Advanced Human Dissection- Clinical Application Quiz 1

C5, C6, C7....

"Keeps the wings from heaven" (contributes to the long thoracic nerve, if there is injury to this nerve, winged scapula can result)

How many pairs of denticulate ligaments are there?

- 21 total pairs, so they are not found between all dorsal and ventral rootlets - The inferior-most pair is at the level of the conus medullaris, namely between T12 and L1 segmental nerve roots, and its pia mater fuses with the filum terminale

Spinal nerves

- 31 pairs - Contain both sensory and motor axons - 8 cervical nerves - 12 thoracic nerves - 5 lumbar nerves - 5 sacral nerves - 1 coccygeal nerve

Allen Dexter, a 19-year-old college student, was rock climbing when he fell 30 feet to the ground. Paramedics arriving at the scene found him lying in the supine position, unable to move any extremities and complaining of neck pain. He was awake, alert, and oriented to his current location, the date and day of the week, and the details of his fall. His responses to questioning were appropriate. He complained that he could not feel his arms and legs. His pupils were equal and reactive to light. He showed no other signs of injury except for several scrapes on his arms. His vital signs revealed a blood pressure of 110 / 72, heart rate of 82 beats per minute, respirations of 18 per minute. The paramedics applied a cervical collar, placed him on a back board, immobilized his head, and transported him to the trauma center by helicopter. Upon examination at the hospital, Allen had minimal biceps brachii stretch reflexes, but no triceps or wrist extensor reflexes. All other muscle stretch reflexes in the upper and lower extremities were absent. His perception of sensory stimuli ended bilaterally at an imaginary line drawn across his chest about 3 inches above the nipples (i.e. everything below

- A spinal cord injury on the level of C5 means that the sympathetic nervous system cannot communicate with the parasympathetic ganglion in the lateral horn of the spinal cord, since these fibers originate in the thoracic region (below C5). - Similarly, the postganglionic neurons of the SNS could not effectively communicate with its target organs sweat glands, subcutaneous blood vessels, arrector pili m. This helps to explain why Allen's skin was dry and he was feverish (he could not sweat and subsequently release body heat) - SNS is also responsible for elevating heart rate and increasing blood pressure, which would help explain why Allen's heart rate and blood pressure fell

Serratus anterior m action

- Abducts and draws scapula forward - When muscle is denervated, "winged scapula" is present

Deltoid m action

- Abducts arm (after first 15 degrees to about 90 degrees) - Anterior fibers flex and medially rotate arm - Posterior fibers extend and laterally rotate arm

The intervertebral disks:

- Add 1/4 to the entire length of the vertebral column - Act as shock absorbers between vertebral bodies - Are not found between all adjacent vertebrae - Cartilaginous joints

Deep brachial artery

- Also called the profunda artery - It is the primary blood vessel in the upper arm - Supplies blood to the muscles of the upper arm and to the shaft of the humerus. Once it branches, it also supplies blood to the elbow joint, the forearm, and the hand

Intrinsic back muscles

- Also called true back muscles - They are located deep to the extrinsic muscles, being separated from them by the thoracolumbar fascia. - Their primary function is to produce movements of the vertebral column. - These muscles are divided into superficial, deep, and deepest layers.

Greater occipital nerve

- Arises from the medial branch of the dorsal ramus of C2 - Supplies the skin over the occipital bone and the upper posterior neck

Glenohumeral joint

- Ball and socket joint - Comprises a larger, round humeral head and a shallow glenoid cavity - Highly mobile, and thus, needs structures to stabilize it

Splenius capitis m and splenius cervicis m action

- Bilateral: head extension - Unilateral: lateral flexion and rotation of the head

Obliqus capitis superior m action

- Bilateral: head extension - Unilateral: lateral flexion to the same side

Ramus communicans

- Branches of a spinal nerve - Preganglionic is white due to myelination - Postganglionic is grey due to lack of myelination

Posterior circumflex humeral artery

- Crosses through the quadrangular space with the axillary nerve - Once the posterior circumflex humeral artery branches off from the axillary artery, it distributes oxygenated blood to the shoulder joint and deltoid

Arachnoid mater

- Delicate membrane made of fibrous and elastic tissue that lines the dural sac and the dural root sleeves - Encloses the CSF-filled subarachnoid space containing the spinal cord, spinal nerve roots, and spinal ganglia - Held against the dura but separable from it - In a lumbar puncture, the arachnoid mater is pierced

Posterior shoulder injections often result in neuromuscular injuries. Which structures are at risk for injury? Give an example of functional loss if these structures are injured.

