Musculoskeletal, Skin, and Connective Tissue - Anatomy and Physiology Flashcards
1
Q
Epidermis layers from surface to base
A
- Californians Like Girls in String Bikinis
- Stratum Corneum (keratin)
- Stratum Lucidum
- Stratum Granulosum
- Stratum Spinosum (spines = desmosomes)
- Stratum Basale (stem cell site)
2
Q
Epithelial cell junctions (410)
- Tight junction
- Adherens junction
- Desmosome
- Gap junction
- Integrins
- Hemidesmosome
A
- Tight junction (zonula occludens)
- Prevents paracellular movement of solutes
- Composed of claudins and occludins.
- Adherens junction (zonula adherens)
- Below tight junction, forms “belt” connecting actin cytoskeletons of adjacent cells with CADherins (Ca2+-dependent adhesion proteins).
- Loss of E-cadherin promotes metastasis.
- Desmosome (macula adherens)
- Structural support via keratin interactions.
- Autoantibodies –> pemphigus vulgaris.
- Gap junction
- Channel proteins called connexons permit electrical and chemical communication between cells.
-
Integrins
- Membrane proteins that maintain integrity of basolateral membrane by binding to collagen and laminin in basement membrane.
- Hemidesmosome
- Connects keratin in basal cells to underlying basement membrane.
- Autoantibodies –> bullous pemphigoid.
- Hemidesmosomes are down “bullow”
3
Q
Knee injury
- Presents with…
- “Anterior” and “posterior” in ACL and PCL refer to…
- Abnormal passive abduction –>
- Abnormal passive adduction –>
- McMurray test
- Unhappy triad
A
- Presents with acute knee pain and signs of joint injury/instability:
- “Anterior” and “posterior” in ACL and PCL refer to sites of tibial attachment.
- Anterior drawer sign –> ACL injury
- Posterior drawer sign –> PCL injury
- Abnormal passive abduction (valgus stress) –> MCL injury
- Abnormal passive adduction (varus stress) –> LCL injury
- “Anterior” and “posterior” in ACL and PCL refer to sites of tibial attachment.
- McMurray test
- Pain on external rotation –> medial meniscus
- Pain on internal rotation –> lateral meniscus.
-
Unhappy triad
- Common injury in contact sports due to lateral force applied to a planted leg.
- Classically, consists of damage to the ACL, MCL, and medial meniscus (attached to MCL)
- However, lateral meniscus injury ismore common.
4
Q
Clinically important landmarks
- Pudendal nerve block
- Appendix
- Lumbar puncture
A
- Pudendal nerve block (to relieve pain of delivery)
- Ischial spine.
- Appendix
- 2/3 of the distance between the umbilicus and the anterior superior iliac spine (ASIS), just proximal to the ASIS (McBurney point).
- Lumbar puncture
- Iliac crest.
5
Q
Rotator cuff muscles
- Shoulder muscles that form the rotator cuff:
- Innervation
A
- Shoulder muscles that form the rotator cuff:
-
Supraspinatus (suprascapular nerve)
- Abducts arm initially (before the action of the deltoid)
- Most common rotator cuff injury.
-
Infraspinatus (suprascapular nerve)
- Laterally rotates arm
- Pitching injury.
-
Teres minor (axillary nerve)
- Adducts and laterally rotates arm.
-
Subscapularis (subscapular nerve)
- Medially rotates and adducts arm.
- SItS (small t is for teres minor).
-
Supraspinatus (suprascapular nerve)
- Innervated primarily by C5-C6.
6
Q
Wrist bones
- Wrist bones
- Most commonly fractured carpal bone
- Carpal tunnel syndrome
- Guyon canal syndrome
A
- Wrist bones
- Scaphoid, Lunate, Triquetrum, Pisiform, Hamate, Capitate, Trapezoid, Trapezium [A].
- So Long To Pinky, Here Comes The Thumb
- Scaphoid (palpated in anatomical snuff box) is the most commonly fractured carpal bone and is prone to avascular necrosis owing to retrograde blood supply.
-
Carpal tunnel syndrome
- Entrapment of median nerve in carpal tunnel
- Nerve compression –> paresthesia, pain, and numbness in distribution of median nerve.
- Dislocation of lunate may cause acute carpal tunnel syndrome.
-
Guyon canal syndrome
- Compression of the ulnar nerve at the wrist or hand, classically seen in cyclists due to pressure from handlebars.
