Scapula

2. Humerus

Articular surface involved in shoulder joint

1. Glenoid cavity of scapula

2. Head of the humerus

Factors providing stability of shoulder joint 

1. Rotator cuff muscles 

Click here to know more about rotator cuff muscles

2. Glenoid labrum

Movements of shoulder joint

1. Flexion

2. Extension

3. Adduction

4. Abduction 

5. Medial rotation

6. Lateral rotation

7. Circumduction (not a particular movement but rather it is a combination of all six movements)

Ligaments of shoulder joint

1. Capuslar ligament

2. Transverse humeral ligament

3. Coracohumeral ligament

4. Glenoidal labrum

Bursae present in shoulder joint

1. Subacromial bursae

2. Subscapularis bursae

3. Infraspinatus bursae

Relations

1. Superiorly

Coracoacromial arch, subacromial bursae, supraspinatus and deltoid muscle.

2. Inferiorly 

Long head of triceps brachii, axillary nerves and posterior circumflex humeral artery.

3. Anteriorly 

Subscapularis, coracobrachialis, short head of bicep brachii and deltoid muscles

4. Posteriorly

Infraspinatus, teres minor and deltoid muscles.

5. Within the joint

Long head of biceps brachii.

Blood supply 

1. Anterior and posterior humeral vessels.

2. Suprascapular vessels.

3. Subscapular vessels.

Nerve supply

1. Axillary nerve.

2. Musculocutaneous nerve.

3. Suprascapular nerve.

Click here to check my playlist on nerves of upper limb.

Main muscles producing movements of shoulder joint.

1. Flexion

a. Pectoralis major 

b. Anterior deltoid

2. Extention

a. Posterior deltoid

b. Lattisimus dorsi

3. Adduction

a. Pectoralis major

b. Lattisimus dorsi

c. Biceps brachii

d. Triceps brachii

4. Abduction 

From - 

a. 0° to 15° - Supraspinatus

b. 15° to 90° - Middle Deltoid

c. 90° to 180° - Serratus anterior and trapezius

5. Internal rotation

a. Pectoralis major

b. Anterior deltoid

c. Lattisimus dorsi

d. Teres major

6. External rotation 

a. Posterior deltoid

b. Infraspinatus

c. Teres minor

Clinical anatomy 

1. Frozen shoulder

2. Shoulder joint dislocatiom

3. Shoulder tip pain

Pain gate theory diagram.

Quadriceps muscle.

There are four muscles present in the anterior compartment of thigh. Those four muscles provides stability to the knee joint and helps in extention of knee. 

Name of quadriceps muscles - 

1. Rectus femoris

a. Origin - From anterior inferior iliac spine and groove above brim of acetabulum.

b. Insertion - Base of patella. 

c. Nerve supply - Femoral nerve (L1, L2,          L3).

d. Action - Extension of knee.

2. Vastus lateralis

a. Origin - Upper part of intertrochanteric         line of femur.

b. Insertion - Lateral and upper border of        patella.

c. Nerve supply - Femoral nerve.

d. Action - Extention of knee.

3. Vastus medialis

a. Origin - Lower part of intertrochanteric         line of femur.

b. Insertion - Upper and medial border of        patella. 

c. Nerve supply - Femoral nerve. 

d. Action - Extention of knee. 

4. Vastus intermedius

a. Origin - Upper 2/3rd anterior and lateral      surfaces of shaft of femur

b. Insertion - Lateral border of patella.

c. Nerve supply - Femoral nerve. 

d. Action - Extention of knee.

NOTE - 

Vastus medialis has also two  parts

1. Vastus medialis longus(VML)

2. Vastus medialis oblique(VMO) 

VMO exercises are very helpful in knee pain specially in arthritis

VMO isometric contraction

Femoral artery.

Femoral artery is a continuation of external iliac artery after passing through the inguinal ligament.  

Femoral artery has three divisions -

1. Superficial

Superficial femoral artery has following three branches -

a. Superficial epigastric artery

b. Superficial external pudendal artery

c. Superficial circumflex iliac artery

2. Deep

Deep femoral artery has following three branches - 

a. Deep external pudendal artery

b. Muscular artery

c. Profunda femoris artery

3. Descending genicular artery 

It is itself a branch of femoral artery which supplies to the knee joint.

Diagram of femoral artery -