- Deltoid paralysis (would result from injury to axillary nerve and posterior circumflex humeral artery) - Would result in functional losses such as difficulty abducting the arm from 15-90 degrees

Types of neurons in different horns of spinal cord

- Dorsal: pseudounipolar neurons - Ventral: multipolar - Lateral: multipolar

Trapezius m action

- Elevates shoulder - Retraction, depression, elevation of scapula - Superiorly rotates glenoid cavity - Neck extension

Possible movements of the spinal column via intrinsic back muscles

- Flexion (touching your toes) - Extension (bending backwards) - Lateral bending - Rotation (either of head and neck only, or of the entire torso)

Intervertebral disc blood supply

- Have no significant vascular structures - They receive their blood supply by diffusion through the vertebral body endplates - A network of vessels located centrally in the endplate allows nutrients to diffuse into the nucleus pulposus and annulus fibrosis

Slipped disk

- Herniation of the nucleus pulposus through the anulus fibrosis - Usually happens in the posterolateral direction - Once a disk herniates, it usually puts pressure on the nerve roots or the dorsal root ganglion exiting the intervertebral foramen at or below its level

Interesting phenomenon- disk herniations

- If a disc herniates in the lumbar region, for example between L5 and S1, it will be affecting the S1 spinal nerve. - This is because the L5 nerve lies immediately below the L5 pedicle, above the herniating disc and is not affected However, the S1 nerve roots are already proceeding laterally toward the S1 intervertebral foramen, so it is usually caught by the herniating L5- S1disc.

Meningitis

- Infection of the meninges (either bacterial or viral) - Patients typically present with the triad of fever, headache, and signs of meningeal irritation (such as neck stiffness)

Nucleus pulposus

- Inner structure of the vertebral disc - Gelatinous - High water content - Resists axial forces

Pia mater

- Innermost meningeal layer - Closely follows entire spinal cord and directly covers the roots of spinal nerves and the spinal blood vessels - Inferior to the conus medullaris, the pia mater continues as the filum terminale

Tibialis posterior m action

- Inversion and assists in the plantar flexion of the foot at the ankle - The tibialis posterior has a major role in supporting the foot's medial arch

Extrinsic back muscles

- Lie most superficially on the back - These muscles are also called immigrant muscles, since they actually represent muscles of the upper limb that have migrated to the back during fetal development. - These muscles are divided into superficial and intermediate

Lateral horn of spinal cord

- Location of cell bodies of sympathetic preganglionic fibers - These preganglionic neurons (myelinated) will travel and join spinal nerve and synapse with postganglionic neuron - Postganglionic neurons will travel with spinal nerve to reach target organs: sweat glands, subcutaneous blood vessels, arrector pili muscle

Ventral horn of the spinal cord

- Location of cells bodies of motor neurons - These motor neurons leave the spinal cord through the ventral root, join a spinal nerve, and then divide into the ventral and dorsal primary rami

Dorsal root ganglion (DRG)

- Location of the cell bodies of somatic sensory neurons - Cells from the dorsal root ganglia transmit somatic sensation from the areas like the skin to the CNS

Ventral and dorsal roots of a spinal nerve

- Made of the ventral and dorsal rootlets, which come from the spinal cord - Ventral root contains efferent (motor) fibers, while the dorsal root contains afferent (sensory) fibers - The two roots eventually fuse to form the spinal nerve, which gives off the dorsal and ventral rami

Borders of the lumbar triangle

- Medially: latissimus dorsi - Laterally: external oblique - Inferiorly: iliac crest

Spinal nerves are:

- Mixed nerves that carry motor, sensory, and autonomic signals between the spinal cord and the body - In the body, there are 31 pairs of spinal nerves, one on each side of the vertebral column

Parts of an intervertebral disk

- Outer anulus fibrosus - Inner nucleus pulposus (cartilaginous structure that is highly elastic and compressible)

Annulus fibrosus

- Outer portion of the disc - Made of lamellae * Layers of collagen fibers * Arranged obliquely 30 degrees * Reversed contiguous layers - Great tensile strength

What provides structure to the glenohumeral joint?