- A fall on an outstretched hand that damages the hook of the hamate can cause ulnar nerve injury.
7
Q
Brachial plexus (proximal –> distal) (413)
A
- Randy Travis Drinks Cold Beer
- Roots
- Trunks
- Divisions
- Cords
- Branches
8
Q
Brachial plexus lesions (413)
- Upper trunk
- Lower trunk
- Posterior cord
- Long thoracic root
- Axillary nerve
- Radial nerve
- Musculocutaneous branch
- Median branch
- Ulnar branch
A
- Upper trunk
- Erb palsy (“waiter’s tip”)
- Lower trunk
- Claw hand (Klumpke palsy)
- Posterior cord
- Wrist drop
- Long thoracic root
- Winged scapula
- Axillary nerve
- Deltoid paralysis
- Radial nerve
- “Saturday night palsy” (wrist drop)
- Musculocutaneous branch
- Difficulty flexing elbow, variable sensory loss
- Median branch
- Decreased thumb function, “Pope’s blessing”
- Ulnar branch
- Intrinsic muscles of hand, claw hand
9
Q
Erb palsy
- Injury
- Causes
- Muscle deficit
- Functional deficit
A
- Injury
- Traction or tear of upper (“Erb-er”) trunk: C5-C6 roots
- “Waiter’s tip”
- Causes
- Infants—lateral traction on neck during delivery
- Adults—trauma
- Muscle deficit
- (1) Deltoid, supraspinatus
- (2) Infraspinatus
- (3) Biceps brachii
- Functional deficit
- (1) Abduction (arm hangs by side)
- (2) Lateral rotation (arm medially rotated)
- (3) Flexion, supination (arm extended and pronated)
10
Q
Klumpke palsy
- Injury
- Causes
- Muscle deficit
- Functional deficit
A
- Injury
- Traction or tear of lower trunk: C8-T1 root
- Causes
- Infants—upward force on arm during delivery
- Adults—trauma (e.g., grabbing a tree branch to break a fall)
- Muscle deficit
- Intrinsic hand muscles: lumbricals, interossei, thenar, hypothenar
- Functional deficit
- Total claw hand: lumbricals normally flex MCP joints and extend DIP and PIP joints
11
Q
Thoracic outlet syndrome
- Injury
- Causes
- Muscle deficit
- Functional deficit
A
- Injury
- Compression of lower trunk and subclavian vessels
- Causes
- Cervical rib injury
- Pancoast tumor
- Muscle deficit
- Intrinsic hand muscles: lumbricals, interossei, thenar, hypothenar
- Functional deficit
- Atrophy of intrinsic hand muscles
- Ischemia, pain, and edema due to vascular compression
12
Q
Winged scapula
- Injury
- Causes
- Muscle deficit
- Functional deficit
A
- Injury
- Lesion of long thoracic nerve
- Causes
- Axillary node dissection after mastectomy, stab wounds
- Muscle deficit
- Serratus anterior
- Functional deficit
- Inability to anchor scapula to thoracic cage –> cannot abduct arm above horizontal position
13
Q
Axillary nerve
- Nerve type and level
- Causes of injury
- Presentation
A
- Nerve type and level
- Upper extremity nerve (C5-C6)
- Causes of injury
- Fractured surgical neck of humerus
- Anterior dislocation of humerus
- Presentation
- Flattened deltoid
- Loss of arm abduction at shoulder (> 15 degrees)
- Loss of sensation over deltoid muscle and lateral arm
14
Q
Musculocutaneous nerve
- Nerve type and level
- Causes of injury
- Presentation
A
- Nerve type and level
- Upper extremity nerve (C5-C7)
- Causes of injury
- Upper trunk compression
- Presentation
- Loss of forearm flexion and supination
- Loss of sensation over lateral forearm
15
Q
Radial nerve
- Nerve type and level
- Causes of injury
- Presentation
A
- Nerve type and level
- Upper extremity nerve (C5-T1)
- Causes of injury
- Midshaft fracture of humerus
- Compression of axilla (e.g., due to crutches or sleeping with arm over chair (“Saturday night palsy”)
- Presentation
- Wrist drop: loss of elbow, wrist, and finger extension
- Decreased grip strength (wrist extension necessary for maximal action of flexors)
- Loss of sensation over posterior arm/forearm and dorsal hand
16
Q
Median nerve
- Nerve type and level
- Causes of injury
- Presentation
A
- Nerve type and level
- Upper extremity nerve (C5-T1)
- Causes of injury
- Supracondylar fracture of humerus (proximal lesion)
