High-Yield Anatomy

Question 1

What is the action of the supraspinatus muscle and which nerve innervates it?

Answer 1

Nerve: suprascapular
Action: Arm abduction
Tested with the “empty can” test

Question 2

What is the action of the infraspinatus muscle and which nerve innervates it?

Answer 2

Nerve: suprascapular
Action: lateral rotation of the arm

Question 3

What is the action of the teres minor muscle and which nerve innervates it?

Answer 3

Nerve: axillary
Action: arm adduction and lateral rotation

Question 4

What is the action of the subscapular muscle and which nerve innervates it?

Answer 4

Nerve: upper and lower subscapular nerve
Action: arm adduction and medial rotation

Question 5

Which muscle and nerve are responsible for the first 0º to 15º of arm abduction?

Answer 5

Muscle: supraspinatus
Nerve: suprascapular

Question 6

Which muscle and nerve are responsible for 15º to 100º of arm abduction?

Answer 6

Muscle: deltoid
Nerve: axillary

Question 7

Which muscle and nerve are responsible for abducting the arm greater than 90º?

Answer 7

Muscle: trapezius
Nerve: accessory (CN XI)

Question 8

Which muscle and nerve are responsible for abducting the arm greater than 100º?

Answer 8

Muscle: serratus anterior
Nerve: long thoracic

Question 9

Lateral epicondylitis results from which repetitive motion and can impair what motor action?

Answer 9

Lateral epicondylitis (tennis elbow) comes from repetitive extension (backhand shots) –> this inflammation can impair the extensor carpi radialis brevis and result in impaired wrist extension

Question 10

What are the bones of the wrist:

Answer 10

Scaphoid, Lunate, Triquetrum, Piriformis, Hamate, Capitate, Trapezoid, Trapezium (has more syllables)

Question 11

Carpal tunnel syndrome involves compression of which nerve, and occurs between which structures?

Answer 11

• Compression of the median nerve, usually betwen the carpal bones and transverse carpal ligament

Question 12

A fracture of the surgical neck of the humerus or anterior dislocation of the humerus injures which nerve and presents with which physical exam findings?

Answer 12

• Axillary nerve (C5-6)
• Presents with: flattened deltoid, loss of arm abduction at should (>15º), loss of sensation over deltoid and lateral arm

Question 13

Compression of the upper trunk injures which nerve and presents with which physical exam findings?

Answer 13

• Musculocutaneous nerve (C5-C7)

- Loss of forearm flexion and supination, loss of sensation over lateral forearm

Question 14

A midshaft fracture of the humerus or compression of the axilla from crutches injures which nerve and presents with which physical exam findings?

Answer 14

• Radial nerve (C5-T1)
• Wrist drop, loss of elbow, wrist and finger extension
• Decreased grip strength and loss of sensation over posterior arm/forearm and dorsal hand

Question 15

A supracondylar fracture of the humerus injures which nerve and presents with which physical exam findings?

Answer 15

• Median (C5-T1)
• “Ape hand” - unable to oppose thumb, and “Pope’s blessing”-unable to flex lateral fingers or wrist
• Loss of sensation over thenar eminence and dorsal and palmar aspects of lateral 3 and 1/2 fingers

Question 16

A superficial laceration of the palm injures which nerve and presents with which physical exam findings?

Answer 16

• Recurrent branch of the median nerve (C5-T1)
• “Ape hand”
• Loss of thenar muscle group: opposition, abduction, and flexion of thumb
• No loss of sensation

Question 17

What is the function of the dorsal interossei of the hands?

Answer 17

Finger abduction (feel your hand—you can actually feel these muscles moving with abduction)

Question 18

What is the function of the palmar interossei of the hands?

Answer 18

Finger adduction (again, feel your hand—you can actually feel these muscles moving with adduction)

Question 19

What is the function of the lumbricals of the hand?

Answer 19

MCP flexion, PIP and DIP extension (“Duck hand” or “sock puppet hand”)

Question 20

Injury to the iliohypogastric nerve (T12-L1) presents with which sensory and motor deficit?

Answer 20

Sensory: suprabupic region - causes burning or tingling pain in surgical incision site that radiates to the inguinal/suprabupic region
Motor: transversus abdominus, internal oblique (right there!)

Question 21

Injury to the genitofemoral nerve (L1-L2) presents with which sensory and motor deficit?

Answer 21

Sensory: scrotum/labia and medial thigh –> loss of anterior thigh sensation below the inguinal ligament (i.e. in the FEMORAL triangle)
Motor: cremaster –> absent cremaster reflex

Question 22

Injury to the obturator nerve (L2-L4) presents with which sensory and motor deficit?

Answer 22

Sensory: medial thigh
Motor: thigh adductors (obturator externus, adductor longus, adductor brevis, gracilis, pectineus, adductor magnus)

Question 23

Injury to the femoral nerve (L2-L4) presents with which sensory and motor deficit?

Answer 23

Often caused by pelvic fracture
Sensory: anterior thigh, medial leg
Motor: quadriceps, iliopsoas, pectineus, sartorius –> loss of thigh flexion and leg extension

Question 24

Injury to the sciatic nerve (L4-S3) presents with which sensory and motor deficit?

Answer 24

Often caused by a herniated disc
Sensory: posterior thigh
Motor: semitendinosus, semimembranosus, biceps femoris, adductor magnus

Question 25

Injury to the common peroneal nerve (L4-S2) presents with which sensory and motor deficit?

Answer 25

Caused by compartment syndrome - compression of the lateral aspect of the leg or fibular neck fracture
Sensory: dorsum of foot
Motor: biceps femoris, tibialis anterior, extensor muscle of foot –> presents with foot drop (inverted and plantar-flexed at rest, loss of eversion and dorsiflexion = steppage gait)

Question 26

Injury to the tibial nerve (L4-S3) presents with which sensory and motor deficit?

Answer 26

Sensory: sole of foot
Motor: tricpes surae, plantaris, poplitus, flexor muscles of foot
TIP: tibial nerve INVERTS and PLANTARFLEXES –> can’t stand on TIP toes if injured
- unable to curl toes and loss of sensation on sole

Question 27

Injury to the superiorgluteal nerve (L4-S1) presents with which motor deficit?

Answer 27

Trendelenburg gait - pelvic tilts when standing on the leg that is ipsilateral to the lesion, because the weight-baring leg is unable to maintain alignment of the pelvis through hip abduction (gluteus medius, gluteus minimus, tensor fascia latae)

Caused by injury during intramuscular injection to the upper medial gluteal region (UMM…I wouldn’t do that = UM –> upper medial)

Question 28

Injury to the inferior gluteal nerve (L5-S2) presents with which motor deficit?

Answer 28

Motor: gluteus maximus –> unable to climb stairs or rise from seated position due to loss of hip extension