- Rotator cuff as a dynamic stabilizer - Capsule, labrum complex, and glenohumeral ligaments as static stabilizers

Denticulate ligaments

- Specializations of pia mater that extend from the lateral surface of the pia, helping to suspend the spinal cord in the subarachnoid space - Form longitudinal shelves that separate dorsal and ventral rootlets

Lumbar cistern

- Subarachnoid space in the lower lumbar spinal cord - Enlargement of the subarachnoid space in the dural sac, distal to the conus medullaris - Contains CSF and the nerve roots of the cauda equina

Rotator cuff muscles

- Supraspinatus - Infraspinatus - Teres minor - Subscapularis

Why do many patients experience a headache after a spinal tap?

- The dura mater has a rich supply of pain receptors that respond to stretch and tension. It is believed that the decrease in CSF volume, however small, following a lumbar puncture causes the brain to sag a bit. - This stretches the dura, which in turn causes severe headaches - In order to avoid this, the patient is asked to lay down with the head at a slightly lower level than the body (i.e. no pillow)

What position is a patient placed in during a lumbar puncture? Justify this anatomically.

- The patient is asked to flex his or her back as much as possible during a LP, either sitting up or lying on their side in the fetal position (lateral recumbent) - This increases the space between the spinous processes

Filum terminale internum

- Thread-like extension of the pia mater that extends from the conus medullaris - Eventually, will become enclosed in the filum terminale externum, which is a thread-like extension of the dura mater extending below the end of the dural sac (at the S2 level)

A patient goes in for a spinal tap and is then advised to remain in the horizontal position for up to an hour after the procedure. Why is this?

- To prevent low pressure headaches, especially when lots of CSF is withdrawn - The most common complication following LP is post-dural puncture headache (PDPH), which can be as high as 70%

A child is diagnosed with myelomeningocele right after birth. What would you expect to find?

- Xray shows non-union of the vertebral arches. MRI reveals that the spinal cord and meninges are protruding out into the swelling - Chiari II malformation (change in brain position) - Hydrocephalus - Cystic swelling in the lower lumbar region

Xanthochromia

- Yellow decolorization of CSF - Presence of xanthochromia means that there is presence of red cells in the cerebrospinal fluid - With time, the red cells breakdown, releasing heme, which is subsequently degraded into the yellow-green pigment bilirubin causing the characteristic yellow color in patients with xanthochromia.

A 17-year-old male military recruit presents to the emergency room complaining of nausea, fever, and a severe headache. He is currently living in barracks and shares a living space with his fellow recruits. On physical exam, he has a rash on his abdomen and states that it hurts to look into the light and bending his neck downward produces pain as well. It assumed the patient has an infection of the central nervous system. The patient undergoes a lumbar puncture and 10 ml of fluid are removed. How long will the brain take to replenish the lost fluid?

1 hour (Normal CSF production is about 0.3 mL/min, meaning that most of the fluid removed during a lumbar puncture is easily replaced within one hour)

Filum terminale externum (aka coccygeal ligament)

A continuation of the dura mater that extends below the end of the dural sac to attach to the coccyx

Gluteus medius m action

Abduct hip joint when contralateral lower limb is raised (unsupported)- when muscles are denervated or weakened, the Trendelenburg sign is present

Gluteus minimus m action

Abduct hip joint when contralateral lower limb is raised (unsupported)- when muscles are denervated or weakened, the Trendelenburg sign is present

Patient is diagnosed with an injury of the brachial plexus resulting in damage of the suprascapular and axillary nerves. Following the above injury, which of the movements of the arm at the shoulder would you expect to be totally lost? Explain.

Abduction and lateral rotation (supraspinatus, infraspinatus, deltoid, and teres minor are all affected)

Lordosis

Abnormal anterior curvature of the spine

Adductor magnus m action

Adduction, flexion, medial rotation of thigh

Teres major m action

Adducts arm, medially rotates arm, assists in arm extension

External intercostal m action

Aids forced inspiration by elevating ribs

Jeff, a 35-year-old male, presents with severe neck pain from a whiplash injury sustained when his car was struck from behind. Radiographic studies reveal trauma to the ligament lying on the anterior surface of the cervical vertebral bodies. Which ligament is this?