- Carpal tunnel syndrome and wrist laceration (distal lesion)
- Presentation
- “Ape hand” and “Pope’s blessing”
- Loss of wrist and lateral finger flexion, thumb opposition, lumbricals of 2nd and 3rd digits
- Loss of sensation over thenar eminence and dorsal and palmar aspects of lateral 31⁄2 fingers with proximal lesion
- Tinel sign (tingling on percussion) in carpal tunnel syndrome
17
Q
Ulnar nerve
- Nerve type and level
- Causes of injury
- Presentation
A
- Nerve type and level
- Upper extremity nerve (C8-T1)
- Causes of injury
- Fracture of medial epicondyle of humerus “funny bone” (proximal lesion)
- Fractured hook of hamate (distal lesion)
- Presentation
- “Ulnar claw” on digit extension
- Radial deviation of wrist upon flexion (proximal lesion)
- Loss of flexion of wrist and medial fingers, abduction and adduction of fingers (interossei), actions of medial 2 lumbrical muscles
- Loss of sensation over medial 11/2 fingers including hypothenar eminence
18
Q
Recurrent branch of median nerve
- Nerve type and level
- Causes of injury
- Presentation
A
- Nerve type and level
- Upper extremity nerve (C5-T1)
- Causes of injury
- Superficial laceration of palm
- Presentation
- “Ape hand”
- Loss of thenar muscle group: opposition, abduction, and flexion of thumb
- No loss of sensation
20
Q
Distortions of the hand
- For each
- Location of lesion
- Context
- Presentation (image)
- “Ulnar claw”
- “Pope’s blessing”
- “Median claw”
- “OK gesture” (with digits 1-3 flexed)
A
- “Ulnar claw”
- Location of lesion: Distal ulnar nerve
- Context: Extending fingers/at rest
- Presentation: Image 1
- “Pope’s blessing”
- Location of lesion: Proximal median nerve
- Context: Making a fist
- Presentation: Image 1
- “Median claw”
- Location of lesion: Distal median nerve
- Context: Extending fingers / at rest
- Presentation: Image 2
- “OK gesture” (with digits 1-3 flexed)
- Location of lesion: Proximal ulnar nerve
- Context: Making a fist
- Presentation: Image 2
21
Q
Functions of hand muscles
- Thenar vs. hypothenar
- Thenar
- Hypothenar
- Dorsal vs. palmar
- Dorsal interosseous muscles
- Palmar interosseous muscles
- Lumbrical muscles
A
- Thenar vs. hypothenar
- Thenar
- Median
- Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis.
- Hypothenar
- Ulnar
- Opponens digiti minimi, Abductor digiti minimi, Flexor digiti minimi brevis.
- Both groups perform the same functions: Oppose, Abduct, and Flex (OAF).
- Thenar
- Dorsal vs. palmar
- Dorsal interosseous muscles
- Abduct the fingers.
- DAB = Dorsals ABduct.
- Palmar interosseous muscles
- Adduct the fingers.
- PAD = Palmars ADduct.
- Dorsal interosseous muscles
- Lumbrical muscles
- Flex at the MCP joint
- Extend PIP and DIP joints.
30
Q
Muscle conduction to contraction (417)
A
- Action potential depolarization opens presynaptic voltage-gated Ca2+ channels, inducing neurotransmitter release.
- Postsynaptic ligand binding leads to muscle cell depolarization in the motor end plate.
- Depolarization travels along muscle cell and down the T tubule.
- Depolarization of the voltage-sensitive dihydropyridine receptor, mechanically coupled to the ryanodine receptor on the sarcoplasmic reticulum, induces a conformational change, causing Ca2+ release from sarcoplasmic reticulum.
- Released Ca2+ binds to troponin C, causing a conformational change that moves tropomyosin out of the myosin-binding groove on actin filaments.
- Myosin releases bound ADP and subsequently, inorganic PO43– displacement of myosin on the actin filament (power stroke).
- Contraction results in shortening of H** and **I** bands and between **Z lines
- HIZ shrinkage
- The A band remains the same length
- A band is Always the same length
- Contraction results in shortening of H** and **I** bands and between **Z lines
32
Q
Smooth muscle contraction (418)
A
- Increased _Ca_2+ –> _C_ontraction
- Nitric oX**ide –> rela**Xaxation