Anterior longitudinal ligament

Lesser occipital nerve

Arises from the ventral ramus of C2

Deltoid m innervation

Axillary nerve

Teres minor m innervation

Axillary nerve

A football player suffers a herniated (ruptured) intervertebral disk in his neck. The disk compresses the spinal nerve exiting through the intervertebral foramen between the 5th and 6th cervical vertebrae. Which spinal nerve is affected?

C6

The number of vertebrae and number if spinal cord segments are the same in each region except:

Cervical (there are 8 cervical spinal cord segments but 7 cervical vertebrae)

An open arterial anastomosis in the shoulder occurs between the suprascapular artery and which other artery?

Circumflex scapular artery

Normal CSF

Colorless and odorless

Biceps femoris short head innervation

Common fibular nerve

Ventral rami

Contribute to the formation of plexuses: - C1-T1: cervical and brachial plexuses - T11-Co1: lumbar-sacral plexuses - T1-T11: become intercostal nerves - Supply sensory innervation to the skin of the anterior trunk and limbs and motor innervation to the skeletal muscles of the neck, trunk, and extremities. Primary function is MOTOR

A patient is suspected of having bacterial meningitis. As part of the diagnostic procedure, a lumbar puncture is to be performed. The attending physician asks you where she should insert the spinal needle to withdraw CSF. You answer; Just below the spine of the 4th lumbar vertebra". What reference point would you use to identify the spine?

Crest of the ilium

In the fracture of the midshaft of the humerus, which artery is most likely to be injured?

Deep brachial artery

The nerve which passes through the quadrangular space of the posterior shoulder innervates which muscle?

Deltoid (axillary nerve passes through the quadrangular space and innervates the deltoid)

Patient has a history of a fracture of the surgical neck of the humerus four months ago complicated by an injury of the nerve. X-ray scan of the arm reveals that the bone has healed completely, but the ability to abduct the arm beyond 15 degrees has not returned. Which muscles are paralyzed?

Deltoid, teres minor (both are supplied by the axillary nerve, so if one is denervated and experiences a loss of function, the other will also)

In old age, the supraspinatus tendon is sometimes ruptured where it blends with the capsule of the shoulder joint. Following this kind of injury, one might expect:

Difficulty in abducting the arm (the first 15 degrees, after that, the deltoid will take over and continue abducting the arm)

Along with sweating, which other physiological event would be stimulated by nerves with the same initial pathway (lateral horn, anterior root, spinal nerve, white ramus communicans, paravertebral ganglion)?

Dilation of the coronary arteries

The part of a spinal nerve that supplies the true back muscles and the skin overlying them is the:

Dorsal primary ramus (supplies sensory innervation to the skin of the back and motor innervation of the true back muscles)

Levator scapulae m innervation

Dorsal scapular nerve (C5)

Rhomboid major m innervation

Dorsal scapular nerve (C5)

Rhomboid minor m innervation

Dorsal scapular nerve (C5)

Levator costarum m action

Elevates ribs for deep inspiration

Levator scapulae m action

Elevates scapula

In the final stages of labor, a caudal anesthetic is sometimes given via a needle inserted into the sacral hiatus. The anesthetic is thus placed around the outside of the sacral spinal nerve roots and into the :

Epidural space

Maria, a 29-year-old pregnant woman, is in the final stages of labour and suffers from severe uterine pain due to acute contractions of the uterus. The obstetrician orders a caudal anaesthetic to be administered through the sacral hiatus. Into which space in the sacral canal is the anaesthetic placed?

Epidural space

What muscle is innervated by the posterior rami?

Erector spinae (iliocostalis, longissimus, spinalis)

Which muscle is innervated by posterior (dorsal) rami?

Erector spinae group (iliocostalis, longissimus, spinalis)

Erector spinae group action

Extends and laterally bends the trunk, neck, and head (Chief extensor of the vertebral column)

Gluteus maximus m action

Extends thigh and trunk, laterally rotates hip joint

Triceps brachii long head action

Extension and adduction of the arm at the shoulder, extension of the forearm at the elbow

Transversospinalis group action

Extension and stabilization of vertebral column

Rectus capitis posterior major m and rectus capitis posterior minor m action

Extension of head and neck

Biceps femoris long head action

Extension of hip joint, flexion of knee joint

Biceps femoris short head action

Extension of hip joint, flexion of knee joint

Semimembranosus m action

Extension of hip joint, flexion of knee joint

Semitendinosus m action

Extension of hip joint, flexion of knee joint

Triceps brachii medial and lateral head action

Extension of the forearm at the elbow

(T/F) The vertebral venous plexus does not communicate with the systemic venous system, including the azygous system of veins

False, the vertebral venous plexus does communicate with the azygous system of veins

(T/F) There is no communication between vertebral venous plexus and prostatic veins caudally

False, there is proficient communication between vertebral venous plexus and prostatic veins (allowing for the potential for prostate cancer to spread rapidly)

Vastus lateralis m innervation

Femoral nerve

Fibularis longus and brevis mm action

Foot eversion

As the spinal needle in the above question (lumbar puncture) is being inserted, which ligament would it pass through on its way to the subarachnoid space?

From superficial to deep: - Skin - Subcutaneous tissue - Supraspinous ligament - Interspinous ligament - Ligamentum flavum - Dura mater - Subarachnoid space- contains CSF

The conus medullaris:

Gives origin to most of the cauda equina (most of the cauda equina originate from the conus medullaris and then travel to the vertebral foramina inferior)

Erector spinae muscles

Iliocostalis, longissimus, spinalis

Where do most disc herniations occur?

In a posterolateral direction (the posterior longitudinal ligament, which helps reinforce the posterior aspect of the anulus fibrosus, thins laterally)

Why is it relatively safe to insert a needle directly above or below L4?

In an adult, the spinal cord usually ends at the inferior border of L1 of the superior border of L2. At the L4 level, the nerve roots are suspended in CSF and can float away from the pressure of the needle, so these roots will not be damaged by the needle

How do spinal nerve locations differ among different regions of spinal vertebrae?

In the cervical region, the spinal nerves emerge above the vertebrae of the same number, while in the thoracic, lumbar, and sacral regions, the spinal nerves emerge below the vertebrae of the same number

Gluteus maximus m innervation

Inferior gluteal nerve

A man is in an auto accident and sustains several injuries, among them are: 1. Skin lacerations: - on the back of his head in the occipital area, - on his chest just above the nipple, - on the lateral side of his arm, - lateral forearm at midlength, - dorsal hand between his thumb and index finger. 2. Abrasions and contusions (bruises) about his right shoulder 3. A fractured right radius near its distal end Later, while undergoing physical therapy because of his shoulder injury, he comments that it is very painful when his forearm is brought across his chest (medial or internal rotation of the humerus). You deduce that the pain is due to stretching of the lateral (external) rotators of the shoulder. Which muscle was most likely the source of his pain? infraspinatus latissimus dorsi rhomboideus major supraspinatus teres major

Infraspinatus

An elderly man complained of pain in his shoulder when he brought his forearm and hand behind his back while dressing. It was determined that the pain was caused by stretching of the lateral rotators of his arm during this motion. Which muscle(s) were most likely involved?

Infraspinatus, teres minor, and deltoid (posterior fibers) are all responsible for lateral rotation at the glenohumeral joint

Supraspinatus m action

Initiate abduction of glenohumeral joint

Dorsal rami

Innervate the deep back muscles and skin of the back

While moving into a new apartment, a student lifting a heavy box of books experiences a sharp pain in his back, radiating down the anterior thigh and medial side of his leg. After several days of misery, he finally goes for treatment and is told that he has herniated intervertebral disk at the L4 level which is compressing a spinal nerve where it exits the vertebral column. The point of compression is the:

Intervertebral foramen

Flexor digitorum longus m action

Inversion and assists in the plantar flexion of the foot at the ankle (flexion of phalanges II-V)

Flexor hallucis longus m action

Inversion and assists in the plantar flexion of the foot at the ankle, flexes the great toe

Vastus lateralis m action

Knee extension

In adults, the conus medullaris of the spinal cord is normally positioned at which vertebral body levels?

L1-L2

It is decided to image the spinal cord and spinal nerve rootlets by doing a myelogram (injection of a radio-opaque dye into the subarachnoid space followed by a radiograph). In order to inject the dye without injury to the spinal cord, the injection is usually done below what vertebral level?

L4

It is decided to image the spinal cord and spinal nerve rootlets by doing a myelogram (injection of a radio-opaque dye into the subarachnoid space followed by a radiograph). In order to inject the dye without injury to the spinal cord, the injection is usually done below what vertebral level? Explain

L4 (In an adult, the spinal cord usually ends at the inferior border of L1 or the superior border of L2. Therefore, it is relatively safe to insert a needle above or below L4).

A man has a herniated intervertebral disk between the fourth and fifth lumbar vertebrae. If this disk compresses the spinal nerve in the intervertebral foramen immediately posterior to this disk, which spinal nerve would be affected?

L5

Sandra, a 45-year-old woman, has had mild pain over her left lower back that radiates to her left lower limb, for the past 2 years. After lifting a heavy case of soft drinks, the pain intensified and she was admitted. Radiographic examination revealed disk herniation between vertebral levels L4 and L5. Which nerve was most likely affected by the disk herniation?

L5

A 35-year-old male patient is undergoing endoscopic thoracic sympathectomy for benign paraganglioma near T1 and T2 of his spine. Sectioning of the rami communicants between the sympathetic trunk and spinal nerve of T1 and T2 would result in which of the following?

Lack of axillary sweating

In order to expose the spinal cord from the posterior side, it is necessary to remove the:

Laminae, spinous processes, and ligamentum flavum (additionally, the supraspinous and infraspinous ligaments need to be removed)

John Smith, a 23-year-old male, has finally reached one of his goals of running the Boston Marathon. The following questions deal with the functions of his nervous system during the race. 1. The sun peaks over the trees just after the race starts, raising the air temperature dramatically. John begins to sweat more profusely. Starting in the correct horn of the gray matter of the spinal cord, describe the initial pathway of the nerves responsible for his sweating.

Lateral horn, anterior root, spinal nerve, white ramus communicans, paravertebral ganglion

Infraspinatus m action

Lateral rotation of glenohumeral joint

Teres minor m action

Lateral rotation of glenohumeral joint arm

Gemellus superior m, obturator internus m, and gemellus inferior m action

Laterally rotate thigh

Piriformis m action

Laterally rotates and abducts thigh

After a penetrating wound in the area of the posterior axillary fold, a patient had weakness in extension and adduction of the arm. Which muscle is likely involved?

Latissimus dorsi

After a penetrating wound in the area of the posterior axillary fold a patient had weakness in extension and adduction of the arm. Which muscle is likely involved?

Latissimus dorsi m

What muscles are medial (internal) rotators at the glenohumeral joint?

Latissimus dorsi, pectoralis major, teres major, subscapularis, deltoid (anterior fibers)

If one does a laminectomy (removing the laminae of two adjacent vertebrae) to expose the spinal cord, which ligament must be removed?

Ligamentum flavum

Supracristal line

Line connecting the top of the two iliac crests, passes through the spinous process of the L4 vertebra

Serratus anterior m innervation

Long thoracic nerve (C5, 6, 7)

Teres major m innervation

Lower subscapular nerve

A patient complains of pain on the lower left side of her back. A radiograph confirms a hernia passing posterolaterally immediately superior to the iliac crest. This hernia passes through the:

Lumbar triangle

Subscapularis m action

Medial rotation of glenohumeral joint

Latissimus dorsi m action

Medial rotation, extension, adduction of atm at shoulder(glenohumeral) joint

Hiatus of the sacral canal

Normal feature that results from the failure of fusion of the laminae or the fifth sacral segment during development

Tom, a 65-year-old male, is admitted to A&E with severe back pain and inability to move his left leg. Radiographic studies reveal a herniated disk between vertebral levels L5 and S1. Which structure herniates?

Nucleus pulposus

Adductor magnus m innervation

Obturator nerve

Vertebral canal/vertebral foramen

Opening formed by the combination of the body and vertebral arch

Foramen magnum

Opening in the occipital part of the skull

Soleus m action

Plantar flexion of foot

Gastrocnemius m action

Plantar flexion of foot (of talocrural joint), knee flexion

Quasimodo, the "Hunchback of Notre Dame", suffered from an abnormal thoracic curvature called kyphosis. In this condition the accentuated convexity of the curvature is:

Posterior

Triceps brachii (long/medial/lateral head) innervation

Radial nerve

A woman riding a mountain bike on a rough trail hits a rut and is thrown from the bike. Her upper arm hits a tree, fracturing the humerus just below the insertion of the teres major muscle. Later, during examination, it is noted that she cannot extend her forearm at the elbow. Which nerve must have been injured?

Radial nerve (innervates the triceps brachii m, which is responsible for extension of the forearm at the elbow)

What 2 structures supply the triceps brachii m?

Radial nerve and deep brachial artery

Serratus posterior superior m action

Respiratory muscle that elevates the upper ribs

Serratus posterior inferior m action

Respiratory muscle that pulls down the lower ribs

Rhomboid major m action

Retracts and elevates scapula

Rhomboid minor m action

Retracts and elevates scapula

A scaffold falls on the right shoulder of a construction worker lacerating the side of his neck and suprascapular area, severing C5 spinal nerve just lateral to the vertebral column. Subsequent to the injury, the patient could not elevate the tip of his shoulder or retract it and had difficulty fully abducting his arm. Given this scenario answer the following questions. The patient was unable to retract his scapula because of paralysis of the trapezius and_____________________________

Rhomboid major and minor (responsible for elevating and retracting the scapula. They are also innervated by the dorsal scapular nerve, which comes from C5)

Obliqus capitis inferior m action

Rotates head

Both the dural sac and subarachnoid space end at which vertebral level?

S2

Both the dural sac and the subarachnoid space end at which vertebral level?

S2

Transversospinalis muscles

Semispinalis, multifidus, rotatores

A neuron with a cell body in the dorsal root ganglia could convey what type of fibers?

Sensory from the skin overlying the trapezius muscle

Postoperative examination revealed that the medial border and inferior angle of the left scapula became unusually prominent (projected posteriorly) when the arm was carried forward in the sagittal plane, especially if the patient pushed with outstretched arm against heavy resistance (e.g., a wall). What muscle must have been denervated during the axillary dissection?

Serratus anterior

A 55-year-old woman was submitted to surgery to remove her left breast in which a malignant tumor had been found. Following the mastectomy, her recovery proceeded well, except that she noticed that she was experiencing weakness in her left shoulder and had considerable difficulty raising her left arm above her head, even two months after her surgery. Her husband also noticed that her left scapula seemed to protrude posteriorly to a greater extent than the one on her right side. This phenomenon is called a "winged scapula". Concerned, she went to see her doctor. She was referred to a neurologist, who performed electromyography (EMG) and nerve conduction studies to determine the source of the weakness. What muscle was affected? What nerve innervates the affected muscle?

Serratus anterior m, which is innervated by the long thoracic nerve

George Jr., a neonate, has a cystic swelling in the lower lumbar region. X-ray shows non-union of the vertebral arches of L4-L5. MRI revealed that the spinal cord is in the normal position, but the meninges are protruding out into the swelling. What condition is this?

Spina bifida cystica with meningocele

Olive, a 1-year-old baby girl, was brought to the clinic for a routine check-up. The baby appears normal, except for a dimpling of the skin in the lumbar region with a tuft of hair growing from the area of the dimple. You reassure the mother that this is not a rare occurrence. What is this condition?

Spina bifida occulta

Trapezius m innervation

Spinal accessory nerve (CN XI)

While wandering around in the dark in an unfamiliar home, a visitor accidentally walks into a plate glass door. The door shatters and a shard of glass severs the posterolateral aspect of the woman's neck. Examination reveals that the she is unable to elevate the tip of her shoulder on the injured side. The nerve injured is:

Spinal accessory nerve (CN XI)- innervates trapezius m, which is responsible for elevating the shoulder

A patient is suspected of having bacterial meningitis. A lumbar puncture is performed to remove cerebrospinal fluid (CSF) for analysis. The fluid would be removed from the:

Subarachnoid space at the level of L4

Which muscle is the strongest medial rotator of the arm?

Subscapularis

Medial rotators of the arm

Subscapularis, pectoralis major, teres major, latissimus dorsi, deltoid (anterior fibers)

Fibularis longus and brevis mm innervation

Superficial fibular nerve

Gluteus medius m innervation

Superior gluteal nerve

Gluteus minimus m innervation

Superior gluteal nerve

Boundaries of the quadrangular space

Superior: Teres minor Inferior: Teres major Lateral: Surgical neck of humerus Medial: Long head of triceps

Erector spinae group innervation

Supplied by the dorsal (posterior) rami of the spinal nerves

Transversospinalis group innervation

Supplied by the dorsal (posterior) rami of the spinal nerves

Following a gunshot wound to the shoulder, a patient is unable to abduct the arm between 0 and 15 degrees, with reduced lateral rotation of the humerus. What nerve is probably injured?

Suprascapular (innervates the supraspinatus m, which is responsible for initiating abduction of the arm)

Infraspinatus m innervation

Suprascapular nerve

Supraspinatus m innervation

Suprascapular nerve

A person sustains a left brachial plexus injury in an auto accident. After initial recovery, the following is observed: 1) the diaphragm functions normally, 2) there is no winging of the scapula, 3) abduction cannot be initiated, but if the arm is helped through the first 15 degrees of abduction, the patient can fully abduct the arm. From this amount of information, which muscle was denervated due to the brachial plexus injury?

Supraspinatus

Lateral rotators of the arm

Teres minor, infraspinatus, deltoid (posterior fibers)

Dermatome

The area of skin innervated by the cutaneous branches of a single spinal nerve (this same area of skin will receive some additional innervation from branches of both the spinal nerve of the segment above and the segment below)

Explain why dislocations of the humerus most commonly occur in a downward direction

The rotator cuff gives strength to the capsule of the shoulder all around the joint except inferiorly

Latissimus dorsi m innervation

Thoracodorsal nerve (C7, 8)

During a triathalon biking accident, a rider fell and landed with the handlebar of her bike forced upward into her right axilla. Subsequently, while swimming in another triathalon event, she found that her right arm tired so badly during the swimming portion that she could barely finish the event. During examination it was found that movements involving adduction, medial rotation and extension of her arm were particularly weak and affected her swimming stroke. The nerve injured was the:

Thoracodorsal nerve (innervates the latissimus dorsi m, which is an important muscle for adduction, medial rotation, and extension of the arm)

Biceps femoris long head innervation

Tibial nerve

Flexor digitorum longus m innervation

Tibial nerve

Flexor hallucis longus m innervation

Tibial nerve

Gastrocnemius m innervation

Tibial nerve

Semimembranosus m innervation

Tibial nerve

Semitendinosus m innervation

Tibial nerve

Soleus m innervation

Tibial nerve

Tibialis posterior m innervation

Tibial nerve

Cedric, a 53-year-old male, was in a head-on collision that caused the dens of his axis to dislodge and impale the spinal cord, causing quadriplegia. Which ligament was torn?

Transverse ligament of the atlas

Loss of function, paralysis, of which muscle would result in drooping or sagging of the shoulder?

Trapezius

The transverse cervical artery is severed in an auto accident . What muscle would be affected the most?

Trapezius m (the transverse cervical artery supplies blood to the trapezius)

(T/F) Blood flow in the vertebral venous plexus is bidirectional, meaning it provides a potential route for the spread of infection or tumor

True

(T/F) Vertebral venous plexus extend from the head to the pelvis

True

(T/F) Vertebral venous plexus is a group of veins and venous plexuses that freely communicate because they lack valves

True

(T/F) Vertebral venous plexus is a main venous drainage while standing

True

(T/F) Vertebral venous plexus may serve as a transport system for metastases from the breast, prostate, ovary, and uterus to the vertebral bodies and the cranial cavity

True

(T/F) When inferior vena cava is partially occluded, vertebral venous plexus provides an alternate route for blood return to the right side of the heart

True

Subscapularis m innervation

Upper and lower subscapular nerves (C5, 6)

A 45-year-old man complained to his physician that the muscles of his upper limb were weak and he felt clumsy while walking. Tests revealed that he had amyotrophic lateral sclerosis (Lou Gehrig's disease), a disease which attacks the neurons of the voluntary motor system. Where would one expect to see atrophic or degenerated nerve cell bodies?

Ventral horn of the spinal cord

Because of their structure and interconnections, which veins are especially important in the metastatic spread of cancer?

Vertebral venous plexus (most other veins have valves, which would direct the flow of blood and stop some of the metastatic spread)

If in the process of doing a lumbar puncture a spinal needle was inserted posteriorly in the midline until it had just penetrated the posterior longitudinal ligament, would the needle have entered the subarachnoid space?

Yes

If in the process of doing lumbar puncture a spinal needle was inserted posteriorly in the midline until it had just penetrated the posterior longitudinal ligament, would the needle have entered the subarachnoid space?

Yes (although, you would not want the needle to penetrate this ligament. Instead, you would want to stop and withdraw CSF upon entering the arachnoid space).

How can you find the L4 level in a patient?

You find the tops of the 2 iliac crests and draw a line connecting them, the line should be going through the spinous processes of the L4 vertebra